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CV > Neurohumoral Control Of The Heart And Circulation > Flashcards

Neurohumoral Control Of The Heart And Circulation Flashcards

1
Q

This operates the visceral reflexes

A

Autonomic nervous system

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2
Q

__________ primarily controls the heart, and _______ controls the vasculature and excitatory functions of the heart

A

Parasympathetic nervous system

Sympathetic nervous system

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3
Q

This receives input from baro and chemo receptors

A

NTS

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4
Q

Parasympathetic is excitatory or inhibitory?

A

Inhibitory

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5
Q

Extrinsic control of peripheral blood flow is mainly mediated by what?

A

Sympathetic nervous system

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6
Q

Nervous control of the circulation affects what global functions?

A
  • Redistributing blood flow
  • Increasing pump activity of the heart
  • providing rapid control of blood pressure
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7
Q

During sympathetic stimulation, sympathetic nerves release what?

A

Norepinephrine

-acts directly on alpha adrenergic receptors

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8
Q

During sympathetic stimulation the adrenal glands release what?

A
  • mostly epinephrine (80%)

- lesser amount of norepinephrine (20%)

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9
Q

Norepinephrine released fro the sympathetic nerves has a long or short period of action

A

Short

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10
Q

____________ is a principle vasoconstrictor

A

Norepinephrine

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11
Q

T/F: epinephrine will cause vasodilation in a few tissues due to beta 2 adrenergic stimulation

A

True

Dose dependent. Will become vasoconstrictor at higher doses

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12
Q

What do the adrenergic receptors do when stimulated?

A 
Alpha: 
-vasoconstriction
Beta 1:
-increased heart rate
-increased contractility
Beta 2:
-vasodilation 
-bronchodilation
-uterine relaxation
-glycogenolysis
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13
Q

Sympathetic activation of the heart does what?

A
  • chronotropy = HR
  • inotropy = contractility
  • dromotropy = conduction velocity
  • lusitropy = relaxation
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14
Q

Cardiac contraction and relaxation are both accelerated by activation of what 2 things?

A
  • catecholamines

- adenylyl cyclase

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15
Q

Increase in cAMP activates a protein kinase which phosporylates the ca++ channel in the sarcolemma resulting in a greater influx of what?

A

Calcium

This causes an increase in contractility

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16
Q

When contractility is increased, relaxation is also enhanced (lusitropy) by the uptake of what by the sarcoplasmic reticulum?

A

Calcium

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17
Q

Name the 6 cardiovascular reflexes

A
  1. Baroreceptor reflex
  2. Atrial trench receptor reflexes (bainbridge reflex)
  3. Behold-jarisch reflex (ventricular receptor reflex)
  4. Chemoreceptor reflex
  5. CNS ischemic response (Cushing response)
  6. Diving reflex
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18
Q

Where are baroreceptors located?

A

Carotid sinus

Aorta arch

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19
Q

Baroreceptor reflex

A
  • responsible for rapid adjustments in BP
  • Stimulated when stretched
  • signals transported through herings nerve to glossopharangel nerve, NTS

-aortic transported by vagus nerve to NTS

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20
Q

Baroreceptor reflex reduces the daily variation in BP by how much from that which would occur if this system was not present?

A

1/2 - 1/3

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21
Q

This helps with postural changes in BP

A

Baroreceptor reflex

*this functions well within normal BP range, if out of range have difficulty

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22
Q

Atrial stretch receptors are sensitive to what?

A

Volume

Stretching—>increased water and sodium excretion

23
Q

Baroreceptors are sensitive to what?

A

Pressure

24
Q

Atrial stretch receptors are located where?

A
  • vena cava: right atrial junction

- pulmonary vein: left atrial junction

25
Q

Bainbridge reflex

A
  • Increased intravascular volume
  • atrial stretch receptors
  • medullary activation (via vagus nerve)
  • increased sympathetic activity to SA node
  • increased HR
26
Q

If you give a volume of fluid fast what will happen to HR?

A

If will increase due to the bainbridge reflex

  • degree and direction of HR change depends on the prevailing HR
  • slow baseline HR->see increased HR with infusion
  • high baseline HR-> see decreased HR with infusion
27
Q

What are some of other cardiac reflexes due to atrial stretch receptor activation?

A
  • decreased sympathetic activity to kidney -> increased UO
  • decreased vasopressin (ADH) -> increased UO and decreased water reabsorption, decreased BP
  • increased atrial natriuretic peptide -> increased natriuresis, increased UO, decreased BP
28
Q

Behold-Jarisch Reflex is AKA

A

Ventricular receptor reflex

29
Q

What is the ventricular receptor reflex?

A

Responds to noxious ventricular stimuli
negative reflex

Will see:

  • hypotension
  • bradycardia
  • coronary artery dilation
30
Q

What elicits the ventricular receptor reflex?

