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Comparative Homeostasis Human vs. Krill

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Emily Murphy

on 4 June 2013

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Transcript of Comparative Homeostasis Human vs. Krill

Comparative Homeostasis Human vs. Krill By Emily Murphy Human Digestion Water Balance The Circulatory System and Transport Waste Removal and the Excretory System Gas Exchange and Respiration Reproduction Introduction The human body exchanges Oxygen for Carbon Dioxide by way of the Respiratory System. In the course of breathing air in and out, we're really taking one specific molecule out of the air (Oxygen), and putting a new molecule (Carbon Dioxide) into it. Structure and Function Air Going into Body Blood Without Oxygen Blood With Oxygen Air Going out Body Air goes through the Respiratory System,
and eventually the oxygen in that air gets absorbed by blood vessels, which go to the heart. The heart then spreads the now oxygen-rich blood throughout the body. The Nose and Mouth Air enters the respiratory system through the holes in the body known as the nose and mouth. As air enters the nose and mouth, it is passed through to the Pharynx, after being partially cleaned, moistened, and warmed. Many large dust particles are filtered in the nose by hairs and cilia in the nasal cavity. The Pharynx The pharynx is a passageway for both air and food. It is commonly referred to as the throat. At the pharynx, food and air separate. Food goes into the Esophagus to go through digestion, and air goes into the trachea. There is also a flap of skin called the Epiglottis, which covers up one of the tubes when the other is being used, to prevent choking and other hazards. Choking is caused when food goes into the trachea by accident, and blocks up the lungs, which stops breathing. The Respiratory System is made up of:
Diaphragm/Pleural Membrane
All of which contribute to the process of oxygen absorption. The Trachea and Larynx After going through the Pharynx, food moves into the esophagus, and air goes into the Trachea. The Trachea is the windpipe, and also contains the Larynx, which are two folds of tissue that make up the vocal cords. The vocal cords produce sound when muscles pull them together, and air is forced through them. This causes the vocal cords to vibrate, making sound. Air moves though the trachea and the Larynx, and goes into the Lungs. The Lungs The trachea sends air into the lungs, which are the final step in oxygen extraction. The lungs are made up of several different parts, and air keeps traveling through them as they get smaller and smaller. The process starts with the Bronchus, then goes into the Bronchioles, and ends up with the Alveoli and Capillaries. The Bronchi The lungs start with the biggest part, and work their way down to the smallest. The Bronchi are the biggest parts of the lungs. As the trachea goes down, it splits in two, and forms the bronchi, one going into each lung. Then, the bronchi split into two, and those split, making smaller and smaller appendages branching out. Eventually, they from Bronchioles. These are versions of bronchi. There is no great difference besides size. Alveoli At a certain point, the alveoli grow off of the bronchioles. An alveolus is an air sac that provides the actual function of gas exchange. In the alveoli, oxygen found in the air diffuses through the alveoli into the capillaries. Carbon Dioxide also diffuses the other way, back into the air. All of the molecules in the air that aren't oxygen just go back out of the lungs along with the Carbon Dioxide. Alveoli actually make up the surface of the lungs. In reality, the smooth piece of tissue we see is made up of millions of tiny cells. Capillaries Capillaries are the smallest blood vessels in the body. Each alveoli is surrounded with capillaries, which is where oxygen is diffused to. When diffusion between the alveoli and the capillaries, the capillaries carry the now oxygen-rich blood to the heart, so it can be distributed. The oxygen actually gets transported by a protein in the blood known as hemoglobin, which gives blood its red color.The capillaries also carry carbon dioxide back to the alveoli to be carried out of the body and back into the air. Breathing Breathing is the action of taking air into and out of the body. The actual process of getting air into the lungs is the job of the diaphragm and pleural membrane. Diaphragm There aren't actually any muscles attached to the lungs, so they can't get air by themselves. Air is forced into the lungs through air pressure. The diaphragm is located in the chest cavity, under the lungs. When you breathe in, the diaphragm contracts, causing the volume of the chest cavity to expand. This causes a partial vacuum, which fills the lungs with air. The opposite happens when you breathe out. The system works because the chest cavity is sealed and doesn't let any air out. Breath Control Breathing is controlled by the Medulla Oblongata, a part of the brain that controls the many internal organs. Certain cells monitor the levels of carbon dioxide in the blood. When the level goes up, nerve impulses alert the Medulla Oblongata. Then, the Medulla Oblongata alerts the diaphragm to contract. The impulse increases with the level of carbon dioxide. Part of breathing is caused voluntarily, and some is subconscious. Obstructions to Breathing Many substances and activities can inhibit the breathing process, but one of the most common is smoking. Cigarettes contain several substances that can damage certain organisms in the lungs and throat. Key among these are Nicotine, Carbon Monoxide, and Tar. Nicotine is a stimulant that increases your heart rate and your blood pressure. It is also the main reason for addiction. Carbon Monoxide is a poisonous gas that blocks the transport of oxygen in hemoglobin, which can limit your breath supply. Finally, there's tar, which can lead to cancer. Smoking can also paralyze the cilia, which means that the cilia can't filter the lungs. Eventually, this leads to a build-up of smoky mucus within the respiratory system. Smoking can also lead to a shortened life span, and several health conditions, including bronchitis, emphysema, cancer, drop in body temperature, and heart disease. Warming, Moistening, and Cleaning the Breath Air isn't the same temperature as our bodies when it's floating around in the atmosphere. Usually, air on Earth is much colder. Therefore, the body has to warm it up. The