digestive

Chapter 21: Digestive Physiology

Q1: Where does digestion mainly take place, and where do absorbed products go?
A1: Digestion takes place mainly in the lumen of the GI tract. Absorbed products pass into the extracellular fluid (ECF) compartment.

Q2: List and describe the four layers of the GI wall (inner to outer).
A2:

  1. Mucosa: Secretion and absorption.

  2. Submucosa: Contains blood vessels and nerves.

  3. Muscularis Externa: Responsible for motility.

  4. Serosa: Protective outer layer.

Q3: What anatomical modifications increase surface area in the stomach and intestine?
A3:

  • Stomach: Gastric pits and folds (rugae).

  • Intestine: Villi, microvilli, and circular folds (plicae circulares).

Q4: What are the functions of the stomach, small intestine, and large intestine?
A4:

  • Stomach: Storage, mechanical and chemical digestion.

  • Small Intestine: Digestion and absorption of nutrients.

  • Large Intestine: Water absorption, electrolyte balance, feces formation.

Q5: What do parietal cells, chief cells, G cells, and mucous cells secrete?
A5:

  • Parietal Cells: HCl and intrinsic factor.

  • Chief Cells: Pepsinogen.

  • G Cells: Gastrin.

  • Mucous Cells: Mucus and bicarbonate.

Q6: What is the role of interstitial cells of Cajal (ICCs)?
A6: They act as pacemakers for smooth muscle contractions, regulating GI motility.

Q7: Describe the three patterns of muscle contraction in the gut.
A7:

  1. Peristalsis: Wave-like contractions for movement.

  2. Segmentation: Mixing contractions for absorption.

  3. Tonic Contractions: Sustained contractions for pressure.

Q8: What are the functions of saliva?
A8: Lubrication, digestion (amylase), antibacterial properties, and taste perception.

Q9: What is the result of food processing in the oral cavity?
A9: Mechanical breakdown (chewing), chemical digestion (amylase), and formation of a bolus for swallowing.

Q10: Describe the cephalic, gastric, and intestinal phases of digestion.
A10:

  • Cephalic Phase: Prepares stomach for digestion via sight, smell, or thought of food.

  • Gastric Phase: Stimulates gastric secretion and motility when food enters the stomach.

  • Intestinal Phase: Regulates gastric emptying and stimulates pancreatic/biliary secretions when chyme enters the small intestine.

Q11: What are the three general functions of the stomach?
A11: Storage, mechanical/chemical digestion, and regulation of chyme release.

Q12: What are the key GI hormones and their functions?
A12:

  • Gastrin: Stimulates gastric acid secretion.

  • Secretin: Stimulates pancreatic bicarbonate secretion.

  • CCK: Stimulates bile release and pancreatic enzyme secretion.

  • Motilin: Regulates GI motility.

Q13: What is the significance of the hepatic portal system?
A13: It transports absorbed nutrients from the intestines to the liver for processing and detoxification.

Q14: What enzymes break down carbohydrates, proteins, and lipids?
A14:

  • Carbohydrates: Amylase, maltase, sucrase, lactase.

  • Proteins: Pepsin, trypsin, chymotrypsin, peptidases.

  • Lipids: Lipase, bile salts.

Q15: What are zymogens?
A15: Enzymes secreted in an inactive form (e.g., pepsinogen, trypsinogen).

Q16: How is fat absorbed, and what are fat-soluble vitamins?
A16: Fats are emulsified by bile salts, digested by lipase, and absorbed as micelles. Fat-soluble vitamins: A, D, E, K.

Q17: What are the key components of bile, and how does it facilitate fat breakdown?
A17: Bile contains bile salts, cholesterol, phospholipids, and bilirubin. It emulsifies fats into smaller droplets for digestion by lipase.

Q18: Diagram the process of carbohydrate, protein, and fat breakdown and absorption.
A18:

  • Carbohydrates: Broken into monosaccharides, absorbed via active transport.

  • Proteins: Broken into amino acids, absorbed via active transport.

  • Fats: Broken into fatty acids and monoglycerides, absorbed via diffusion.

Chapter 24: Immunity

Q1: Define immunity.
A1: The body's ability to resist infection and disease.

Q2: What are the three major functions of the immune system?
A2: Defense against pathogens, removal of damaged cells, and recognition/removal of abnormal cells (e.g., cancer).

Q3: What are primary and secondary lymphoid tissues?
A3:

  • Primary: Bone marrow and thymus (lymphocyte maturation).

  • Secondary: Lymph nodes, spleen, tonsils (immune response initiation).

Q4: What is the difference between innate and adaptive immunity?
A4:

  • Innate: Non-specific, immediate response.

  • Adaptive: Specific, memory-based response.

Q5: Which cells mediate innate and adaptive immunity?
A5:

  • Innate: Neutrophils, macrophages, dendritic cells, NK cells.

  • Adaptive: B cells, T cells.

Q6: What are the five types of white blood cells, and their functions?
A6:

  • Granulocytes: Neutrophils (phagocytosis), eosinophils (parasites), basophils (allergies).

  • Agranulocytes: Lymphocytes (adaptive immunity), monocytes (phagocytosis).

Q7: What is phagocytosis?
A7: The process by which phagocytes engulf and digest pathogens.

Q8: What are PAMPs and PRRs?
A8:

  • PAMPs: Pathogen-associated molecular patterns (on pathogens).

  • PRRs: Pattern recognition receptors (on immune cells that recognize PAMPs).

Q9: What are lymphocyte clones?
A9: Groups of identical lymphocytes that respond to a specific antigen.

Q10: How do memory cells differ from effector cells?
A10:

  • Memory Cells: Long-lived, provide rapid response upon re-exposure.

  • Effector Cells: Short-lived, actively combat current infection.

Q11: What are the five classes of antibodies, and their functions?
A11:

  • IgG: Most abundant, crosses placenta.

  • IgA: Found in secretions (e.g., saliva, milk).

  • IgE: Involved in allergic reactions.

  • IgM: First antibody produced in infection.

  • IgD: Function not fully understood.

Q12: What is the difference between MHC I and MHC II?
A12:

  • MHC I: Presents intracellular antigens to CD8+ T cells.

  • MHC II: Presents extracellular antigens to CD4+ T cells.

Q13: What is the difference between active and passive immunity?
A13:

  • Active Immunity: Acquired through exposure or vaccination (long-lasting).

  • Passive Immunity: Acquired through antibody transfer (short-term).

Chapter 26: Reproductive Physiology

Q1: What is the role of the SRY gene in male development?
A1: The SRY gene on the Y chromosome initiates male development by triggering testes formation.

Q2: What are the key hormones in male sexual development?
A2: Testosterone, DHT, and anti-Müllerian hormone (AMH).

Q3: What is cryptorchidism?
A3: Failure of the testes to descend into the scrotum.

Q4: What are the stages of the menstrual cycle?
A4:

  • Ovarian Cycle: Follicular phase, ovulation, luteal phase.

  • Uterine Cycle: Menstrual phase, proliferative phase, secretory phase.

Q5: What are the key hormones in the menstrual cycle?
A5: FSH, LH, estrogen, and progesterone.