Altered circulation

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  • Created by: evepoag
  • Created on: 25-10-22 11:54
What do blood vessels do in the body?
Provide and maintain blood circulation
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What are the body's conduction and distribution vessels called?
Arteries
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What are the pre-capillary resistance vessels called?
Arterioles
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What are the exchange vessels called?
Capillaries
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What are the blood reservoirs and drainage vessels called?
Veins
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When is blood pressure the highest?
When blood leaves the left ventricle
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When blood is returning to the heart, other mechanisms are needed. What happens when these mechanisms fail?
Blood can pool in the veins resulting in venous hypertension
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The equation for blood pressure is cardiac output x systemic vascular resistance.

What is systemic vascular resistance?
The resistance that the arterial vessels offer to blood flow - diameter of vessels is a major factor in resistance
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What is the equation for cardiac output?
Heart rate x Stroke volume
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What is stroke volume?
The amount of blood ejected from each ventricle on each contraction, normally around 70mls
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What happens if blood pressure is not adequate?
The tissues will not receive an adequate blood supply, leading to tissue damage and cell death
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Why is it important vessel walls of capillaries are only one cell thick?
Enables the exchange of gas, water, nutrients, and waste between blood and tissue cells
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Describe the capillary exchange process
Lymphatic fluid returns to the blood plasma. The blood flows from the blood arteriole into the capillary. Capillary blood pressure drops, allowing some fluid to filtrate out. Some is then reabsorbed, and blood flows from the capillary, into the venue
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What is hydrostatic pressure?
The pressure in the capillary that pushes the tissue fluid from the plasma across the capillary wall into tissue space
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What is osmotic pressure?
Albumin within the plasma provides this pressure, which draws the tissue fluid from the tissue spaces across the capillary wall into the blood circulation
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So what causes the reabsorption of interstitial fluids into the blood circulation?
Albumin
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At the first arterial end of the capillary, is hydrostatic pressure higher or lower than osmotic pressure?
Hydrostatic pressure is higher and osmotic pressure, helps with filtration
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At the last venous end of the capillary, is hydrostatic pressure higher or lower than osmotic pressure?
Osmotic pressure is higher and hydrostatic pressure is lower, so that tissue fluid can be reabsorbed
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What is the difference between blood pressure and osmotic pressure?
Blood pressure pushes plasma OUT of the capillary, osmotic pressure pulls it back in
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If blood pressure is higher than osmotic pressure, what happens?
Outward filtration is favoured
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If osmotic pressure is higher than blood pressure, what happens?
Fluid is pulled back into the capillary
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What 4 things cause altered circulation?
1. Changes in cardiac function
2. Changes in fluid balance
3. Changes in vascular permeability
4. Changes in blood clotting
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Describe the car and gas analogy
The car = tissues.
The gasoline = blood.
The gas pump = heart
The hose = the vasculature.

The heart pumps vasculature into blood, which provides the tissues with blood
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What is a common change in fluid volume?
Hypovolaemia
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What is hypovolaemia?
The loss of circulating fluid volume, this can be due to vomitting, burns, etc.
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How does atherosclerosis or blocked arteries affect blood supply?
The arterial blood vessels become narrowed, blood supply will be reduced to the capillary beds, resulting in tissue injury and ischemia.
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What are 2 common changes in vasculature and what can they result in?
Sepsis and anaphylaxis

They both lead to vasodilation and increased capillary permeability
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Describe sepsis in relation to vasculature changes
In sepsis, the body's irregular inflammatory response to infection leads to vasodilation and increased capillary permeability. This allows a fall in blood pressure and loss of fluid to the interstitial space. This continual lack of fluid can lead to multi
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Describe anaphylaxis in relation to vasculature changes
In anaphylaxis, the body's hypersensitive reaction to an allergen results in release of histamine, causing vasodilation and increased capillary permeability. This leads to a fall in BP, and circulatory collapse
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Describe neurogenic shock in relation to vascular changes
Over-stimulation of the parasympathetic autonomic nervous system or inhibition of sympathetic nervous activity, leads to vasodilation. this can result in spinal cord injuries, etc.
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Using the car analogy, name 4 ways the car can't get gas
1. the gas pump doesn't work = cardiogenic shock
2. there is no gas = hypovolemic shock
3. gas blockage = obstructive shock
4. problem with hose = distributive shock
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Name 2 types of leg ulcers
1. Arterial ulcers
2. Venous ulcers
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Why do arterial ulcers not heal?
They have a lack of arterial blood supply, which can be due to narrowing of blood vessels by atherosclerosis.
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Why is there a high amount of exudate in a venous leg ulcer?
The oedema in the limb due to venous hypertension. It is the excess interstitial fluid that prevents the wound from healing
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In the renin-angiotensin-aldosterone-system (RAAS), how is fluid affected?
Angiotensin 2 releases aldosterone. Aldosterone caused reabsorption of sodium chloride and water in the kidneys, to increase blood pressure
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What hormone is released from the adrenal cortex?
Aldosterone
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In capillary beds, are plasma proteins such as albumin, filtered out to form interstitial fluid?
No
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What action does the Angiotensin II produced by the RAAS system have on blood vessels?
Vasoconstriction
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What is it called when a blood clot that is carried in the blood becomes lodged in an artery?
Embolus
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What is a thrombus?
A blood clot that forms in the vein
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If a thrombus breaks free and travels throughout the bloodstream, what is it called?
An embolus
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If systemic vascular resistance (SVR) falls, but cardiac output stays the same, what will happen to blood pressure?
Blood pressure will decrease
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Is cardiac output falls, but systemic vascular resistance (SVR) stays the same, what will happen to blood pressure?
Blood pressure will decrease
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If cardiac output is unchanged, but systemic vascular resistance (SVR) increases, what will happen to blood pressure?
Blood pressure will increase
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Name the 3 compensatory mechanisms triggered by a decrease in blood pressure
1. RAAS system
2. Increase sympathetic activity
3. Anti-diuretic hormone (ADH) released
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How does histamine affect capillary blood vessels?
Vasodilation and increased permeability
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What is oedema?
Excess fluid in the interstitial space
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3 layers make up the structure of arteries, arterioles, veins and venules. What is the middle tissue layer of the blood vessels composed of?
Smooth muscle
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4 layers make up the structure of arteries, arterioles, veins and venules. What are each of the 4 layers composed of?
1. Outer layer = Connective tissue
2. Middle layer = Smooth muscle
3. Inner layer = Endothelium
4. Basement membrane
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Other cards in this set

Card 2

Front

What are the body's conduction and distribution vessels called?

Back

Arteries

Card 3

Front

What are the pre-capillary resistance vessels called?

Back

Preview of the front of card 3

Card 4

Front

What are the exchange vessels called?

Back

Preview of the front of card 4

Card 5

Front

What are the blood reservoirs and drainage vessels called?

Back

Preview of the front of card 5
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