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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?

24
Q

Atrial stretch receptors are located where?

A
  • vena cava: right atrial junction

- pulmonary vein: left atrial junction

25
Bainbridge reflex
- Increased intravascular volume - atrial stretch receptors - medullary activation (via vagus nerve) - increased sympathetic activity to SA node - increased HR
26
If you give a volume of fluid fast what will happen to HR?
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
What are some of other cardiac reflexes due to atrial stretch receptor activation?
- 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
Behold-Jarisch Reflex is AKA
Ventricular receptor reflex
29
What is the ventricular receptor reflex?
Responds to noxious ventricular stimuli *negative reflex* Will see: - hypotension - bradycardia - coronary artery dilation
30
What elicits the ventricular receptor reflex?
Strong contraction of an underfilled ventricle
31
Peripheral chemoreceptors are located where?
Aortic and carotid bodies
32
Peripheral chemoreceptors are primary concerned with what?
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
The peripheral chemoreceptors are not stimulated strongly until atrial pressure falls below what?
80mmHg
34
Pathway of baroreceptor and chemoreceptor msgs
Hering’s nerve Vagus nerve Vasomotor center of the brain
35
What stimulates the CNS ischemic response?
- 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
What caused a Cushing response?
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
What activates the diving reflex?
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
How can HR change with respirations?
HR increases with inspiration and slows with expiation * increased sympathetic activity with inspiration * increased parasympathetic activity with expiration
39
What are circulating catecholamines?
Epinephrine | Norep
40
Epinephrine will increase what and decrease what?
``` Increase: Cardiac -HR -Inotropy -Dromotropy Vasculature -Resistance ``` Decrease: Vasculature -resistance — some vascular beds constrict, others dilate -Capacitance
41
Norepinephrine increases and decreases what?
``` Increases: Cardiac -HR -Inotropy -Dromotropy ``` Vasculature -Resistance Decreases: Cardiac -HR - will get rebound bradycardia -Capacitance
42
How does the Renin-Angiotensin-Aldosterone System help regulate BP
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
How does atrial Natriuretic peptide work to help control BP?
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
How does vasopressin help to control BP
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
Where is vasopressin formed, stored, and excreted?
- Formed in nerve cells in hypothalamus | - Transported by nerve axons to and stored in posterior pituitary. It is the excreted from there
46
An increase in what ion concentration causes vasoconstriction and why
Calcium ion concentration The generally effect of calcium to stimulate smooth muscle contraction
47
An increase in what ion concentration within the physiological ranges, causes vasodilation and why?
Potassium ion The effect results from the ability of potassium ions to inhibit smooth muscle contraction
48
An increase in what ion concentration causes powerful vasodilation and why?
Magnesium ion Bc magnesium ions inhibit smooth muscle contraction
49
An increase in hydrogen ion concentration (decrease in pH) causes what?
Dilation of the arterioles
50
A slight decrease in hydrogen ion concentration causes what?
Arteriolar constriction
51
An increase in CO2 concentration causes moderate ___________ in most tissues, but marked ________ in the brain
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
Effects of moderate hypoxia on cardiac performance
Indirect effects: | Sympathetic nervous system activation -> increased HR, increased CO, increased contractility
53
Effects of severe hypoxia on cardiac performance?
Direct effects: | Depressed myocardial contractility
54
Indirect and direct effects of hypercarbia on cardiac performance
Indirect - sympathetic nervous system activation - increased HR, increased CO, increased contractility Direct -depressed myocardial contractility

Advanced Pathology (27 decks)

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