Cardiovascular Physiology Flashcards
why is the heart important ?
transport and temperature regulation
describe the organization of the CV system:
-arteries become arterioles then capillaries
- capillaries reunite to form venues and then veins
- rest of the body
where do arteries carry blood ?
away from the heart
where do veins carry blood ?
towards the heart
between arteries and veins which have more pressure and musculature ?
arteries
what are the two circuits of the body ?
pulmonary and systematic
what is the pulmonary circuit responsible for?
lungs / upper body
what is the systemic circuit responsible for ?
rest of the body circulation
what carries oxygen-rich and CO2 poor blood ?
veins
what carries oxygen-poor and CO-rich blood ?
arteries
how much % of the body is pulmonary circuit ?
15%
how much % of the body is systemic circuit ?
85%
within the systemic circuit what % is arteries, veins and capilaries ?
- arteries = 10%
- capillaries = 5%
- veins = 70%
how does blood travel through the heart ?
- blood from upper body goes through the superior vena cava and blood from the lower body goes through the inferior vena cava into the right atrium
- blood does into the right ventricle (through the tricuspid valve/right AV valve)
- blood goes through the pulmonary valve
- blood exists through the pulmonary artery to the lungs
- blood returns oxygenated into the left atrium
- blood goes through the bicuspid valve into the left ventricle
- blood goes to the aorta
- blood then gets distributed throughout the body
what are the two types of myocardial cells ?
contractile and nodal & conducting
name some differences between skeletal and cardiomyocytes ?
- skeletal = motor neuron action potential while cardiomyocyetes = electrically connected
- skeletal have mitochondria whole cadiomyocytes have a LOT of mitochondria
describe nodal and conducting cells:
minimal actin and myosin but self-excitable
what are some examples of nodal & conducting cells :
SA node (pacemaker), AV node, purkinje fibers and bundle of his
what does the AV node do ?
controls messages and creates desired heart rate (slows down from SA node)
what is depolarization ?
cell becomes more positive than RMP
what is repolarization ?
positive cell returns to RMP
what is the RMP of a neuron vs nodal cell ?
-70 mV and -60mV
what is the threshold of a neuron vs nodal cell ?
-55mv and -40mV
what are two differences between neurons and nodal cells ?
- RMP and threshold
- calcium presence in nodal cells
describe the SA nodal action potential :
- always fluctuating
- RMP, goes to threshold,
- depolarizes then depolarizes back to RMP
within the conducting system which AP propagation ?
SA node
what dos the AV do ?
regulate heart rate after the SA node
in order for muscle to contract what do you need ?
need an action potential first
what does a electrocardiogram do ?
- records the electrical activity of the heart
in an ECG what are the four letters ?
P, QRS, and T
what does P, QRS and T represent ?
P =atrial depolarization
QRS = ventricular depolarization
T = ventricular repolarization
what 5 things can an ECG tell us ?
- heart rate
- heart damage
- conduction issues
- rhythm disturbance
- effects of drugs
what is the resting heart rate of the average person ?
70 beats/min
how does heart rate change ?
sympathetic & parasympathetic stimulation
what is parasympathetic ?
rest and digest
what is sympathetic ?
fight and flight
what are 4 characteristics of parasympathetic innervation ?
- slower heart rate
- increase K permability
- decease Na permeability
- decrease Ca permeability
what are 3 characteristics of sympathetic innervation ?
- faster heart rate
- increase Na permability
- increase Ca permability
what does permability mean in the sense of “increase Ca permability” ?
more calcium coming in
between the sympathetic and parasympathetic innervation which has a faster/slower heart rate ?
sympathetic = faster
parasympathetic = slower
between ACh and NE, which is associated with parasympathetic and sympathetic ?
ACh = prasympathtic
NE = sympathetic
what does systole mean ?
contraction
what does diastole mean ?
relaxation
when do ECG events occur in regards to a heart muscle contraction ?
the ECG events occur before heart muscle contraction
what are the five cardiac cycle heartbeat events ?
- atrial systole
- iso-volumetric ventricular systole
- ventricular systole
- isovolumeetric ventricular diastole
- late ventricular diastole
how does blood move (in regards to pressure gradient) ?
blood moves down a pressure gradient
what does systole mean ?
contraction
what is phase 1 of the ECG ?
atrial systole
what does diastole mean ?
relaxed (isn’t changing)
when does systole occur ?
when the heart contracts to pump blood out
when does diastole occur ?
when the heart relaxes after contraction
what is atrial systole ?
contraction of the atrial
what happens to pressure in atrial systole ?
pressure increases
what happens to volume in atrial systole ?
volume increases
what do you need in order to have a contraction in the heart ?
action potential
what is phase 2 of ECG ?
isovolumetric ventricular systole
what happens to pressure in isovolumetric ventricular systole ?
pressure increases
what happens to volume in isovolumetric ventricular systole ?
no change
what are the valves doing during isovvolumetric ventricular systole ?
all valves closed
if a phase begins with “isovolum” what does this mean ?
volume stays the same
what is phase 3 of the ECG ?
ventricular systole
what happens to pressure in ventricular systole ?
pressure increases
what happens to volume in ventricular systole ?
volume decreases
what are the valves doing during ventricular systole ?
aortic valve open
if pressure is high in the ventricles what does that mean for the aorta ?
aortic pressure is lower
what is phase 4 of the ECG ?
isovolumetric ventricular diastole
what happens to pressure in isovolumetric ventricular diastole ?
pressure decreases
what happens to volume in isovolumetric ventricular diastole ?
no change
what are the valves doing during iso-volumetric ventricular diastole ?
all valves closed
what is phase 5 of the ECG ?
late ventricular diastole
what happens to pressure in late ventricular diastole ?
pressure decreases
what happens to volume in late ventricular diastole ?
volume increases
what are the valves doing during late ventricular diastole ?