same thing happens with moisture in the air, and with dust particles and other things in the air. When air travels along the Respiratory System, it is warmed, moistened, and cleaned until it is sufficient. This is done mostly by cilia and mucus along the surface of many tissues. Mucus is generated all along the Respiratory System, and its job is to moisten and filter the air of particles. The cilia also filters out dust and other particles, and sweeps them away as well as excess mucus. Mucus is expelled either through swallowing or spitting out. This is a picture of cilia, magnified to 2,560 times its normal size. Blood The blood is the fluid in the human body that delivers oxygen and other nutrients to every cell in the body. It also delivers waste products, like carbon dioxide, back from the cells. Blood is made up of three parts: Red blood cells, White blood cells, and Plasma. Red Blood Cells Red blood cells are the cells that carry nutrients throughout the body. Their color comes from Hemoglobin, making it red. These blood cells are shaped like disks, thinner on the inside and thicker on the outside. Red blood cells aren't like the other cells in the body. Red blood cells don't have nuclei when they mature. The nuclei and organelles are forced out of the cells during the maturing process. These cells are also made out of bone marrow, and are only active in the blood for about 120 days, after which they are destroyed by the liver and the spleen. There are about 5 million red blood cells in every one ml of blood, and red blood cells are also called Erythrocytes. White Blood Cells White blood cells are much less prominent in the blood than red blood cells (about 1 white blood cell for every 700 red blood cells), but they also preform a very important task in the body. White blood cells are also known as Leukocytes, and their primary job is to attack unknown, foreign cells in the body. They can last anywhere from several days to months. There are several different kinds of white blood cells. The most common, the Phagocyte, is a white blood cell that engulfs and digests foreign cells. The Different Types of White Blood Cells Nuetrophils: Eosinophils: Monocytes Lymphocytes: Engulf and destroy small bacteria/foreign substances Attack parasites and limit inflammation associated with allergic regions Give rise to leukocytes that engulf and destroy large bacteria Some destroy foreign cells by causing their membranes to rupture. Some develop into cells that produce antibodies, which target specific foreign substances Plasma Blood Clotting and Platelets Plasma is a straw-colored fluid that makes up all the blood that isn't red and white blood cells (about 55%). Plasma is made up of water, dissolved gases, salts, nutrients, enzymes, hormones, waste products and plasma proteins. It is divided into three groups: Albumins, Globulins, Fibrinogen. Albumins monitor osmotic pressure and blood volume, as well as transporting fatty acids, hormones, and vitamins, which Globulins do also. Fibrinogen is a protein which induces blood clotting. Blood is regenerative, but only to a certain point. After that point, blood loss can be quite dangerous, even fatal. To prevent this, the body goes through blood clotting. Blood clotting is done with plasma proteins and platelets. A platelet is a cell that is formed out of large bone marrow cells. One bone cell can form thousands of platelets. Each piece is wrapped in cell membranes. Clotting happens when the platelets find a broken blood vessel. The platelets get very sticky, and from group around the rupture. Then they release a protein called Clotting Factor. Clotting factors cause many different kinds of chemical reactions. Thromboplastin: Thrombin: Converts prothrombin into thrombin A sticky enzyme that helps convert fibrinogen into fibrin filaments. The filaments form a blood clot. Hemophilia is a genetic disorder that causes a defective protein in clotting pathway. Introduction The circulatory system is the system that regulates blood, and delivers nutrients to and from the cells in the body. This system consists primarily of a network of blood vessels and the heart, but it also works closely with the digestive system, the respiratory system, and the excretory system in its mission to supply the body with a transport system. Structure and Function The circulatory system consists of the heart and a network of blood vessels throughout the body. The Heart The heart is the organ in the body that is responsible for sending blood throughout the body. Blood Flow in the Heart There are four sections of the heart: Two atria, and two ventricles. There is a set of one atrium and one ventricle for each part of the circulatory system. The two systems are the Pulmonary Circulation System, which pumps blood between the heart and the lungs, and Systemic Circulation System, which pumps blood between the heart and the rest of the body. The left side of the heart is the Systemic System, and the right is the Pulmonary System. Blood enters the heart through the atria, and then moves into the ventricles during a contraction. Then the blood moves out of the ventricles, either to the lungs or the rest of the body. Valve A layer of connective tissue called a valve separates the atria from the ventricles, much like the epiglottis in the Respiratory System. When blood moves from the atria, it opens the valve, which closes the ventricles. The purpose of the valve is the keep blood flowing in one direction, which increases efficiency. Pulmonary System The Pulmonary System sends carbon dioxide-rich blood to the lungs to be oxygenated. Once the blood has exchanged oxygen for carbon dioxide, it returns to the heart, where it is distributed by the Systemic System. Systemic System The Systemic System takes the oxygen-rich blood from the Pulmonary System, and distributes it to every cell in the body. There, the oxygen is exchanged for carbon dioxide, and the blood returns to the heart to be oxygenated once more. The Heartbeat Heartbeat isn't entirely controlled the nervous system, but it is influenced by the automatic nervous system. When the need arises, neurons in the sympathetic nervous system stimulate the muscle fibers that cause the heart to beat. The same thing happens when decreasing. Neurons from the parasympathetic nervous system send a message for the heart not to beat. The stimulant rate changes as the body's needs increase and decrease. Contractions There are two muscle fiber networks that control the heart. One is in the atria, and