circulatory system part 4 Flashcards
Cardiac output is what?
equation?
Volume of blood pumped per unit time
CO=HRxSV
rate of contraction (beats per minute)
s
What is stroke volume?
volume of blood pumped with each beat
stroke volume= end diastolic volume- ensystolic volume
how can cardiac output be modified?
by regulating heart rate and/or stroke volume (chronotropy, inotropy
What is heart rate modulated by?
autonomic nerves and adrenal medulla
What is stroke volume modulated by?
various nervous, hormonal, and physical factors
Effects of norepinephrine on cardiomyocytes?
nervous and endocrine systems can cause the heart to contract more forcefully and pump more blod with each beat
Control of stroke volume:
what is the Frank-Starling effect?
increase end-diastolic volume results in a more forceful contraction and increase SV
length-tension relationship for muscles
heart automatically compensates for increase in volume of blood returning to the heart
Control of stroke volume:
Level of sympathetic activity shifts what?
the position of the cardiac muscle length-tension realationship
Regulation of blood flow:
Law of bulk flow: Q= delta P/R
what are the variables?
Q= flow
Delta P= pressure drop
R= resistance
Regulation of blood flow:
Poiseuille’s equation:
Q=delta P x Pie x r ^2/ 8Ln
L = length n= viscosity of fluid r= radius
Regulation of blood flow:
what is the primary driving force of blood through organs?
pressure
Regulation of blood flow:
what is Vasoconstriction and Vasodilation?
small changes in radius - large changes in resistance and flow
Regulation of blood pressure:
How does the body maintain a near constant mean arterial pressure? (MAP)
Body varies cardiac output (CO)
and total peripheral resistance (TPR)
Regulation of blood flow:
Arterioles control blood distribution how?
because arterioles are arranged in parallel, they can alter blood flow to various organs
- vasocanstrication and diolation
changes in resistance alter flow
Regulation of blood flow:
How does the body control vasoconstriction and vasodilation?
autoregulation:
-direct response of the artiole smooth muscle
Intrinsic factors:
- metabolic state of the tissue
Extrinsic factors:
-Nervous and endocrine system
Metabolic activity of tissues:
Smooth muscle cells in arterioles are senstivie to what?
conditions of extracellular fluid
Metabolic activity of tissues:
levels of metabolities alter what?
vasoconstriction and vasodilation
Metabolic activity of tissues:
Bloodflow is matched to what?
metabolic requirements
Metabolic activity of tissues:
Exercise - decrease o2 increase co2 causes what?
vasodilation
Metabolic activity of tissues:
Paracrine- nitric oxide casues what?
vasodilation
Neural and endocrine control of flow:
Nerepinephrine from sympathetic neurons cause what>
Vasoconstriction of arteriols
decrease in sympathetic tone causes what?
Vasodilation
What are the other hormones what affect vascular smooth muscles?
Vasopressin (ADH) causes what?
from posterior pituitary causes general vascoconstriction
What are the other hormones what affect vascular smooth muscles?
Angiotension 2
Produced in response to decreased blood pressure causes generalized vasoconstriction
What are the other hormones what affect vascular smooth muscles?
atrial natriuretic peptide (ANP)
produced in response to increase blood pressure promotes generalized vasodilation
Baroreceptor reflex:
what are these and where are they?
strtch-sensitive mechano-receptors are in walls of many blood vessels
especially carotid arteries and aorta
send nerve signals to medulla
They regulate MAP
(Spock pinch?)
What is spock pinch
our nerdy teacher wants us to relate this to star trek
he pinches the baroreceptors and decreases blood flow causes them to pass out
