Ex. Phys. Cardiovascular System Flashcards
cardiovascular system main purposes
deliver O2, nutrients, hormones, etc. to tissues via the blood circulation
remove CO2, waste products, metabolic intermediates, etc. from the tissues via the blood circulation
cardiovascular system structures
myocardium heart chambers heart valves heart innervation blood vessels
myocardium
primary muscle tissue of the heart
contains short, branched, single-nucleated cells (myocytes)
myocytes utilize gap junctions to propagate electrical signals quickly for synchronized cardiac contraction
myocytes are involuntarily and automatically controlled
heart chambers
RA
RV
LA
LV
RA
collects de-oxygenated venous blood from systemic curculation via the superior and inferior vena cava and pumps it into the right ventricle
RV
recieved de-oxygenated blood from the right atrium and pumps it through the pulmonary artery to lungs
LA
collects oxygenated blood from lungs via the pulmonary vein and pumps it into the left ventricle
LV
received oxygenated blood from the left atrium and pumps it through the aorta into systemic circulation
heart valves
-subsets
atrioventricular (AV) valves -tricuspid valve -mitral (bicuspid) valve semilunar (SL) valves -pulmonary valve -aortic valve
tricuspid
allows blood to flow from the RA into the RV
mitral
allows blood to flow from the LA into the LV
pulmonary
allows blood to flow from the right ventricle into the pulmonary artery (then to the lungs for reoxygenation)
aortic
allows blood to flow from the left ventricle into the aorta (then out to the systemic circulation)
heart innervation
sinoatrial node
-located in right atrium; heartbeat is initiated here via depolarization of atria
-spontaneously depolarizes at a regular rhythm, hence its nickname as the “pacemaker” of the heart
-ANS also innervates the SA node to influence node activity, and can, therefore, control HR
atrioventricular node
-located in RA
-receives action potential “wave” from SA node and delays it to give both atria time to contract before sending the signal to the bundle of His
Bundle of His
-located in between the R and L atria and ventricles
-gives rise to bundle branches in the intraventricular septum
-bundles relay action to depolarize the purkinje fibers
Purkinje fibers
-terminal innervations within the myocardium of the R and L ventricles
-receive action potential to depolarize and stimulate both ventricles to contract
blood vessels
arteries arterioles capillaries venules veins
arteries
largest vessels for systemic blood delivery
have thick, muscular walls that can contract (due to autonomic innervation) to direct blood flow, yet are highly elastic to withstand high pressures
arterioles
smaller branch of arteries
have thin, but muscular walls that can contract to direct blood flow
capillaries
smallest vessels
thin walls permit gas exchange, but have no muscle to control blood flow
venules
smaller branch of veins
thin, compliant walls help store a lot of blood, and one-way valves to facilitate blood flow back to heart
veins
largest vessels for systemic blood return
have compliant, muscular walls and one-way valves to facilitate blood return to heart
cardiovascular circuits
pulmonary circulation
systemic circulation
pulmonary circuiaton
the heart is connected to the lungs via the pulmonary arteries and veins, which forms a pulmonary circuit
flow of blood through pulmonary circuit
- de-oxygenated blood is received by the RA via the superior and inferior vena cava
- RA depolarizes and contracts. when the pressure exceeds 10 mmHg (during contraction), the tricuspid valve opens and allows blood to flow into the RV
- RV depolarizes and contracts, pressure increases to 15-25 mmHg, which closes the tricuspid valve, thereby blocking blood flow back into the RA. the increase in pressure also opens the pulmonary valve, directing de-oxygenated blood flow to the lungs via the pulmonary arteries
- after passing through the lungs, oxygenated blood is received by the LA via the pulmonary veins
- LA depolarizes and contracts. when atrial pressure exceeds 10 mmHg (during contraction) the mitral valve opens and allows blood to flow into the LV
- LV depolarizes and contracts, pressure increases to 15-25 mm Hg, which closes the mitral valve, thereby blocking blood flow back into the LA. The increase in pressure also opens the aortic valve, directing oxygenated blood through the aorta and into the systemic circulation
- vii. After passing through the systemic circulation (e.g. muscles, skin, etc.) the de-oxygenated blood is returned to the heart via the superior and inferior vena cava.
