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NUR1112- Bioscience > 9: Circulation system > Flashcards

9: Circulation system Flashcards

1
Q

3 layers of blood vessel walls?

A

Tunica intima- inner layer
Tunica media- middle layer
Tunica extrena- outer layer

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2
Q

Central space of vessel?

A

Lumen

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3
Q

Tunica intima structure

A

inner endothelium

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4
Q

Tunica media structure

A
  • Smooth muscle

- Elastin (vaso constriction and dilation)

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5
Q

Tunica externa

A
  • tough connective tissue

- Collagen fibres- strong and connective

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6
Q

3 types of arteries

A

Elastic (conducting vessels)
Muscular (distributing vessels)
arterioles (resistance vessels)

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7
Q

Elastic arteries aka…

A

Conducting vessels

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8
Q

Muscular arteries aka….

A

Distributing vessels

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9
Q

Arterioles aka…

A

resistance vessels

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10
Q

Elastic arteries

A
  • thin-walled
  • located near the heart
    Elastin present in all lumen
  • conduct vessels away from the heart
  • 1-2.5cm diameter
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11
Q

Muscular arteries

A
  • distal to elastic arteries
  • thick tunica media
  • Distributing vessels that change diameter to control pressure and therefore flow
  • 0.3-1cm diameter
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12
Q

Arterioles

A
  • smallest arteries
  • can easily chnage lumen size and therefor play a major role in blood pressure and flow
  • 10um- 0.3 mm
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13
Q

Capillaries general properties

A
  • 1mm long
  • 8-10 um diameter
  • composed of tunica intima
  • exchange vessels for nutrients, wastes, gases, hormones etc.
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14
Q

three types of capillaries

A

Continuous capillaries
Fenestrated capillaries
Sinusoidal capillaries

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15
Q

Continuous capillaries components

A
  • composed of tightly joined endothelial cells forming a smooth lining.
  • Intercellular clefts allow limited fluids and small solutes to pass through.
    Pinocytotic vesicles= ferry larger solutes across the capillary wall
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16
Q

Fenestrated capillaries

A

pores
Endothelial cells that contain pores aka fenestrations
- porse= increase permeability thus increasing exchange.
- found in area of active filtration (kidneys), absorption (small intestines) and endocrine glands

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17
Q

Sinusoidal capillaries

A

Leaky capillaries

  • large endothelial cells (sinusoids) and fenestration
  • when blood flow is low large molecules and cells can pass through
  • found in liver, lymphoid organs, adrenal medulla
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18
Q

Capillary beds

A

the connection between terminal arterioles and postcapillary venules.
- flow is controlled by venules dimaterter

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19
Q

Capillary diameter is effected by

A 
immediate environment (temp)
Sympathetic control (muscle demands)
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20
Q

Terminal arterioles

A

Oxygenated blood carries in capillary beds

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21
Q

Postcapillary venules

A

carry deoxygenated blood away from capillary beds

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22
Q

Venules and veins structure anf function

A
  • capillaries- venules- veins
  • large lumen= easy blood flow
  • Tunic intima folds into valves to prevent back flow
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23
Q

Capacitance vessels

A

thick tunica externa proves support for accommodating a large blood volume.

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24
Q

Blood flow

A

Volume of blood flow through a vessel at a given time period
- measured in ml/min
- varies with demand
flow is determined by blood pressure and resistance

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25
Q

Blood pressure

A

the force exerted on a vessel wall by the blood in that vessel

  • measured in mmHg
  • generated by the pumping action
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26
Q

Resistance

A

is a measure of the amount of friction blood encounters as it flows through vessel.
- opposition to blood flow

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27
Q

Primary sources of total peripheral resistance (TPR)

A

Blood viscosity
Total blood vessel length
Blood vessel diameter

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28
Q

Viscosity

A

thickness/stickiness of fluid

- caused by concentration of blood cells ad plasma proteins.

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29
Q

Haematocrit

A

proportion of RBC in blood

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30
Q

Vessel length

A

resistance increases as the vessel length increases
- relatively constant in adults but changes as children grow.
+1kg weight= 1km more blood vessels

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31
Q

Vessel diameter

A

amount of contact surfaces determines the amount of friction. more friction= more resistance= reduced blood flow

  • think vasoconstriction (when cold to preserve energy) and vasodilation (when hot to exert heat)
  • decreased diameter by plaque creates turbulence aka increased resistance as more blood hits the vessel walls
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32
Q

Flow=

A

Pressure/resistance

MAP/R

33
Q

Systemic blood pressure

A

the pumping action of the heart generates pressure which drives blood flow to the systemic circuit.

