Digestive System Flashcards
Functions of Digestive System
The mechanical and chemical breakdown of food and the absorption of nutrients. Excretion of waste.
Consists of alimentary canal and accessory organs
Mucosa - protects tissues and carries on absorption
Submucosa - glands, blood vessels, nerves
Muscular Layer - smooth muscle, pushes food (PERISTALSIS)
Serosa - lubricates surfaces
Two types of bowel movements
Mixing Movements:
mix food with digestive juices
Propelling Movements:
called peristalsis; pushes food down the tube
Mouth
Mouth - begins digestion by chewing and mixing with saliva
Palate - forms roof of oral cavity (hard and soft)
Uvula - back of the mouth
Tongue
Tongue - moves food, connects to floor of mouth via frenulum
Amylase
Amylase - enzyme breaks down starch into sugars
Mucus cells also produce mucus for lubrication during swallowing
Esophagus
The muscular tube that carries food and liquids from your mouth to the stomach.
Four regions of the stomach
There are four main regions in the stomach: the cardia, fundus, body, and pylorus.
The cardia (or cardiac region) is the point where the esophagus connects to the stomach and through which food passes into the stomach.
Located inferior to the diaphragm, above and to the left of the cardia, is the dome-shaped fundus.
Below the fundus is the body, the main part of the stomach.
The funnel-shaped pylorus connects the stomach to the duodenum. The wider end of the funnel, the pyloric antrum, connects to the body of the stomach.
Pyloric canal
The narrower end is called the pyloric canal, which connects to the duodenum.
Pyloric sphincter
The smooth muscle pyloric sphincter is located at this latter point of connection and controls stomach emptying.
In the absence of food, the stomach deflates inward, and its mucosa and submucosa fall into a large fold called a ruga.
Stomach lining
Mucus prevents stomach from digesting itself, small openings called gastric pits contain glands
Glands secrete gastric juices to breakdown food
Pepsin
Pepsin - most important digestive enzyme for breaking down food
Mechanical Digestion
Mechanical - Food being broken down in smaller pieces (ex: chewing and churning of the stomach)
Chemical Digestion
Chemical - Substances in our digestive organs are released that change food particles into particles that are chemically different (ex: acids and bases)
Chyme
Chyme is the semi-fluid mass of partly digested food that is expelled by a person’s stomach, through the pyloric valve, into the duodenum.
Small Intestine
Chyme released from the stomach enters the small intestine, which is the primary digestive organ in the body. Not only is this where most digestion occurs, it is also where practically all absorption occurs.
Duodenum
The shortest region is the 25.4-cm (10-in) duodenum, which begins at the pyloric sphincter. Just past the pyloric sphincter, it bends posteriorly behind the peritoneum, becoming retroperitoneal, and then makes a C-shaped curve around the head of the pancreas before ascending anteriorly again to return to the peritoneal cavity and join the jejunum.
Jejunum
The jejunum is about 0.9 meters (3 feet) long (in life) and runs from the duodenum to the ileum. Jejunum means “empty” in Latin and supposedly was so named by the ancient Greeks who noticed it was always empty at death. No clear line exists between the jejunum and the final segment of the small intestine, the ileum.
Ileum
The ileum is the longest part of the small intestine, measuring about 1.8 meters (6 feet) in length. It is thicker, more vascular, and has more developed mucosal folds than the jejunum. The jejunum and ileum are tethered to the posterior abdominal wall by the mesentery. The large intestine frames these three parts of the small intestine.
Large Intestine
The large intestine is subdivided into four main regions: the cecum, the colon, the rectum, and the anus. The ileocecal valve, located at the opening between the ileum and the large intestine, controls the flow of chyme from the small intestine to the large intestine.
Cecum
Cecum - start of large intestine, has an attached appendix
Colon
Colon - 4 sections Ascending Transverse Descending Sigmoid
Rectum
Rectum – stores waste before it is expelled from the body
Anus
Anus - muscular sphincter which controls the exit of waste
Function of Large Intestine
Secretes mucus, reabsorbs water, contains bacteria to aid in digestion
Mass Movements (defecation) - removes undigested food
The main job is: Water Reabsorption
Bristol Stool Chart
Diagnostic medical tool designed to classify the form of human feces into seven categories. Type 1 and 2 - Constipation Type 3 and 4 - Normal Type 5 - Lacking Fiber Type 6 - Mild Diarrhea Type 7 - Severe Diarrhea
Liver
The liver is the largest gland in the body, weighing about three pounds in an adult. It is also one of the most important organs. In addition to being an accessory digestive organ, it plays a number of roles in metabolism and regulation. The liver lies inferior to the diaphragm in the right upper quadrant of the abdominal cavity and receives protection from the surrounding ribs.
Gallbladder
The gallbladder stores and concentrates bile, releasing it when it is needed by the small intestine.
Pancreas
The pancreas is responsible for secretion of digestive enzymes and bicarbonate
