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Cardiovacular System > Structure and Function of the Circulation > Flashcards

Structure and Function of the Circulation Flashcards

1
Q

What is haematocrit?

A

Ratio of volume of red blood cells to total volume of blood

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2
Q

What is the equation for resistance?

A

Blood viscosity x vessel length all over vessel radius ^4

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3
Q

What is the portal system?

A

Passing from one capillary bed to another capillary bed without passing through heart

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4
Q

Is the resistance higher or lower in the systemic system compared to the pulmonary system?

A

Higher- it is longer and more complex

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5
Q

Is the pressure higher or lower in the systemic system compared to the pulmonary system?

A

Higher

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6
Q

What is the major determinant of arterial blood pressure and blood flow?

A

Vessel resistance which is determined by vessel radius

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7
Q

The dicrotic notch shows what?

A

The aortic valve closing rapidly due to pressure

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8
Q

Where is the biggest pressure drop in the circulation?

A

Biggest pressure drop is in the arterioles (particularly to the organs), because of their small radius and therefore high resistance

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9
Q

Capacitance vessels are also known as what?

A

The veins- hold largest share of blood

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10
Q

Cardiac output

A

Amount of blood out of ventricles into cardiovascular system

The amount of blood the heart pumps through the circulatory system in a minute

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11
Q

What is the BP equation?

A

BP (mean arterial blood pressure)= CO x TPR (total peripheral resistance)

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12
Q

How is blood pressure regulated?

Name all the receptors

A

Neural Regulation:
Arterial baroreceptors- in carotid sinus + aortic arch
Chemoreceptors- in carotid body- check pH and CO2
Mechanoreceptors

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13
Q

What do baroreceptors do? how?

A

Regulate arterial pressure
Continuously send nerve impulses to cardiovascular centre in medulla.
The higher the arterial pressure the more impulses that go to the brain.

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14
Q

How do baroreceptors realise that the blood pressure too high?

A

They are mechanoreceptors

Realise if stretched and so increase firing rate to medulla oblongata

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15
Q

Which nerves send which baroreceptor signals to brain?

A

Baroreceptors in the aortic arch send through the vagus nerve
Baroreceptors in the carotid sinus send through the glossopharyngeal nerve to the medulla oblongata

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16
Q

What is the neural pathway to decrease heart rate with medulla oblongata?

A

Vagus nerve change frequency signal to medulla oblongata cause decrease HR

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17
Q

Which hormones help regulate blood volume and blood pressure?
Does it increase or decrease blood pressure?

A

Aldosterone - increases BP
ADH (Antidiuretic hormone;vasopressin)- increases BP
Type A and Type B Natriuretic Peptides- decreases BP
Angiotensin II
Adrenaline

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18
Q

Aldosterone is released from where? effect of the release?

A

Released from adrenal cortex

Increases sodium and water reabsorption from kidneys

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19
Q

ADH is released from where? Effect of the release?

A

Released from posterior pituitary in response to increased blood osmolality
Increases water reabsorption from kidneys and vasoconstriction

20
Q

Type A and Type B Natriuretic Peptides releases in response to what? effect?
(ANP and BNP)

A

In response to high volume load (stretch) on atria and ventricles
Increases sodium and water excretion from kidneys (and vasodilation)

21
Q

What effect does adrenaline have on blood pressure?

A

It can increase it or decrease it depending on which receptor it binds to

22
Q

Adrenaline is released from where

A

Adrenal medulla in response to SNS (sympathetic nerve stimulation)

23
Q

Alpha-1 adrenergic receptor causes what

A

Vasoconstriction- increases blood pressure

24
Q

Beta-2 adrenergic receptor causes what?

A

Vasodilation- decreases blood pressure

25
Q

Under normal physiological levels does adrenaline increase or decrease blood pressure?

A

Decrease due to its increased sensitivity for beta-2 compared to alpha-1 receptors

26
Q

Under high dose of adrenaline, what effect does it have? why?

A

Increases blood pressure, alpha-1 receptors more numerous than beta-2 so overall effect is vasoconstriction

27
Q

What does Angiotensin II do?

A

Vasoconstrictor activated by angiotensin converting enzyme (ACE) within blood vessels= increases blood pressure

28
Q

What are the layers of the blood vessel?

A

Tunica interna/intima (inner most)
Tunica media- middle
Tunica externa-outer

29
Q

When do arteries stretch and recoil?

A

Elastic artery walls stretch during systole

Inward elastic recoil during diastole propels blood and sustains high blood pressure

30
Q

What is active hyperaemia?

A

Ability of arterioles to vasoconstrict/dilate rapidly and extensively allows them to adjust blood flow to tissues according to metabolic demand

31
Q

What are the three types of capillary?

A

Continuous- most- allow only some water soluble molecules across
Fenestrated- fluid exchange
Discontinuous/sinusoid- allow proteins and entire cell to go across epithelial wall

32
Q

How to calculate velocity of blood?

A

Blood flow/ cross sectional area

33
Q

As the cross sectional area increases what happens to the velocity?

A

The velocity decreases

34
Q

Net filtration pressure

A

Net sum of filtration and absorption across capillary bed

35
Q

Fluid exchange between capillaries and surrounding fluid is determined by what

A

Hydrostatic pressure and osmotic pressure

36
Q

When is osmotic pressure higher than hydrostatic and vice versa?

A

Hydrostatic pressure greater than osmotic pressure at arteriole end
Osmotic pressure greater than hydrostatic pressure at venule end

37
Q

What aids venous return from lower half of body?

A

Skeletal muscle pump and respiratory pump
Respiratory pump- during inspiration increase abdominal pressure, decrease intrapleural pressure therefore help blood back to heart

38
Q

What does venous return determine?

A

End- diastolic volume, therefore stroke volume, therefore cardiac output

39
Q

What does venoconstrictino do?

A

Shunts blood from peripheral to central vessels, blood return to heart quicker, increase sttroke volume

40
Q

Release of what hormone causes venoconstriction?

A

Alpha 1 receptors affected- norepinephrine from sympathetic neurones induces venoconstriction

41
Q

What do elastic arteries do?

A

Conserve pressure and flow during diastole- convert intermittent flow to continuous flow - buffer systolic rise in pressure

42
Q

What do muscular arteries do?

A

Distribute blood, adjust blood flow to tissues- conduit vessels

43
Q

What do arterioles do?

A

Control arterial pressure and local blood flow- resistance vessels

44
Q

What do capillaries do

A

Transfer of nutrients/waste products between cells

45
Q

What do veins do?

A

Return blood to heart

Cardiovacular System (12 decks)

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