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Prob set 6
Terms in this set (55)
180. What adrenergic receptors are found within the entire heart (as a complex organ of many tissues)?
Beta 1 receptors
181. How does stimulation of beta-1 receptors within ventricular muscle directly affect SERCA?
What secondary effects (2 distinct effects) does this have?
SERCA pumps a higher proportion of Ca++ back into the S.R.
Secondary: this enables relaxation & filling of the heart
182. What effect(s) does increased PSNS stimulation have on the heart?
Do muscarinic receptors have en effect on ventricular contractility or a ventricular inotropic effect?
Suppression of funny current = decrease in heart rate
Slight decrease in contractility of the atria
PSNS has NO effect on ventricular activity
183. What two primary measures are monitored that affect cardiovascular function?
Which one are we not discussing further until pulmonary?
Arterial blood pressure & arterial gas levels
Arterial gas levels
184. Which effect would a sympathetic antagonist drug cause? More than one may apply:
a. positive inotropic,
b. slightly negative inotropic,
c. positive chronotropic,
d. negative chronotropic
b. slightly negative inotropic
d. negative chronotropic
185. If a drug caused the sinoatrial node myocytes to increase the hyperpolarization (more negative) after an action potential, would this cause an increase or decrease in heart rate?
Decrease in HR due to longer time it takes for the SA node to reach threshold
186. What second messenger effects are seen in response to a stimulated Beta-1 versus a stimulated M2 Muscarinic receptor?
Beta 1 receptors upregulate cAMP → upregulate PKA → causes phosphorylation of L-type Ca++ channels = increased contractility
M2 receptors decrease [cAMP] → decreases PKA → decreased HR
187. How would a cholinergic antagonist affect contractility of the ventricles?
How would it affect heart rate?
No effect (PSNS & M2 agonists/antagonists have no inotropic effects)
188. Relative to controlling autonomic activity directed at the heart, where are the arterial baroreceptors found (2 locations)?
Aortic arch & Carotid sinuses
189. If arterial blood pressure suddenly increases, how does this affect autonomic activity and what changes occur in the heart?
Decreased SNS activity (to reduce blood pressure)
This Suppression of cardiac stimulation acts to reduce blood pressure
190. Where is the integration center for the visceral reflexes that govern the activity of the heart?
191. Would plasma hypercalcemia cause a positive or negative inotropic effect on contractile cardiocytes? Why?
Increased global Ca++ increases force production and thus contractility = positive inotropic
192. How would hemorrhage affect the relative activities of the SNS and PSNS?
How would this compensate for the hemorrhage relative to heart activity and what consequent effect would this have on arterial pressure?
Increased SNS activity & decreased PSNS activity
Because SNS is activated, heart rate increases and thus elevates arterial pressure to compensate for the effects of hemorrhage
193. How and why does blood pressure vary as blood travels through arteries, arterioles, capillaries, venules and veins? Where is pressure lowest?
Pressure varies because all vessels have a resistance and resistance decreases pressure
Pressure is lowest in veins
194. What key protein within the walls of large arteries diminishes/dampens/attenuates the pulse pressure?
How does this protect and benefit vessels and their functions downstream?
Ensures proper systole/diastole so that when blood reaches the capillaries, pulsation is diminished to prevent peaks of pressure from damaging delicate capillaries
195. What typically happens in old age to arteriolar/capillary pulse pressure and systolic blood pressure? Why?
Arteries harden and lose elasticity, thus dampening is less effective
Pulse pressures are more extreme in the capillaries
196. Which category of systemic vessels (arteries, arterioles, capillaries, venules or veins) have the largest total cross-sectional area?
197. Which category of systemic vessels have the greatest rate of flow?
The slowest rate of flow?
Greatest flow = arteries
Slowest flow = capillaries
198. Which vessels are the most compliant?
199. Where are one-way valves found in the vasculature? Why are they only necessary there?
Found in veins to ensure one-way movement back to the heart (to overcome the resistance of gravity)
200. What autonomic receptors are found in the smooth muscle of veins?
Which system stimulates them and what does it cause?
Alpha-1 adrenergic receptors
How venoconstriction affect cardiac output and arterial pressure (step by step)?
