Exam 1 in One Page - Physiology I

Equations¶

Osmolality: c · n. Molality times particles per solute. NaCl gives 2, glucose 1.
Osmotic pressure: π = n · C · R · T · φ. R = 62.36 L·mmHg/(K·mol), T = 310 K.
Diffusion rate: ∝ (gradient × area × temperature × permeability) ÷ (thickness × molecular weight × medium density).
Nernst: E_X = −(61.5/z) · log₁₀([X]_i/[X]_o). z = −1 for Cl⁻, +2 for Ca²⁺.
Ion current: I_X = G_X(V_m − E_X).
Chord conductance: V_m = Σ (G_X/G_total) E_X.
Excitability gap: threshold − V_m. Smaller means more excitable.
Length constant: λ = √(r_m/r_i). Assignment 2 only.
Size principle: I = CV. Smaller cell, smaller C, less current needed.
Power: P = F × v. Peaks near one third of maximum force.

Numbers¶

Body water / ICF / ECF (70 kg)	42 / 28 / 14 L
Normal osmolality	280–310, target 290
Normal saline	154 mmol/kg, 308 mOsm
E_K / E_Na course chart	−88 / +61 mV
E_Ca / E_Cl	+123 / −47 mV
Neuron resting / threshold	−70 / −60 to −55 mV
Neuron AP peak / duration	+30 mV / 1 ms
Na⁺-K⁺ pump	3 out / 2 in
Electrotonic / saltatory	0.5–2 / 10–150 m/s
Skeletal AP / twitch	2 ms / 10–100 ms
ATP: CP / glycolysis / oxidative	1 / 2 / 34 (FFA 90–140)
Durations: CP / glycolysis	~10 s / < 2 min
Unfused / fused tetanus	~25 / ~50 Hz
Cardiac AP / twitch	~200 / ~400 ms
Cardiac resting / peak	−90 / ~+20 mV
Cardiac Ca²⁺ in / SR	20 / 80%
Removal SERCA / NCX / PMCA	70 / 28 / 2%
Smooth twitch	~5 s

Chains to narrate cold¶

Negative feedback: perturbation → sensor → afferent → integrating center vs set point → error signal → efferent → effector.
Resting potential: K⁺ leak out >> Na⁺ leak in, plus electrogenic pump.
Action potential: threshold → Na⁺ channels open → +30 mV, Na⁺ inactivates, K⁺ opens → repolarize → hyperpolarize → reset.
Synapse: AP → Ca²⁺ in → exocytosis → receptor on next cell.
NMJ: AP → ACh → nicotinic → EPSP → muscle AP → acetylcholinesterase.
Skeletal EC coupling: T tubule → DHPR → RyR → Ca²⁺ → TnC → tropomyosin → cross-bridge.
Cross-bridge: A·M → ATP binds, detaches → hydrolysis recocks → bind → P_i off → power stroke → ADP off.
Smooth: Ca²⁺ → calmodulin → MLCK → phosphorylated myosin → cross-bridge. Off: MLCP unopposed.
Cardiac: phase 2 Ca²⁺ in → RyR → CICR → TnC → contraction.
Sympathetic heart: NE → beta-1 → cAMP → PKA → Ca channel, RyR, phospholamban, TnI.

Traps the keys and the quiz bank have already set¶

Chloride’s z is −1. Forgetting the sign flips E_Cl.
Normal saline is iso-osmotic at 308, just inside the 280–310 range.
A regulated variable is a quantity. “Dehydration” is a state, and gets half credit.
Two different Nernst figures exist. Calculate from the course chart.
“Secondary active” means the driving gradient was built by a pump elsewhere.
Graded potentials have no threshold and no refractory period. Both are separate points.
Stimulating mid-axon propagates both ways. Only normal initiation is one-way.
Ouabain changes V_m gradually, not instantly. The “how fast” is its own point.
Cyclic AMP lowers smooth muscle force and raises cardiac muscle force.
Frank-Starling is proximity and calcium sensitivity, not overlap.
Parasympathetic effects on cardiac muscle are real but weak.
Cardiac muscle cannot be tetanized. Smooth muscle can.
Glucose does not dissociate. Multiply by 1, not 2.
The quiz bank’s osmolality target is “about 300.” The lecture says 290. Pick whichever is offered.
Resting potential “pick 2”: the Na⁺-K⁺ pump and K⁺ leak channels.
“Which body systems this semester”: muscular, cardiovascular, respiratory. Check all three.
Cardiac Ca²⁺ binds troponin C. The Assignment 4 key misprints this as tropomyosin.
Lidocaine binds open and inactivated Na⁺ channels, not resting ones.
Deep red is Type I. Type IIa is medium red. Type IIx is pale and the most powerful.
MLCP does not need Ca²⁺ and does not touch MLCK. It just dephosphorylates.
Skeletal muscle clears Ca²⁺ with SERCA only. Cardiac and smooth use SERCA, NCX, and PMCA.