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2.1 Control and Integrative Physiology > Mairead - Neural and Hormonal Control of Vasculature > Flashcards

Mairead - Neural and Hormonal Control of Vasculature Flashcards

1
Q

What is the goal of the CVS regulation?

A

To ensure blood flow changes occur:
- at an appropriate time
- in the right area
- without drastically affecting blood flow to vital organs

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2
Q

What factors are involved in the regulation of CVS function

A

Local factors

Neural factors

Hormonal factors

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3
Q

Write about how local factors are involved in the regulation of CVS function
(4)

A

Result in a change in blood flow pattern in
response to a change in metabolism.

Called autoregulation.

Provides an immediate and localised
adjustment in perfusion

If this fails, neural factors work

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4
Q

What is autoregulation

A

A change in blood flow pattern in response to a change in metabolism

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5
Q

What does autoregulation do

A

Provides an immediate and localised adjustment in perfusion

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6
Q

When do neural factors work

A

If local factors fail

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7
Q

Write about how neural factors are involved in the regulation of CVS function
(4)

A

They result in a change in blood flow between
regions of the body.

Neural factors change blood flow in response to changes in blood pressure and blood
gases.

This is mediated by an ANS change.

ANS output changes Cardiac Output and
Peripheral Resistance

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8
Q

What affect do neural factors have

A

They change blood flow between regions of the body

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9
Q

Neural factors change blood flow in response to what

A

Response to changes in blood pressure and blood gases

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10
Q

What is responsible for changing blood pressure and blood gases

A

This is mediated by an ANS change

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11
Q

ANS affects what values

A

Cardiac Output and Peripheral Resistance

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12
Q

Write about how hormones are involved in the regulation of CVS function
(6)

A

Enhance the short term response and

Direct the long term response.

Affect cardiac output and peripheral resistance and in the longer term regulate blood volume and blood composition.

In addition to barororeceptors and chemoreceptors…

Volume change detected as pressure and osmolarity (osmoreceptors) in renal tissue and
hypothalamus.

Gas disturbance (O2) detected in renal tissue

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13
Q

What do hormones do in general

A

Enhance the short term response of ANS

Direct a long term response

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14
Q

What do hormones affect in the CVS
(4)

A

Cardiac output

Peripheral resistance

Blood volume

Blood composition

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15
Q

What exactly is stress

A

Increased physical demand

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16
Q

What will bring on stress
(5)

A

Exercise
Fever
Haemorrhage and dehydration
Tumour growth
Psychological stress

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17
Q

What is the demand and or change in exercise?

A

ih i

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18
Q

What is the short term response to exercise?

A

bo

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19
Q

What is the long term response to exercise?

A

bob

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20
Q

What is the demand and or change to tumours

A

bo

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21
Q

What is the long term response to tumours

A

bou

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22
Q

What is the blood change/response to haemorrhage/dehydration

A

bo

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23
Q

What is the short term response (nervous) to haemorrhae/dehydration

A

buo

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24
Q

What is the long term response to haemorrhage/dehydration

A

bio

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25
Q

Comment on autoregulation and local factors
(4)

A

Make minute to minute adjustments in blood flow.

Vasodilation and vasoconstriction of precapillary
sphincters.

Usually operate within the capillary bed.

Vasodilation at a local level is brought about by products
of metabolism

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26
Q

What products of metabolism bring about vasodilation at a local level in capillary beds
(7)

A

Gases (low O2 and high CO2)

Lactic acid, H+

NO, histamine

K+

Rising temperature

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27
Q

Why do products of metabolism being about vasodilation

A

These factors relax smooth muscle of arterioles and improve nutrient supply

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28
Q

What brings about vasoconstriction at a local level
(2)

A

Prostaglandins and thromboxane

Endothelins

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29
Q

Write about prostaglandins and thromboxane in vasoconstriction

A

These are released by platelets and WBCs to contain inflammation

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30
Q

Write about endothelins in vasoconstriction

A

These are released from damaged endothelial cells

They have their effect on smooth muscle of arterioles within a tissue or organ

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31
Q

What are the functions of autoregulation
(2)

A

Protects the capillaries from high pressure

Ensures adequate O2 supply

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32
Q

Define autoregulation

A

The maintenance of nearly normal levels of blood flow despite marked changes in arterial pressure

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33
Q

What is long term regulation of blood flow?
(3)

A

A response to sustained high blood pressure

A response to chronically overactive tissue

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34
Q

Why is long term regulation of blood flow needed

A

To gradually increase blood supply to match the metabolic need

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35
Q

Comment on angiogenesis factor

A

Increases vascularity

Has been isolated from cancerous tissue

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36
Q

Write a note on regulation of blood flow through skeletal muscle

A

Decreased blood flow when muscles contract and constrict arterioles

Skeletal muscle have alpha- and Beta- adrenergic receptors

Alpha-adrenergic receptors vasoconstrict at rest

B-adrenergic receptors vasodilate

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37
Q

Write about the neural mechanisms of regulating CVS

A

Regulated by the ANS CVS regulatory centres of the
hypothalamus and brainstem.