one is in the ventricles. When a fiber is stimulated by the neurons, it causes a chain reaction, and the whole system contracts. Sinatrial Node The Sinatrial Node is a small group of cardiac muscle cells found in the right atrium. A contraction starts here, and works its way to the rest of the muscles. After the Sinatrial Node, the impulse is spread to the ventricle fiber networks, then the contraction occurs, and blood leaves the heart. Aorta The Aorta is a series of large blood vessels found in mammals through which blood travels from the left ventricle to all over the body (except for the lungs). When leaving the heart, oxygenated blood goes through the aorta, and goes into the blood vessels. Heart Diseases and Conditions Many things can lead to conditions in the circulatory system. Some of the most dangerous are the ones pertaining to the heart. These can include high blood pressure, heart attacks, or strokes. High blood pressure causes the heart to work harder, therefore weakening the blood vessels. It also increases the likelihood of heart disease. A heart attack occurs when a coronary artery gets blocked, which blocks oxygen. Strokes are when a blood clot block oxygen from a part of the brain. When the brain cells can't get oxygen, they begin to die. Strokes can also happen when an artery bursts in the brain, causing the brain to flood in blood. Both can cause paralysis, loss of speech, or death. Blood Vessels There are three kinds of blood vessels in the body: Arteries, Veins, and Capillaries. Arteries The arteries are the blood vessels that carry oxygenated blood to the cells in the body. Arteries have very thick wall made of connective tissue, epithelial tissue, and smooth muscle, which help arteries to expand under pressure. Veins Veins are the blood vessels that carry de-oxygenated blood back to the heart so it can be oxygenated once more. Veins are made of the same materials as Arteries, although veins are usually placed nearer to skeletal muscles, which help to force blood through the veins, because blood flow occurs against gravity. Because the veins are de-oxygenated, many believe that veins are blue. This isn't entirely true. Veins are darker than arteries because of the lack of oxygen, but they still contain hemoglobin, which is the protein that makes blood red. Capillaries The capillaries are the smallest blood vessel in the body, with their walls only being a cell thick, and blood cells only passing through in single file. Capillaries bring nutrients and oxygen to tissues, where they go through diffusion, and in return, the capillaries get carbon dioxide and wastes generated by the cell. Blood Pressure The force of blood going through the arteries is called Blood Pressure. Without this pressure, the heart would stop pumping. Blood Pressure is measured regulated in two ways: The Sensory Neurons, and the Kidneys. The Sensory Neurons send impulses to the Medulla Oblongata, and neurotransmitters are released to either relax or tighten the smooth muscles. The Kidneys remove water from the blood when blood pressure is too high, which reduces blood volume and pressure. Circulatory Disorders There are many thing that can go wrong with the Circulatory System, including heart disease. One of the most common Circulatory disorders is caused by a condition called Atherosclerosis. Atherosclerosis is when plaque builds up on the walls of the arteries, and it can cause an increase in blood pressure and the likelihood of blood clots. Other disorders include high blood pressure, heart attacks, and strokes. You can help lower the risk of such things in your body by exercising, which increases heart efficiency, as well as controlling your weight, body fat and stress level, and eating a healthy diet with a low amount of saturated fats, as well as not smoking. The Lymphatic System During circulation, about three liters of fluid leaks out of the blood every day. The Lymphatic System is a network of vessels that collect fluid and return it to the blood. This fluid is called lymph, and it is make out of a combonation of fats, vitamins (specifically A, D, E, and K) and water. The lymph collects in special capillaries, and then flows into vessels that get progressively bigger. Eventually, it flows into the lymph duct, and is returned to the circulatory system via the superior vena cava, which is under the clavicle bones. Along the lymph vessels are lymph nodes,which trap bacteria and micoorganisms from getting back into the blood. Lymph is a very crucial part of nutrient absorption. Introduction The digestive system is the system that gives us nutrients and energy. These are derived from food, which the Digestive System breaks down until it is at the right level to be of use to the body. Structure and Function The Digestive System is one long tube that is coiled up inside the body. This tube is made up of:
Salivary Glands
Small Intestine
Large Intestine
Rectum The Mouth and Salivary Glands The mouth is the first part of digestion, being the part where you put food into your body for the first time. The mouth breaks down food both mechanically and chemically, mechanically with teeth, and chemically with saliva. Saliva is a combination of water and enzymes, primarily Amylase, and enzyme that breaks down starch into individual sugar monomers (glucose). The salivary glands are controlled by the nervous system, and saliva is released when the body detects food. Saliva also contains Lysosome, an enzyme that fights infection by digesting the cell walls of bacteria. The teeth are anchored in the bones of the jaw, and their job is to do the majority of the mechanical work needed in digestion. Teeth are made of a material that is tougher than bone, and is strengthed with a coating of mineralized enamel. Esophagus The esophagus is the tube between the mouth and the stomach. Food is pushed into the Esophagus by the tongue and the Pharynx, and it begins the journey to the Stomach. The chewed food, now called a bolus, is moved by contractions of the smooth muscles in a motion called Peristalsis. At the end of the Esophagus is the cardiac sphincter, which leads into the stomach. This thick ring of muscle opens to let boli through. Stomach The Stomach is an organ that continues both mechanical and chemical digestion. Chemical digestion in the stomach is a process of the stomach lining producing mucus, pepsin, and hydrochloric acid through millions of tiny gastric glands. The mucus lines and protects the stomach wall, while the pepsin breaks down proteins in the food. Hydrochloric acid is highly acidic, and can be quite dangerous to the body when not properly contained. As mechanical digestion, the stomach swishes the stomach fluids and food together, making a mixture called chyme. After one to two hours, the pyloric valve opens and the chyme goes into the Small Intestine. Pancreas and Liver The chyme goes from the stomach to the first part of the small intestine. Once there, the chyme gets mixed with digestive fluid from the Pancreas, Liver, and the lining of the Small Intestine. The Pancreas is a gland that produces:
