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The Human Body

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Sana Chowdhry

on 10 January 2014

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Transcript of The Human Body

The Human Body
The human body is a magnificent thing, one that has been thoroughly examined for ages, and more to come. Specifically, the digestive system, the circulatory system, the respiratory system, as well as the reproductive system, take part in the majority of the functions of the human body. Without these systems, humankind would not exist, and it is for this reason that these systems have been studied in depth. All scientists ask the same question, how is it possible that such complexity has arisen and developed within the human race?
The Four Main Systems of the Human Body
By: Sana Chowdhry
Circulatory System
The circulatory system is essential to the human body. It is needed to circulate oxygen, blood, and other vital nutrients through the cells and and organs. Without this complex system, our bodies would quickly become malnourished and would not be able to retain nutrients the way it currently does.
Respiratory System
The respiratory system is responsible for the exchange of oxygen with an organism's environment. As seen in the circulatory system, oxygen plays an essential role in the human body. Therefore, respiratory organs, such as lungs, are largely important when it comes to oxygen absorption and distribution throughout the body. In this area of the presentation, the complex, yet condensed, system will be taken apart and examined thoroughly.
Reproductive System
The reproductive system is essential as it is needed to reproduce organisms. In humans, the male and female organisms contain different reproductive systems with their individual reproductive organs.

The journey through the digestive system begins at the mouth, where the food enters. It is here that the food is broken down through chewing, and moistened and prepared with the addition of saliva. The saliva mainly conforms the food into a mushy substance that will allow the food to easily enter the pharynx, which is the place where the next step of the process occurs.
Small Intestine
Large Intestine
non accessory organ
The pharynx is where the food passes through next, and ultimately, it is a passageway that opens into the esophagus, and the windpipe. However, to ensure that the food moves into the esophagus, the epiglottis directly below the pharynx points downward. This way, the food can pass directly through without getting caught in the windpipe.
accessory organ
The food then travels down the esophagus into the stomach, after the esophageal sphincter relaxes. Here the esophagus aids the food by contracting its muscles. This allows the food to move along swiftly into the stomach.
accessory organ
non accessory organ?
Once the cardiac sphincter relaxes, the food enters the stomach. Here, it makes a quick pit stop as the stomach releases gastric juice and enzymes to aid in the process of breaking down the food. Once the food has been broken down as much as it can, it makes its way to the small intestine.
non accessory organ
The food, or now chyme (mixture of food and gastric juices), enters the duodenum, after passing the pyloric sphincter, to interact with the juices secreted from the pancreas, gallbladder, as well as the liver.
accessory organ
The organ that is responsible for creating the majority of the enzymes that enter the small intestine, specifically the duodenum. These enzymes include trypsin and chymotrypsin.
accessory organ
The gallbladder is mainly in charge of concentrating and storing bile, which is brought into the digestive system in the duodenum. Bile is composed of the blood cells that we no longer need, therefore, the gallbladder sends the bile to the duodenum so that it can travel through the rest of the digestive system, and be secreted through the anus,
accessory organ
This is where bile is initially produced. Bile digests and absorbs fats, and also carries products that must be excreted.
non accessory organ
Now that the food has been broken down enough, the jejunum uses its villi to sweep nutrients, vitamins, and other essential substances, into the bloodstream.
non accessory organ
The ileum's main function is to absorb any nutrients that the jejunum might have missed. Some of the main products that it absorbs are vitamin B12 and bile salts.
Ascending Colon
Transverse colon
Salivary Glands
accessory organ
In charge of creating saliva, the salivary glands are located within the mouth. The saliva produced contains enzymes that can partially break down food before it makes its way through the long journey that is the digestive system.
The food drops out of the ileum, landing into the cecum. At this point, the cecum gets to work by fermenting, or chemically reacting and taking apart whatever is left.
non accessory organ
Descending Colon
Here, in the first part of the colon, any food that is no longer useful for the body is pushed towards the ascending colon, which, by contracting its muscles, pushes the remains through until it will make its way out as waste.
non accessory organ
Serving as a bridge for the ascending and descending colon, the transverse colon sucks up any last minerals and water that the food could be holding. The strong muscles push the food along the lengthiest part of the colon, and by the end, the food is guaranteed to be of no use any longer.
non accessory organ
Now that the food has been utilized in any and every way possible, it is pushed into the descending colon, where it will solidify until it can be secreted as waste. Its journey through this part of the colon is how the food becomes solid, turning into feces.
