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Agents that increase cGMP promote smooth muscle ____________ (contraction/relaxation?)
An increase in ______________ is needed to support the increased O2 usage in the heart.
Blood flow to local regions of the brain is matched to ______________, mediated by ________.
neural activity, pCO2
Blood flow to skeletal muscle during exercise increases by what 2 mechanisms?
arteriolar vasodilation, opening precapillary sphincters
Blood flow to the GI tract is increased/decreased during exercise?
By what molecular mechanisms does cAMP affect smooth muscle?
PKA phosphs MLCK (inhibiting), and also stimulates K channels, hyperpolarizing the cell membrane and reducing Ca influx through voltage gated Ca channels
cAMP has what effect on smooth muscle?
Cardiac output will always _________ during exercise due to __________ signals.
increase, sympathetic
Cerebral circulation does not respond to _____________tone.
Coronary blood flow increases in proportion to __________.
cardiac output
Disruption of the basal lamina in renal glomerular capillaries will result in what pathological condition?
During exercise, does renal blood flow increase or decrease?
During exercise, increase in cardiac output is balanced by ______________.
decrease in total peripheral resistance
During isometric exercise, _________ effects outweigh the _______________ effects.
sympathetic vasoconstrictive, local vasodilatory
From what does the heart muscle derive the largest proportion of its energy?
fatty acid oxidation and lactate in circulation
High temperatures stimulate sweat glands which secrete _______, dilating blood vessels locally through increases in which molecules?
bradykinin, NO and cAMP
How do capillaries aid in maintaining cardiac output following loss of blood volume?
pressure at the arteriolar end of capillaries diminishes therefore decreasing hydrostatic pressure of the capillary, favoring reabsorption
How do glomerular capillaries ensure constant filtration?
hydrostatic pressure of the capillary always exceeds oncotic pressure of the capillary
How do NO and ANF differ in their mechanisms of generating cGMP?
ANF activates a membrane bound guanine cyclase, whereas NO diffuses through the membrane to activate a cytoplasmic guanine cyclase
How do systolic and diastolic pressures change during exercise, and what effect does this have on pulse pressure?
systolic increases, diastolic stays the same or decreases, increase in pulse pressure
How does adenosine promote VSM relaxation?
diffuses out of metabolically actie cells and acts as a paracrine factor, activating A2a receptors, which couple to adenylate cyclase and increase cAMP
How does hypoxia promote VSM relaxation?
hypoxia induced decrease in intracellular ATP will activate ATP-sensistiive K channels and hyperpolarize the cell
How much oxygen does the heart extract in coronary circulation?
In most capillaries, filtration occurs at the ________ end of the capillary and reabsorption happens at the ___________end.
arterial, venous
In order to cool the body during core temperatures, cutaneous blood flow will increase/decrease?
In skeletal muscle, catecholamines can act as a ____________ via what kind of receptors?
vasodilator, beta-2
In the GI tract and the skin, catecholamines usually act as ______________ via what kind of receptors?
vasoconstrictors, alpha-1
In the lungs, low pO2 causes vessels to dilate or constrict?
In the skin, if core temperature is _________, sympathetic tone increases and blood flow _________.
low, decreases
Is coronary blood flow higher during systole or diastole?
The ANS decreases the sympathetic tone in the skin when the core temperature is ____________ and therefore blood flow ____________.
high, increases
The C wave in the venous pressure curve refers to what?
impact on the jugular vein of the sudden pressure rise in the carotid artery during the rapid ejection phase
The composition of lymph is roughly similar to that of plasma except for a lower _________ content.
The decline in the C wave of the venous pressure curve refers to what?
decrease in atrial pressure during the rapid ejection phase
The falling arm of the V wave in the venous pressure curve corresponds to what?
emptying of the R atria and connected great veins during slow filling of ventricles
The increase in pulmonary ventilation during exercise exactly mathes the increase in ________________, so that __________________ does not decrease.
oxygen consumption, arterial oxyen concentration
The movement of small polar molecules such as water, ions, glucose, and amino acids through capillaries occurs mostly through ______________.
intercellular junctions
The pressure in most capillaries is approximately ___________.
15-35 mmHg
The rising arm of the V wave in the venous pressure curve corresponds to what?
filling of R atrium and connected great veins during reduced ejection
The small increment in pressure called the A wave in the venous pressure curve corresponds to what?
Atrial systole
The upward slope of the A wave in the venous pressure curve corresponds to what?
diastasis - blood returning from periphery or lungs to atria and ventricles
Through what intermediary does cGMP affect Ca levels?
Vasodilation at the level of the arteriole will have what effect on the capillaries?
increased filtration
Vasodilationof working skeletal muscles during exercise id sriven by metabolism and starts at _______________, working back to more ____________ vessels.
terminal arterioles, proximal
What are 4 sensors of increased metabolic activity that may override neural signals on smooth muscle?
adenosine, CO2, K, decreased O2
What are myogenic effects?
Muscles contract in response to increased luminal pressure, possibly through activation of stretch sensitive cation channels, causing vessel diameter to shrink in response to pressure increase
What are the 3 effectors of PKG?
inhibition of Ca channels, activation of K channels (hyperpolarizing and therefore deactivating Ca channels), and activating a phosphatase that dephosphorylates myosin
What effect will endurance exercise have on mean arterial blood pressure?
increase modestly
What effect will vasoconstriction and hemorrhage have on the capillaries?
decrease capillary hydrostatic pressure
What factors allow for increased venous return during exercise to sustain increased cardiac output?
contraction and relaxation of muscles will pump blood, venous valves, ventilation making thoracic pressures more negative
What happens to total peripheral resistance during exercise?
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