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The Heart > Circulation > Flashcards

Circulation Flashcards

(67 cards)

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1
Q

What is % CO through the liver

A

27%

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2
Q

What is % CO through the kidney

A

22%

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3
Q

What is % CO through the muscle

A

15%

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4
Q

What is % CO through the brain

A

14%

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5
Q

What is % CO through the skin

A

6%

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6
Q

What is % CO through the bone

A

5%

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7
Q

What is % CO through the heart

A

4%

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8
Q

What is % CO through the rest of the system

A

3.5%

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9
Q

What is % CO through the bronchi

A

2%

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10
Q

What is % CO through the thyroid

A

1%

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11
Q

What is % CO through the adrenal

A

0.5%

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12
Q

Describe the arteries

A

Low resistance

Elastic

Cushion systole

Maintain blood flow to organs during diastole

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13
Q

Describe arterioles

A

Principal site of resistance to vascular flow

Determined by local, neural and hormonal factors

Major role in determining arterial pressure

Major role in distributing flow to tissue/organs

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14
Q

What is myogenic tone

A

Vascular smooth muscle is never completely relaxed

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15
Q

Describe capillaries

A

Slow flow

Flow determined by
- arteriolar resistance
- no. of open pre-capillary sphincters

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16
Q

Describe veins

A

Compliant

Low resistance conduits

Capacitance vessels

Up to 70% of blood flow but only 10mmHg

Valves aid venous return against gravity

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17
Q

Define CO

A

HR x SV

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18
Q

Define BP (MAP)

A

CO x TPR (total peripheral resistance)

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19
Q

Define pulse pressure

A

Systolic - diastolic pressure

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20
Q

Define mean arterial pressure

A

Diastolic pressure + 1/3PP

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21
Q

What governs flow

A

Ohm’s law

Poiseuille’s law

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22
Q

Describe Frank-Starling Mechanism

A

SV increases as end-diastolic volume increases

Due to length-tension (L-T) relationship of muscle

Increase EDV = increase stretch = increase force of contraction

Cardiac muscle at rest is NOT at its optimal length

Increase VR = Increase EDV = Increase SV = Increase CO

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23
Q

Define blood pressure

A

Pressure of blood within and against the arteries

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24
Q

When is blood pressure highest

A

When ventricles contract - systole

100-150mmHg

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25
When is blood pressure lowest
When ventricles relax - diastole 60-90mmHg Not 0 due to aortic valve and aortic elasticity
26
Define mean arterial pressure
D + 1/3(S-D)
27
What artery is used to measure BP
Brachial artery
28
What are the components of BP control
Autoregulation Local mediators Humoral factors Baroreceptors Central (neural) control
29
Describe myogenic autoregulation
Stretch of vascular smooth muscle Contraction until diameter is normalised or slightly reduced
30
What organs have good autoregulation
Renal Cerebral Coronary
31
What organs have moderate autoregulation
Skeletal muscle Splanchnic
32
What organ has poor autoregulation
Cutaneous
33
Local humoral factors - what are the vasoconstrictors
Endithelin-1 Internal blood pressure (myogenic contraction)
34
Local humoral factors - what are vasodilators
Hypoxia Adenosine Bradykinin NO K+, CO2, H+ Tissue breakdown products
35
Is NO a vasodilator or vasoconstrictor
Vasodilator
36
Circulating hormonal factors - vasoconstrictors
Epinephrine (skin) Angiotensin II Vasopressin
37
Circulating hormonal factors - vasodilators
Epinephrine (muscle) ANP
38
Describe intrinsic and extrinsic control
Intrinsic control dominates to maintain BF to vital organs Skin - BF vasoconstrictor response to temp (extrinsic) Skeletal muscle - Dual effects. Rest vasoconstrictor (extrinsic) tone dominant, exercise intrinsic mechanisms predominate
39
Local control - endothelium
Essential for control of circulation Uses NO, prostacyclin, endothelin
40
Is prostacyclin a vasodilator or vasoconstrictor
Vasodilator
41
Is endothelin a vasodilator or vasoconstrictor
Vasoconstrictor
42
Describe baroreceptors
Pressure sensing Firing rate is proportional to MAP and PP - integrated by the medulla Increased BP = Increased firing = Increased PNS/Decreased SNS = Decreased CO/TRP = Decreased BP Vice versa
43
What is the location of baroreceptors
Primary (arterial) - carotid sinus - aortic arch Secondary - veins - myocardium - pulmonary vessels Afferent - glossopharyngeal Efferent - sympathetic and Vagus
44
What does arterial baroreceptors play a key role in
Short term regulation of BP - minute to minute control - response to exercise - haemorrhage If arterial pressure deviates from norm for more than a few days adapt to a new baseline pressure
45
What is the major factor in long-term BP control
Blood volume
46
Describe cardiopulmonary baroreceptors
Atria, ventricles, PA Stimulation - decrease vasoconstriction = decrease BP Decrease in angiotensin, aldosterone and vasopressin = fluid loss Play an important role in blood volume regulation
47
Describe the central neural control loop
Baroreceptors signal to brain stem Either + or - sympathetic = + or - vasoconstrictors Effects HR, SV, vessel diameter BP + or -
48
Describe arterial baroreceptors affect on central control
Increase arterial pressure = increased baroreceptor firing - decreased sympathetic outflow to heart, arteries and veins - increased sympathetic outflow to heart
49
Describe the role of central chemoreceptors
Increase PaCO2 = vasoconstriction - increase peripheral resistance, increase BP Decrease PaCO2 = decrease medullary tonic activity, Decrease BP Similar changes with pH PaO2 less effect on medulla - decreased = vasoconstriction - serve decrease = general depression
50
What is the effect of PaO2 mainly by
Peripheral chemoreceptors
51
What is the short term control of BP
Baroreceptors
52
What is the long term control of BP
Volume of blood Na+, H20, RAAS, ADH
53
Describe the minute by minute feedback loop
Blood pressure Baroreceptor discharge Sympathetic and Parasympathetic outflow Vasomotor tone and CO
54
What is the location of chemoreceptors
Peripheral - carotid body - aortic body Central - medulla oblongata
55
Define cushings syndrome
Clinical manifestation of pathological hypercortisolism from any cause
56
What circulation do both lungs have
Bronchial and pulmonary
57
What is the bronchial circulation
Supplied O2 and nutrients to meet metabolic needs
58
What are the adaptations of the pulmonary circulation
Low pressure - mean arterial pressure 5-15mmHg Low resistance
59
What is the mean arterial pressure of the systemic circualtion
93mmHg
60
What are extrinsic controls of cardiovascular system
Neural Hormonal Reflex Chemical regulatory mechanisms
61
What do extrinsic factors control
Regulate HR Myocardial contractility Vascular smooth muscle maintain CO, blood flow distribution and arterial blood pressure
62
What is the role of intrinsic factors of control
Vary stroke volume by affecting the myocardial contractility Can change the sarcomere length or independent of the cell length change using other agents
63
Define Ohm's Law
Pressure gradient/resistance
64
Define Poiseuille's equation
Flow = radius to the power of 4
65
What is the cushings phenomenon
NS response to increased intracranial pressure leads to Increased BP Irregular breathing Brachy cardia
66
What are the constituents of plasma
91.5% water 7% proteins
67
Describe plasma proteins
Carrier proteins e.g. albumin, globulin Immunoglobulins Clotting factors

The Heart (12 decks)

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