non accessory organ
Sigmoid Colon
Here, the waste finally makes its way into the rectum, once it passes through the S-shaped column that is the sigmoid colon.
non accessory organ
The final waiting room for the waste, that expands like an elastic bag until it is filled with enough feces. At this point, the feces are pushed with enough force and pressure from being condensed for so long, and they swiftly travel to the anus
non accessory organ
The anus' main function is to push out the feces by contracting its muscles. In order to do so, there are two sphincters that aid the human body in determining when it has acquired enough waste to expel. The sphincters include the inner anal sphincter and the outer anal sphincter.
non accessory organ
Inner Anal Sphincter
Outer Anal Sphincter
Otherwise known as the controlled sphincter, it is the sphincter that allows us to control our bowels and defecation. We are able to utilize our outer anal sphincter to control our bowels and defecate when necessary, which is what we learn to do at a young age.
non accessory organ
The inner anal sphincter cannot be controlled voluntarily, and it signals when the feces are near the outer anal sphincter. This sphincter is what tells our body that we have to go to the bathroom, which is then carried out by the outer sphincter.
non accessory organ
Esophageal Sphincter
Remains contracted and stiff until saliva or bolus is swallowed. This sphincter keeps anything from entering the esophagus, unless you swallow, which relaxes the muscles.
non accessory organ
Cardiac Sphincter
non accessory organ
A most essential sphincter, the cardiac sphincter contracts and relaxes to ensure that the food does not travel back up the esophagus after it has been ingested.
Pyloric Sphincter
non accessory organ
The pyloric sphincter acts as a gateway between the stomach and the duodenum, opening and closing to allow food to pass.
Why do we have to digest large molecules?
Large molecules, such as proteins, contain a lot of nutrients that are essential to our bodies. Therefore, the multiple areas of the digestive tract allow us to break down relatively large molecules into smaller pieces, so we can extract and absorb the materials necessary to survive.
Importance of Enzymes
Enzymes in the digestive system ensure that the food is broken down completely. Without them, we wouldn't be extracting all of the vitamins and minerals we need to survive. Essentially, they break down the food enough so that it can enter our bloodstream and travel to all parts of our body.
Physical Digestion Vs. Chemical Digestion
BOTH break down food into smaller bits so that it can travel easily through the digestive tract. They make it easier for nutrients to be extracted.
When we mechanically break down our food, such as when we are chewing. Physical digestion also includes peristalsis, which is when our muscles are contracting to transport our food to different areas of the digestive tract
Chemical digestion is needed to take apart food on a molecular level. It breaks down the nutrients enough so that our body can absorb them. The nutrients can be transported by traveling into your blood stream, once they are small enough to dissolve easily into water, and pass through the cell membrane.
What is it?
Jaundice diseases occurs in a body that has too much bilirubin. Bilirubin is a remnant of when iron is extracted from the hemoglobin, and it is released through waste. However, when the liver is unable to get rid of all the bilirubin, it builds up in the body and is then secreted out of the bloodstream and into tissues.
Signs and Symptoms
The most obvious sign that a person has jaundice disease is if they have a yellowish tint to their skin color. Furthermore, as seen in the pictures above, a person with jaundice can have a yellowish tint in their eyes. In babies, jaundice can trigger irritability, arching of the back, shortness of breath, or even seizures.
Jaundice is present in about 20% of all newborn infants immediately after their birth, and it usually goes away after the first week. However, some older adults also have jaundice, but is is less common as jaundice is usually a sign of other major diseases in the body.
Treatment Options
In the most mildest of cases, babies are placed under a blue light to manipulate the bilirubin so that it is excreted. However, if the light does not help, the baby can take dosages of medication and protein to rid of jaundice. In a worst case scenario, blood must be extracted from the baby, little by little, rebalanced in bilirubin, then inserted back into the infant.
Gastroesophageal Reflux Disease (GERD)
What is it?
As shown in the diagram, a person with GERD has a weak lower esophageal sphincter. This results in acidic liquid exiting the stomach and traveling back up the esophagus. Ultimately, the stomach is not able to always retain the liquid.
Signs and Symptoms
Common symptoms include:
heartburn, most commonly
bad breath
ear aches
Obviously, these symptoms are quite similar to a person with acid reflux, or a bulimia, as all disorders show signs of how acidity affects the body.
