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BIOSCIENCE > week 8 - CIRCULATORY SYSTEM > Flashcards

week 8 - CIRCULATORY SYSTEM Flashcards

1
Q

elastic arteries

A

conducting vessels: conduct blood away from the heart
- thick walls
- elastin

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2
Q

muscular arteries

A

distributing vessels: change diameter to control blood flow to the body regions and organs
- thick tunica media

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3
Q

arterioles

A

resistance vessels: change their diameter to control resistance to blood flow - controls blood flow to capillary vessels
- vasoconstriction and vasodilation
- tunica media

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4
Q

capillaries

A

exchange vessels: exchange nutrients, wastes, gases, hormones with interstitial fluid

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5
Q

capillary beds

A
  • terminal arteriole supplies bed
  • post capillary venue drains bed
  • blood flow in bed controlled by arterioles
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6
Q

continuous capillaries

A
  • present in most tissues
  • endothelial cells
  • intercellular cleft and pinocytotic vesicles
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7
Q

fenestrated capillaries

A
  • contain pores
  • increase permeability to allow rapid exchange of fluids and small solutes
  • filtration (kidneys) - absorption
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8
Q

large veins (veins)

A

capacitance vessels: thick tunica externa provides support for accommodating a large blood volume - returns blood to the heart

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9
Q

small veins (venules)

A
  • drain capillary beds
  • thick walls
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10
Q

blood flow

A
  • the volume of blood flowing through a vessel or organ or the entire circulation in a given time period
  • measured in ml/min
  • determined by blood pressure and resistance
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11
Q

blood pressure

A
  • force exerted on a vessel wall by the blood in that vessel
  • expressed in mmHg
  • measured as systemic arterial blood pressure in large arteries in the heart
  • force generated by pumping action of the heart - keeps blood moving
  • moves from area of high pressure to low pressure
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12
Q

resistance

A
  • the measure of the amount of friction blood encounters as it flows through a vessel
  • sources of peripheral resistance - blood viscosity, vessel length, vessel diameter
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13
Q

blood viscosity

A
  • thickness or stickiness of a fluid
  • varies in blood cell numbers, increase in haematocrit, decrease in haematocrit, plasma volume
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14
Q

vessel length

A
  • resistance to flow increases as vessel length increases
  • changes overtime with growth
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15
Q

vessel diameter

A
  • the amount of contact between 2 vessels determines the amount of friction
  • increase in vessel diameter - decrease contact between vessel walls = increase friction = increase resistance to flow
  • vasodilation
  • vasoconstriction
  • increase action of heart - CO
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16
Q

blood flow determined by

A

F= P/R

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17
Q

systolic pressure

A
  • peak pressure generated in the large arteries by ventricular contraction
  • 90-120mmHg
  • systolic pressure increases as compliance decreases - afterload
18
Q

diastolic pressure

A
  • pressure in the large arteries during ventricular contraction
  • 60-100mmHg
19
Q

arterial blood pressure

A
  • systolic and diastolic blood pressure
    2 factors
  • compliance
  • stroke volume
  • not consistent
20
Q

pulse pressure

A

systolic P - diastolic P
- declines with distance from heart
- pulse points

21
Q

mean arterial pressure

A
  • pressure that propels blood through vessels
  • average between systolic and diastolic
    MAP= diastolic P + (1/3 X PP)
  • anything that increases CO or R will increase BP
22
Q

hypotension

A

systolic below 90mmHg

23
Q

hypertension

A

transient elevation - exercises

24
Q

chronic hypertension

A

systolic > 140mmHg
- risk factors smoking, stress, diet, obesity, age, health

25
Q

capillary blood pressure

A

ranges from
- 35mmHg at arterial end of capillary bed
- 15mmHg at the venous end of capillary bed
- low pressure required because high pressure would damage thin walls

