B9: Animal Physiology, Circulation, Respiration and Homeostasis
Official Cambridge & Imperial ESAT specification requirements for Animal Physiology, Circulation, Respiration and Homeostasis on the Biology paper. Understand the syllabus boundaries, spot distractor traps engineered by examiners, and master the 2-step Sub-90 shortcuts that compress solve time well below the 88.8-second cutoff.
Official Syllabus Subtopics
Requirements specified in the UAT-UK framework
- 1Mammalian double circulatory system: systemic vs pulmonary circuits
- 2Cardiac cycle pressure-volume curves: atrial systole, ventricular systole, and diastole
- 3Heart valve actions: atrioventricular (bicuspid/tricuspid) and semilunar valves
- 4Blood vessels: thick elastic arteries (withstanding high pressure), wide-lumen veins with valves, thin single-cell capillaries
- 5Pulmonary ventilation mechanics: diaphragm and intercostal muscle contractions altering thoracic volume and pressure
- 6Renal physiology: nephron ultrafiltration at glomerulus/Bowman’s capsule, selective reabsorption in proximal convoluted tubule (PCT), loop of Henle countercurrent multiplier, and ADH osmoregulation
- 7Nervous coordination: reflex arc (sensory, relay, motor neurones), action potential propagation, and chemical synaptic transmission
- 8Endocrine homeostasis: negative feedback loops, insulin and glucagon blood glucose regulation
Sub-90 Exam Speed Tips
How top candidates solve this spec under the 88.8s clock
On cardiac cycle pressure graphs, the AV valve closes when ventricular pressure exceeds atrial pressure; the aortic valve opens when ventricular pressure exceeds aortic pressure.
In the nephron, glucose is 100% reabsorbed in the proximal convoluted tubule (PCT) via active transport under normal physiological conditions.
Examiners engineer distractor options using common algebraic expansions and sign slips. Always test structural ratios or invariants before calculating arithmetic values.
Tested Topics in Specification B9
Master the individual question patterns and Sub-90 shortcuts for this specification.
Cardiac Cycle Pressure/Valve Traces, ECG Intervals & Thorax Ventilation Mechanics
Valve Rule: Valves are passive one-way doors that open when upstream P > downstream P and snap shut at the exact graph intersection where downstream P > upstream P. Inhalation = Contract -> Flatten -> Volume UP -> Pressure DOWN.
Renal Vessels, Nephron Ultrafiltration, Selective PCT Reabsorption & ADH Osmoregulation
ADH Rule: More ADH = More Collecting Duct Permeability = More Water Reabsorbed into Blood = Less, More Concentrated Urine. In a healthy nephron: Protein in filtrate = 0; Glucose in urine = 0.
Nervous Reflex Arc, Synaptic Neurotransmission & Endocrine Homeostasis (Insulin/Glucagon, Thermoregulation & Menstrual Cycle)
Two classic physiology traps to eliminate immediately: (1) Blood vessels NEVER move closer to the skin; (2) Electrical impulses NEVER cross a synapse (neurotransmitters diffuse). Reflex arc order: Stimulus -> Receptor -> Sensory -> Relay (CNS) -> Motor -> Effector.
Ready to Master Specification B9 Under Exam Conditions?
Practice timed questions under the authentic Pearson VUE interface with live split stopwatch pacing, dry-wipe scratchpad, and distractor forensics.