GERD is quite common in adults, a minor case being heartburn. Statistics show that 60% of adults will experience GERD at least once a year! Unless it occurs quite frequently, it is relatively harmless, as the only real damage that arises from the disease is the damage that acidity brings.
Treatment Options
Minor cases of GERD can be put to rest with acid reflux medication such as TUMS. In more extreme cases, however, medication must be used to decrease acid amounts, and also heal the damages caused by acid when it leaves the stomach.
Mechanical Digestion
Carbohydrates are first broken down when they are chewed in the mouth. While food is being chewed, the lysozyme and amylase enzymes in saliva help to partially break down carbohydrates so they can enter the stomach.
Small Intestine
Here is where the carbohydrates are most extensively broken down, chemically. Enzymes secreted by the pancreas, mentioned before, break down the macromolecules into smaller monomers that can be transferred throughout the body. Breaking carbohydrates down to this extent is essential, otherwise we would not be able to utilize the nutrients effectively.
The Stomach
By now, the carbohydrates make their way into the stomach. Not much digestion happens here, however, the carbohydrates must travel through the stomach to reach the small intestine.
That being said, lipids are digested in the small intestine, specifically the duodenum. The bile from the liver and the enzyme, lipase, helps break down lipids so that they can be transported to any part of your body
The enzymes released in the gastric juices of the stomach are responsible for breaking down proteins. Due to the fact that proteins are so complex, they need to travel through both the stomach and small intestine's path to be thoroughly digested and broken down into their monomers, amino acids.
The digestive system is in charge of deriving energy from the food that you eat. Furthermore, whatever is in the food that the body does not need, the digestive system converts it to waste so that it can be excreted.
Digestive System
Arteries, Veins and Capillaries
Arteries branch out into arterioles
These arterioles connect to capillaries
Layers of smooth muscle around the blood vessels

They are all types of blood vessels
Capillaries bunch together, forming venules.
Venules form veins.
carry oxygenated blood away from the heart, to the organs
Very thick muscular walls that result in high pressure and pumping of blood through contractions
Thin inner tube, just enough for blood to pass through (most of it is muscle for pumping)
Very thin walls to allow for efficient diffusion
Nutrients, oxygen and waste diffuse through capillary beds
Not much contraction, just enough to allow the blood to flow efficiently
Smallest and thinnest out of the three blood vessels
Carry deoxygenated blood into the heart
Contain valves so that blood does not flow backwards.
Thick inner tube for a lot of blood to flow through

http ://www.youtube.com/watch?v=JA0Wb3gc4mE
Blood Flow through the Heart
Summary of blood flow:
Blood enters the right atrium through the vena cava (superior or inferior)
Tricuspid valve connects the right atrium to the right ventricle
Blood is pushed into the pulmonary artery, acting as a "fork in the road", both sides pumping blood into the lungs
Blood enters lungs, is oxygenated, then re-enters the heart through the pulmonary veins.
Once in the left atrium, the mitral valve connects the blood's path to the left ventricle
The blood leaves the left ventricle to be transported throughout the entirety of the body.
What is blood made of?
There are 4 main components of blood
Commonly known as white blood cells, leukocytes are the infection battling components of our blood. These blood cells play a large role in the body's immune system. These cells, like all blood cells, originate from bone marrow. More specifically, the stem cells within the bone marrow which can transform into any type of blood cell. There are two main types of white blood cells, agranulocytes and granulocytes. The main difference between these two types of cells is that granulocytes divide into granules, as their name suggests. Agranulocytes, however, divide into lymphocytes which make up between 20-40% of the total white cells in the body. Overall, the types of white blood cells and their function in the body revolve around fighting infections and bacteria.
One of the most essential components for the accident prone, platelets are the cells within blood that are responsible for forming clots when skin is broken. The platelets recognize a break in the skin as a result of the blood vessel being damaged. In reality, when you see a scab has formed, it is "patching up" a broken blood vessel until it can heal so that the blood can continue flowing through your body (similar to how a tire is patched up so air does not leak out). To activate the platelets, the blood vessel sends out a signal, and through cellular communication, the platelets respond and bind to the blood vessel. When they bind, they change shape so that they look like a net, strong enough to keep the blood cells from pouring out.
The net-like characteristic that holds the blood cells from being pushed out of the blood vessels can be seen here.
