humoral and nervous control of circulation (midterm 2)

Question 1

what do tissues control and how

Answer 1

their own blood flow - the greater the metabolic needs of a tissue, the greater the blood flow

Question 2

what are the two forms of blood flow control and what are their differences

Answer 2

acute - seconds to minutes
long term - days, week, months (better control)

Question 3

what is a major determinant of control of blood flow

Answer 3

oxygen deficiency (lower oxygen pressure leads to greater blood flow)

Question 4

what is vasodilator theory

Answer 4

decreased blood flow, decreased oxygen increases the formation of vasodilator compounds (i.e. adenosine), which increases vessel diameter and blood flow increases

Question 5

what is oxygen demand theory

Answer 5

decreased blood flow leads to decreased oxygen pressure leading to decreased vessel muscle tone/contraction, leading to increased vessel diameter and therefore increased blood flow

Question 6

how is blood flow autoregulated

Answer 6

blow flow is maintained despite changes in arterial blood pressure
increased arterial pressure leads to increased blood flow, which leads to normal blood flow

Question 7

what is the metabolic theory of acute blood flow control

Answer 7

arterial pressure increases, blood flow increases, nutrition is too high, blood vessel diameter decreases, blood flow decreases

Question 8

what is the myogenic theory of acute blood flow control

Answer 8

arterial pressure increases, blood flow increases, smooth muscle cells contract, vessel diameter deceases, blood flow decreases

Question 9

what is blood flow driven by for kidneys, brain, and skin

Answer 9

kidneys: filtration needs
brain: oxygen delivery and co2 removal
skin: temperature regulation

Question 10

what is tissue vascularity

Answer 10

if there is decreased blood flow that isn’t meeting the needs to a tissue, the number of vessels perfusing the tissue unit can increase to provide sufficient blood flow

driven by max need, not average

Question 11

what is angiogenesis

Answer 11

the growth of new blood vessels via vessels sprouting from small venules or capillaries

Question 12

what is collateral circulation

Answer 12

increased vascular density when an artery or vein is blocked to restore blood flow

Question 13

what are vasoconstrictors and examples

Answer 13

narrowing of blood vessels

norepinephrine, angiotensin, vasopressin, endothelin

Question 14

what are vasodilators and examples

Answer 14

open (dilate) blood vessels

bradykinin, serotonin, histamine, prostaglandins

Question 15

where does nervous regulation occur through

Answer 15

the autonomic nervous system (involuntary), which acts through sympathetic and parasympathetic systems

Question 16

what is the sympathetic system

Answer 16

impacts vasculature and heart

Question 17

what is the parasypathetic system (vagal system)

Answer 17

impacts heart

Question 18

what occurs when sympathetic system is stimulated

Answer 18

increased vascular resistance, decreased vascular diameter, decreased blood flow, increased cardiac output

all maintain blood pressure

Question 19

what occurs when parasympathetic system is stimulated

Answer 19

decreased SN rate, decreased heart rate

Question 20

where is the vasomotor system located and what does it act under

Answer 20

bilaterally in the reticular substance of the medulla and lower third of the pons

acts under both sympathetic and parasympathetic stimulation

Question 21

what does the vasomotor center do under normal conditions

Answer 21

sends signals that act to maintain sympathetic signals that act to maintain sympathetic vasoconstrictor tone

Question 22

what happens when the vasomotor center is blocked by spinal anesthesia

Answer 22

loss of vessel tone and arterial pressure drops dramatically

Question 23

what restores vessel tone in the vasomotor center

Answer 23

stimulation by norepinephrine, which increases blood pressure

Question 24

what does the sympathetic vasoconstrictor system function to do

Answer 24

control cardiac output - increases pressure (cardiac output) with vasoconstriction
- decreases pressure (cardiac output) with vasodilation

Question 25

what do baroreceptors do

Answer 25

stretch receptors in the corrotid arteries and aorta in response to an increase in pressure in order to decrease arterial pressure again

Question 26

where are signals transmitted from for baroreceptors to work

Answer 26

from each carotid sinus through Hering’s nerve to the glossopharyngeal nerve and then to the tractus solitarius in the medullary of the brain

• signals from the aortic arch are transmitted through the vagus nerve into the same area of the medulla

Question 27

what are the specific changes in arterial pressure that impact impulse transmission in Hering’s nerve

Answer 27

little change = < 60 mmHg
change in impulses = 60 - 180 mmHg
big change in impulses = steep slope
increased duration = decreased HR and decreased heart contraction

Question 28

what do functional baroreceptors look like plotted

Answer 28

steep peak; disrupted is more of a small, jagged curve - system resets after 1 or 2 days