Exam 3 Flashcards
eccentric hypertrophy:
volume loading
concentric hypertrophy
pressure loading
triggers for vasodilation in the heart:
- vasodilators released from cardiac cells with low O2
- NO released from coronary vessels from shear stress
how much O2 is extracted from arterial blood at normal resting HR?
70%
potent vasodilators:
- adenosine
- CO2
- NO
- H+
- K+
- prostaglandins
epicardial vessels have more _____ receptors:
alpha
intramuscular arteries have more ____ receptors
Beta
parasympathetic effect on coronary blood flow:
neurotransmitter: ACh
action: vasodilates coronary arteries
indirect effect:
-decrease HR, metabolic demand
-vasoconstriction
sympathetic effect on coronary blood flow:
neurotransmitter: NE
action: vasocontriction (alpha receptors)
indirect effect:
-increase HR, myocardial contractility, metabolic demand
-vasodilation
effect of epinephrine on coronary blood flow:
vasodilation (beta receptors)
-actions same as NE
a-VO2
- indicates oxygen uptake into the tissue
- bigger the difference the more oxygen that was extracted from the blood
HR max:
- responsiveness of heart to adrenergic stimulation
- no difference between the sexes
- no change with training
why does SV plateau between 50%-70% of VO2 max?
-decreased filling time
SVmax increases with training because:
- blood volume increases with aerobic training from kidney regulation
- more blood creates greater EDV
- increased EDV then greater contraction of heart
difference in gender for stroke volume?
SV in men greater than SV in women
increased sympathetic stimulation of alpha-receptors cause:
vasoconstriction
venous content for a-vO2 diff determined by:
- capillarity
- # open capillaries
- myoglobin
- mitochondrial density
- mitochondrial enzymes
byproducts that would cause vasodilation are:
adenosine
CO2
low O2 level
relationship between BP and local blood flow/cardiac output?
the need to maintain BP determines the local blood flow and cardiac output
ohm’s law:
difference in pressure over resistance in the vessel
resistance of entire circulatory system is called:
total peripheral resistance
short term regulation of mean arterial pressure is primarily:
under neural control
the integration center of short term BP control:
medulla
effectors of short term BP control
organs
blood vessels
controllers of short term BP control:
- the autonomic nervous system
- mostly sympathetic
- is what connects integration center to organs
location of cardiopulmonary baroreceptors:
- large veins
- pulmonary vessels
- atria
- ventricles
function of cardiopulmonary baroreceptors:
- sense a decrease in pressure secondary to decrease in blood volume
- on beat by beat basis
arterial baroreceptors have what type of feedback?
negative feedback loop
cardiopulmonary baroreceptors have what type of feedback?
feedforward
glomerular filtration rate is dependent on:
renal blood flow
pressure diuresis
-increased body fluid, increases arterial pressure, increases water excretion
pressure natriuresis
increased arterial pressure increases sodium excretion
stimuli for ADH secretion:
- increased osmolarity
- decreased blood volume
- decreased blood pressure
- nasea
- hypoxia
renin response to fall in pressure
-renin released from JG cells into afferent arteriole
epinephrine increases CO by:
- increasing HR (B1)
- increasing SV (B1)
epinephrine’s effect on TPR:
- alpha adrenergic: vasoconstriction
- B2 adrenergic: vasodilation
SNS activity is increased by a ____ in arterial baroreceptor firing frequency
decrease
rate pressure product=
HR x SBP
-reflects myocardial work and myocardial demand for O2
Fick’s equation:
rate of diffusion of O2 and CO2 is dependent on:
- pressure gradient
- wall thickness
what largely determines the oxygen carrying capacity of blood?
hemoglobin
what favors oxygen unloading in muscle:
increased H+ (acidity) and temperature of a muscle
factors effecting oxygen uptake and delivery:
- oxygen content of blood
- amount of blood flow to the muscles (capilary density)
- local conditions within th emuscle (mitochondria density, myoglobin, pH, temp, etc)
MVO2
-myocardial oxygen demand
MVO2 effected by:
- HR
- SBP (resistance the heart is pumping against)
afterload:
- determined by what arteries are vasodilated and vasoconstricted
- the pressure in the aorta
- viscosity plays minimal role compared to diameter of vessel
preload:
pressure that blood exerts on heart in diastole