Most commonly acknowledged out of all the components of blood, erythrocytes are known as red blood cells. These blood cells are most probably the most well known because they are the ones responsible for transporting oxygen throughout the body. It is these cells that absorb the oxygen when being pumped through the heart so that it can be transported to almost all cells in the body. However, keeping in mind that carbon dioxide is a byproduct, red blood cells remove the CO2 after giving oxygen to the tissue. One can perceive these blood cells as a filtration system for tissue, inserting oxygen and removing CO2.
Lastly, there is plasma. Plasma is the liquid portion of the blood. This liquid-type substance is composed of water combined with essential materials, some of which include lipids, proteins, and salts. Plasma serves as a "river" that transports materials listed above (nutrients) as well as blood cells around the body.
So then why is the shape of a red blood cell so important?
The structure of red blood cells is essential to their function. These cells are unique in their composition due to the fact that they lack a nucleus and other cellular components of a eukaryotic cell. As their main role is to hold oxygen, they contain hemoglobin and other components for that sole purpose. Furthermore, the cell is very flat to allow for easy diffusion of oxygen, and is also very flexible to allow smooth mobility.
Different variations of the circulatory system
The circulatory system of a fish is closed, as is apparent through the diagram, and it's heart only has two chambers. It can be seen from the image that the blood must travel through the system to the gills to be oxygenated. Upon completion of a cycle, the blood enters the heart deoxygenated, and heads for the gills once again.
A bird's circulatory system is designed specifically for it to be efficient throughout the bird's active life. Quite similar to the circulatory system of humans, birds have separated pathways for oxygenated and deoxygenated blood, with a 4 chambered heart to connect the pathways. Furthermore, the lungs are involved in the pathway as well. What sets birds apart from other mammals is how much blood they pump and the fact that their heart is relatively larger. As mentioned before, all of these special features are due to the fact that birds are extremely active, and their circulatory system is responsible for ensuring that the bird's metabolism can keep up with its activity.
Amphibians are unique because they have two atria and only one ventricle. Both pathways, containing both oxygenated and deoxygenated blood, travel through the system and meet back in the single ventricle. This type of system is advantageous for amphibians because it produces high pressure to push the blood flow through the system.
A reptilian circulatory system can be recognized by its divided ventricle. The ventricle in its system is divided to minimize any mixture of oxygenated and deoxygenated blood. As all other systems, the blood flows through the lungs from the right atrium, enters the left atrium, then travels to the aorta. The deoxygenated blood then makes its way back to the lungs. This is also seen in the mammalian system, the only difference being the divided ventricle.
The circulatory system of a mammal has four chambers, making it the most complex. As seen in the diagram, the deoxygenated blood (blue) enters the right atrium and right ventricle and travels to the lungs. From here, the blood leaves the lungs oxygenated and enters the left atrium and left ventricle. Once the blood has rotated in the left side of the heart, it turns around and enters the aorta, which transports the blood to virtually every part of the body. Then the blood returns to the heart deoxygenated to take part in the cycle all over again.
Open vs. Closed Circulatory System
heart or heart-like organ involved to pump blood
blood vessels present
Blood involved
blood is pumped through a heart-like organ and then branches out from the blood vessels
Blood gets directly in contact with tissue.
Blood remains in the blood vessels' path
Blood vessels branch out into capillaries, blood stays inside but diffusion occurs for circulation.
An example would be the circulatory system of a grasshopper. As the diagram shows, the cycle is similar to the closed system in its structure, however, the main difference is that the system is legitimately open. This break in the blood vessel allows the blood to spread out and circulate throughout the grasshopper.
An example of a closed circulatory system would be of a worm. As the diagram portrays, the blood never leaves the actual vessels. Instead, the vessels branch out to allow easy diffusion of materials.
What is it?
An arrhythmia is any type of irregularity in a person's heartbeat. The irregularity can cause the heart beat to speed up, slow down, occur irregularly (without rhythm), or occur before its meant to. Each of these specified types of arrhythmia have their own specific name and information. Any factor that damages the performance of a heart (eg; heart attack, smoking, diabetes, alcohol abuse, etc) can damage the heart and cause issues in the way it beats.
Signs and Symptoms
Depending on the type of arrhythmia, the person's heartbeat might increase or decrease in speed. Also, as a result of the irregularity, the person can experience dizziness or shortness of breath, which could even result in fainting. Usually, the person suffering from arrhythmia feels tired or weak due to the heart's inefficiency.
Arrhythmia is very common all over the world, and it is for this reason that there is no exact number or percentage that shows its prevalence. Scientists have, however, discovered that arrhythmia is increasingly common as a person ages, and is an even higher risk for one who has had heart surgery of some sort.