Cardiac regulation by altering the
cardioacceleratory output or the cardioinhibitory
output of medulla oblongata.

Blood Vessel diameter is regulated by the
vasomotor centre in MO. This alters
vasoconstriction or vasodilation.

Heart and Blood vessels have ANS tone. This
means that the ANS is active at rest and can be
regulated.

Respiratory centres in the pons and medulla
oblongata

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38
Q

What are the CVS regulatory centres?

A

Hypothalamus

Brainstem

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39
Q

How does the hypothalamus and brainstem regulate the CVS

A

By altering the cardioacceleratory output or the cardioinhibitory output of medulla oblongata

40
Q

The blood vessel diameter is regulated by what?

A

The vasomotor centre in medulla oblongata

41
Q

What does the vasomotor centre in the medulla oblongata do
(2)

A

Regulates the blood vessel diameter

Thus alters vasoconstriction or vasodilation

42
Q

Heart and blood vessels have ANS tone, what does this mean

A

This means that the ANS is active at rest and can be regulated

43
Q

Where are the respiratory centres in the brain?

A

In the pons and medulla oblongata

44
Q

Write a note on reflex control of CVS
(5)

A

Reflex Control of CVS Function is in response to
changes in blood pressure or changes in blood
gases (or blood pH).

Bainbridge (atrial) Reflex is the response to
raised venous return.

Barroreceptor Reflexes are the response to
blood pressure change.

Chemoreceptor reflex is the response to blood
gas composition.

If the pressure and gases are reduced by a
reduction in blood volume a further long term
response may be required

45
Q

What is reflex control of CVS function done in response to?
(3)

A

Changes in blood pressure

Changes in blood gases

Changes in blood pH

46
Q

What is the Bainbridge (atrial) reflex?

A

The response to raised venous return

47
Q

What are the Barroreceptor reflexes

A

The response to blood pressure change

48
Q

What is the chemoreceptor reflex

A

The response to blood gas composition

49
Q

What may be required if the pressure and gases are reduced by a reduction in blood volume?

A

A further long term response may be required

50
Q

What is the response to raised venous return

A

Bainbridge reflex

51
Q

What are the response to blood pressure change

A

Barroreceptor reflexes

52
Q

What is the response to blood gas composition

A

Chemoreceptor reflex

53
Q

Write a note on the Baroreceptor reflex
(3)

A

Sensory stretch receptors in the walls of the blood vessels perceive change in pressure

Receptors are found in
- the aortic sinus
- the carotid sinus
- the walls of the Right Atrium
- JGA of the Kidney

When these receptors are stimulated the reflex adjust the blood pressure and may also require a blood volume adjustment

54
Q

Where are baroreceptors found?
(4)

A

The aortic sinus

The carotid sinus

The walls of the right atrium

JGA of the kidney

55
Q

What happens when baroreceptors are stimulated?

A

The reflex adjusts the blood pressure and may also require a blood volume adjustment

56
Q

How does the nervous system control blood flow in response to elevated blood pressure
(4)

A

Decrease CO by stimulation of the parasympathetic and inhibition of the sympathetic
division.

Widespread peripheral vasodilation by inhibition
of the sympathetic.

Dilation of the veins

Result is ↓ CO (by ↓hr and/or ↓ SV) and ↓ blood
pressure

57
Q

How does the nervous system control blood flow in response to when blood pressure falls
(4)

A

Increase CO by stimulation of the sympathetic and inhibition of the parasympathetic (cardiac)

Peripheral vasoconstriction by stimulation of the sympathetic (vasomotor centre)

Result is in ↑CO (by ↑HR and ↑ SV) and ↑ blood pressure.

May also include venoconstriction to move some of the venous reserve

58
Q

What do chemoreceptors and osmoreceptors do?

A

Respond to changes in CO2, O2, Na+ and pH of the blood and CSF

59
Q

Where are chemoreceptors and osmoreceptors located
(5)

A

The carotid bodies

Aortic bodies

Medulla oblongata (central chemoreceptors)

JGA of the Kidney

Hypothalamus (central osmoreceptors)

60
Q

Write a note on the nervous control of blood gases
(5)

A

If blood O2 decreases and CO2 and H+ increases
the cardiac, vasomotor centres and the respiratory
centres are stimulated.

Homeostasis is restored by increasing CO and
increasing blood pressure.

Increased blood flow to skeletal muscle will result
in decreasing of the total peripheral resistance.

AND

The respiratory centre is also stimulated to
increase CO2 elimination and O2 pickup

61
Q

What does decreased O2, increased CO2 and H+ stimulate?

A

Cardiac, vasomotor centres and the respiratory centres

62
Q

How is blood gas homeostasis restored?

A

Increasing CO and increasing blood pressure

63
Q

What happens when there is increased blood flow to skeletal muscle?

A

This will result in decreasing of the total peripheral resistance

64
Q

What happens when the respiratory centre is stimulated?

