CV5 Cardiac Cycle and Vent Performance Flashcards
The heart accepts blood at ___ pressure during ____ and the propels it forward at ____ pressures during ____
low, dias, high, sis
If cardiac output is intermittent how does tissue bloof flow remian relatively constant?
Distension of the aorta and its braches during systole and elastic recoil during diastole
Stephen Hales
Drew the analogy b/w resistance and compliance elements of the CV to a windkessel reservoir
Otto Frank
Formualted the two-element windkessel model consisting of a resistance and compliance element
Cardiac cycle
Sequence of electrical and mechanical events that repeats with every heartbeat
For a typical heart rate of ___ bpm the cardiac cycle has a total time of
75bpm, 0.8s
What produces heart sounds?
opening and closing valves
Stroke volue
The amount of blood pumped by the LV during one cardiac cycle
Calculate SV
SV=LVEDV=LVESV
Ejection fraction should exceed
SV/LVEDV
55% in a healthy person
Greater venus return means __ filling pressure
greater
Preload
Force that stretches the relaxed muscle fiber (end-diastolic volume)
LVEDPtm = ____ - _____
LVEDPtm= LVEDP - pericardial pressure
Frank-Starling “Law of the Heart”
SV increases in response to an increase in the volume of blood
Inflow phase (Phase 1)
Mitral valve is open
Aortic valve is closed
Isovolumic contraction
Both valves closed - no flow
Outflow phase
Mitral valve closed
Aortic valve open
Isovolumic relaxation
Both valves closed no flow
Phase 1 - Inflow
Diastole (passive and active)
Mitral valve open - Aortic valve closed
Rapid vent filling
Diastasis - decreased vent filling
Atrial cont - vent filling
Phase 3 (Outflow)
Systole
Mitral valve closed - aortic valve open
Rapid vent ejection
Decreased vent ejection
Phase 4
Diastole
Both valves closed
Cardiac cycle
seq of elctrical and mech events
Cardiac reserve
The difference b/w a person’s max output and output at rest
Preload
Force that stretches the relaxed muscle fiber (EDV)
What determines the preload?
Venous return and filling time
The load the vent faces before it contracts EDV
preload
Normal EDV is ____ mL and is optimal because
120, optimal overlap of actin and myosin in sarcomere
Frank-Starling law of the heart
stroke volume increases in response to an increase in the volume of blood filling the heart when all other factors remain constant
Contractility
Cardiac performance at a given preload and afterload (ejection fraction) Rate of pressure development (P/t)
When we exercise we have ___ ___ of contractility
increased force
Afterload
The load the vent faces before it begins to contract (aortic pressure)