Treatment Options
The fact that arrhythmia is caused by a heart defect leads to multiple treatment options. In some cases, the disorder can be cured by simply taking medications called antiarrhythmics. These medicines regulate heart beats so that they lie within the normal range. Certain types of arrhytmias can even be cured by blood thinners, which prevent blood clotting that can result from uneven pumping of the heart. In extreme cases however, the patient must undergo a surgery. In this procedure, the patient could either receive a pacemaker, or even have to undergo a heart valve replacement. In other cases, exercises can be done to relieve the patient temporarily. The most common cure that most patients are treated by are the different types of medications.
Varicose Veins
What is it?
Veins contain valves prevent blood-flow in the opposite direction (back towards the heart). When the valves weaken, the blood flow does not follow the correct path through the circulatory system, and the blood begins building up. This build up of blood causes swelling in the veins, producing a disease called varicose veins. Heavy weight on your legs can cause the veins to weaken and swell.
Varicose veins are not as common as arrhythmia. In fact, they occur in 25% of women and 18% of men. The fact that these veins are more common in women can be related to pregnancy and the weight that it places on women's legs. Furthermore, this disease has genetic influence and if the parents suffer from it, there is a 90% change that their children will suffer from it too.
Signs and Symptoms
The first sign of varicose veins are the most obvious; green bulging veins on the legs. In a minor case, the feet feel swollen and are hurting. In advanced cases, the entire leg can swell and the skin can become thin and dry. Overall, the leg looks diseased and deteriorates in health.
Treatment Options
The veins are mostly painful, and do not cause serious harm. However, people suffering from the varicose veins often do not like its appearance. For this reason, compression stockings can be worn to reduce the bulging of the veins. Or to decrease constant blood flow, the legs can be propped up. To permanently rid of the issue, surgery or procedures can be done to destroy or tie off the vein.
The Adaptations of Alveoli
Alveoli are the tiny sacs of air that are the smallest structures in the lungs. These structures have adapted in multiple ways to allow efficient gas exchange, or diffusion.
Surface Area
The first, and most obvious, way that alveoli aid in efficient gas exchange is their vast surface area. As it is well known, diffusion is directly related to the surface area to volume ratio. Increasing the amount of alveoli increases the surface area to volume ratio, as the small bulbs contain more surface area for gas exchange
Thin Walls
Another important aspect of diffusion is the actual surface through which a substance has to pass. To avoid any disturbance due to thick layer, the alveoli is surrounded by a wall that is only one cell thick. This allows for quick diffusion as the substances do not have to cross a large area to carry out gas exchange.
As mentioned in the circulatory system, capillaries are efficient for diffusion due to the fact that they branch out, are very thin, and lead directly into the blood stream. Therefore, the capillaries on alveoli are yet another adaptation that increase the efficiency of diffusion. Immediately after gas exchange has occured, the capillaries carry the substances directly into the blood stream. In other words, the capillaries allow for quick delivery.
CO2 and O2's Transportation in the Blood
Oxygen is constantly entering the body, and carbon dioxide is constantly leaving it. However, due to the fact that oxygen is so important to the body, it is often stored and transported efficiently. The red blood cells are responsible for oxygen transportation, more specifically, the hemoglobin within these cells. When there is a high amount of oxygen in the body, the hemoglobin become completely saturated. However, when CO2 levels are high, hemoglobin begins releasing this oxygen to prevent damage within the tissues. CO2 transportation is entirely different. A small amount of the CO2, 5%, is actually within the plasma, and another 10% binds to the protein haemoglobin. Majority of it binds with water to form carbonic acid, which is stored in the red blood cells. To avoid a drastic change in the pH levels of blood due to the acidity, there are buffers such as the carbonic-acid-bicarbonate buffer.
From the Air to Alveoli
Oxygen in the air diffuses across the walls of the alveoli after it is inhaled and travels to the lungs. Here, the oxygen transforms states so that it goes from being a gas to blending in with the plasma in blood.
Moving to the Red Blood Cells
Once the oxygen has entered the plasma, it moves towards the red blood cells that are floating around nearby. Upon entering the RBC, the oxygen encounters hemoglobin.