systemic circulation
once blood is ejected from the heart it enters the systemic circuit whereby it is transported to other tissues in the body and eventually returns back to the heart
important cardiovascular parameters
HR SV ejection fraction (EF) cardiac output (Q) SBP DBP mean arterial pressure (MAP) total peripheral resistance (TPR) rate pressure product
HR
the number of times a heart contracts, or “beats” within a given time period (usually per minute)
balance between SNS stimulation (Norepi and Epi) and PSNS stimulation (Ach) influence determines the “chronotropic” state, or pacing of HR
in the absence of SNS and PSNS stimulation, the SA node will automatically depolarize the heart to establish a default HR
resting: 60-100
aerobic exercise: up to 200-220 bpm
resistance exercise: slightly elevated from rest
stroke volume (SV)
- what is it
- influenced by
- SV =
- resting
- aerobic exercise
- resistance exercise
the ABSOLUTE amount (mL) of blood pumped out of the left ventricle each heart beat
influenced by
-total blood volume
-venous return
SV = end diastolic volume - end systolic volume
resting: 75 mL/beat
aerobic exercise: up to 150 mL/beat
resistance exercise: probably won’t change much from rest
ejection fraction (EF)
- what is it
- EF =
- resting
- aerobic exercise
- resistance exercise
the RELATIVE amount (%) of blood pumped out of the left ventricle each heart beat
EF = (SV/EDV) x 100
resting: 55-60%
aerobic exercise: up to 70-75%
resistance exercise: probably won’t change much from rest
cardiac output (Q)
- what is it
- huge determinant of…
- Q =
- resting
- aerobic exercise
- resistance exercise
the RATE of blood flow through the heart per minute huge determinant of blood pressure Q = HR x SV resting: 5 L/min aerobic: up to 20-25 L/min resistance: slightly elevated from rest
systolic blood pressure (SBP)
- when does it happen and what happens
- resting
- aerobic exercise
- resistance exercise
during ventricular contraction (systole) blood fills arteries and increases the pressure exerted on the arterial walls
resting: 115-120 mmHg
aerobic exercise: up to 200 mmHg
resistance exercise: up to >300 mmHg
diastolic blood pressure (DBP)
- when does it happen and what happens
- resting
- aerobic exercise
- resistance exercise
during ventricular relaxation (diastole) the driving force behind blood flow is diminished, so arterial pressure falls
resting: 75-80 mmHg
aerobic: no change or slight decrease in DBP
resistance: >250 mmHg
mean arterial pressure (MAP) -provides indication of... -MAPrest or resistance = MAPaerobic = -resting -aerobic exercise -resistance exercise
provides an indication of systemic perfusion pressure
-the pressure required to push blood into tissues
MAPrest or resistance = DBP + 0.33 (SBP-DBP)
MAPaerobic = DBP + 0.50 (SBP-DBP)
resting: 90-95 mmHg
aerobic: increases from rest; extent is dictated by exercise intensity
resistance: huge increase from rest during muscular contractions, but not during muscle relaxation
Total Peripheral Resistance (TPR)
- represents
- important regulator
- TPR=
- Resting
- Aerobic
- Resistance
represents the total amount of pressure in the systemic circulation that “opposes” or “resists” blood flow
important regulator of systemic blood flow
TPR=MAP/Q
resting: 18-19 mmHg•min/L
aerobic: decreases from rest
-extent is dictates by exercise intensity
-this is good, because blood can travel to where it is needed easier
resistance: huge increase from rest during muscular contractions, but not during muscle relaxation
Rate Pressure Product
- indication of
- RPP=
- resting
- aerobic
- resistance
indication of the O2 requirements of the heart
RPP= HR x SBP
resting: 7200-12000 bpm•mmHg
aerobic: increases from rest
-extent is dictated by exercise intensity
resistance: increases from rest during muscular contractions, but not during muscle relaxation
what regulates the cardiovascular system
autonomic nervous system heart systemic circulation muscle pump respiratory pump exercise pressor reflex
ANS governs heart and systemic circulation via
SNS
PSNS
feedback from baroreceptors and chemoreceptors
SNS
- function
- releases
- release induces…
function
-drives HR, SV, and blood flow during exercise
releases Norepi (adrenaline) at sympathetic nerve endings (B1 heart receptors) to upregulate cardiac function
-sympathetic cardiac nerve hits SA node, AV node, and some Purkinje fibers
Norepi activation of a1 arterial receptors induces vaso/venoconstriction, increases BP, and speeds up blood flow
-arteries/veins have smooth muscle, which can be told what to do
PSNS
- function
- releases
- releases induces
function -"trims out" SNS activity during exercise, but typically does not override it releases Ach at parasynpathetic nerve endings (M2 heart receptors) to downregulate cardiac function Ach activation of B2 arterial receptors induces vaso/venodilation, decreases BP, and slows blood flow
feedback from baroreceptors and chemoreceptors
- feedback in response to
- will elicit
feedback in response to localized metabolite accumulation and stress on vessel walls
will elicit an appropriate SNS or PSNS response
ANS note
at rest, always a balance between SNS and PSNS activity, but during exercise and activity, SNS activity tends to predominate
heart
- function
- heart performance regulating factors
function -regulates MAGNITUDE of blood flow through body factors -preload -afterload -contractility
preload
- represented by
- what is it
- -Frank-Starling Law
- influenced by
represented by EDV
ability to return blood to heart via venous return
-Frank-Starling Law: the heart will pump the blood it receives
influenced by muscle pump, respiratory pump, abdominal muscles, and degree of vaso/venoconstriction
afterload
- represented by
- what is it
- influenced by
represented by TPR or MAP
pressure the heart has to overcome to eject blood into systemic circulation, “arterial blood pressure”
influenced by degree of vaso/venoconstriction and vessel health
contractility
-what is it
strength of ventricular contraction influenced by intracellular [Ca2+] preload, and ANS nervous innervation
systemic circulation
- regulates
- influence by
regulates DISTRIBUTION of blood flow through body
influenced by
-neural mechanisms
-metabolic conditions
neural mechanisms
central command center sends blood when it is anticipated via SNS upregulation (feed forward system)
baroreceptors monitor blood pressure (feedback system), which influences SNS or PSNS activity
metabolic conditions
- within muscle capillaries
- endothelial-derived relaxing factors
within muscle capillaries, increased H+, CO2, lactate, and adenosine buildup promote increased blood flow
EDRFs
-such as nitric oxide (NO)
-released from vessel walls to increase local vasodilation and blood flow
the local vasodilation that occurs due to EDRFs…
overrides SNS command to vasoconstrict, which allows working muscles to receive the blood that they need
muscle pump
-what is it
muscle contraction compresses local veins
one-way valves prevent venous blood from flowing backward, so blood is pushed back toward heart
respiratory pump
-what is it
expansion of thoracic cavity decreases pressure of thoracic cavity, which facilitates venous blood return to heart
like sucking liquid into a syringe
exercise pressor reflex
- what is it
- functions
reflexive response to muscle contraction that increases SNS activity to ensure adequate blood delivery to muscles
functions
-increases BP, HR, and Q
-induces vasoconstriction to help redirect blood to active tissues
ways to influence preload
change body position -upright to recumbant -don't fight gravity --will lead to lower HR and higher SV hydrate well -increases blood volume
