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23 Cards in this Set
- Front
- Back
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3 phases of cardiac cycle (systole/diastole)
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1) ventricular filling (diastole)/ atrial systole
2) ventricular systole/ atrial diastole/ ejection of blood from ventricles (pressure in ventricles increases: AV valve closes, blood begins to flow into aorta or pulmonary trunk) 3) relaxation of atria and ventricles |
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end diastolic volume
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max. vol. of blood in ventricles at end of ventricular diastole.
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end systolic volume
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amt of blood left in ventricles after ventricular systole
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stroke volume
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EDV - ESV = SV
amount of blood moved in each beat of the heart |
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cardiac output
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CO = SV x bpm
volume pumped by heart per minute |
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3 things that affect stroke volume
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1) preload: amt. of blood entering the heart; stretching of heart increases contraction strength (high EDV = high SV)
2) contractility: – epinephrine or norepinephrine (from sympathetic neurons or as hormones) increases Ca++ influx, which increases the force of contraction (increases SV) 3) afterload: arterial blood pressure determines how much blood can be ejected from ventricles (low pressure in aorta = high SV) |
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heart rate can be modified by:
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autonomic innervation:
1) vagus nerve: parasympathetic - decelerates heart rate 2) cardiac nervE: sympathetic - increases heart rate -cardiac centers are in the medulla |
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Cardiac muscle contraction (3 steps)
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1) Depolarization caused by opening of voltage-gated Na+ channels --leads to action potential
2) Action potential opens Ca++ channels and triggers Ca++ release from extracellular space and SR 3) Excitation-contraction coupling occurs |
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Cardiac conduction through autorhythmic cell contraction
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1) Slow influx of Na+ causes potential to slowly rise -leads to depolarization of pacemaker potential
2) Depolarization reaches a threshold for action potential that opens Ca++ channels which causes rapid depolarization 3) Repolarization occurs, K+ efflux restores negative potential |
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the P wave in EKG
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corresponds to atrial depolarization
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the QRS complex in EKG
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Q wave corresponds to atrial repolarization; R wave corresponds to ventricular depolarization
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the T wave in EKG
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corresponds to ventricular repolarization
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3 layers of arteries and veins
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the three tunica layers: tunica intima, tunica media, tunica externa
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tunica intima (interna)
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inside endothelial layer that lines the lumen of all vessels
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tunica media
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smooth muscle and elastic fiber layer, regulated by sympathetic nervous system; controls diameter of vessel thru vasoconstriction/vasodilation of vessels
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tunica externa (adventitia)
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outer layer tha tprevents vessel from getting too big; has collagen fibers that protect and reinforce; restrict amt of stretching; larger vesselgs have vasa vasorum (small vessels of their own)
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3 types of arteries
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1) elastic arteries/conducting vessels; most elastic- including aorta and its major branches
2) muscular arteries/distributing vessels 3) arterioles- lead into capillary bed |
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3 types of capillaries
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1) continuous capillaries- most common; diffusions occurs thru intercellular cleft; held together by tight jxns
2) fenestrated capillaries- has many pores- found in small intestine, endocrine glands, kidneys) 3) sinusoid capillaries- leaky, with large holes; allow passage of proteins and large molecules from surrounding tissues; found in liver, bone marrow, lymphoid tissue, and in some endocrine organs |
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3 factors contributing to movement of blood through veins
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1) respiratory pump- when diaphragm contracts, abdomen increases in pressure (when inhale); blood draw towards heart
2) muscular pump- contraction of skeletal muscle causes increase in pressure which "milks" blood towards heart 3) valves prevent backflow during venous return/ blood flows down to heart b/c of gravity |
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neural control (short-term mechanism) that controls blood pressure
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neural controls from symp and parasymp NS; maintain MAP by vasodconstriction (SNS) and vasodilation (lack of SNS control); regulated by vasomotor centers of medulla
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chemical control (short-term mechanism) that controls blood pressure
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BP regulated by chemoreceptor reflexes sensitive to O2 and CO2; chemorecep in carotid and aortic bodies; reflexes that regulate blood pressure are integrated in medulla; if body has high CO2 and low O2 -blood vessels dilate (pressure decreases)
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chemicals that increase blood pressure
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adrenal medulla hormones: norepinephrine and epinephrine
antidiuretic hormone (ADH): causes intense vasoconstriction in cases of extremely low BP angiostensin II - kidney release of renin generates angiotensin II, which causes intense vasoconstriction endothelium-derived factors |
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chemicals that decrease blood pressure
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atrial natriuretic peptide (ANP): causes blood volume and pressure to decline
nitric oxide (NO)- has brief but potent vasodilator effects inflammatory chemicals- histamine, prostacyclin, kinins are potent vasodilators alcohol- cause BP to drop by inhibiting ADH |
