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Transcript of Digestive System
•Right side of the abdominal cavity beneath diaphragm Function
•Produce substances that break down fat
•Convert glucose to glycogen
•Make urea (main substance in urine)
•Filter harmful substances from blood
•Storage of vitamins/minerals (A,D,K,B12)
•Produces cholesterol- produces 80% of cholesterol in body
How it works
•Blood carried to liver by 2 large vessels (heptic artery, portal vein)
•Heptic artery carries oxygen-rich blood from heart
•Portal vein carries blood containing digested food from small intestine
•Hepatitis- inflammation of liver
•Cirrhosis- liver starts to deteriorate and malfunction
due to injury-more common in men then women Gallbladder •Pear shaped Location
•Near duodenum and liver
•Connected to them by small tubes
•Stores bile (bile- digestive liquid produced by liver- breaks down fat)
How it works
•Stored in gall bladder- bile becomes concentrated- more powerful
•When food containing fat reaches small intestines, bile helps break it down
•Cholecystitis- inflammation of gall bladder
•Gall bladder cancer
•bottom of chest
•accepts/stores food that enters it
How it works
•glands in lining of stomach produce stomach acid
•muscles in stomach help to move food around/mix thoroughly
•stomach acid breaks down the food
•acid also kills bacteria
•when food leaves stomach, it’s a thick liquid
•muscles push digested food to small intestines
•peptic ulcers- sores that form in the stomach
Pancreas •small, flat
•behind stomach and sits close to the duodenum
•connected to duodenum by a tube called the pancreatic duct
•source of enzymes required to chemically break down fats
•makes insulin- helps balance blood sugar levels in body
How it works
•when food reaches stomach then duodenum, organs give off signals to pancreas telling it to give off it’s digestive enzymes
•enzymes transferred to the duodenum where they neutralize acid/break down fats, carbohydrates, and proteins into smaller molecules (nutrients)
•pancreatitis- inflammation of pancreas
Salivary Glands Location
•keeps mouth/other parts of body moist
•breaks down food/lubricates the passage of food
How it works
•made of clusters of cells called acini
•fluid made by cells contains water, electrolytes, mucous, enzymes and all flow into collecting ducts
•in ducts, composition is altered- most of sodium reabsorbed, potassium secreted, lots of bicarbonate ion is secreted
•small collecting ducts in salivary glands lead to larder ducts, which eventually make a single large duct that empties into the mouth 9 oral cavity)
Types of salivary glands
•parotid glands- produce serous*, watery secretion
•sublingual glands- creates saliva that is mostly mucous
*within blood Parotid gland
Submandibular gland Sublingual gland Appendix WHAT IT IS: A small finger-like pouch connected to the cecum (which is part of the large intestine). A branch of the cecum. FUNCTION: There is no know purpose, though some researchers believe that a long time ago it might have been useful (as part of the digestive system) but humans don’t need it anymore. There are theroies about the purpose of the appendix; it might produce B-lymphocytes, or “attract” infections in the body(to the appendix) ,that would localize the infection to one organ that isn’t important to body function. Because the appendix has no particular function DISEASES/PROBLEMS:
-Appendiciticus is a when you appendix becomes inflamed. There are many ways that could happen; it might happen after an infection in the intestine or something (poo or food) could get stuck in the appendix and then the appendix swells and gets easily infected by bacteria. If the infected appendix isn’t removed then it could burst and spread bacteria.
-appendiceal cancer (very rare)
Anus WHAT IT IS: The external opening of the rectum or the ring of muscle at the bottom of the rectum, which prevents anything from coming out until you want it to. PURPOSE: To excrete waste. DIEASES/PROBLEMS:
The walls are made up of 3 layers; the serosa is the outside lining and it’s really thin. The muscle is made up of rings of muscle and is very thick. Those muscles work together to slowly squeeze food along. That action is called peristalsis. And the inside lining is called the mucosa, which is also very thin.
Intestines Small Intestine WHAT IT IS: A 6.7 meter long tube that has a 3.5 to 5 centimeter diameter. It greyish-purple in color and is packed inside your stomach. The small intestine takes the food that the stomach started to break down and breaks it down even more. The lining of the small intestine is wavy and covered in villi, which increases the surface area of the small intestine. Villi are like small fingers and microvilli cover the villi; they are even smaller fingers. The pancreas, liver and gallbladder send different juices to the duodenum (the first part of the small intestine), and the juices help digest the food and allows the body to absorb the nutrients. The small intestine passes the nutrients from the food into the blood. The parts of the food that’s unusable to the body goes on to the large intestine (to be sorted).
From the villi to the capillaries: each villi contains a network of capillaries and the nutrients pass from the villi to the capillaries by a process called absorption.