Hormones that regulate blood sugar
Enyzmes that break down carbohydrates, proteins, lipids, and nucleic acids
Sodium Bicarbonate, which neutralizes stomach acid, because acid can change and damage enzymes and proteins
The Liver is an organ above the stomach that produces bile (lipids and salts), which dissolves fats in food. Bile is stored in the Gallbladder. Small Intestine The Small is divided into three parts:
Duodenum: Smallest, and First
The majority of chemical digestion takes place in the Small Intestine, and it is adapted to absorb nutrients. The surface is folded, and the folds are folded, etc. All these folds are covered in a folded projection called a villus. Then all the villi are covered in microvilli, thus making the surface of the small intestine much greater than it seems at first. The villi's job is to absorb the nutrients found in the chyme. As the chyme is moved along the Small Intestine with contractions, the nutrients are absorbed into either the capillaries or the lacteal. Most carbohydrates and proteins go into the capillaries, while fatty acids go into the lacteal. About three meters long Large Intestine When food finally enters the Large Intestine, it is essentially nutrient-free. All that's left is water, cellulose, and a few other non-digestables. The main job of the Large Intestine is to extract water from the materials left. The water is removed from the Large Intestine, leaving a concentrated waste product. The Large Intestine also has colonies of bacteria on its surface which help to break down the waste a little bit more, as well as produces certain compounds for the body, like Vitamin K. Then, the waste goes to the rectum an is expelled from the body. Nutrients and Energy Food is required for energy in humans. The cells in the body use chemical energy in glucose and other sugar to make ATP. Calories Energy in food is measured buy burning. A calorie is the amount of energy required to raise the temerature of one gram of water by one degree Celssius. A Calorie is a term used to measure the energy stored in food. One Calorie is equal to 1000 calories. The average teen needs about 2200 Calories (Female) 2800 (Male). Most food is used feul, but some of it is ued as raw materials. The raw materials are used to make new macromolecules such as proteins for cell reactions, phospholidsin cell membrans, and DNA. Uses for Food Most food is used fuel, but some of it is used as raw materials. The raw materials are used to make new macromolecules such as proteins for cell reactions, phospholidsin cell membranes, and DNA. Food has less than 45 substances that are needed in the body but the body can't actually manufacture itself. Nutrition is the study of food and its effects on the body. It tries to determine how food helps the body meet all of its needs. To achieve a balanced diet, many different foods are required Nutrients Neccessary in the Body The nutrients that the body needs are water, carbohydrates, fats, proteins, vitamins, and minerals. Water Water is critical to every cell in the body, because of body processes an chemical reactions. Water also makes up the majority of blood, lymph, and other body fluids. Humans need about a liter of water a day. If not, it can cause dehydration, which causes problems in the Circulatory, Respiratory, and Nervous Systems. Drinking lots of water keeps he body healthy. Carbohydrates Carbohydrates are a main source of energy within the body. It can be found in monosaccaraides, polysaccharides, and starches. These are broken down into Glucose during digestion, which is absorbed into the bloodstream. Some of these glucose molecules are used immediately, and some are made into glycogen, a plysaccaraide that is stored in the liver and the skeletal muscles, which functions as an extra sugar. Humans also need Fiber, which is found in Cellulose. Cellulose is a complex carbohydrate that humans cannot break down, which is why we cannot eat trees. Fiber is necessary to the diet, as it helps muscles to move food and waste throughout the digestivea dn excretory systems. Fats Fats (Lipids) are made from fatty acids and glycerol in the body. The body needs additional fatty acids to meet all of its needs, although some can be found in vegetable oil. Lipids are used for:
Protecting Body Organs
Insulating the Body
Storing Energy
Producing Myelin
Producing hormones
Helping to absorb fat-soluble vitamins
Lipids can fall under two classifications, saturated and unsaturated. Saturated fats have single bonds between carbon atoms, so it can have the maximum hydrogen molecules loaded on. Unsaturated fat have at least one double bond, so there are less hydrogen atoms. In general, people eat more fat than they need. Proteins Proteins have a ton of roles within the body. There are twenty different amino acids that are used to make proteins. The body can only produce twelve of them, so the other eight must be consumed. These are called essential amino acids, found in meat, eggs, and dairy, but not in plants Vitamins A vitamin is an organic molecules that help regulate the body's processes. Some vitamins are made in the digestive tract, but most are obtained through food. Vitamin deficiency can be extremely serious, and even fatal. There are 14 essential vitamins needed in the body. Fat-Soluble Vitamins Vitamin A Vitamin D Vitamin E Vitamin K Biotin Vitamin C Choline Pantothenic and Folic Acid Niacin Vitamin B , B , B and B Water-Soluble Vitamins 1 6 12 2 Minerals Minerals are inorganic molecules that the body needs. These include:
Minerals are not digested like other nutrients. They are found in the tissues of plants and animals, and they can be lost in sweat, urine, and waste. The six main elements needed for life are: C H N O P S a
n y
n i
n x
n h
s u
