cardiovascular system L5-10 Flashcards
functions of CVS
controlled/ continuous transfer
hormone transport
homeostasis
CVS structure
2 circulations in series (systemic> high and pulmonary> low)
unidirectional flow
equal blood vol in each circulation
which vessels carry blood away from heart?
aorta
pulmonary artery
which vessels carry blood into heart?
vena cava
pulmonary vein
atrioventricular valves
R - tricuspid
L- mitral/ bicuspid
semilunar valves
R- pulmonary
L- aortic
stroke volume
volume of blood pumped by 1 ventricle
average stroke volume
~75ml at rest
cardiac output
volume of blood pumped per ventricle per minute
cardiac output formula
heart rate * stroke volume
venous return
amount of blood returning to heart
at steady state VR=CO
arteries properties
high pressure
elastic
function for distribution
arterioles properties
high resistance
blood flow control to tissues
capillaries function
thin wall
arranged in parallel
exchange function
veins properties
decreasing pressure
one-way valves
capacitance/ collection function
pressure of fluid in motion rule
decreases with distance due to friction
pulse pressure
systolic pressure - diastolic pressure
biggest drop in pressure
from arterioles
mean arterial pressure
pressure averaged over time
blood flow relation to resistance
blood flow proportional to 1/ resistance
Darcy’s law
flow = change in pressure/ resistance
resistance factors
distance
vessel radius
blood viscosity
poiseuille’s law
flow proportional to change in pressure * radius^4
blood flow
volume/ minute
blood velocity
distance travelled / minute
blood velocity factors
flow
cross-sectional area
cardiac muscle cells
striated with T-tubules > SR
actin/ myosin/ troponin sarcomere
a.p generation to elevate cytoplasmic Ca2+ for contraction in excitation-contraction coupling
autorythmic
nerve supply regulated HR
2 groups of myocytes
conducting > fast spread of a.p’s
work> generate atrial/ ventricular force
heart beat initiation location
sino atrial node in right atrium
synctium
work cells interlinked by intercalated discs
spread of excitation from SAN
conducting fibres in atria/ ventricles
cell-cell via gap junctions
pacemaker potential function
spontaneously depolarizes to threshold so AP is generated, setting HR
ionic basis of electrical activity of SAN
- slow initial depolarization
- full depolarization
- repolarization
- minimum potential phase
slow initial depolarization of SAN
cation leak via non-spec cation leak channels in PM
full depolarization of SAN
at threshold, v-gated Ca2+ channels open and Ca2+ enters cell
repolarization of SAN
Ca2+ channels close and K+ open
minimum potential phase of SAN
K+ remains open
membrane hyperpolarization and non-specific cation channels open, repeating cycle