Absorption into the Hemoglobin
A protein called hemoglobin absorbs oxygen so that one oxygen molecule binds to each of the 4 molecules of heme. These iron-containing molecules bind to the oxygen, and once all four contain an oxygen molecule, the hemoglobin is completely saturated. A hemoglobin molecule that is completely saturated with oxygen is called oxyhemoglobin.
From the Air to Heme
Firstly, air is inhaled through the nose and the mouth, and travels down the trachea into the lungs through the bronchi. As it travels, the air is filtered by the mucus in the trachea.
Once in the lungs, the air continues to travel through the extensions of the respiratory organ, making its way to to the bronchioles
The bronchioles lead directly to the alveoli, where the gas exchange actually occurs.
What is physically happening to the lungs will be broken down below.
The ribcage expands with the aid of the intercostal muscles to allow room for the inflated lungs.
The chest is further hollowed out by the diaphragm, which pulls downwards to increase the area of the chest and make way for the lungs.
The lungs expand completely without added pressure on the chest or ribcage, and no damage is done to the lungs.
Physical Changes :
The diaphragm returns to its normal position and presses on the lungs.
The intercostal muscles also relax and the volume that expanded to make room for the inflated lungs returns to its normal size.
This constriction of space adds pressure to the lungs, forcing the air out once the gas exchange has occurred.
The air is pushed out of the lungs as a when a person squeezes an untied, inflated, balloon.
Click here for an animation of this explanation:
(The link will be opened separately on a new tab
Cystic Fibrosis
What is it?
Cystic Fibrosis is a disease where the mucus that is within the lungs is generated at a thicker consistency. This disease clogs the lungs, making it difficult to breathe. Obviously, the disease would also eventually damage other organs in the body due to lack of proper respiration.
Signs and Symptoms
Most obvious signs of CF are terrible and frequent lung infections as well as difficulty breathing. Also, constant coughing would be present. More unrelated symptoms include salty tasting skin (salt on the surface) as well as greasy bowel movements, or issues with bowel movements.
CF is a genetically inherited disease. Every year, around 1,000 patients are diagnosed with CF, 70% of them no older than 2 years. Almost half (45%) of the entire CF population is 18 years or older. CF is becoming increasingly common among this generation
Treatment Options
There are multiple treatment options to weaken the effects of CF, but they cannot completely rid of the disease. Firstly, there is chest physical therapy. There are multiple machines and methods that can be used to soften the mucus so that the patient can cough it up. some of these machines include ones that give off electric vibrations that loosen the mucus. Also, antibiotics and anti-inflammatory medications can be taken to lessen infections and swelling of the lungs and allow easier breathing. Lastly, if the condition is very bad, the patient must be hospitalized to allow doctors to provide oxygen therapy, or maybe even a lung transplant. There are multiple other treatments that doctors recommend as well, however these are the most common.
A lung suffering from CF
What is it?
A person who suffers from bronchitis is inflamed bronchial tubes. This means that it is difficult for a sufficient amount of air to enter their lungs every time they inhale. Acute bronchitis is a slight infection that can be easily taken care of. However, those who have chronic bronchitis will find that their bronchial tubes are constantly irritated causing extreme discomfort and illness.
Signs and Symptoms
Those who suffer from bronchitis experience constant coughing as well as discomfort. Similar to feeling as though one is suffocating, the patient is constantly coughing up mucus. Also, flu-like symptoms such as exhaustion and fevers can arise.
About 12 million Americans are CB patients, with around 120 thousand new cases each year. Not surprisingly, 90% of these cases are caused by smoking. Smoking greatly irritates and weakens the lungs, which is why if a person smokes, they are at high risk of developing CB (chronic bronchitis).
Treatment Options
If one has acute bronchitis, they must treat themselves as if they had the flu, resting and taking normal medications to ease pain and discomfort. If one is suffering from CB, firstly, they must quit smoking if they smoke. Medications to expand the airways or irritate the bronchi might be administered to cough up the phlegm. Also, oxygen therapy might be required due to lack of oxygen intake caused by inflamed airways.
Asexual Reproduction vs. Sexual Reproduction
Occur in plants and animals.
Daughter cells are produced.
A single cell is used to produce daughter cells.
Present in bacteria and some plants.
Has different methods such as binary fission, mitosis and budding. Binary fission involves a parent organism dividing into two identical organisms. Mitosis involves cells dividing without fertilization, while budding involves organisms growing off of their parent, similar to how coral grows.
Seen in simpler organisms.
Male and female gametes combine to produce the daughter cells.
Genes combine differently to create variation.
