Ch. 25 Flashcards
endocardium
inner layer of the heart- lines the chambers, reduces friction as blood passes through the chambers
myocardium
middle layer of the heart- does majority of pumping/ contracting
epicardium
the outer layer of the heart; double-layered pleural sac, allows for reduction of friction,
flow of blood starting from superior/inferior vena cava
superior vena cava (from head and arms), or the inferior vena cava (from trunk and legs), into the right atrium, through the tricuspid valve into he right ventricle, up through the pulmonary semilunar valve, pulmonary trunk, left or right pulmonary artery into the lungs.
flow of blood from the lungs
from the lungs, blood flows in through branches of the left pulmonary vein, into the left atrium, through the mitral (bicuspid) valve, into the left ventricle, up through the aortic semilunar valve, into the right pulmonary artery, through the aortic arch, and out the descending aorta.
the atriums are surrounded by what kind of muscle
thin muscle
the ventricles are surrounded by what kind of muscle
thick muscle
Functions of the Circulatory
System
TRANSPORT- Delivers oxygen and nutrients to the tissues,
Carries waste products from cellular
metabolism to the kidneys and other excretory
organs, Circulates electrolytes and hormones, Transports various immune substances that
contribute to the body’s defense mechanisms
- helps regulate temperature
Low Pressure Pulmonary System
Gas Exchange
Low Pressure
Highly Distensible (stretchy)
Fluctuations
Arterial System/High Pressure Systemic
Circulation
O2 and Nutrients to tissues
High Pressure
Thick Walled (arteries are not stretchy)
cardiac output =
stroke volume x heart rate
blood flow
cardiac output is dependent on
Pressure Resistance Flow Distensibility ]Compliance
laminar blood flow
Reduces friction & prevents clotting factors from coming in
contact with the vessel wall
turbulent blood flow
Disordered flow
The blood moves crosswise and lengthwise in blood
vessels.
distensibility
Stretch and Accommodation of Volume
relative to pressure
Veins - More Distensible; Thinner
Arteries - Less Distensible; The Thicker &
bigger the vessel the greater the pressure it
has
compliance
(willingness to do what it is asked to do/ does it have more give)
Quantity Stored Relative to Pressure
Veins (super stretchy) vs Arteries (not v stretchy, cannot hold a large volume)
systole
Ventricles contracting and emptying of blood
diastole
ventricles relaxing and filling with blood
phases of the cardiac cycle
Atrial systole Ventricular systole Ventricular ejection Ventricular relaxation Ventricular filling
atrial systole (contraction)
Atria are Low Pressure Storage Chambers
70% of Blood flows Passively to Ventricles
Kick at end Represents last 30% (squeezes to get that last little bit of blood out)
ventricular systole
Ventricles contract Blood Moves Out The pressure of the blood forces the atrioventricular valves (tricuspid and Mitral) to shut - (producing the heart sound ‘lub’) - Coincides with S1
diastole
Ventricles relaxed
Blood entering atria
Blood under high pressure in the arteries
(pulmonary and aortic) causes the semi lunar (pulmonic and aortic) valves to shut
This produces the second heart sound, ‘dub’ -
corresponds to S2
cardiac output is
the Volume of blood flowing
through either the systemic or
pulmonary circuit in liters per minute
CO = HR x SV (stroke volume)
heart rate is
number of heart beats per minute
normal 60-100 bpm
increased HR and decreased stroke volume
Stroke volume us
the amount of blood pumped out by a ventricle with each beat at the end of diastole (Even after the heart contracts there will be some residual blood left over in the ventricle)
- preload, afterload, (myocardial) contractility
regulation of stroke volume
preload
pressure/stretch/Left Ventricular Wall stress at the end of diastole; depends on both heart and vascular system –the amount of filling of the ventricle during relaxation
preload is increased in
Increased circulating volume; (too much volume)
Heart Failure
Anything that increases amount of blood entering heart
preload is decreased in
Decreased circulating volume (bleeding,3rd spacing/fluid moving out of the vascular space)
Anything that reduces amount of blood entering into heart
afterload
resistance to ejection during systole; depends on both heart and vascular system - the force that opposes ejection of blood from the heart
afterload is increased in
Systemic resistance or High Blood
pressure
Myocardial Infarcts / Cardiomyopathy
- Lead to Compensatory RAAS, increase ADH - Leading
to Arterial Vasoconstriction & Venous constriction
afterload is decreased in
decreased volume
Frank-Starling law of the
heart & Sympathetic stimulation
contractility- Within limits, the greater the stretching of the muscle fibers (preload), the greater the force of contraction.
The extra force of contraction is necessary to pump the increased volume of blood from the ventricle.
Cardiac output increases
myocardial contractility
the ability of
the heart muscle to contract, the force of
contraction –
Shortening and Lengthening of cardiac fibers
(Actin and Myosin)
increased contractility
positive inotropic drugs (good squeeze drugs)
sympathetic stimulation (fear anxiety)
hypercalcemia
decreased contractility
drugs, infarction, cardiomyopathy, hypoxia
