mammalian digestion Flashcards
What are the two main parts of the mammalian digestive system?
Alimentary canal (digestive tract).
Accessory glands (secrete digestive juices via ducts).
What are the accessory glands of the digestive system?
3 pairs of salivary glands.
Pancreas.
Liver.
Gallbladder.
How does food move through the digestive tract?
Peristalsis (wave-like contractions of muscles).
What are sphincters, and what do they do?
Ring-like valves at junctions between compartments that regulate food passage.
What are the three main digestive sphincters?
Cardiac (between esophagus and stomach).
Pyloric (between stomach and small intestine).
Anal (controls waste elimination).
What does the tongue do in digestion?
Forms food into a bolus.
Pushes bolus into pharynx for swallowing.
What happens in the oral cavity during digestion?
Mechanical digestion (chewing).
Chemical digestion (salivary amylase breaks down starch).
Mucus lubricates food.
What prevents food from entering the trachea?
Epiglottis (a flap of tissue that covers the trachea during swallowing).
What are the functions of the stomach?
Stores food.
Churns food into chyme.
Secretes gastric juice for digestion.
What are the components of gastric juice, and what do they do?
HCl – Breaks down extracellular matrix in food.
Pepsin – Enzyme that breaks proteins into polypeptides.
Mucus – Protects stomach lining.
What prevents self-digestion in the stomach?
Mucus lining and replacement of epithelial cells every 3 days
What is chyme?
A mixture of gastric juices and food formed in the stomach.
What is the function of the pancreas in digestion?
Produces an alkaline solution that neutralizes stomach acid
Secretes digestive enzymes.
What is the function of the liver in digestion?
Produces bile, which helps emulsify fats.
Where is bile stored?
In the gallbladder.
Where does most digestion and absorption occur?
In the small intestine.
What are the three parts of the small intestine?
Duodenum – Receives chyme and digestive juices.
Jejunum – Major site of nutrient absorption.
Ileum – Absorbs remaining nutrients.
What structures increase the surface area of the small intestine for absorption?
Villi and microvilli
How are nutrients distributed after absorption?
Nutrients enter capillaries and veins.
Blood travels to the liver via the hepatic portal vein for processing.
What are the functions of the liver in nutrient distribution?
Regulates nutrient distribution.
Detoxifies harmful substances.
Stores energy-rich molecules.
What are the functions of the large intestine?
Reabsorbs water from undigested material.
Forms feces.
What is the cecum, and what does it do?
A pouch at the junction of the small and large intestine, important for fermenting plant material.
How does food move through the large intestine?
Segmentation (back-and-forth movement).
Takes 12-24 hours to pass through.
What causes diarrhea?
Less water than normal is reabsorbed due to irritation of the large intestine.
What causes constipation?
Too much water is reabsorbed, making feces hard and compacted.