Menstrual Cycle
Estrous Cycle
Menstrual cycles are restricted to female primates and few other animals. The cycle occurs when the female ovulates and includes the shedding of the lining of the uterus. Upon shedding the lining, the female rids of the egg that would have been utilized if she had fallen pregnant. The egg cannot be seen when it is disposed of, however, the uterus lining is seen as blood that is secreted from the vagina. This vaginal bleeding continues for around a week, which is the average period of the menstrual cycle.
Unlike the menstrual cycle, the estrous cycle is for female mammals in general. It involves the period during which the mammal ovulates, with the peak of the cycle being where ovulation occurs. This peak induces an added need for sexual activity within the mammal to allow mating to occur with a male. Visible signs such as behavior can indicate the peak, which is called the "heat" period. No fluid is secreted due to the fact that the uterus is able to reabsorb the endometrium.
Menstrual Cycles
Apart from the estrous cycle, mammals undergo other types of menstrual cycles as well, including the ovarian and uterine cycle.
The ovarian cycle is used to categorize the actual physical changes within the ovaries which allow an egg to develop. Within these physical changes, many hormones are involved and feedback mechanisms are utilized to cause change. The hormone that initiates this cycle is called estrogen, which is commonly recognized as the "female hormone". This hormone is released from the actual ovary from where it travels to the brain to be received. As a form of positive feedback, the estrogen triggers the release of a hormone called GnRH and LH. Once LH is released, it travels back to the ovary where it will cause estrogen to be released once more, creating a cycle. Once the hormones have circulated multiple times, around the time the ovulation occurs, a hormone called progesterone inhibits the release of GnRH. This negative feedback intercepts the positive feedback, prohibiting the GnRH from stimulating the release of LH. This cycle controls hormones using feedback mechanism to develop the egg that can potentially become fertilized.
It is important to recall that the menstrual cycle has one main outcome, which is to prepare the lining of the uterus, and shed the lining if it is not utilized. The same hormones involved in the ovarian cycle are involved in this cycle. As mentioned before, the ovarian cycle causes estrogen to constantly be released from the ovaries. As a result, the lining within the ovaries, more specifically in the uterus, thickens. This thickening of the tissue cushions the egg that develops during the ovarian cycle. The estrogen is produced by a hormone called FSH, which causes eggs to develop. As a form of negative feedback, the estrogen halts the production of FSH to ensure that multiple eggs do not form in the ovary. Lastly, towards the end of the cycle, the LH hormone releases the egg into the ovary to allow fertilization to occur. This is at the peak of the cycle, and usually at this time the female becomes sexually aroused. However, if the egg is not utilized, the cycle is completed with the shedding of the uterus lining , a process called menses. This shedding occurs when the estrogen and progesterone levels drop. The endometrium, or uterus lining, begins diminishing and is disposed of during menstruation.
The three main stages of embryonic development consist of cleavage, gastrulation and organogenesis. Upon fertilization, the egg and sperm fuse to form a zygote, which throughout development is called an embryo.
As the name cleavage indicates, the first portion of embryonic development consists of the division of cells. To simplify the process, the cell divides to produce daughter cells, splitting DNA as well as other cellular components. It is important to note that the cell does not increase in size, rather breaks apart into multiple cells. The process is similar to watching a sugar cube crumble; the amount of sugar remains constant. As the number of cells multiplies, the cells continuously gather in a way that they from a shell around a blastocoel. At this point in development, the embryo is recognized as a
, which is formed from a mass of cells otherwise known as a
(the morula forms when the ovum divides). From this point, the blastula moves onto the next section of development.
During gastrulation, the cells that have already divided begin to compose specific tissues known as the endoderm, ectoderm, and mesoderm. These tissues will, in time, form the differentiated parts of the embryo including the gut, epidermis, and skeleton. In other words, this portion modifies the embryo. To continue development, the embryo, now called the
with its three layers of differentiated tissue, enters the oranogenesis stage.
The process of organogenesis is where the specialized tissues actually combine to form organs within the embryo. This is the last process in the development of the embryo.

All About Germ Layers...
As mentioned before, during gastrulation, 3 layers of tissue are formed when the cells divide into three types. These layers are called germ layers, separated into the ectoderm, mesoderm, and endoderm. The ectoderm is responsible for producing the central nervous system, the epidermis, the peripheral nervous system and more. The mesoderm forms the bone, muscle, cartilage, and important membranes. Lastly, the endoderm produces epithelial lining for organs as well as parenchyma cells.