34
Q

Explain the systemic blood pressure gradient

A

Blood pressure is at it highest in the aorta and reduces the further away it gets from the heart.

35
Q

Arteriole blood pressure determined by

A
  1. compliance- stretch of vessel

2. Stroke volume- volume of blood forced into vessel after ventricular contraction

36
Q

Systolic pressure range

A

90-120 mmHg

average= 120

37
Q

Systolic blood pressure

A

peak pressure generated in the large arteries when the ventricle contracts
- increases as compliance decreases (afterload)

38
Q

Diastolic pressure range

A

60-80 mmHg

39
Q

Diastolic blood pressure

A

pressure in the large arteries during ventricular relaxation
average= 80

40
Q

Pulse pressure equation

A

pulse pressure= systolic pressure - diastolic pressure

- felt at superficial arteries at common carotid and radial

41
Q

Mean arterial pressure definition

A

MAP= pressure that propels blood through the vessels

- declines with distance away from heart

42
Q

MAP equation

A

MAP= diastolic pressure + (1/3 x pulse pressure)

43
Q

Hypotension

A

systolic blood pressure of 90mmHg

- dizziness and fainting

44
Q

Hypertension

A

transient elevation due to exercise, illness, emotions

chromic hypertension= sustained systolic blood pressure >140mmHg

45
Q

Capillary pressure

A

ranges from 15-35 mmHg.

- cant be to great otherwise damage and excess excretion of fluid are risked

46
Q

Venous blood pressure

A

aprox. 15mmHg

47
Q

Venous return mechanisms

A
  1. valves- compartmentalise blood and stop backflow
  2. muscular pumps- skeletal muscles that push blood towards heart
  3. respiratory pump- pressure changes during breathing help squeeze abdominal veins
  4. pulsation- of near by arteries
  5. venoconstriction- tunica media under sympathetic control
48
Q

3 factors the determine blood pressure (thus flow)

A

Cardiac output
Peripheral resistance
Blood volume

49
Q

Describe the effect of cardiac output on blood flow/pressure

A
  • rapid and short term
50
Q

What effects cardiac output (8)

A
  • EDV (preload)
    • Blood volume
    • Venous return
    • ESV
    • Contractility
    • ANS
    • Hormones
  • Plasma electrolytes
51
Q

Describe the effect of resistance on blood flow/pressure

A
  • rapid and short term
  • altered by changing
  • arteriole diameter (vaso constriction/dilation)
52
Q

Describe the effect of blood volume on blood flow/pressure

A
  • slower, long term regulation of BP
  • controlled by renal/endocrine mechanisms
  • changes in blood volume alter venous return and therefore EDV and preload
53
Q

4 blood pressure regulation levels

A
  1. Autoregulation
  2. Neural regulation
  3. renal mechanisms
  4. Endocrine regulation
54
Q

What is autoregulation

A

the tissue regulates it own diameter to regulate flow and pressure.

55
Q

What are the two types of autoregulation?

A
  1. metabolic control- when CO2 increases, o2 and pH decrease arterioles dilate to increase blood to lungs to get co2 respired out out
  2. myogenic (muscle) control - high systemic blood pressure makes arterioles stretch and reflex constriction which changes blood flow
56
Q

What are the three types of neural regulation

A
  1. Cardioinhibitory centre
  2. Cardioacceleratory centre
  3. Vasomotor centre
57
Q

How does the cardioinhibitory centre work as neural regulation to regulate blood flow/pressure?

A

parasympathetic input into SA and AV nodes slows heart rate

58
Q

How does the cardioacceleratory centre work as neural regulation to regulate blood flow/pressure?

A

sympathetic input to SA and AV nodes increases heate rate and therfore CO, sympathetic input into to ventricular myocardio=um= more blood to muscle=harder pump=increased CO

59
Q

How does the vasomotor centre work as neural regulation to regulate blood flow/pressure?

