Digestive System
Describe the primary functions of the large intestine
What is: absorption of water and electrolytes, and formation and storage of feces.
What is the main muscle responsible for changing the volume of the thoracic cavity during breathing?
What is the diaphragm?
This part of the heart receives oxygen-rich blood from the lungs.
What is the left atrium?
The general term for the subunits that make up carbohydrates.
What are monosaccharides?
These folds in the stomach lining allow it to expand after a large meal.
What are rugae?
The muscular contractions that move food through the digestive tract.
What is peristalsis?
This is the term for the volume of air that remains in the lungs after a maximal exhalation.
What is residual volume?
Why do veins have valves, and why are they especially important in the legs?
What is: to prevent backflow; they help return blood to the heart against gravity?
This process breaks glycosidic linkages in polysaccharides by using water and an enzyme.
What is enzymatic hydrolysis?
The trachea is reinforced with these structures to prevent collapse during breathing.
What are cartilage rings?
Identify and describe one major adaptation of the stomach lining that protects it from self-digestion.
the secretion of mucus by goblet cells forms a protective barrier against acidic gastric juice?
Explain the difference between external and internal respiration.
What is: external respiration is the exchange of gases between alveoli and blood; internal respiration is the exchange between blood and body tissues?
Which blood vessels have the greatest total cross-sectional area, and how does this affect blood flow?
What are capillaries; their large area slows blood flow, allowing efficient exchange?
Describe the structure of a triglyceride and explain how it is broken down during digestion.
A triglyceride has one glycerol and three fatty acids. Lipase breaks it down into monoglycerides and free fatty acids for absorption.
During protein digestion, this enzyme is secreted in an inactive form and activated in the presence of stomach acid.
What is pepsin (secreted as pepsinogen)?
Explain how the liver contributes to nutrient metabolism and detoxification immediately after nutrient absorption.
What is: via the hepatic portal vein, absorbed nutrients pass through the liver where metabolism, storage, and detoxification occur before entering systemic circulation?
Explain the mechanism by which changes in blood pH influence breathing rate, including the receptors involved.
Chemoreceptors in the medulla and carotid bodies detect pH changes from CO₂ levels, stimulating increased ventilation to restore pH balance?
Trace the path of blood from the right atrium to the left atrium, naming all major vessels, valves, and chambers.
What is: right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs → pulmonary vein → left atrium?
Identify the specific bond formed between amino acids and name the reaction that creates it.
What is a peptide bond, formed by dehydration synthesis?
Explain why a high temperature can permanently deactivate an enzyme.
What is because it denatures the enzyme by disrupting hydrogen bonds and altering its 3D structure?
Describe the process of fat digestion and absorption from emulsification to lymphatic entry.
What is: bile emulsifies fats → lipase breaks triglycerides into monoglycerides and fatty acids → absorbed → enter lacteals (lymphatic system)?
Name three structural features of alveoli that optimize gas exchange and explain how each helps.
What are: thin walls (short diffusion distance), large surface area (maximizes contact), and moist lining (dissolves gases for easier diffusion)?
Explain how the SA node functions as the heart's pacemaker.
What is: it generates electrical impulses that initiate each heartbeat and coordinate atrial contraction?
Compare the structures of cellulose and starch and explain why only one is digestible by humans.
Starch has α-glucose linkages digestible by amylase; cellulose has β-glucose bonds humans lack enzymes to break.
Explain how diffusion is common amongst the respiratory, digestive, and circulatory systems—and describe the role of concentration gradients in each case.
What is: in the alveoli, oxygen diffuses into blood and CO₂ out due to gas concentration gradients; in the small intestine, nutrients like glucose diffuse into capillaries because they're more concentrated in the lumen; in systemic capillaries, oxygen and nutrients diffuse from blood to cells where concentrations are lower?