What is it?
Infertility is a disorder within the male or female reproductive system. The disorder can only be blamed if the couple has been actively attempting to conceive for at least a full year (not conceiving after months of intercourse does not necessarily deem someone infertile). The name for this type of infertility is primary infertility. There is however, another form of infertility called secondary infertility. This type of infertility allows women to conceive once, but not after that. The direct result is that a couple would only be able to give birth to one child.
Signs and Symptoms
The most obvious symptom is that a couple is unable to conceive. Whether the issue lies with the male or female, the outcome is that the couple does not get pregnant. There are, however, additional symptoms that affect the female and male reproductive systems respectively. In females, issues with menstruation, acne flare ups, hair loss and weight gain can occur. The symptoms are similar to a woman who takes steroids. In men, the male can experience alterations in sexual drive, hair loss, lumps in testicles or small and tight testicles. The men's symptoms are less noticeable due to the face that they do not fall pregnant themselves.
Infertility is a global issue. That being said, the global prevalence of infertility is yet to be determined as the environment also impacts a couple's ability to conceive. For example, one-fourth of all couples in third world countries are infertile. This is most probably related to the fact that medical care and treatment is limited in those areas. Further research indicates that around 10% of women between the ages of 15 and 44 have difficulty conceiving. All in all, infertility is common issue with grave consequences.
Treatment Options
The most commonly recognized solution for infertile couples is artificial insemination. This is a common solution because in most cases, the main issue is the lack of successful transport of the sperm to the egg. If the infertility issue lies within the male, this process usually solves the problem. In some cases, all men need are medications to aid in ejaculation and sperm count. In females, however, at times there can be difficulty in the actual formation of the egg. For this issue, medication is needed as artificial insemination would not produce an egg. Women can also be injected with hormones to stimulate their reproductive system. In extreme cases, surgery might be necessary.
What is it?
Gonorrhea is one of the many sexually transmitted diseases around the world. If a mother has gonorrhea, it is possible that she passes it to her child as well. The disease is caused when the bacteria begins to grow within a person's body. In order to survive, the bacteria needs a moist environment, which is why it can be found near the reproductive areas (which are always moist). Also, the bacteria can be found in the mouth as seen in the previous image.
Signs and Symptoms
Both men and women experience similar infection-like symptoms. They will find greenish-yellow discharge from their penis or vagina. Also, they will experience burning while urinating, and they will have swollen sex organs. Females experience added symptoms such as irregular bleeding between periods. Also, when involved in oral sex, the mouth and throat can burn and swell as well.
Due to the fact that sexual activity is increasing in teens, the prevalence of gonorrhea is increasing as well. As it is widely understood, STDs are transmitted when a person has multiple sexual partners. The fact that this is becoming more common in teens has led to the point where there are an estimated 700,000 cases of gonorrhea a year, and that is only in the US.
Treatment Options
As gonorrhea is an infection, it needs to be treated with antibiotics. Whether they are taken orally or injected, they should be administered as soon as possible to stop the growth of the bacteria. If the issue is not handled immediately, there can be permanent damage such as infertility.
In the process of spermatogenesis, a diploid spermocyte undergoes meiosis I to divide into two cells. These two cells are called secondary spermatocytes. As the process continues, the cells undergo meiosis II to produce four spermatids. After wards, spermiogenesis occurs to produce 4 spermatozoa. This process can be seen in the diagram to the right. In simpler words, the process carries out like so:
spermatogonia --> primary spermatocytes --> secondary spermatocytes --> spermatids --> spermiogenesis --> sperm
To begin, oocytogenesis takes place forming primary oocytes. These oocytes will ungergo meisos after being produced. They are produced when primordial oocytes undergo mitosis. After the first stage of meitoic division, the oocyte divides into a secondary oocyte and a first haploid. Follicles then thicken to form the secondary follicle, which will eventually become the Graafian follicle. This follicle stores the secondary oocyte, which it will release once it has reached the surface of the ovary. The second meiosis will occur when the oocyte is fertilized by the sperm, at which point it will produce an ovum and a second haploid.
By: Sana Chowdhry
Campbell Biology Ninth Edition Textbook
Cytoplasm is unequally divided during this process due to the fact that only one of the four cells produced becomes the egg, or the gamete. This cell obtains the most cytoplasm in order to allow sufficient substance within the most important daughter cell.
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