Module 20: Digestive System Flashcards
What is another name for the digestive tract?
Alimentary canal
Four layers of tissue make up the walls of the digestive tract. Describe the mucosa
Innermost layer – consist of three layers, an inner layer of epithelium, a layer of loose connective tissue, and a thin layer of smooth muscle
What is the function of the muscularis?
regularly contracts and relaxes to propel food through the digestive tract
What is mechanical digestion?
Involves physically breaking down food into smaller pieces, beginning with chewing in the mouth and continuing with contractions and churning in the stomach and small intestine
What is chemical digestion?
Uses digestive enzymes produced in the salivary gland’s, stomach, pancreas, and small intestines to break down food particles into nutrients (such as glucose, amino acids, and fatty acids) that cells can use
What is the peritoneum?
Large membrane in the abdominal cavity that connects and supports internal organs
What are mesenteries?
Layers of visceral peritoneum which suspend the digestive organs within the abdominal cavity while anchoring them loosely to the abdominal wall
What do the mesenteries contain and supply?
Blood vessels, nerves, lymphatic vessels, and lymph nodes That supply the digestive tract
What is the greater omentum and its function?
Portion of the mesentery- extends from the greater curvature of the stomach and hangs down over the small intestines.
Function - Prevents friction and helps localize infection
What is the lingual frenulum?
A fold of mucous membrane that anchors the tongue to the floor of the mouth
What is the difference between the hard palate and soft palate?
Hard palate - Separates the mouth from the nasal cavity
Soft palate - consists of mostly skeletal muscle, forms an arch between the mouth and nasopharynx
What does saliva consist of?
Mostly water, but also containing mucus, an enzyme that kills bacteria, antibacterial compounds, electrolytes, and two digestive enzymes - amylase and lipase
What is the function of amylase in the saliva?
Breaks down starch
What is the function of lipase in saliva?
Begins the digestion of fat
What saliva gland becomes swollen with the mumps?
Parotid gland
What connects the pharynx to the stomach?
Esophagus
The muscularis layer of the stomach has an extra layer of oblique muscle. What does this allow the stomach to do?
contract and churn vigourously as it processes food
What happens to the rugae of the stomach when we eat?
the rugae flatten and the stomach expands
What is the role of mucous cells in the gastric pit?
secrete mucus, which protects the stomach lining and keeps the stomach from digesting itself
What is the role of the parietal cells in the gastric pit?
Secrete hydrochloric acid and intrinsic factor. Hydrochloric acid helps kill microbes in swallowed food
What is the role of chief cells in the gastric pit?
secrete digestive enzymes, such as pepsinogen
What is the role of Enteroendocrine cells in the gastric pit?
Secrete the hormone ghrelin (which stimulates the hypothalamus to increase appetite) and gastrin (which influences digestive function)
What is chyme?
Semi-fluid mixture of small food particles and gastric juice
What are the primary functions of the liver?
Storing and releasing glucose, processing vitamins and minerals, filtering toxins, and recycling old blood cells
Where is the portal vein carrying nutrient rich blood to the liver from?
The digestive organs and spleen
What is the role of the hepatic artery?
Delivers oxygenated blood from the aorta to the liver
Where does bile come from?
Produced in liver and stored in gallbladder
What is the role of Kuppfer cells?
Phagocytic cells - remove bacteria, worn out red blood cells, and debris from the bloodstream
How is blood filtered?
The blood filters through the sinusoids, allowing the cells to remove nutrients (such as glucose, amino acids, iron, and vitamins) as well as hormones, toxins, and drugs
What substances does the liver secrete into the bloodstream?
clotting factors, albumin, angiotensinogen, & glucose
What been carries the process blood out of the liver?
Central vein
What is the main purpose of the gallbladder?
Stores and concentrates bile
What is the exocrine function of the pancreas?
secretes about 1.5 L of pancreatic juice – essentially digestive enzymes and an alkaline fluid - into the small intestine
What is the role of the acinar cells?
Secrete digestive enzymes in an inactive form
Once activated in the duodenum, the enzymes help break down lipids, proteins, and carbohydrates
What is the role of duct cells?
Ducts Converge on the main pancreatic duct, which joins the bile duct at the hepatopancreatic ampulla
Most chemical digestion, and most nutrient absorption, occurs where?
Small intestine
What is the role of intestinal contractions in digestion?
Contractions in the small intestine -
help break down food particles
mix food with digestive juices
bring digested food in contact with intestinal mucosa to facilitate absorption
Where does segmentation occur?
Involves ring-like constrictions that occur at intervals along the small intestine
When does peristalsis begin?
When most of the nutrients have been absorbed and undigested residue remains
What increases the surface area of the small intestine, and why is this important?
circular folds, villi, & microvilli.
Help to maximize the absorption of vital nutrients
What is the role of the circular folds in digestion?
Slow the progress of chyme and increase its contact with mucosa
What is the role of the villi?
Epithelial cells covering the villi have a brush border of ultrafine microvilli. Besides further increasing the absorptive area, the microvilli produce digestive enzymes
What is the role of the goblet cells?
Secrete mucus that helps the passage of food
Where does the large intestine begin?
Cecum
What is the function of the large intestine in digestion?
Absorbs large amounts of water from the residue before passing the resulting waste material out of the body
What is the role of the bacteria found in the large intestine?
- Some digest cellulose and other materials that don’t have digestive enzymes
- other bacteria produce significant amounts of vitamins, particularly vitamin K and a B vitamin
What is the body’s primary energy source?
Carbohydrates
Carbohydrates consist of saccharides (sugars), what are the three saccharides?
Polysaccharides
Disaccharides
Monosaccharides
Polysaccharides contain many saccharide groups linked together, these include
Starches and glycogen
Disaccharides contain two saccharide groups linked together, these include
Sucrose, lactose, and maltose
Monosaccharides contain one saccharide group, these include
Glucose, fructose, and galactose
How many calories should adults obtain from carbohydrates?
40% to 50%
What is the primary goal of glucose catabolism?
To generate ATP
What are processes called that occur without oxygen?
Anaerobic
What are processes call that occur with oxygen?
Aerobic
Carbohydrate metabolism occurs in three phases, what are they?
- Glycolysis
- Anaerobic fermentation
- Aerobic respiration
What begins protein digestion in the stomach?
Pepsin (Acts on protein molecules by breaking peptide bonds)
What role does the pancreas play in the digestion of proteins?
Releases trypsin and chymotrypsin into the small intestine to break up peptide bonds
Protein digestion in the small intestine finishes with peptidases. What are peptidases, And what do they do to finish the process?
Brush border enzymes – break the remaining chains into individual amino acids which are then absorbed into the bloodstream
What is the main role of lipids? What are the 3 other roles?
Act as a reservoir of excess energy
- enables absorption of certain vitamins (ie. A, D, E, K)
- Contributes to cellular structure
- Insulates and protects the body
