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Circulatory Physiology Flashcards

1
Q

Factors affecting blood flow

A

-Increases with greater pressure gradient
-Decreases with greater resistance (radius of vessel which has a factor of r ^ 4), viscosity)

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2
Q

Which component of systemic circulation has lowest pressure gradient?

A

Venae cavae

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3
Q

Why do veins have valves?

A

To prevent regurgitation

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4
Q

What are arteries reinforced with?

A

Collagen and elastin

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5
Q

What are capillaries a single layer of?

A

Endothelium

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6
Q

Why do arteries have lots of collagen and elastin fibres?

A

-Collagen provides tensile strength
-Elastin provides stretch and recoil of walls

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7
Q

Atherosclerosis

A

-Build up of cholesterol within arteries

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8
Q

Do arteries have high or low resistance?

A

Low because their diameter is so big

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9
Q

Are arterioles high or low resistance?

A

High

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10
Q

Causes of arteriolar vasoconstriction

A

-Increased oxygen
-Decreased CO2
-Increased sympathetic stimulation (epinephrine)
-Cold

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11
Q

Causes of arteriolar vasodilation

A

-Decreased oxygen
-Increased CO2
-Increased acid
-Increased K+
-Increased osmolarity
-Increased Nitric oxide
-Decreased sympathetic stimulation
-Histamine release
-Heat

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12
Q

How do arterioles smooth out pulsatile flow?

A

-They get the flow of blood down to a speed that the capillaries can handle

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13
Q

What do precapillary sphincters do?

A

-Open and close capillary beds when they aren’t in use or not necessary
Open= relax
Closed=constrict

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14
Q

What do metarterioles do?

A

-They maintain flow of blood through capillary beds , even when the sphincters turn off blood flow
-Runs between an arteriole and a venule

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15
Q

Why do capillaries have so much branching?

A

To increase surface area

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16
Q

Capillary types

A

Continuous

Fenestrated

Sinusoids

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17
Q

Continuous capillaries

A

-Most common
-Least permeable
-Muscles, lungs, brain, CT

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18
Q

Fenestrated capillaries

A

-Have pores
-More leakage
-Kidneys, small intestine

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19
Q

Sinusoid capillaries

A

-Large clefts for RBCs, proteins
-Liver, bone marrow, spleen

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20
Q

Equation for net pressure in capillary

A

Net pressure = hydrostatic pressure - colloid osmotic pressure

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21
Q

What other vessel do lymph vessels resemble?

A

Veins - they become bigger and bigger and stretch out with more fluid. They also have valves

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22
Q

Functions of the lymphatic system

A

-Return of excess filtered fluid
-Defence against disease
-Transport of absorbed fat
-Return of filtered protein

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23
Q

Edema

A

-Swelling of tissues
-Occurs when too much interstitial fluid accumulates

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24
Q

Causes of Edema

A

-Reduced concentration of plasma proteins (reduces osmotic pressure)
-Increased permeability of capillary wall
-Increased venous pressure
-Blockage of lymph vessels