r Water balance is a homeostatic system that operates in a way that we are aware of, unlike the majority. Dehydration Dehydration is caused by a lack of water in the body's systems. this can be caused by vigorous exercise, disease, or not drinking enough water. It is usually prevents by the Hypothalamus. The Hypothalamus has cells that monitor the water level in the blood. As the water level decreases, the concentration of dissolved material goes up. The Hypothalamus responds to this either by signaling the pituitary gland to ADH (antidiuretic hormone) which stimulates the kidneys to slow down water removal, or it causes the sensation of thirst. When you drink after being dehydrated, the majority of the water goes into the blood (usually about one or two liters). This should cause a disturbed equilibrium, but it doesn't, because it is prevents by the homeostatic nature of the system. When there's too much water, the Pituitary Gland doesn't produce as much ADH, and the kidneys remove more water. The price of being alive is that every cell in the body produces wastes, like excess salts, carbon dioxide, and urea. Excretion is the process by which metabolic wastes are eliminated. There are three organs used for Excretion: The Skin, Lungs, and Kidneys, but the main organ is the Kidney. Kidneys The kidneys are about the sized of a closed fist, located around the lower back area. Urine is carried through the Ureter to the Urinary Bladder, where it waits to be excreted. The kidney process starts when waste-laden blood enters the kidneys through the renal artery. The job of the kidneys is to extract the excess urea, water, and other waste products. Once cleaned, the blood goes back to circulate in the body Kidney Structure The kidney has two seperate regions: an inner region, the Renal Medulla, and an outer region, the Renal Cortex. The actual functional units in the Kidneys are the Nephrons. Nephrons A nephron is a small, independent blood-filtering unit in the renal cortex of the kidney. There are about 1 million nephrons per kidney, and each has its own blood supply.
The parts of the nephron are:
Bowman's capsule
Collecting Duct
Henle Filtration Filtration is the actual process of blood cleaning. There are three processes in Filtration: Filtration, Extraction, and Secretion. Filtration After entering th nephron, blood goes to the Glomerolus. The glomerolus is a small network of capillaries encased in the upper part of the nephron. The Bowman's capsule encases the Glomerolus, and it, along with the walls of the capillaries are permeable. When the blood is under pressure, it is possible for fluid to flow from the blood to the Bowman's Capsule. This process is filtration. The materials usually filtrated include:
Amino Acids
Certain Vitamins Reabsorption and Secretion The kidneys filter all the blood in about 45 minutes, but not all the filtrate is excreted. Most of the fluid extracted goes back into the blood. This is called Reabsorption. The nutrients in the filtrate is removed through active transport, and they are all reabsorbed by the capillaries. The water is also returned with Osmosis. Approximately 99% of the water that goes into the kidneys is returned to the blood. Other materials are secreted into the filtrate by the capillaries, such as excess hydrogen ions. The material that remains after the processes of reabsorption and secretion is urine. The loop of Henle concentrates the urine, minimizing the amount of water that is lost in excretion. The purified blood goes back into circulation, and the urine gets collected in the urinary bladder through the collecting duct. Urine is stored in the urinary bladder until it is expelled through the urethra, a tube through which urine and semen are released out of the body. Urea Urea is a toxic compound is produced when amino acids are used for energy. Urea is originally derived from ammonia, which is much more toxic than urea. It is so toxic because it is a nitrogenous waste. Many mammals convert ammonia into urea. Solid Wastes Solid waste is excreted from the body in the form of feces, a concentrated mass of cellulose and other wastes that cannot be digested. Making this waste is the job of the large intestine. Kidney Control Kidneys are crucial to maintaining homeostasis. Its activities are mostly influenced by blood composition and regulation hormones. The two combine to maintain the ideal composition. When liquids are ingested, the water concentration goes up. This would cause the body to swell, but the kidneys prevent that. When the water level in the blood rises, the rate of reabsorption lowers, and the same thing happens with salts. Introduction Reproduction is the process of making a new individual. Reproduction is not crucial to individual survival, but it is crucial to the survival of a species. The human reproductive system is centered around gametes, which are specialized cells involved in sexual reproduction. Sexual Development A vertabrate at any stage of development prior to birth or hatching is called an embryo. During the first six weeks of growth, male and female embryos stay the same. The first major change in devlopment is the reporductive organs. The main hormones of sexual reproduction are Testosterone, Estrogen, and Progesterone. In females, the ovaries produce Estrogen and Progesterone, and in males, the testes produce Testoserone. Sexual development continues after birth, and the main point of that is puberty. Puberty is a period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. After puberty, the sexual organs are fully developed. Puberty usually happens one year earlier in females, and can happen anywhere from ages 9-15. It begins when the Hypothalamus signals the body to increase hormones that affect gonads, which are a reproductive gland that produces gametes. Males Male reproductive development starts when hormones stimulate the production of Testosterone, a sex hormone that is necessary for the production of sperm and the development of male reproductive parts. Testosterone produces an increase in body size, the growth of body hair, and voice lowering. The combination of a sex hormone called FSH and Testosterone start sperm production, and puberty is complete when there's a lot of sperm. The male reproductive system is made up of:
Vas Deferens
Certain parts are internal, and some are external. This is crucial for sperm development, because the ideal temperature for sperm is about three degrees colder than the normal body temperature. Sperm Sperm is the male reproductive gamete formed through Meiosis. Sperm has a haploid nucleus, meaning it only has one set of DNA, and are made up of:
Head (Nucleus)
Midpiece (Mitochondrin)
