Chapter 14 Cardiac Output, Blood Flow and Blood Pressure Flashcards

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1
Q

SA norde rhythmically excited at how many bpm

A

100bpm

pacemaker potential

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2
Q

What 2 ways does the Parasympathetic nervous system control on heart rate…

A

Resting state 70-75 bpm

ACh release from Parasympathetic nervous system causes heart rate lower than 100bpm

In addition to this, increase permeability to K results in slower rate of depolarisation

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3
Q

What 3 ways does the Sympathetic nervous system control on heart rate

A
  1. NE from sympathetic nervous system and E from adrenal medulla bind to Beta-Adrenergic receptors in SA node to increase heart rate
  2. Increase permeability of HCN channels = faster rate of depolarisation = increase heart rate
  3. Increase contractility and faster contraction and relaxation
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4
Q

How is the SA node effected by autonomic nerve activity

A
  1. Sympathetic: Increased rate of diastolic depolarisation = Increase cardiac rate
  2. Parasympathetic: Decrease rate of diastolic depolarisation = decreased cardiac rate
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5
Q

How is the AV node effected by autonomic nerve activity

A
  1. Sympathetic: Increased conduction rate

2. Parasympathetic: Decreased conduction rate

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6
Q

How is the Atrial muscle effected by autonomic nerve activity

A

Sympathetic: Increased strength of contraction

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7
Q

How is the Ventricular muscle effected by autonomic nerve activity

A

Sympathetic: Increased strength of contraction

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8
Q

What happens if EDV (Preload) increases

A

Greater Stroke volume

Because Frank-Starling law of heart

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9
Q

What is resistance

A

Impedance to blood flow

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10
Q

What happens if total peripheral resistance (afterload) increases

A

Greater pressure in the arterial system
Increased afterload
Lower Stroke volume

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11
Q

What happens when there is a greater arterial pressure

A

Increased after load

Therefore, heart must work harder to eject blood

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12
Q

What are the 3 ways stroke volume is regulated

A
  1. EDV
  2. TPR
  3. Contractility
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13
Q

How does contractility regulate stroke volume

A

Sympathetic system and adrenal medulla release E and NE to increase ventricular contractility = increase stroke volume

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14
Q

What is Frank-Starling law of the heart

A

As EDV increases so does stroke volume

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15
Q

At rest is the cardiac muscle length short or long

A

Short

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16
Q

With a greater EDV there is greater…

A

stretch = cardiac muscle length

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17
Q

What does a greater muscle length result in

Because

A

Increases strength of contraction

Because there is:

  1. Optimal alignment of actin and myosin
  2. Increased release of Ca from SR
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18
Q

EDV is effected by…

A

venous return

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19
Q

What does an increase in peripheral resistance do to Frank-Starling law

A
  1. Increase peripheral resistance decreases SV
  2. More blood remains in ventricle = increases EDV
  3. Increase stretch
  4. Stronger contraction to eject blood
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20
Q

Cardiac output =

A

Cardiac rate x stroke volume

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21
Q

What 3 main ways can you increase stroke volume

A

Increase:
EDV
NE delivery
E delivery

(Decrease):
Peripheral resistance

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22
Q

What 3 main ways can you increase heart rate

A

Increase:
NE delivery
E delivery

Decrease:
Parasympathetic

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23
Q

Sympathetically mediated venoconstriction can increase what

A

venous return to the RIGHT side of the heart

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24
Q

Extracellular fluid represents how much of the total bodies water

How much of that is made up of blood and ISF

A

1/3 of total body

This 1/3 is made up of 20% blood and 80% ISF

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25
Q

What pressure causes fluid to filter out of vessels into the ISF

A

Blood pressure

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26
Q

What pressure causes water to be absorbed from tissues to vessels

A

Osmotic pressure

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27
Q

Blood volume is regulated by… (3)

A
  1. Drinking
  2. Urine volume
  3. Distribution of water between plasma and ISF
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28
Q

How do the kidneys play a role in blood volume

A
  1. Urine is derived from blood plasma

2. ADH and Aldosterone act on kidneys to regulate blood volume

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29
Q

How is water lost by the body (4)

A
  1. Excretion of urine
  2. Exhalation of air
  3. Sweating
  4. Faeces
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30
Q

What is filtration

A

movement of fluid and solutes OUT of the blood

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31
Q

What is absorption

A

movement of fluid and solutes INTO the blood

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32
Q

What pressure causes filtration of fluid out of capillaries

A

Hydrostatic pressure

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33
Q

What is the hydrostatic pressure at the:
Arteriolar end
Venular end
of systemic capillaries

A
Arteriolar = 37 mm Hg
Venular = 17 mm Hg
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34
Q

Why is ISF hydrostatic pressure low

A

Due to drainage into lymphatic vessels

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35
Q

What substances are filtered with the fluid

A

Solutes such as glucose, salts, ions

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36
Q

What substance is lower in the ISF compared to plasma

Why

A

Protein

To big to fit through capillary pores

37
Q

What is the Net filtration pressure

A

Hydrostatic pressure of capillary blood minus hydropstatic pressure of ISF

38
Q

3 rules of starling forces

A
  1. There is a constant interchange of plasma and ISF
  2. Difference between capillary hydrostatic pressure and ISF hydrostatic pressure favours filtration OUT of capillary
  3. Water concentration difference between plasma and ISF favours absorption of ISF INTO capillary
39
Q

