75, heart cycle and murmurs

Exam 3

what does the pumping function of the heart creats

a pressure gradient that guarantees blood flor

what is systole

when the ventricles contract, blood is ejected into circulation

active phase

both AV valves are closed to prevent back flow

both semilunar valves are open, allowing blood to leave

what is diastole

after ejection is completed, the ventricles relax and fill again

passive phase

both semilunar valves are closed to prevent backflow from ejection

both av valves are open to allow blood to flow from large veins through atria into ventricles

what are atrial systole and diastole

shorter and begin and end before the related ventricular actions

what is phase 1 of the cardiac cycle

ventricular filling

diastole

what is phase 2 of the cardiac cycle

atrial contraction or atrial systole

diastole

what is phase 3 of cardiac cycle

isovolumetric ventricular contraction

systole

what is phase 4 of the cardiac cycle

ventricular ejection

systole

what is phase 5 of the cardiac cycle

isovoulmetric ventricular relaxation

diastole

what phases of the cardiac cycle are in diastole

5,1, and 2

what phases of the cardiac cycle are in systole

3 and 4

what is S2

DUB

closing of the semilunar valves and is the loudest over these valve areas

after ventricular ejection, during diastole

what is S3

ventricular filling

what is S4

atrial contraction or atrial systole

semilunar valve closure in horses

when are S3 and S4 used

in horses

what phase are S2,3, and 4 associated with

diastole

what phase is S1 associated with

systole

what is S1

LUB

AV valve closure and is loudest over mitral or tricuspid valve

pulse occurs just after S1

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What is preload

the degree of tension or stretch of the ventricular muscle when it begins to contract

amount of ventricular stretch at the end of diastole

what is preload also called

left Ventricular end-diastolic pressure (LVEDP)

what is the analogy for preload

heart loading up for its next big squeeze of ventricles during systole

more air you blow into a balloon, the greater the stretch

what is afterload

load or force against which ventricular muscle exerts its contractile force

amount of resistance the heart must overcome to ope the aortic valve and push blood into the systemic circulation

what is afterload also called

systemic vascular resistance (SVR)

what is the balloon analogy for afterload

to get the air out of the balloon, it must push against the knot of the balloon

what did Otto frank and ernest henry starling discover

increased preload/LVEDP leads to stronger contraction and greater stroke volumes

what can modify the frank-starling mechanism

afterload and inotropy of the myocardium

what is the mechanism of the frank-starling mechanism in the heart

when the ventricular filling is increased, the myocardial fibers and their sarcomeres are stretched, optimizing the length-tension relationship of the sarcomere

at the same time, toponin C becomes more sensitive to calcium as the sarcomeres stretch, accelerating the interaction between actin and myosin, leading to more force

what are heart sounds

phsyiological noises generated by the oscillation of blood (turbulent flow) and vibration of muscles and valves

valves are involved, but not the source

what is the diastolic S-3 sound

low frequency

associated with rapid ventricular filling

pathological in small animals

what is the diastolic S-4 sound

low frequenct

associated with atrial contraction

pathological in small animals

pumping function creates a pressure gradient that guarantees blood flow

what are heart murmurs

abnormal heart noises

either abnormalities of S1 or S2

what generates heart murmurs

turbulent blood flow through:

altered valves

abnormal openings between arteries and between heart chambers

benig murmurs: anemia

what is stenosis

an aquired or congenitally undersized valve of blood vessel

why does stenosis cause a murmur

blood is being pushed through a narrower diameter

when the heart valves are open

when does stenosis of the semilunar valves occur

systole

when does stenosis of the atrioventricular veins occur

diastole

what is insufficiency

leakage of a valve during its closure

blood squeezing throguh the opening between the leaflets in the reverse direction

when does insufficiency occur

when the heart valves close

systole: inatrioventricular valves

diastole: in semilunar valves

what is mitral valve stenosis

the mitral valve does not open as wide as it shoyld

blood flow from left atrium to the left ventricle is partially restricted

what is mitral valve insufficiency or regurgitation

the mitral valve leaks when the left ventricle contracts and some blood flows backwards into the left atrium

what can be observed on ultrasound in mitral valve insufficiency

enlargment of the left atrium and structure changes of the anterior leaflet of the mitral valve

when does the mitral valve insufficiency murmur begin

during the QRS complex (systole) and ends during the T wave (end of systole)

during diastole the murmur dies out

what does patent mean

remainds open

what is Patent ductus arteriosus (PDA)

one of the 3 most common congenital heart defects in dogs

what is the ductus arteriosis

a part of the muscular blood vessel

prostaglandins relax it during fetal development

what happens in the heart in a normal birth

lung expansion occurs, and oxygen tension in the systemic vasculature increases

lung expansion and the vasodilation of the pulmonary blood vessels reduce the pulmonary resistance to the blood flow

what happens to cause PDAA

the ductus arteriosus contracts under a higher oxygen tension, and the smooth musch then undergoes generation and fibrosis

what is PDA characterized by

ductal smooth muscle hypoplasia