Enzyme on Head Structure and Function Sperm goes from where it's made in the seminiferous tubes, and gos to the Epididymis. The Epididymis is a structure in which sperm are fully matured and are stored. The Vas Deferens carries the sperm from the Epididymis to the urethra. The Urethra is a tube through which urine and semen are released from the body. In males, the urethra goes through the penis. There are three glands in the male reproductive system: The Seminal Vesicles, the Prostrate Gland, and the Bulbourethral Gland. Their job is to make seminal fluid, which makes semen when it is combined with sperm. there are anywhere from 50-130 million sperm in one milliliter. Sperm is released during sexual excitment, and it is controlled by the automatic nervous system. Females Again, puberty starts with the release of hormones, which stimulate the production of estrogen, a sex hormone needed to make eggs, and for female sexual development. Estrogen affects hip width and breast development. The Female Reproductive System is made of:
Fallopian Tubes
About one egg a month is produced by this system. Egg Development Egg Development starts in the ovaries, with ovulation, the process of releasing an egg. The egg then travels from the ovary to the Fallopian Tubes. The Fallopian Tubes are two fluid-filled tubes in human females through which and egg passes after its release from the ovary. The egg is pushed along the walls of fallopian tubes by cilia as it goes to the Uterus. Ovaries have follicles, which surround eggs. A follicle is a cluster of cells surrounding a single egg cell. The eggs mature in the follicles. Females are born with about 40,000 immature eggs, but only about 400 will be released as mature eggs. Once a month, a follicle gets big, and forms an egg through meiosis. After Meiosis, there is one large haploid egg, and three polar bodies, which are discarded. The uterus is the organ in the Female Reproductive System in which a fertilized egg full develops. If the egg is fertilized by sperm, it remains in the Uterus. If not, it is expelled, along with the uterus lining. The Vagina is the canal of the Reproductive System. It leads from the Uterus to the outside of the body. Menstrual Cycle The Menstrual Cycle is the process in which an egg develops and is relaxed from an ovary and the Uterus is prepared to receive a fertilized egg. This process takes place about every 28 days, and is regulated by hormones and negative feedback mechanisms. Process 1. An egg is released
2a. If egg is fertilized, it gets placed in the Uterus.
2b. The egg is discharged with the Uterin Lining.

There are four phases: Follicular, Ovulation, Leutal, and Menstruation. The Follicular Phase The follicular phase happens when the estrogen level in the body is low. Then, the Hypothalamus stimulates the release of more hormones, which cause one or more follicles to mature. Then the surrounding cells raise the estrogen level, and the uterin lining thickens. The entire process is about 10 days long. Ovulation Ovulation is the shortest phase, only lasting about 4 days. During that time, the
hypothalamus stimulates the release of sexual hormones, which ruptures the follicle, releasing the egg into the fallopian tube. The Leutal Phase The leutal phase begins after the egg is released. Th egg moves along the Fallopian Tube, and the broken follicle turns into a corpus luteum, a sort of yellow body. This releases more Estrogen and Progesterone, and these stimulate more growth in the Uterin lining. The growth also increases the blood volume. The egg has the chance to be fertilized while in the Fallopian Tube. If that happens, the egg starts to divide in successive powers of two within the uterus. At a certain point, a ball of cells are implanted in the uterin lining, and the uterus releases hormones to keep the corpus leutum working as the Uterus nourishes and protects the growing embryo. Menstruation Menstruation occurs when fertilization doesn't happen. Instead of staying in the uterus, the egg passes through it. The corpus leutum disintegrates, and the hormone level goes down. Soon after, the uterin lining detaches from the uterus, and it is discharged out of the vagina along with the egg. A new cycle begins during th first day of menstruation, and everything starts over again. Fertilization Feritlization is the process of sperm joining an egg. This happens during sexual intercourse, where semen is ejaculated into the into the vagina. The sperm swim to the fallopian tubes, and tries to gain access to a binding site. A binding site is a place on the surface of the egg where a sperm uses the enzyme on its head to gain access. Only about 1% of sperm ejaculated ever get as far as the Fallopian tubes. When the sperm enters the egg, the tail of the sperm comes off, and the nuclear membranes around the DNA in both cells breaks down, and they join together. The now-fertilized egg, or zygote, then starts to divide into two cells, and those two divide etc. Development of the Embryo It takes about 9 months for a human embryo to fully develop. It starts with a single cell splitting, and those cells splitting. After about 4 days of that, the cells from a Morula (about 50 cells), and after a week, they make a Blastocyst (a fluid filled cavity around the embryo), which gets implanted into the uterin lining. This is implantation. Then, gastrulation happens. Gastrulation is the process of cell migration by which a third layer of cells is formed in the blastocyst. These three layers are the Ectoderm, the mesoderm, and the Endoderm. All the tissues of the embryo are formed from these three. The blastocyst also forms a bunch of important membranes, like the amnion and the clorion. After three weeks, the nervous and digestive systems have begun to form. The clorion forms an organ called the placenta. The placenta is the embryo's version of the Respiratory, Digestive, and Excretory systems. it does this by difusing nutrients from the mother's blood to the embryo's blood, so as to prevent complications. Much of what the mother takes into her body goes also into the embryo. After eight weeks, the embryo starts being called a fetus. The fetus's main organs are formed after about three months, as well as the formation of the umbilical cord, which connects the fetus and placenta. During months 4-6, the tissues already existing become more complex, and begin to function. The mother's abdomen, not the stomach, grows to accommodate the growing fetus, which now is about 35 centimeters long. In the last three