Anatomy_ heart pump physiology Flashcards
(28 cards)
What are the main arteries in the heart?
Left main CA
Right main CA
List the layers of the arterial walls (from superficial to deep):
Tunica adventitia
Tunica media
Tunica intimia
In contrast to skeletal muscle, heart muscle cannot _______ ? why?
- tetanize; due to phase 2 of AP (plateau)
Inward movement of
-Ca2+ sustains depolarization longer than skeletal muscle
What sets fiber length in Heart?
Left ventricular- EDV or preload
Define end diastolic volume (EDV):
volume of blood in the ventricle at the end of filling (diastole)
Define end systolic volume (ESV):
volume of blood left in the ventricle at the end of contraction (systole)
Define stroke volume (SV):
SV is the volume (mL) of blood ejected from the left ventricle with each contraction
What are the determinants of SV?
Preload, afterload, contractility
The difference between EDV and ESV (EDV-ESV)
What measurement is the best indicator of heart performance and disease prognosis?
Ejection fraction
What are the determinants of EF?
Stroke volume divided by EDV
What is a normal EF?
50-75%
LV norm: 62%
Define cardiac output (CO):
the volume of blood ejected from the left ventricle every minute
What are the determinants of CO?
HR x SV
Define preload:
diastolic filling of the left ventricles
Define afterload:
the resistance to emptying during contraction. The pressure the LV must generate to squeeze blood into the aorta
What does the Frank Starling Law of the heart?
the FS law suggests that the heart will contract with greater force when preload (EDV) is increased; length-tension principle.
Define myocardial contractility:
the squeezing contractile force that the heart can develop at a given preload or cardiac stretch
What regulates an increase in myocardial contractility?
- beta- sympathetic adrenergic nerve activity (most influential)
- catecholamines (epinephrine norepinephrine)
- amount of contractile mass
- Drugs can alter (e.g., digitalis, sympathomimetics)
What determines preload or EDV?
venous return
What factors can decrease myocardial contractility?
- loss of contractile mass - myocardial Infarction
- myocardial muscle disease - cardiomyopathy
- drugs: anesthetics, barbiturates
Define systolic blood pressure (SBP):
pressure measured in brachial artery during systole (ventricular emptying and ventricular contraction period)
Define diastolic blood pressure (DBP):
pressure measured in brachial artery during diastole (ventricular filling and ventricular relaxation)
Define mean arterial pressure (MAP):
“average” pressure throughout the cardiac cycle against the walls of the proximal systemic arteries (aorta)
How is MAP measured?
.33 x (SBP-DBP) + DBP