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25
Venule
-Formed when capillary beds unite -Very porous to allow fluids and WBCs into tissues -Thin walls -Eventually turn into veins
26
Why do larger venules have one or two layers of smooth muscle cells?
-To reinforce and not be as leaky
27
Do veins have low or high pressure/resistance?
-Low pressure -Low resistance -Slow flow
28
How do venule sinuses act as reservoirs?
-Blood isn't always moving around the body when activity is low -Blood hangs out in sinuses until it is needed
29
Where do capillaries drain into?
Venules
30
What decreases venous return?
-Venous compliance (stretchiness of vessel)
31
What increases venous return?
-Driving pressure from cardiac contraction -Sympathetically induced venoconstriction -Skeletal muscle activity -Effect of venous valves -Respiratory activity -Effect of cardiac suction
32
Varicose veins
-Veins with a weak valve so it allows back-flow -Blood gets stagnant and clots
33
Atheromas
-Fatty plaques within vessel walls (usually caused by injury to vessel wall) -Restricts blood flow with clot formation -Forms with obesity, inactivity, smoking, alcohol, genetics, diabetes -Risk for cardiac ischemia, infarct and stroke
34
Arteriosclerosis
-Hardening of the arteries -Thickening of wall and formation of fibrous plaques -Stiffer blood vessels create faster flow and higher blood pressures -Risk for cardiac events -Treat with exercise, diet changes, blood pressure medication, anti-coagulants
35
Peripheral Vascular Disease
-Decreased flow to the peripheral vessels -Can cause pain, fatigue, poor circulation -Can lead to heart attack, stroke, or tissue necrosis -Obesity, diabetes, smoking, high cholesterol
36
Deep vein thrombosis
-Thrombus (blood clots) form -Blood is not moving from things like immobility -Needs anti-coagulants
37
Aneurysms
-Bulge in vessel wall that can rupture and lead to hemmorhagic strokes in the brain -Fusiform: bulge on both sides -Saccular: bulges on one side -Dissection: inner wall pulls away from outer wall
38
Aortic dissection
-Where the inner wall of the aorta gets a split, allows blood into the side and the outer wall pulls away and "balloons" due to high pressure -The force of blood within the balloon causes the aortic dissection to spread -A: all of aorta -B: only in ascending region -C: descending aorta
39
How do we fix aortic dissections?
-Stents to replace segments of the aortic wall -Grafts to replace the arch of the aorta
40
Embolism
-Sudden blockage of a blood vessel -Can be from blood clots, fat deposits, tissue fragments, cancer cells, clumps of bacteria, bubbles of air
41
Ischemic strokes
-Due to thrombus or embolus or plaque blockage -87% of strokes
42
Haemorrahic strokes
-Wall rupture in blood vessel -Bleeding into brain
43
Primary determinants of blood pressure
-Cardiac output -Total peripheral resistance
44
Equation for mean arterial pressure
Mean arterial pressure = cardiac output x total peripheral resistance
45
Short-term control of blood pressure is done by:
-Baroceptors -Pressure receptors send input to cardiovascular centre, which affects output to heart and blood vessels
46
Sequence of events of baroreception regarding high blood pressure
1) Blood pressure rises above normal range 2) Baroreceptors in carotid sinuses and aortic arch are stimulated 3) Impulses from baroreceptors stimulate cardioinhibitory center and inhibit vasomotor center 4) Sympathetic impulses to heart cause HR, contractility and CO to decrease 5) Rate of vasomotor impulses allows vasodilation 6) Cardiac output and R return blood pressure to homeostatic range
47
Sequence of events in baroreception regarding low blood pressure
1) Blood pressure falls below normal range 2) Baroreceptors are inhibited 3) Impulses from baroreceptors stimulate cardioacceletory center and stimulate vasomotor center 4) Sympathetic impulses to heart cause HR, contractility and CO to increase 5) Vasomotor fibres stimulate vasoconstriction 6) Cardiac output and R return blood pressure to homeostatic range
48
What are the long term mechanisms of blood pressure?
Renal regulation: -Control BP by altering blood volumes -Direct renal mechanism or indirect (renin-angiotensin) hormonal mechanism
49
Direct renal mechanism of blood pressure
-Alters blood volume independently of hormones -Increased BP or blood volume: Increased filtration, causes the kidneys to eliminate more urine, thus reducing BP -Decreased BP or blood volume causes the kidneys to conserve water, and BP rises
50
Indirect renal mechanism of blood pressure
-Senses BP is too low -Sends rhenin --> angiotensin 2 -Increases vasoconstriction -Angiotensin 2 --> aldosterone and ADH secretion -Conservation of fluid -Raises BP
51
Hypotension
-Blood pressure is below 100/60 mmHg
52
Hypertension
-Blood pressure is above 140/90 mmHg -Primary and secondary
53
Primary hypertension
-Execessive salt intake or hormones -Abnormalities in arterioles -Poor kidney function (RAAS) -Age/genetics -Stress -Smoking -Diet/obesity
54
Secondary hypertension
-Accounts for about 10% of hypertension cases -Occurs secondary to another known primary problem -Renal hypertension, endocrine hypertension, neurogenic hypertension.
55
Complications of hypertension
-CHF -Stroke/heart attack -Spontaneous hemorrhage -Renal failure -Retinal damange
56
Treatments of hypertension
-ACE inhibitors, beta blockers, Ca blockers -Diet, exercise
57
Hypotension
-Low blood pressure -Occurs when there is too little blood to fill the vessels or heart is too weak to drive the blood -Dizziness, fainting, blurry eyes, confusion, palpitations -Alcohol may make it worse (RAAS)
58
Orthostatic postural hypotension
-Transient hypotensive condition resulting from insufficient compensatory responses to gravitational shifts in blood when person moves from horizontal to vertical position
59
Circulatory shock
-Occurs when blood pressure falls so low that adequate blood flow to the tissues can no longer be maintained Hypovolemic: low volume Cardiogenic: heart produced Vasogenic: vessel produced Neurogenic: nerve produced
60
Effect of high CO2 and low O2 in systemic arteries
Vasodilation
61
Effect of low O2 in pulmonary vessels
Vasoconstricts to redirect blood flow to alveoli that are better
62
Bulk flow of water in capillaries
Arterial end: -hydrostatic BP is higher than osmotic pressure -water moves out Venous end: -hydrostatic BP less than osmotic pressure -water moves back in Remaining: -Goes into lymph -3L / day

KNES260 (13 decks)

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