bio 30 digestion test
How much food does an adult consume between ages 18-38?
About 20,000 kg, approximately 1 metric tonne per year.
Why do humans need a constant source of food?
To provide energy for biochemical reactions in metabolism.
What are the five basic activities of the digestive system?
Ingestion, movement, digestion, absorption, and elimination.
What influences specialization in different digestive regions?
Diet and method of ingestion (e.g., prechewed, liquid, unchewed food).
What is a "bolus"?
A small lump of chewed food formed during ingestion and moved through the digestive tract by peristalsis.
What is ingestion?
The act of eating, where food is taken into the digestive tract.
What is peristalsis?
The muscular movement of food through the digestive tract via waves of contractions that move a bolus along the tube gut.
What is digestion?
The physical and chemical breakdown of food, primarily by enzymes, into smaller molecules.
What is absorption?
The process where digested nutrients and water are absorbed into the body, primarily through the walls of the small and large intestines.
What is egestion?
The elimination of undigested material and waste from the body in the form of feces.
Where does most enzymatic digestion and nutrient absorption occur?
In the small intestine.
What is the function of the rectum?
Consolidation and storage of feces before elimination.
What is the colon’s main function in humans?
Absorption of water and minerals.
What does the stomach do?
Secretes acid and pepsin, stores and mixes food.
What does the pancreas produce?
An alkaline, enzyme-rich fluid to aid in digestion.
What is the role of the liver in digestion?
Produces bile and performs various homeostatic functions.
What does the salivary gland produce, and what is its function?
Produces saliva containing amylase, an enzyme that begins the breakdown of starch.
What is emulsification in digestion?
The forced mixing of fats to increase their surface area for enzyme action.
What is the purpose of bile, and where is it stored?
Bile neutralizes stomach acid and emulsifies fats; it is stored in the gall bladder.
What are the roles of villi and microvilli in the small intestine?
Increase surface area for nutrient absorption.
Why are protein-digesting enzymes like trypsin and pepsin secreted in inactive forms?
To prevent the digestion of proteins within the body’s own cells.
What are rugae in the stomach, and what is their purpose?
Folds in the stomach lining that allow it to expand as it fills.
What are the Crypts of Lieberkühn?
Tubular glands in the intestine that secrete an alkaline fluid to aid in digestion.
What is the function of goblet cells in the gut?
To produce mucus that protects and lubricates the lining of the digestive tract.
What is the role of the cardiac and pyloric sphincters?
Control food entry and exit in the stomach, preventing backflow.
What happens in the large intestine?
Absorption of water, minerals, and some vitamins; formation and storage of feces.
What is the appendix, and does it have a function?
A small sac that may have minor immune functions
How do the anal sphincters control defecation?
One sphincter is involuntary, triggered by stretching; the other is under voluntary control.
What happens when blood glucose rises after eating?
The pancreas releases insulin, which converts glucose to glycogen, lowering blood glucose
What happens when blood glucose drops from not eating?
The pancreas releases glucagon, converting glycogen to glucose, raising blood glucose.
What is appendicitis, and what causes it?
Inflammation of the appendix, often caused by trapped food or feces
What are symptoms and treatment options for appendicitis?
Symptoms: abdominal pain, fever, nausea, vomiting. Treatment: antibiotics or surgery.
How can you prevent appendicitis?
A fiber-rich diet, healthy weight, regular exercise, and avoiding smoking/alcohol.
What are bile salts?
Bile salts are substances made by the liver that help break down fats in the small intestine, making it easier for the body to digest and absorb them.
What role does the gallbladder play in digestion?
It stores bile produced by the liver and releases it into the small intestine to aid fat digestion.
What is chyme?
A soupy mixture of partially digested food and digestive juices formed in the stomach before moving to the small intestine.
Why does the pH vary in different parts of the digestive tract?
Different enzymes work best at different pH levels, so each region has the ideal pH for its specific digestive enzymes.
What is the role of the brush border in the small intestine?
The brush border, formed by microvilli on epithelial cells, contains enzymes that finish breaking down nutrients for absorption.
How do intestinal crypts (Crypts of Lieberkühn) support digestion?
They produce an alkaline fluid to maintain an optimal pH for enzymes and contain cells that secrete mucus for protection and lubrication.
What function does the large intestine serve in water balance?
It reabsorbs water from waste, helping to form solid feces and prevent dehydration.
Why is alcohol absorbed more quickly on an empty stomach?
With no food to slow it down, alcohol passes directly into the bloodstream through the stomach lining, speeding up its effects.
Stomach for the diagram (5)
Secretion and Source- gastric juice: stomach
Site of Action- stomach
Active Enzyme- pepsin
Substrate and Products- protein to peptides
Control of Secretion- reflex stimulation, stretching stomach walls, hormone gastrin
Pancreas for the diagram (5)
Secretion and Source- pancreatic juice: pancreas
Site of Action- duodenum
Active Enzyme- pancreatic amylase, trypsin, chymotripsin, pancreatic lipase
Substrate and Products- starch to maltose, protein to peptides, protein to peptides, fats to FAs and glycerol
Control of Secretion- via release of hormones secretin and cholecystokinin
Small Intestine for the diagram (5)
Secretion and Source- intestinal juice and enzymes: small intestine
Site of Action- small intestine
Active Enzyme- maltase, peptidases
Substrate and Products- maltose to glucose, polypeptides to amino acids
Control of Secretion- reflex action and contact with intestinal wall
What is mastication?
large particles are mixed with salvia and broken into smaller particles by chewing