Human Physiology II — High-Yield Review

Highest-Yield Facts by Unit

Unit 1 — Heart

• High yield: Cardiac output (CO) = heart rate (HR) × stroke volume (SV).
• Fast-response contractile cells vs slow-response pacemaker cells (funny current If, SA node).
• High yield: Stroke volume = EDV − ESV; regulated by preload (Frank-Starling), contractility (inotropy), afterload.
• Cardiac cycle: atrial systole → isovolumetric contraction → ejection → isovolumetric relaxation → filling.

Unit 2 — Hemodynamics

• High yield: Flow = ΔP/resistance; resistance ∝ 1/r⁴ (Poiseuille) — radius dominates.
• High yield: MAP = diastolic + 1/3(pulse pressure).
• Starling forces govern capillary exchange; edema from imbalance.

Unit 3 — Blood

• High yield: Hemostasis = vascular spasm → platelet plug → coagulation cascade → fibrinolysis.
• Intrinsic vs extrinsic vs common pathway; thrombin converts fibrinogen → fibrin.

Unit 4 — Respiratory

• High yield: Boyle's law drives ventilation; surfactant lowers surface tension (Laplace).
• High yield: FEV1/FVC < 0.7 → obstructive; ↓ both → restrictive.
• O₂-Hb curve shifts right (Bohr, ↑T, ↑2,3-BPG) → unloading; CO₂ → bicarbonate + carbamino.

Unit 5 — Renal

• High yield: GFR autoregulated (myogenic + tubuloglomerular feedback); measured by creatinine clearance.
• High yield: Countercurrent multiplier (loop of Henle) concentrates urine; ADH inserts aquaporin-2.

Unit 6 — Acid-Base

• High yield: Buffers (bicarbonate) → respiratory compensation (PCO2) → renal compensation (H+ secretion, new bicarbonate).
• Metabolic vs respiratory acidosis/alkalosis.

Unit 7 — GI

• High yield: Enteric nervous system; slow waves (Cajal cells) set rhythm.
• Gastrin, CCK, secretin; HCl (parietal), pepsinogen (chief), bicarbonate (duct), bile salts.

Unit 8 — Endocrine

• High yield: HPT axis (TRH→TSH→T3/T4); HPA axis (CRH→ACTH→cortisol).
• Insulin (anabolic) vs glucagon (catabolic); fed vs fasting states.

Unit 9 — Reproductive

• High yield: Male HPG axis (GnRH→FSH/LH→testosterone); erection = parasympathetic (NO), ejaculation = sympathetic.
• Female: ovarian cycle (follicular → ovulation → luteal) + menstrual cycle; LH surge → ovulation.
• Parturition = positive feedback (oxytocin + prostaglandins).

Comparison Tables

Cumulative Self-Check (20 questions)

1. Write the cardiac output equation.
2. What is the dominant factor in vascular resistance?
3. Define mean arterial pressure.
4. Sequence the four phases of hemostasis.
5. Name the two pathways of the coagulation cascade and their convergence.
6. Which law explains inspiration (pressure-volume)?
7. What distinguishes obstructive from restrictive disease on spirometry?
8. Which factors shift the O₂-Hb curve right, and what does that mean?
9. Name the three processes of urine formation.
10. What is the countercurrent multiplier, and what does it do?
11. How does ADH concentrate urine?
12. Name the three lines of acid-base defense in order.
13. What generates GI slow waves?
14. Name the source and action of gastrin and CCK.
15. Trace the HPT axis.
16. Differentiate insulin from glucagon action.
17. What triggers the LH surge?
18. What drives parturition (feedback type)?
19. Differentiate primary from secondary (intrinsic/extrinsic) hemostasis.
20. What does the baroreceptor reflex do?

Answers and Rationales

1. CO = HR × SV.
2. Vessel radius (resistance ∝ 1/r⁴).
3. MAP = diastolic + 1/3(systolic − diastolic).
4. Vascular spasm → platelet plug → coagulation → fibrinolysis.
5. Intrinsic and extrinsic converge on the common pathway (factor X → thrombin → fibrin).
6. Boyle's law (P × V constant) — diaphragm lowers intra-alveolar pressure below atmospheric.
7. Obstructive = FEV1/FVC < 0.7; restrictive = both FVC and FEV1 reduced (ratio normal/high).
8. ↑Temp, ↑PCO2/↓pH (Bohr), ↑2,3-BPG — right shift = easier O₂ unloading.
9. Filtration, reabsorption, secretion.
10. Loop of Henle + vasa recta create a medullary osmotic gradient to concentrate urine.
11. ADH inserts aquaporin-2 in collecting duct → water reabsorption.
12. Buffers → respiratory (PCO2) → renal (H+ secretion/new bicarbonate).
13. Interstitial cells of Cajal.
14. Gastrin (G cells) → HCl; CCK → gallbladder contraction + pancreatic enzyme secretion.
15. Hypothalamus (TRH) → pituitary (TSH) → thyroid (T3/T4), negative feedback.
16. Insulin = anabolic (uptake/storage); glucagon = catabolic (glycogenolysis, gluconeogenesis).
17. Rising estrogen (positive feedback) mid-cycle.
18. Positive feedback — oxytocin + prostaglandins amplify contractions.
19. Primary = platelet plug; secondary = coagulation cascade (fibrin).
20. Buffers short-term BP changes (negative feedback via heart rate and vessel tone).

Last-Minute Review

• Cardiovascular: CO = HR×SV; preload/afterload/contractility; MAP; Starling forces; baroreflex.
• Respiratory: ventilation (Boyle, surfactant), volumes/capacities, gas exchange (Fick, V/Q), transport (O₂ curve, CO₂ forms), control (central/peripheral chemoreceptors).
• Renal/acid-base: filtration → reabsorption → secretion; countercurrent; RAAS; buffers → respiratory → renal compensation.
• GI: enteric nervous system, slow waves, hormones, digestion/absorption.
• Endocrine: HPT/HPA axes, insulin/glucagon, fed/fasting.
• Reproductive: HPG axes, ovarian/menstrual cycles, parturition, lactation.

Related

• Subject overview
• Topic 04 — Cardiac Output and its Regulation
• Topic 17 — Glomerular Filtration
• Topic 22 — Acid-Base Balance