Cardiovascular Physiology Flashcards
- Conduits
- Create Resistance
- Exchange
- Capacitance
- Large and small arteries
- Arterioles
- Capillaries
- Large and small veins
Negative resting potential of K and Na in heart
IC [K] > EC [K]
EC [Na]
Action potential phases
Phase 0: rapid depolarization (increased Na+ permeability)
Phase 1: slight repolarization (Cl- follows in)
Phase 2: plateau (Na and Ca in, K out)
Phase 3: rapid repolarization (increased K permeability)
Phase 4: restoration (active Na/K pumps)
Steps of contraction
- Depolarization
- Ca2+ to myofilaments during phase 2
- Ca2+ binds to troponin C
- Troponin-I slides off actin
- Binding site for myosin uncovered
- Power stroke with resulting shortening
Stages of contraction
Atrial systole –> isovolumetric contraction –> rapid ejection –> isovolumetric relaxation –> rapid ventricular filling
Heart sounds
I: MV and TV closure
II: AV and PV closure
III: rapid filling sound (MR, TR, ASD)
IV: atrial systolic sound (AS, PS, HTN)
Nicotinic receptor locations
All autonomic ganglion
Adrenal medulla
Neuromuscular junction
Muscarinic receptor locations
All effector organs
Alpha receptors
Excitatory except in GI tract
Beta receptors
Inhibitory (except in heart)
Beta 1: heart
Beta 2: bronchi, blood vessels
6 functions of the cardiovascular system
Transport and distribution of metabolic material
Removal of metabolic waste
Regulation of body temperature
Humoral communication from source to target
Adjustment of oxygen and nutrient conditions
Defense system against foreign invasion
What vessels have the highest pressure and smallest cross sectional area
Arteries
What vessels have the highest pressure drop and lowest blood volume
Arterioles
What vessels have the largest cross sectional area and lowest velocity
Capillaries
What vessels have the most volume and lowest blood pressure
Veins
Resting action potential
-90mV
3 membrane characteristics that cause resting potential to be -90mV
- High K inside, high Na outside, but K diffuses out much more easily than Na diffuses in
- Negatively charged proteins inside cell that can not diffuse out
- Na/K pump pumps more Na out then it does K in
Threshold value of action potential
-60 to -70mV
Only phase in action potential that requires oxygen and energy
Phase 4 because use Na/K pump
Explains why ST segments in EKG show oxygen delivery
Two gates for the rapid Na channels
M gate: activation
H gate: deactivation
M gate opens to allow rapid depolarization, H gate closes at -50 to -60mV (plateau phase)
5 difference between action potential of cardiac muscle cells and conduction cells
- Resting potential of -60 to -70
- Slow rising phase 0 (have much fewer Ma fast channels)
- No phase 1
- No plateau
- Gradually Depolarizing phase 4 (K accumulates in cell over time)
Example of drug that will increase slow of conduction cell phase 4 (so increases heart rate)
Norepinephrine
Examples of drugs that will decrease slope of phase 4 in conduction cells (slow heart rate)
Acetylcholine
Procainamide
Quinidine
Affect of a positive change (toward 0mV) of threshold potential
Takes longer to reach, slows heart rate