26
Q

venous blood pressure

A

fairly consistent vascular pressure in vein or atria of heart

27
Q

venous return

A
  1. valves compartmentalise blood to shift in small volumes
  2. muscular pump: skeletal muscles contraction squeeze veins and help push blood towards the heart
  3. respiratory pump: pressure changes during breathing
  4. pulsations of nearby arteries
  5. venoconstriction of tunica media under sympathetic contact
28
Q

cardiac output

A
  • rapid, short-term regulation of BP and blood flow
  • CO = SV X HR
  • determined by EDV, BV, venous return, ESV, contractility, ANS , hormones and plasma electrolytes
  • directly determines blood pressure
29
Q

peripheral resistance

A
  • rapid, short-term regulation of BP and BF
    -vasoconstriction = increase R - decrease F
  • vasodilation = decrease R - increase F
30
Q

blood volume

A
  • slower, long-term regulation of BP
  • controlled by renal and endocrine mechanisms
  • increase BV - more blood pushing against walls - increased BP
31
Q

auto-regulation: local regulation of BP and flow

A
  • tissues regulate their own BP and flow in response to local conditions by altering arteriole diameter to regulate BP into capillary beds
  • intrinsic regulation
  • metabolic control
  • myogenic (muscle) control
32
Q

neural regulation

A
  1. cardioinhibitory centre: parasympathetic input - slows HR - decreases CO
  2. cardioaccelatory centre: sympathetic input into SA and AV nodes = increased HR and increased CO - sympathetic input into ventricular myocardium - increased force of contraction - increased stroke volume - increase CO
  3. vasomotor centre: sympathetic vasomotor fibres to the smooth muscle of arterioles - changes in vasomotor tone - changes in vessel diameter- peripheral blood vessels
    - increased sympathetic activity - increased vasomotor tone - vasoconstriction - increased BP
33
Q

neural regulation: baroreceptor reflex

A
  • function rapidly to protect against short-term changes in BP - maintain BP
  • temporary pooling of blood due to gravity - decreased BP - blood flow to brain reduced - inadequate oxygen supply - dizziness and fainting
  • carotid baroreceptor sinus reflex
  • aortic baroreceptor reflex
34
Q

renal mechanisms

A
  1. direct mechanism
    - increased BP - activates baroreceptor reflex - peripheral vasodilation/vasoconstriction - (dilation) - increased renal blood flow - increased filtration rate in kidneys - increased urine production - decreased BV - decreased BP
  2. indirect mechanism
    - decrease in BP - angiotensin II production
35
Q

endocrine regulation

A

hormones that increase BP
- adrenalin and noradrenalin: rapid increase in CO and peripheral vasoconstriction
- angiotensin II: vasoconstriction, thirst, and promotes secretion of aldosterone and ADH

hormones that decrease BP
- atrial natriuretic peptide: produced by the heart in response to high BP - opposes the actions of angiotensin II - decrease in BV and BP

36
Q

capillary dynamics

A
  • slow and intermittent
  • controlled by arteriole diameter in response to local conditions
  • involves exchange of solutes and bulk flow of fluid
37
Q

capillary exchange

A
  1. diffusion through an endothelial membrane (lipid-soluble substances)
  2. movement through intercellular clefts (water-soluble substances)
  3. movement through fenestrations (water-soluble substances)
  4. active transport via vesicles = endocytosis and exocytosis (large substances)
38
Q

bulk flow of fluid

A
  • moves out of the capillary at the arterial end and into the capillary at the venous end
  • fluid moves through intercellular clefts, fenestrations and sinusoids
  • determines relative fluid volumes of the blood and ISF
  • direction of movement determines by 2 opposing forces
39
Q

hydrostatic pressure

A
  • force exerted by fluid pushing against a tissue wall
  • capillary hydrostatic pressure
  • pushes fluid and solutes out of capillaries through intercellular clefts/fenestrations/sinusoids at the arterial end of the bed
40
Q

colloid osmotic pressure

A
  • force related to the tonicity of a solution-pulling force
  • capillary colloid osmotic pressure
  • due to the presence of solutes within the plasma that are unable to diffuse out of the capillary - these solutes pull fluid back into the capillaries at the venous end of the bed
41
Q

veins for venipuncture

A

the median cubital vein, located in the cubital fossa (the fold of the elbow) connects the basilic and cephalic veins

42
Q

net filtration pressure

A

hydrostatic pressure - colloid osmotic pressure and determines volume of ISF

BIOSCIENCE (10 decks)

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