months of the mother's term with the fetus, it doubles in size, and goes through a series of changes to get ready for the outside world. A fetus born too early can suffer severe breathing problems and other complications. Childbirth Several factors affect childbirth. It starts with the release of the hormone Oxytocin from the pituitary gland. Oxytocin stimulates involuntary muscles in the uterine wall, which begin rhythmic contractions. This is called labor. The cervix opens wide enough for the baby's head to pass through, and the sac around the baby breaks, causing fluid to come out of the vagina. The contractions then force the baby out of the Uterus. As soon as the baby is born, it starts breathing, and the placenta starts to dry up. The umbilical cord is still attached to the baby, but it is cut off and usually discarded. After the birth of the baby, the placenta and the protective sac are discharged. Krill Respiration Circulation Digestive Water Balance Excretory System Reproduction Krill, like many oceanic creatures, have gills, which take care of their exchange of Oxygen and Carbon Dioxide. Introduction Introduction Structure and Function There is relatively little information on this subject, but the little serves that there are suggest that Krill's gills are located near the front of the body, where water diffuses across membranes, and carbon dioxide diffuses the other way, where it is released into the ocean waters. The oxygen then goes to the blood and it distributed. Crustaceans also have a mechanism that prevents water actually being let in through the gills. They have spiracles, which allow the secretion of oxygen into the body. These are the gills of krill, not to scale. Comparison Human Krill Similarities Both secrete Oxygen for Carbon Dioxide
Both diffuse gases across membranes Secrete Oxygen with alveoli, which lead to blood capillaries.
Must preform Oxygen exchange in air
Oxygen must go through a complicated process within the body before it can actually enter the blood Secrete oxygen directly from outside environment using gills
Must preform Oxygen exchange with gills
There is only straight diffusion, no process of cleaning or moistening. Introduction Krill, like many other organisms, have hearts and a fluid that transports Oxygen to all the cells in the body. The major difference in Krill is the actual fluid that transports the Oxygen. Instead of blood, Krill have a fluid called Hemolymph, which is similar to blood. Structure and Function Heart The heart is located in the Pericardium, which is a double membrane sac which envelops and protects the heart. The layer in contact with the heart is referred to as the visceral layer, and the outer layer, which is in contact with the surrounding tissue, is referred to as the parietal pericardium. Hemolymph flows out of the pericardium through valvular opening called ostia, and it flows in through the pericardial cavity. The ostia, like in certain parts of the human heart, have valves within their arteries that prevent the Hemolymph from going in the wrong direction. When the heart contracts, it sends blood out to the body, and the blood volume within the pericardium goes down, as well as the pericardial pressure. This causes blood to flow into the pericardial cavity. To let blood back into the pericardium, the heart must have some way to expand after contracting. It gets that through two things: Natural elasticity and a hard outer covering which it is connected to. When this stretches during contraction, the elasticity pulls the heart back into shape. There isn't a great pressure within this structure, but there is enough to keep it running smoothly. Heartbeat Krill's heartbeat is incredibly variable, because outside factors affect it. This can cause strange outcomes. Most of the rate of beating depends on light and temperature. When there is more light, and/or a higher temperature, the heart beats quicker. The rate has been known to double when there is a 10 degreetemperature rise Celsius. Heartbeat is also controlled internally. The actual function of the beat occurs in nerve cells lining the heart,whcih is neurogenic. The heart rate can be invreased with Acetycholine. Acetycholine is a chemical found in vertabrate neurons that carries information across the synaptic cleft, the space between two nerve cells. It is made within the parasympathetic fibers. It is also affectd by Adrenaline. Hemolymph Hemolymph is fluid similar to blood and lymph. It consists of free-floating haemocytes. Haemocytes A haemocyte is a red blood cell found in invertabrates. They are more like leucocytes, being without color, hemoglobin, or a nucleus, protecting the body from microorganisms and foreign substances. Haemocytes are phagocytic, meaning tht they engulf and digest debris and invading microoganisms. Hemolymph circulates in the Hemcoel, which is the body cavity in between organs whereby hemolymph circulates through. It also contains the protein Haemocyanin, which is the protein which carries Oxygen within Mollusks and Crustaeceans. Haemocyanin is blue when it is carrying Oxygen. The pigment of Hemolymph is not within the cells, bt in the plasma. Hemplymph also contains white blood cells, which, like in mammal blood, are responsible for resisting infection and bacterial fungi. Some also do transport within the body. A haemocyte magnified to 400x its normal size. Comparison Human Krill Similarities Both have circulatory fluid
Fluid has white blood cells, red blood cells, and plasma
Both have hearts, whose vessels have valves to prevent backflow
Have fluid that carry Oxygen
Enhanced by chemicals
Under pressure
Have protein in fluid which carries Oxygen Fluid within system: Blood
Protein carrying oxygen: hemoglobin
Blood: Red Fluid carrying oxygen: Hemolymph
Hemolymph is not red
Protein carrying oxygen: haemocyanin Digestion in Krill is, again, very limited. What is available say that Krill have a very high energy level, which is one of the reasons that they are preyed on by many other organisms. Because of their high energy demand, Krill have developed specific enzymes in the digestive tract that help them to utilize food efficiently. These include cellulase, laminannase, and endochitinase. Endochitinase is a chitinolytic enzyme that digests chitinous food into oligomers, polymers which consists of more than one monomer. This takes place in the stomach, and the degradation of these to Amino Acids takes place in the midgut. The Krill Digestive System consists of:
Ectodermal Foregut