A

It will increase CO2 elimination and O2 pickup

65
Q

What is the short term response to lowered blood volume

A

To maintain the circulation by maintaining cardiac output and blood pressure

Nervous control mainly

66
Q

What is the long term response to lowered blood volume

A

Response is to restore blood volume (and pressure) and blood composition (plasma proteins, fluid and formed elements)

Endocrine control mainly

67
Q

What hormones are involved in the control of CVS function in response to fluid disturbance
(5)

A

Adrenaline and noradrenaline

Anti-diuretic hormone

Renin-angiotensin-aldosterone system (RAAS)

Erythropoietin

ANP and BNP

68
Q

What physiological parameters can be changed in response to fluid disturbance
(5)

A

Vasoconstriction/vasodilation

Heart rate and stroke volume adjustment

Fluid retention/loss

Increased/decreased ingestion of salt and water

Replacement of cells and plasma proteins

69
Q

How does adrenaline and noradrenaline affect fluid balance

A

These are released from the adrenal medulla as part of the flight and fight response

They prolong and extend the nervous response

70
Q

How do adrenaline and noradrenaline act to change fluid balance?
(4)

A

Increasing cardiac output

Increasing blood pressure

Elevating available energy

Shifting fluids to important areas

71
Q

Write a note on antidiuretic hormone

A

Produced in the hypothalamus and released from the posterior pituitary gland in response to nervous stimulation

72
Q

When is ADH released
(3)

A

Increased osmolarity of the extracellular fluid (detected by osmoreceptors in the hypothalamus)

Decreased arterial pressure in the hypothalamus

Stimulation by the hormone angiotensin

73
Q

What detects increased osmolarity of the extracellular fluid

A

Osmoreceptors in the hypothalamus

74
Q

How does antidiuretic hormone work
(3)

A

Increasing water reabsorption in the descending convoluted tubule and collecting duct of the kidney

Vasoconstriction (in response to acute lowering of blood pressure)

Stimulation of thirst

75
Q

Renin is released from where?

A

The JGA of the kidney

76
Q

Renin is released from the JGA of the kidney in response to?
(4)

A

Decreased blood flow and pressure in the kidney

Reduced GFR

Decreased Na+ in the filtrate

Stimulation of sympathetic ANS

77
Q

What does Renin do?

A

Convert inactive angiotensinogen to angiotensin I in the blood

78
Q

What is ACE

A

Angiotensin converting enzyme

79
Q

What does ACE do?

A

Angiotensin I is converted to Angiotensin II in the lung capillary tissue

80
Q

What does Angiotensin II do?
(4)

A

Stimulates the release of aldosterone from adrenal cortex

Stimulates vasoconstriction

Promotes ADH release

Promotes thirst -> ingestion of fluid

81
Q

What does aldosterone do?
(3)

A

Increases salt reabsorption in the kidney

Increases the sensitivity of the tongue salt receptors

Stimulates ADH release

82
Q

Where is EPO produced?

A

In the JGA of the kidney

83
Q

When is EPO produced?

A

In response to low blood partial pressure of oxygen (PO2)

84
Q

When will low blood oxygen happen?
(3)

A

Renal blood flow is decreased

In anaemia

In lung problems e.g. at high altitude

85
Q

EPO works in the bone marrow to do what?
(2)

A

Stimulate RBC number and increase the rate of maturation of RBC’s

EPO therefore restores blood volume and improves the O2 carrying capacity of the blood

86
Q

What is the response to stretching of the Atrial Pressure receptors
(4)

A

Increase venous return stretches the receptors

Results in increase of sympathetic outflow (Bainbridge reflex)

CO increases by increased HR and SV

Reflex release of ANP and BNP hormones also strives to reduce blood volume by inhibition of ingestion of fluid and by increased urinary output

87
Q

What hormones are responsible for reducing blood volume by inhibition of ingestion of fluid and by increased urinary output?

A

ANP

BNP

88
Q

What happens in fluid overload
(2)

A

Over ingestion

Renal failure

89
Q

What does ANP stand for?

A

Atrial Natriuietic peptide

90
Q

What does BNP stand for?

A

Brain Natriuretic peptide

91
Q

When and from where is ANP released

A

ANP is released from the atria of the heart in response to stretching during systole

(high blood volume and pressure is sensed)

92
Q

From where is BNP released

A

From the ventricles

93
Q

What are the ANP and BNP responses
(5)

A

Decrease CO and blood pressure

Increased GFR

Natriuresis

Increased water loss at the kidney (by inhibition of ADH)

Depressing the thirst response

94
Q

What is natriuresis

A

Increased Na+ loss at the kidney (by inhibition of Aldosterone)

95
Q

Explain the neural and hormonal reflex responses to haemorrhage
(What is the physiological problem?)

A

Low ventricular return

Loss of plasma proteins

Low Partial pressure of oxygen (PO2)

96
Q

Explain the neural and hormonal reflex responses to haemorrhage
(What reflexes are activated?)

A

Short term response to low blood pressure

Long term response to raised blood Na+, low GFR, low PO2

2.1 Control and Integrative Physiology (21 decks)

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