A&P II Lab: Cardiac Cycle
the first heart sound is a result of closure of the
AV valves
at what point in the cardiac cycle is the pressure in the heart lowest?
diastole
when are AV valves open?
diastole
when are the semilunar valves closed?
diastole
atrial systole
-atria contract -AV valves open -semilunar valves vlosed
early ventricular systole
-atria relax -ventricles contract -AV valves forced closed -semilunar valves closed
early ventricular diastole
-atria relax -ventricles relax -AV valves closed -semilunar valves closed -atria begin passively filling with blood
late ventricular diastole
-atria relax -ventricles relax -atria passively fill with blood -AV valves open -semilunar valves closed
late ventricular systole
-atria relax -ventricules contract -AV valves remain closed -semilunar valves open
sounds of korotkoff
-characteristic sounds heard when measuring BP --Systolic pressure: pressure in cuff equals arterial pressure, begin to hear sounds. --Diastolic pressure: pressure in cuff drops below minimal pressure in ventricular relaxation, sounds disappear
vasoconstriction
-decreases luminal space -increases resistance -decreases blood flow --Controlled by sympathetic nervous system
blood pressure
-force per unit area exerted on vessel wall by the blood -cardiac output x peripheral resistance (BP=COxPR)
peripheral resistance
-frictional force that opposes blood flow (flow=p/r) -3 main factors affect resistance: --blood vessel length -adults vs children --diameter (and flexibility) -atherosclerosis, arteriosclerosis, medications --viscosity(and volume) -pregnancy, medications, diet
hypertension
-high BP -sustained elevated arterial pressure of 140/90 or higher -primary: due to several risk factors including heredity, diet, obesity, age, stress, diabetes mellitus, and smoking
shock
-hypoperfusion -inadequate circulation of blood (oxygen) to the cells
vasodilation
-increases luminal space -decreases resistance -increases blood flow --Controlled by sympathetic nervous system
hypotension
-low BP -orthostatic: temporary low BP and dizziness when suddenly rising from a sitting or reclining position -acute: important sign of circulatory shock
factors affecting BP
-posture -exercise -cardiovascular disease -diet (salt intake) -medications
congestive heart failure (CHF)
-progressive condition where the CO is so low that blood circulation is inadequate to meet tissue needs -caused by: -coronary atherosclerosis -persistent high blood pressure -multiple myocardial infarcts
vital signs
-pulse points -blood pressure -response to exercise
pulse points
-pulse results from alternating surges of pressure in artery occurring with each beat of left ventricle -average adult between 60-100 -apical pulse counted from heart -pulse deficit - lag time between apical and distal pulse
circulatory signs
-skin color: cyanosis (lips, nail beds). -capillary refill: perfusion, often measured at nail beds. -diaphoresis: clammy, sweaty skin
PR and vessel diameter
-smaller diameter means more blood cells in contact with vessel walls, creating more friction -results in greater resistance and thus greater pressure
systole
-ventricular contraction -pressure in ventricles rises -AV valves close (lub) -ventricular pressure > arterial (aortic) pressure -semilunar valves open -ventricles contract -blood pumped out forcefully -late systole: ventricles relax, semilunar valves shut (dub)
diastole
-ventricular relaxation -low pressure in heart -blood flows passively into chambers -AV valves open -semilunar valves closed -late diastole.atrial systole (atria contract)
cardiac output
-volume of blood pumped out by left ventricle each minute (stoke volume x heart rate)
regulation of cardiac output
HR and SV often change in opposite directions as compensatory mechanisms try to maintain constant cardiac output. Ex: Bleeding
cardiac cycle
all events in 1 heart beat
chambers that just emptied
atrium
after the second heart sound, what are filling with blood? what are empty?
atrium,ventricles
sphygmomanometer
blood pressure cuff
dicrotic notch
brief backflow resulting in closing of semilunar valves
arteriosclerosis
calcified and rigid artery cannon expand; artery walls experience higher pressures
pressure point at side of neck
carotid
what event causes the semilunar valves to close?
dicrotic notch (brief backflow)
pressure point at dorsum of foot
dorsalis pedis
pressure point at front of ear
facial
Tachycardia
fast pulse rate
pressure point at groin
femoral
systolic pressure
highest pressure in artery at peak ventricular contraction
diastolic pressure
lowest pressure during ventricular relaxtion
monosyllables describing the heart sounds are
lub and dup
pressure point at medial malleolus
post. tibial
pressure point at wrist
radial
second heart sound is a result of closure of the
semilunar valves
Bradycardia
slow pulse rate
at what point in the cardiac cycle is the pressure in the heart highest?
systole
when are AV valves closed?
systole
when are the semilunar valves open?
systole
pulse pressure
systolic-distolic
the heart chamber that have just been filled when you hear the first heart sound are the
ventricles
what event causes the semilunar valves to open?
ventricular pressure is higher than atrial pressure
what event within the heart causes the AV valves to open?
when ventricular pressure is lower than atrial pressure