exam 3: cardiac cycle Flashcards
what contracts first because of an AV delay?
then ventricles contract at the same time as the artium
then the ventricles relax
atria
atrium relaxes
cardiac cycle events for a single heartbeat:
1. between beats-
2. artrial systole-
3. atrial diastole/early ventricular systole-
4. late ventricular systole-
5. early ventricular diastole-
6. late ventricular diastole
- between beats- passive filling
- artrial systole- active filling
- atrial diastole/early ventricular systole- isovolumetric contraction
- late ventricular systole- ejection phase
- early ventricular diastole- isovolumetric relaxation
- late ventricular diastole
between beats,
pressure atria _____pressure veins
pressure atria ___pressure ventricles (causes what to happen)
pressure ventricles ____ pressure arteries attached (causes what to happen)
pressure atria < pressure veins
pressure atria >pressure ventricles
-AV valves open
pressure ventricles< pressure arteries
-keeps semilunar valves closed
80% of blood for contraction loaded into ventricles at this time
-between beats
period of passive filling
- atrial systole (atria contracts)
causes pressure in atria to
increase
- atrial systole
pressure atria____ pressure veins
pressure atria ____ pressure of ventricles (causes what)
pressure ventricle ___ pressure arteries
pressure atria> pressure veins
pressure atria>pressure ventricles
-causes av valves to open
pressire ventricles<pressure arteries
-causes semilunar valves to stay closed
20% of blood for contraction loaded into ventricles at this time
-atrial systole
period of active filling
atrial begins to relax as ventricles begin to contract:
pressure of atria=
pressure of ventricles=
atrial diastole/early ventricular systole
pressure of atria= decreases
pressure of ventricles=increases
- atrial diastole/early ventricular systole
pressure atria ___ pressure veins
pressure artia ___ pressure ventricles (causes)
pressure ventricles ___ pressure arteries (causes)
pressure atria < pressure veins
pressure artia < pressure ventricles
-causes av valves to close
pressure ventricles < pressure arteries
-causes semilunar valves to stay closed
rapid rise of pressure in ventricles increases
3. atrial diastole/early ventricular systole
period of isovolumetric contraction
- late ventricular systole
pressure atria ___ pressure veins
pressure atria ___ pressure ventricles (cause)
pressure ventricles ___ pressure arteries (cause)
pressure atria < pressure veins
pressure atria < pressure ventricles
-causes av valves to close
pressure ventricles > pressure arteries
-causes semilunar valves to open and blood flow out
- early ventricular diastole
(getting into ventricular relaxation)
causes pressure of ventricles to=
decreases
- early ventricular diastole
(getting into ventricular relaxation)
pressure atria ___ pressure veins
pressure atria ___ pressure ventricles (causes)
pressure ventricles ___ pressure arteries
pressure atria < pressure veins
pressure atria < pressure ventricles
-causes av valves to stay closed
pressure ventricles < pressure arteries
-causes semilunar valves to close
- late ventricular diastole
pressure atria __ pressure veins
pressure atria ___ pressure ventricles (causes)
pressure ventricles ___ pressure arteries (causes)
pressure atria < pressure veins
pressure atria > pressure ventricles
-av valves open
pressure ventricles < pressure arteries
-semilunar valves closed
vol of blood in ventricle before it contracts
EVD (135)
vol of blood in the ventricle before it relaxes/after it contracts (after ventricular systole)
ESV (65)
volume of blood ejected per beat
SV- stroke volume
EDV-ESV=~70
ejection fraction=
fraction of EDV ejected/beat
SV/EDV
heart sounds (lub dub) due to
valve closure
-abnormal heart sounds
-failure of valves to open completely=
-failure of valves to close properly=
heart murmurs
-failure of valves to open completely=stenosis
-failure of valves to close properly=insufficiency or prolapse
what causes 1st heart sound?
closure of AV valve
what causes 2nd heart sound?
closure of semilunar valves
amount of blood pumped out of each ventricle in 1 minute
cardiac output
CO=HR x SV (heart rate x stroke volume)
CO regulated to match demands of tissues.
increased by:
decreased by:
increased: physical activity, metabolic status, drugs
decreased: blood loss, heart disease
factors that increase HR are called
factors that decrease HR are called
increase= + chronotropic
decrease= - chronotropic
SNS increases HR (___ and ___ cells)
AR and contractile cells
PNS decreases heart rate ( ___ cells only)
AR cells only
which is which:
(SNS and PNS)
- dromotropic and + chronotropic
- dromotropic and - chronotropic
SNS + dromotropic and + chronotropic
PNS - dromotropic and - chronotropic
3 ways SV is altered:
SV=EDV-ESV
- preload (changing EDV)
- afterload (Blood Pressure)
- contractility (force of contraction)
at rest, cardiac muscle sits at a length that is LESS than optimum.
by increasing EDV:
this increases stretch of myocardium
moves resting cardiocytes length towards optimum
increases SV (stroke volume)
what is EDV directy related to
venous return (VR)
rate at which blood is returned to the heart from veins
VR (venous rate)
veins are what kind of vessels?
they can hold up to 60% of the total blood volume
flaccid
Peripheral Venous Pool
the pressure to return blood back to the heart from capillaries is very large/small
small
increase in venous return (VR) by:
(all dependent on one-way valves)
- increase in skeletal muscle pump
- increase in breathing in and out (thoracic pump)
- increase venoconstriction via SNS (a1 adrenergic receptor)
decrease in venous return (VR) by:
- tachycardia (extreme high heart rate)= decrease CO by decrease EDV
- valsalva maneuver (increasing thoracic pressure against closed epiglottis)
what is SV (stroke volume) increase related to?
what is CO (cardiac output) related to?
SV/HR
CO=HR (at normal HR)
