Cardio W1 Flashcards
(132 cards)
muscarinic receptors of the heart and what acts on them
M2 receptors, acetylcholine
inotropic
force
chronotropic
HR
Frank Starling
as EDV increases, the SV increases
beta receptors on the heart and what acts on them
B1 receptors, noradrenaline
what does the PR interval indicate
AV node delay
what are striation of cardiac muscle caused by
contractile fibres
four phases of action potential generation in pacemaker cells
phase 0: Na+ channels open phase 1: Na+ close, transient K+ efflux phase 2: Ca++ open (L-type channels) phase 3: K+ efflux phase 4: resting potential
what is the A band
myosin only
what is the I band
between myosin
what is the H zone
between actin
What is happening when muscle is relaxed
no cross bridge because the actin binding site is blocked by the troponin- tropomyosin complex
what is happening when muscle contracts
Ca++ binds to troponin and pulls the troponin-tropomyosin complex away to expose binding site and cross bridge forms
actin-myosin cross bridge forms, power stroke pulls actin inwards during contraction
time of pacemaker cell AP vs Ventricular muscle AP
250ms, 800ms
what happens to calcium after AP has passed
Ca++ influx ceases and Ca++ goes back into SR by Ca++ATPase (relaxation)
what effects the stroke volume?
preload, afterload, myocardial contractility
Effect of sympathetic stimulation on frank starling curve and shift?
greater contractility, so for every EVD, there is a greater SV
Frank starling curve shifts to the left
How to record BP using kortkoff sounds
record systolic BP when you hear the 1st heart sound, then record diastolic BP when the heart sounds disappear
Normal HR
60-100BPM
normal systemic BP
90/60mmHg to 120/80mmHg
Definition of hypertension
average clinical BP of 140/90mmHg or above and a daytime average of 135/85mmHg or above
What is MABP
average arterial BP during a single cardiac cycle involving contraction and relaxation of the heart
How to calculate MABP
(2D+S)/3 or DBP+ (PP/3)
Normal range for MABP
70-105mmHg