AV valve opens
what is the term for during ONE ventricular systole (contractions) ?
stroke volume
what is cardiac output ?
per min of ventricular contractions
what is the formula for cardiac output ?
heart rate x stroke volume
what two things control stroke volume ?
- autonomic nervous system innervation
- preload on the heart
what does “preload” mean ?
how much blood we can get into ventricle before contraction occurs
what do muscles need more of to better function ?
more blood
what is EDV ?
amount of blood in the ventricle after atrial systole
what is the formula for stroke volume ?
EDV - ESV
what is ESV ?
amount of blood in the ventricle after ventricular systole
what are two major rules regarding the heart ?
- blood will only move down pressure gradient
- blood should never be going in the wrong direction
the more calcium what does this mean for the heart ?
more contractions
when discussing the “load” on the heart prior to contraction what is this “load” ?
the EDV
what happens if muscles are over stretched ?
heart will fail
what is frank-starling’s law ?
“an increase in EDV will cause an increase in stroke volume”
what is MAP (mean arterial pressure) ?
difference between systolic pressure and diastolic pressure
what is the average blood pressure for the healthy individual ?
120/80
in what way does blood move ?
from high to low blood will flow
what is the anatomy of a blood vessel ?
- tunica externa
- tunica media
- tunica interna
what is thicker ? arteries or veins ?
arteries are thicker in order to produce contractions
what is the tunica external made of ?
fibrous connective tissue
what is the tunica media made of ?
smooth muscle and elastic fiber
what is the tunica interna made of ?
endothelial cells
describe the structure of arteries ?
- large diameter
- thin walls compared to diameter
- lost of elastic
describe blood characteristics of arteries ?
- very high blood pressure
- high blood flow
- low resistance, small drop in pressure
what is the main function of arteries ?
distribution vessels
what is the main function of arterioles ?
resistance vessels
describe the structure of arterioles ?
- small diameter
- thick walls compared to diameter
- lots of smooth muscle
- smooth muscle innervated by SNS
describe the blood characteristics of arterioles ?
large drop in pressure and slower blood pressure
what is the purpose of arterioles ?
controls blood flow (vasoconstrictor and vasodilatation)
what does resistance do ?
decreases blood flow
what are the two formulas for blood flow ?
- blood flow = pressure gradient / resistance
and - blood flow = (P1 - P2) x r^4
what is the formula for resistance ?
Lη / r^4
what is the main function of capillaries ?
exchange vessels
describe the structure of capillaries ?
- one endothelial cell thick
- very thin walls
describe the blood characteristics of capillaries ?
- low blood pressure, small drop in pressure
- very low blood velocity
- huge total cross-sectional area for diffusion
- blood flow is very slow
what is the purpose of capillaries ?
to exchange gasses, nutrients, etc.
what does more cross-sectional area = ?
slower flow
what does slower flow =
maximize exchange
between mean blood velocity and total cross sectional area which is highest / lowest for capillaries ?
capillaries highest = for total cross sectional area
and
capillaries lowest = mean velocity
what is filtration ?
movement of fluid OUT of a capillary
what is reabsorption ?
movement of fluid INTO a capillary
what are the four starling forces ?
- capillaries hydrostatic pressure
- interstitial fluid hydrostatic pressure
- capillary plasma osmotic pressure
- interstitial fluid osmotic pressure
which two of the four starling forces go IN to the capillary ?
capillary plasma osmotic pressure and interstitial fluid hydrostatic pressure
which two of the four starling forces go OUT of the capillary ?
capillaries hydrostatic pressure and interstitial fluid osmotic pressure
if the net filtration pressure is a positive number, what does this mean ?
filtration
if the net filtration pressure is a negative number, what does this mean ?
rebsorption
what is the formula for net filtration pressure ?
(out + out) - (in + in)
describe the structure of veins ?
- valves
- large diameter
- very thin walls compared to diameter
- some elastic fibers and smooth muscles
- SNS innervates smooth muscles
describe the blood characteristics of veins ?
- very low blood pressure
- medium blood velocity
why do we regulate blood flow
- increase blood supply to active tissues and decrease it to inactive tissues
- maintain blood supply to vital organs (heart and brain at all times)
- maintain blood pressure (MAP)
- increase/decrease heat loss from the body by redistributing blood
between vasoconstriction and vasodilation, which has less/more flow ?
vasoconstriction = less flow
vasodilation = more flow
what are the three mechanics used to regulate blood flow ?
- local (intrinsic)
- humoral (extrinsic)
- neural (extrinsic)
what is local (intrinsic) ?
tissue environment (temp, gasses and pressure)
what is humoral (extrinsic) ?
substances in blood
what is neural (extrinsic) ?
nervous system
what are the two autoregulatory mechanisms of local (intrinsic) ?
- myogenic theory (muscle stretch)
- metabolic. theory (metabolic needs)
what is the 5 steps of myogenic theory ?
- sudden increase in blood pressure
- this stretches walls of arterioles
- smooth muscle in arteriole walls contracts (reflex)
- vasoconstriction
- decrease blood flow and pressure AFTER constriction
what does the metabolic theory do to CO2 and O2 ?
increases CO2 and decreases O2
what does vasoconstriction and vasodilation do to blood pressure ?
vasoconstriction = will RAISE blood pressure
vasodilation = will LOWER blood pressure
the neural (extrinsic) mechanism is further divided into …
the autonomic nervous system which is ; the sympathetic and parasympathetic nervous system
what are baroreceptors ?
- they monitor blood pressure
- located in walls of aortic arch, carotid sinuses
- send action potentials back to CV central in medulla of brainstem