DIEASES/PROBLEMS: -cancer Duodenum Jejunum Ileum The beginning of the small intestine. It’s also the shortest. The middle of the small intestine. It’s about 1.5-2.5 meters long. The last part of the small intestine. It’s the longest at 5-6 meters long. Large Intestine WHAT IT IS: it is about 1.5 meters long and about 7-10 centimeters in diameter. It begins at the cecum and ends at the rectum. No further breaking down of food is done. PURPOSE: to absorb salts and water from waste foods(colon), absorb certain vitamins (colon), and to store the poo until it is excreted from the body(rectum). DIEASES/PROBLEMS: -cancer Cecum The pouch-like beginning of the large intestine. The cecum, like the appendix, seems to have no particular purpose. It is separated from the ileum by a ileocecal valve. Because the function of an ileocecal valve is to limit the reflux of colonic contents into the ileum, the function of the cecum might be to prevent the waste food from going the other way(the reason why you don’t throw up poo). The other end of the cecum is the colon. The appendix is attached to the cecum. Colon Water and salt from the waste food is absorbed through the sides so the waste becomes more solid. It is also the largest part of the large intestine. There are 4 types to the colon; the ascending, transverse, descending and sigmoid colon. Lots of types of bacteria live in the colon. The colon is also the body’s last chance to absorb water and other minerals. Ascending Transverse Descending Sigmoid DIEASES/PROBLEMS:-colon cancer Rectum That’s where the large intestines pushes the poo into. It is about 20 centimeters long. And that’s where the poo stays until it gets pushed through the anus, which is a ring of muscle at the end of the rectum. HOW IT WORKS: When anything (gas/stool) enters rectum, it sends message to brain by sensors, brain decided whether the contents in rectum can be releases or not ,if contents can be released, sphincters relax allowing materials to escape, if contents can not be released, sphincters contract. DISEASES/PROBLEMS:
hemorrhoids- swollen/inflamed veins
anal laceration- cut inside anus
Mouth -The process of digestion begins even before you put food in the mouth, it begins when the salivary glands are stimulated by the smell or thoughts of a certain food.
-The production of saliva is the first step in digestion. It also prepares the body for a meal
- When food is put in the mouth the tongue moves it around and saliva produce coats and lubricates the food for easier chewing and swallowing.
- The movement of the jaw and tongue help to swallow the food
- As you swallow, a flap automatically covers the entrance of the windpipe (to prevent choking).
-The pharynx, often referred to as the throat, is a hollow tube approximately 5 inches long that starts behind the nose and goes down to the neck to become part of the esophagus.
-The Pharynx is the common path for food, fluids , and air.
-The Pharnynx has 4 parts. Pharnyx Nasopharnyx Oropharnyx Hypopharnyx Behind the nose and is the upper part of the throat. The nostrils lead into the nasopharynx. Two openings on the side of the nasopharynx lead into the ear. The nasopharynx is the most important part in digestive and the respiratory system. Air from the nose passes through here. The oropharynx is the middle part of the throat. The oropharynx includes the soft palate (the back of the mouth), the base of the tongue, and the tonsils. Because food and air both pass through here a flap of connective tissue called the epiglottis closes over the glottis when food is swallowed to prevent aspiration The Hypopharynx is the bottom part of the throat. Air going to the lungs passes through here. Epiglottis -The epiglottis is flap of cartilage located in the throat behind the tongue and in front of the larynx.
-The epiglottis is usually upright at rest allowing air to pass into the larynx and lungs.
-When a person swallows the epiglottis folds backward to cover the entrance of the larynx so food and liquid do not enter the windpipe and lungs.
-After swallowing the epiglottis returns to its original upright position.
Esophagus -the esophagus is the least complex section of the digestive tube.
-Its role in digestion is simple: to convey boluses of food from the pharynx to the stomach.
-The esophagus begins as an extension of the pharynx in the back of the oral cavity.
-then courses down the neck next to the trachea, through the thoracic cavity, and penetrates the diaphragm to connect with the stomach in the abdominal cavity.
the esophagus has four tunics
First, instead of the muscular tunic being entirely smooth muscle, as it is in the stomach and intestines, the wall of the esophagus contains a variable amount of striated muscle
Second, instead of the esophagus being free as it courses through the thoracic cavity, it is embedded in the connective tissue; thus, its outer tunic is referred to as adventitia instead of serosa.
Super Happy Fun Awesome Noodle Hut Birds have a gizzard made of four muscular bands that rotate and shift the food from one area to the next inside the gizzard. This also crushes the food making it easier for the bird to digest. The gizzards in some species of birds contain stone or grit that has been swallowed by the bird to help it digest the food. Birds don’t have teeth to chew their food, so the grit does the job that teeth normally would. Gizzard stones are common between birds and also prehistoric dinosaurs. ...VS... Welcome... ...to a tour of the human digestive system... Note I:(Me, Linda and Julia): BE ENTHUSIATIC (sp?). Act like Ms. Frizzle from the Magic School Bus.
Note II (just me): Remember to delete these notes. Demonstration of how the rectum works... Quiz Time!!!!! Pre-"tour" talk. paragraphs, concept,