A

sympathetic vasomotor fibres to smooth muscles of arterioles increase vessel diameter and therefore flow and CO, hypothalamus input regualted blood flow for body temp (dilation and constriction) and fight/flight response

60
Q

Explain barareceptors

A
  • streach receptors
  • detect changes in pressure
    inform medullary cardiovascular centres
    location: carotid arteries, aortic arch, walls of most large arteries in the neck and thorax
  • initiate the baroreceptor reflex.
61
Q

Name the two baroreceptor reflexs and their function

A
  1. carotid baroreceptor sinus reflex- monitors BP to ensure flow to the brain
  2. Aortic baroreceptor reflex- monitors BP to maintain flow to systemic circuit
62
Q

Barorecptor reflexs function rapidly to protect against short term changes in blood pressure, thus maintaining blood flow.

A

function: rapidly to protect against short term changes in blood pressure, thus maintaining blood flow.

63
Q

Renal mechanisms

A
  1. Direct mechanism- BP directly effects urine production as more blood volume increases the demand for filtration.
  2. Indirect mechanism- involves hormones renin-angiotensin-aldosterone system (RAAS) the release
64
Q

Endocrine regulation

hormones that increase BP include

A

Adrenalin and noradrenalin (increase CO and peripheral vasoconstriction)
Angiotensin 2-> vasoconstriction, thirst and promotes secretion of aldosterone (increases sodium ion and water absorption) and ADH (peripheral vasoconstriction and increase renal water reabsorbtion)

65
Q

Endocrine regulation

hormones that decrease BP include

A

Atrial natriuretic peptide (ANP)

  • produced by atriasl myocardium in fresponse to high blood pressure.
  • opposes the action of angiotensin 2 and decreases BV and BP
66
Q

Describe capillary blood flow

A
  • slow
  • intermittent
  • controlled by arteriole diameter in response to local conditions (high CO2 or low O2)
67
Q

Capillary exchange

A
  • exchange of solutes (gases, nutrients and wastes)

- bulk of fluid flow

68
Q

4 types of capillary exchnage

A
  1. Diffusion through endothelial membranes (lipid soluble substances e.g. o2, CO2)
  2. intercellular clefts (water soluble substances e.g. electrolytes, glucose, amino acids)
  3. Fenstrations (small, water-soluble substances e.g. electrolytes glucose, amino acids)
  4. Active transport via vessel endocytosis and exocytosis (large substances e.g. proteins)
69
Q

Bulk flow refers to

A

movement of fluid across capillary walls

- it determines the relative fluid volumes of the blood and ISF

70
Q

Bulk flow occurs through

A

Intercellular clefts: between endothelial cells in all capillaries
Fenestrations: pores within endothelial cells in some capillaries
Sinusoids: big gaps between endothelial cells in some capillaries

71
Q

What two pressures determine direction and volume of fluid flow

A

Hydrostatic

Colloid osmotic

72
Q

Hydrostatic pressure

A

force exerted by fluid pushing against a tissue wall
Capillary HPc- pushes fluid and solutes out of the capillaries through intercellular clefts/fenestration/sinusoids at arterial end of bed

73
Q

Colloid osmotic pressure

A

force related to the tonicity (solute concentration) of a solution- pulling force
Capillary OPc- sue to solutes within the plasma that are unable to diffuse out of the capillary e.g. proteins
-unable to pull fluid back into the capillaries at the end of the bed.

74
Q

Net filtration pressure=

A

colloid osmotic pressure push and difference between hydrostatic pressure pull

75
Q

Oedema is

A

an abnormal increase of interstitial fluid

  • caused due to increased push or decreased pull
  • increase in capillary hydrostatic pressure

Inflammation increases capillary permeability

  • decreased colloid osmotic pressure due to low levels of plasma proteins due to lover disease or mal nutrition
  • Blockage of lymphatic vessels that prevent fluid drainage from tissues. Parasites, surgical removal
76
Q

Common traits of arteries

A

deep
away from heart
less interconnected
run parallel with veins and nerves that share a similar name

77
Q

Common traits of veins

A

deep or superficial
to heart
more interconnected
run parallel with veins and nerves that share similar name

78
Q

two subdivisions of the circulatory system

A

Pulmonary circuit

  • heart to lungs and back
  • provides no metabolic needs of body tissue

Systemic circuit

  • functional blood supply to body tissues.
  • delivers nutrients, gases, hormones and removes waste

NUR1112- Bioscience (10 decks)

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