What happens to hydrostatic pressure as blood travels further from the heart

A

Decreases

40
Q

What happens to osmotic pressure along the capillary

A

Remains constant

41
Q

Renal hormones affect…

A

Reabsorption

Therefore:
Urine and blood volume

42
Q

What happens if there is more reabsorption

A

Less urine output

Increase blood volume

43
Q

What happens if there is less reabsorption

A

More urine output

Decreased blood volume

44
Q

When is ADH released

A

when hypothalamic osmoreceptors detect an increase in plasma osmolarity

This causes increase water retention

45
Q

What does Aldosterone do

A

Promotes retention of salt

This increases water retention

46
Q

Dyhydration or excessive salt intake leads to what sensation and what effect

What is the response

A

Thirst
Increase blood osmolarity

ADH produced to retain water

47
Q

What does salt deprivation cause

What is the response

A

low blood volume
low blood pressure

Increase salt and water retention by kidney

48
Q

What is the process of Natriuresis

A

Excretion of sodium in urine

49
Q

What hormone is produced by the atria

What does it do

What stimulates the hormone

What is the final result

A

Atrial Natriuretic Peptide (ANP)

Increases Na and Water excretion in urine

Stretching of the atria

Increase urine volume = reduces blood volume

50
Q

What is resistence directly proportional with

A

Length of vessel

Blood Viscocity

51
Q

What is resistance inversely proportional with

A

Vessel radius

52
Q

Unequal resistances to blood flow cause

A

Co2 to be distributed unequally

53
Q

Blood flow is determined by…

A

the pressure difference between MEAN PRESSURE and PRESSURE AT END OF CIRCUIT

54
Q

What happens to pressure as distance increases

A

decreases

55
Q

Mean Arterial pressure =

A

CO X TPR

56
Q

What are the 3 main ways of regulating blood flow

A

Extrinsic control
Intrinsic control
Paracrine control

57
Q

What are the ways of vasocontricting (2)

A
  1. Sympathetic stimulation (NE) of alpha-adrenergic receptors
  2. ADH production
58
Q

What are the ways of vasodilating (3)

A
  1. Sympathetic stimulation (E) of beta-adrenergic receptors
  2. ACh release by sympathetic neurons (skeletal muscle aterioles)
  3. Parasympathetic activity
59
Q

How does paracrine control work

A

Nitric oxide - vasodilates vessels

60
Q

What are the two intrinsic controls

A

Flow autoregulation

Active hyperemia

61
Q

What is flow autoregulation

A

Maintains constant blood flow:

  1. via vasodilation when BP drops
  2. via Vasocontriction when BP increases
62
Q

What is active hyperemia

A

Local vasodilation when metabolism increases

63
Q

What is the baseline of Co2

A

5L/min

64
Q

During exercise there is an increase in..

Which increases…

A

Metabolism

Vasodilation

65
Q

During exercise what happens to allow for more blood to flow to skeletal muscles

A

Vasocontriction of GI system and kidneys via sympathetic activity

66
Q

Training can do what on the heart rate and SV

Why

A

Lower HR because of greater parasympathetic inhibition of SA node

Increase SV because of increased blood volume

67
Q

Resistance is greatest where

Why

A

Arterioles

To reduce blood flow and pressure in capillaries

This increases arterial blood pressure

68
Q

A large capillary cross sectional area causes

A

further reduction in blood flow and pressure

69
Q

Increases in SV, HR and or CO have what effect on blood pressure

A

increases

70
Q

What do kidneys control in the cardiac system

A

Blood volume

SV

71
Q

What does sympathetic NS do

Which does what

A

Stimulates vasocontriction

Which increases:

  1. Blood pressure
  2. Co2
72
Q

What does a Baroreceptor reflex do

A

Maintains blood pressure

73
Q

What does contriction in the arterioles have an effect on arteries and capillaries/veins

A

Arteries = increases pressure UPSTREAM

Capillaries/veins = decreases pressure DOWNSTREAM

74
Q

What are Baroreceptors

What do they maintain

A

Stretch receptors

Maintain MAP

75
Q

Where are Baroreceptors located

A

Aortic arch

Carotid sinuses of heart

76
Q

Baroreceptors AP frequency is directly proportional to what

A

Mean Arterial Pressure

77
Q

What is Hypotension

A

Low blood pressure

78
Q

What is main effect in Hypotension

A

Reduces blood flow to brain and cardiac muscle

79
Q

What are some of the causes of hypotension

A
CV disease
Dehydration
Neural/endocrine defects
Medication
Hemorrhage
80
Q

What is the response to hypotension

A

Baroreceptor reflex

81
Q

What is Hypertension

A

Chronic high blood pressure

Above 140/90 mm Hg

82
Q

What results from hypertension

A

Left ventricle must pump against increase arterial pressure

Leads to heart failure

83
Q

What are some of the causes of hypertension

A

Genetic/environmental (primary)
Arteriosclerosis (secondary)
Endocrine disorder (secondary)

84
Q
What values are considered for:
Normal
Prehypertension
Stage 1 Hypertension
Stage 2 Hypertension
A

Normal = Under 120/80

Prehypertension = 120-140/80-90

Stage 1 Hypertension = 140-160/90-100

Stage 2 Hypertension = Over 160/100

85
Q

What are some of the ways to treat for hypertension

A
Reduce:
Smoking
Alcohol
Sodium intake
Weight

Increase:
Potassium
Exercise
Medication

86
Q

What is heart failure

A

Heart doesnt pump an adequate cardiac output to maintain blood flow

87
Q

What does a low cardiac output lead to

A

Increase fluid retention = increased blood volume + SV

Increase hypertrophy of ventricles = however failing heart cant handle large EDV

88
Q

What causes heart failure

A

Heart attack
Hypertension
Valve insufficiency
Structural damage to coronary