Endodermal Midgut
Ectodermal Hindgut
The Stomach and the midgut are located in the Cephalothorax, one of the main body cavities. The Midgut is made up of numerous blind end tubules, constructed of a monolayer epithelium of specialised cells and glands. It also makes up the outer part layer of the human body. This layer is developed from Embryonic cells (E-cells). E-cells can be made into two different cells. Comparison Human Krill Similarities Both have Stomach and Esophagus
Use enzymes in stomach and following organ to break down food
Both have organs made of epithelial cells
Omnivorous Can digest cellulose
Have guts, not intestines
High energy demand Cannot digest cellulose
Very big degiestive system There is little to no information on theis subject, but from what I can tell, Water Balnce is controlled by the Excretory organs, which keep the Krill's body with enough water entering the body to meet its needs. One of the biggest problems is salt content. There are two different organs that make up the Excretory System: The Antennal Gland and the Maxillary Gland. The antennal gland is a pair of exretory glands in the head, one opening at the end of each antenna. The maxillary gland is the second largest salivary gland, located deep in the mandible. They have the same basic structure, being made up of the end sac and the convualted duct. In most adults, only one of the glands functions at any given time. The system is a main source of regenerated nutrients. The job of the glands is to monitor ionic balance, but the balance of salts and water is also controlled by the gut, because the gut can absorb both. The antennal gland can also reabsorb glucose. Krill, like any other animal, makes ammonia as a by-product of using Amino Acids for energy. Unlike other animals, Krill just excretes the ammonia through its gills, instead of converting it to something less toxic first. Comparison Human Krill Similarities Both need to excrete ammonia
Use Excretory System to get important nutrients into the body while getting unnecessary things out
Release excess water, salt, and ammonia Get rid of ammonia by converting into urea
Excrete through skin, kidneys and large intestine.
Excrete liqiud
Use kidneys to excrete
Excretion glands located in main organ cavity Just excrete ammonia
Excrete through gills
Excretion glands located in antenna Comparison Human
Krill Similarities Both need to get rid of excess water
Get rid of water through excretory system and secretion Biggest problem: Evaporation Biggest problem: Dehydration Krill Reproduction is limited to one period of time out of the year, from around December to Febuary. A few months erlier than that, around September, Krill come out of a phase called Regression. Regression occurs from approximately June to Spetember, when Krill experience four months of darkness. During this, they return to an earlier state, and they shrink in size and lose their mature sexual characteristics. Most scientists think this is based off of the darkness that Krill are subjected to, although some scientists are now saying that it could be caused by an internal mechanism, a biorhythm. Sexual Development begins after this period, so the adults are ready to mate, although mating only takes place when there is an abundance of food. Male Males, like in females, provide the sprem for reporduction. In this case, it comes in the form of littles packages called spermatophores, which encloses a bunch of spermatozoa, and is released during insemination. These speratophores are carried by the front two pairs of abdominal limbs. Special hooks on the legs fix the package inside the females genital area. The preparation of the spermatozoa inhibits swimming, so the males usually produce them during reproduction. Female In the female, the ovaries are the most important thing to re-develop after Regression. Then, gametocytes can be made, and start to accumulate a glycoprotein yolk. A glycoprotein is a protein that has been covalently bonded with a sugar molecule. This process takes place during the entire reproductive season, and its possible for females to go through more than one cycle per season. Each cycle has two parts: The part in which the lipid yolks are accumulated, and when spawning occurs (spawning occurs at the onset of the season). When the egg batch is spawned, storage lipids are put around the ovary, a layer that has high levels of polyunsaturated fatty acids phosphatidylcholine. Phosphatidylcholine is a phospholipid comprising Choline linked to phosphadic acid. Its a major compound of cell membranes and is localized mostly in the outer surface of the plasma membrane, and is a key part of embryo development. Sexually mature females are identified by their swollen thorax, because they're usually carrying anywhere from 1000-2000 eggs in every batch. Reproduction Process There are two parts of Reproduction between the male and the female. The first part has four parts: the chase, the probe, the embrace, and the flex. The second stage is the push. The chase indicates that the male krill has reached sexual maturity, as it is when a sexually mature mle chases a female with a swollen thorax, which is known as a gravid female. Sometimes, two males chase a single female at one time. Then, the male probes the female, probably making sure that she is mature also. Then, they embrace abdomen to abdomen, in which the spermatophores are transfered to the females using the front pelopods. The actual process of tranference is the 'flex.' The male wraps his abdomen around the female, and a rapid spinning occurs for a very short time. After spinning, the male continues to push the female as it swims in slightly larger figures. Once the spermatiphores are emptied inside the female, the spermatozoa are empties out. It is suspected that the 'push' is used to extract the spermatozoa. The gravid females spawn shortly after mating. Krill are broadcast spawners, and the eggs sink after being released. When they hatch, they need to feed within three weeks, because at that point, the food provided by the mother has run out. Comparison Human Krill Similarities Requires egg and sperm
Experience sexual development
Offspring provided with food from mother Fertile one part of year
Lay eggs
Thousands of offspring produced from one mating
Larvae can survive for three weeks without eating after birth Fertile all the time after sexual maturity
Only one offspring at a time
Give birth to fully developed offspring
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