A

Strong contraction of an underfilled ventricle

31
Q

Peripheral chemoreceptors are located where?

A

Aortic and carotid bodies

32
Q

Peripheral chemoreceptors are primary concerned with what?

A

Regulation of respiration

  • decreased in arterial blood O2 tension, CO2 excess, and/or hydrogen excess results in excitation of the vasomotor center
  • this may occur whenever the atrial pressure falls below a critical level (inadequate blood flow to the chemoreceptors)
  • this reflex helps to return the BP back to normal level
33
Q

The peripheral chemoreceptors are not stimulated strongly until atrial pressure falls below what?

A

80mmHg

34
Q

Pathway of baroreceptor and chemoreceptor msgs

A

Hering’s nerve
Vagus nerve
Vasomotor center of the brain

35
Q

What stimulates the CNS ischemic response?

A
  • Decrease blood flow to vasomotor center in medulla
  • increased local concentration of CO2 results in stimulation in the medulla
  • results in increased BP
  • very poor activator of the sympathetic nervous system
36
Q

What caused a Cushing response?

A

Increased intra-cranial pressure

  • special type of CNS ischemic response
  • increased ICP results in increased BP until blood flows once again in the vessels of the brain
37
Q

What activates the diving reflex?

A

Cold water on face
-information relayed to brain stem via facial nerve afferents

Survival mechanism. Body shuts down “less important” parts trying to conserve O2 for heart and brain

38
Q

How can HR change with respirations?

A

HR increases with inspiration and slows with expiation

  • increased sympathetic activity with inspiration
  • increased parasympathetic activity with expiration
39
Q

What are circulating catecholamines?

A

Epinephrine

Norep

40
Q

Epinephrine will increase what and decrease what?

A 
Increase:
Cardiac
-HR
-Inotropy
-Dromotropy
Vasculature
-Resistance

Decrease:
Vasculature
-resistance — some vascular beds constrict, others dilate
-Capacitance

41
Q

Norepinephrine increases and decreases what?

A 
Increases:
Cardiac
-HR
-Inotropy
-Dromotropy

Vasculature
-Resistance

Decreases:
Cardiac
-HR - will get rebound bradycardia
-Capacitance

42
Q

How does the Renin-Angiotensin-Aldosterone System help regulate BP

A

Hypotension, decreased Na delivery, and sympathetic stimulation cause the kidney to release renin

Renin->angiotensin -> adrenal cortex + aldosterone = renal sodium and fluid retention

-this will cause an increase in blood volume, will increase CO, and increase arterial pressure

43
Q

How does atrial Natriuretic peptide work to help control BP?

A

ANP is release by stretch receptors out of the atria

ANP -> affects kidney, decrease release of renin -> natriuesis diuresis -> decrease blood volume and decreased arterial pressure

44
Q

How does vasopressin help to control BP

A

AKA: antidiuretic hormone

Angiotensin II, hyperosmolarity, decreased atrial receptor firing, and sympathetic stimulation -> pituitary to release vasopressin -> vasoconstriction and renal fluid absorption -> increased blood volume and increased arterial pressure

45
Q

Where is vasopressin formed, stored, and excreted?

A
  • Formed in nerve cells in hypothalamus

- Transported by nerve axons to and stored in posterior pituitary. It is the excreted from there

46
Q

An increase in what ion concentration causes vasoconstriction and why

A

Calcium ion concentration

The generally effect of calcium to stimulate smooth muscle contraction

47
Q

An increase in what ion concentration within the physiological ranges, causes vasodilation and why?

A

Potassium ion

The effect results from the ability of potassium ions to inhibit smooth muscle contraction

48
Q

An increase in what ion concentration causes powerful vasodilation and why?

A

Magnesium ion

Bc magnesium ions inhibit smooth muscle contraction

49
Q

An increase in hydrogen ion concentration (decrease in pH) causes what?

A

Dilation of the arterioles

50
Q

A slight decrease in hydrogen ion concentration causes what?

A

Arteriolar constriction

51
Q

An increase in CO2 concentration causes moderate ___________ in most tissues, but marked ________ in the brain

A

Vasodilation
Vasodilation

*however, CO2 in the blood, acting on the brain vasomotor center, has an extremely powerful indirect effect, causing widespread vasoconstriction throughout the body

52
Q

Effects of moderate hypoxia on cardiac performance

A

Indirect effects:

Sympathetic nervous system activation -> increased HR, increased CO, increased contractility

53
Q

Effects of severe hypoxia on cardiac performance?

A

Direct effects:

Depressed myocardial contractility

54
Q

Indirect and direct effects of hypercarbia on cardiac performance

A

Indirect

  • sympathetic nervous system activation
  • increased HR, increased CO, increased contractility

Direct
-depressed myocardial contractility

CV (8 decks)

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