physio test study guide 3+4

what is an electrocardiogram?

provides information about heart’s electrical activity

briefly describe how electrocardiograms are made

• electrodes on skin connected to a voltmeter

  • as chambers in the heart contract and relax, change in polarity is measured

what is the typical heart rate

60-100bpm

bradycardia

slow heart beat below 60bpm

tachycardia

fast heart rate above 100bpm

P-wave

atria contract, push blood into ventricles

QRS complex:

• atria relax while ventricles contract, which forces blood out of the heart 

T wave:

ventricles relax

what is the function of an auricle?

expands atrial volume to hold blood

what is the function of chordae tendinea?

prevents the valve flaps from flipping inwards

what is the function of papillary muscles

prevent mitral and tricuspid flaps from inverting during ventricular contraction

identify the events that produce heart sounds (“luh” and “duh”)

“luh” heard when ventricles contract and AV valves close
“duh” relaxation of ventricles allows semilunar valves to close

what is valvular stenosis

condition where a heart valve becomes narrower or thickened, restricting blood flow through valve

what is valvular insufficiency/regurgitation

occurs when a heart valve doesn’t close completely, causing blood to leak backward instead of forward: “mur-mur” sound

bicuspid vs tricuspid valves

bicuspid: 2 flaps
tricuspid: 3 flaps

differentiate between an AV valve and a semilunar valve

AV (atrioventricular) valves, like the mitral and tricuspid valves, separate the atria from the ventricles

semilunar valves, like the aortic and pulmonary valves, separate the ventricles from the major arteries

differentiate between the pulmonary and aortic semilunar valves

pulmonary sends deoxygenated blood into lungs
aortic valves send blood to the body

define peripheral resistance and blood viscosity.

peripheral resistance:

friction between blood and walls of blood vessels

• blood pressure must overcome peripheral resistance in order to keep flowing 

• changes with diameter of vessel lumen

blood viscosity:

• difficulty with which molecules in a fluid flow past each other

  • greater viscosity → more resistance 

blood cells and plasma proteins increase blood viscosity

Repolarization of muscle fiber

• muscle relaxes

Depolarization of muscle fiber

muscle contracts

explain why veins contain valves, but arteries and capillaries do not

veins: prevent backflow b/c blood is carried w/ gravity
arteries: blood pushed through pressure

brachial

arm

hepatic

liver

carotid/jugalar

head/neck

femoral

thigh

pulmanary

lungs

renal

kidneys

umbilical

fetus/placenta

superior/inferior vena cava

returns blood to heart