Venoconstriction → increased venous pressure → increased venous return to the heart and ventricles → increased EDV → increased SV→ increased cardiac output & arterial pressure
201. Where is capillary density greater, in Type I or Type IIb muscle? Why?
Type I muscle to allow for high aerobic capacity
202. While standing: How would heart rate differ (it does) between standing perfectly still and slightly "wobbling" back and forth? Why? (Assume not enough exercise to elevate heart rate)
Perfectly still: heart rate is increased b/c venous return & stroke volume are impeded due to gravity (heart has to work harder to maintain arterial pressure
203. Why is heart rate elevated during dehydration?
dehydration = low blood volume.
baroreceptors sense this low blood volume and SNS activity is upregulated as a result
204. Does blood flow faster through the aorta or the capillaries? How is this advantageous within capillaries?
It is useful for exchange within the capillaries
205. Does velocity of blood flow always correlate to blood pressure?
207. Which organ has a larger diameter artery that supplies it: A big aerobic organ or a small less aerobic organ?
Big aerobic organ
208. What mechanism or system "roughly" distributes blood proportionally to the appropriate organs and systems during rest vs exercise?
209. Relative to blood pressure homeostasis, how does parasympathetic stimulation affect the vasculature?
PSNS does nothing relative to the vasculature
210. What effect does sympathetic stimulation have upon arterioles of skeletal muscle and why? (mechanism and reason)
Innervation of arterioles (vasoconstriction) diverts blood away from the renal, digestive, and integumentary systems and instead sends more blood (vasodilation) to skel. Muscle, heart, and lungs
211. What types of adrenergic receptors are found within smooth muscle of arterioles leading to the kidney?
What neurotransmitter or hormone stimulates this receptor?
Does sympathetic stimulation stimulate or inhibit this smooth muscle?
Does this depolarize or hyperpolarize the smooth muscle?
Does this increase or decrease the sarcoplasmic calcium within this smooth muscle?
Does this cause vasoconstriction or vasodilation of these vessels?
Does this increase or decrease renal blood flow?
Does this cause an increase in arteriolar resistance or a decrease in resistance?
Decreases renal blood flow
212. Does sympathetic stimulation cause a net vasoconstriction or net vasodilation?
Is this an increase or decrease in total systemic resistance?
How does this affect upstream arterial blood pressure?
How does this affect downstream capillary and venous pressure?
Increases arterial blood pressure upstream
Decreases pressure downstream within the capillaries and veins
213. In summary, what effect(s) does the SNS have on the entire cardiovascular system?
increased arterial pressure during SNS stimulation, vasoconstriction of blood flow to smooth muscle, vasodilation of arteries innervating skeletal muscle,
What effect(s) does the PSNS have on the entire cardiovascular system?
Decreases HR by suppressing funny current
214. Where are baroreflexes integrated?
215. What mechanism "fine-tunes" precise distribution of blood flow to individual capillary beds?
What is the flow of blood to a tissue most proportional to?
The activity level of the tissue and organ
216. What specific tissue is targeted by metabolic regulation of blood flow when an organ is not receiving the proper blood flow?
Arteriolar smooth muscle
217. Does insufficient blood flow to an active tissue cause acidosis or alkalosis?
218. Does a low CO2 level cause arteriolar VC or VD?
Does a low CO2 level cause
Does a low CO2 level cause
Alkalosis or acidosis?
219. What two separate reactions/mechanisms can cause pH to drop in a VERY active tissue bed?
High tissue metabolism results in:
- Increased Co2 levels
- Lactic acid build up
This results in acidosis (or a drop in pH)
220. Why is it important maintain sufficient blood flow to an active tissue?
To prevent severe acidosis
221. Why is it important to prevent "too much" blood flow in a tissue bed? (two distinct good reasons)
To return Co2 and [H+] levels back to normal (prevent alkalosis)
222. Describe the blood flow to the brain as a percentage of cardiac output at rest and whether this is relatively high or low relative to the size of the brain as a proportion of body mass.
14% of cardiac output goes to the brain
this is high, considering the brain is only 2.5% of total body mass
222. Describe the blood flow to the heart as a percentage of cardiac output at rest and whether this is relatively high or low relative to the size of the heart as a proportion of body mass.
Heart = 4% of cardiac output (this is high)
222. Describe the blood flow to the bone as a percentage of cardiac output at rest and whether this is relatively high or low relative to the size of bone as a proportion of body mass.
Bone = 1% (this is low)
222. Describe the blood flow to the skeletal muscle as a percentage of cardiac output at rest and whether this is relatively high or low relative to the size of skel. muscle as a proportion of body mass.
Skeletal muscle = 20% (this is low, as muscle is 40% body mass)
222. Describe the blood flow to the kidneys as a percentage of cardiac output at rest and whether this is relatively high or low relative to the size of the kidneys as a proportion of body mass.
kidneys = 22%
this is high
222. Describe the blood flow to the digestive tract as a percentage of cardiac output at rest and whether this is relatively high or low relative to the size of the digestive tract as a proportion of body mass.
Digestive tract = 27% (this is high, as digestive system is 5% body mass)
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