Week 3 - Lesson 1 (Part 3) Flashcards Preview

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Flashcards in Week 3 - Lesson 1 (Part 3) Deck (33)
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1
Q

What is the essential principle in circulation?

A

That a pressure gradient must be created in order for blood to flow

2
Q

How is a pressure gradient produced?

A

By the contraction of the heart and the resultant ejection of blood into the aorta and systemic vessels

3
Q

How is energy lost in circulation?

A

In the form of heat

4
Q

Vascular resistance

A

Is the resistance to flow that must be overcome to push blood through the circulatory system and create flow

5
Q

Systemic vascular resistance (SVR)

A

Is the resistance offered by the peripheral circulation

6
Q

What is net flow controlled by? (2)

A
  1. Arterial resistance

2. Arteriolar resistance

7
Q

What kind of diameters and resistance to flow do non diseased circulation on arteries have? (2)

A
  1. Diameter = relatively large

2. Resistance = small

8
Q

What are the main resistance vessels?

A

Arterioles

9
Q

How do you preserve blood flow to the capillary bed?

A

With an increase in resistance in a large distributing artery because of atheroma they must be compensated by a decrease in the resistance of the small arteries and arterioles

10
Q

How is flow maintained as a diseases progresses?

A

By arteriolar dilatation

- until a point is reached where the arteriolar network is fully dilated

11
Q

What happens when there is an increase in a degree of stenosis?

A

It leads to a reduction in flow

12
Q

What is the major determinant of vascular resistance?

A

Precapillary arterioles

13
Q

What kind of vessels are precapillary arterioles?

A

Autoregulatory

14
Q

Autoregulatory

A

Vessels that can dynamically change in diameter to increase or reduce blood flow

15
Q

What is an example of autoregulatory?

A

During exercise the arterioles will increase in diameter to allow for increased flow to the muscles
- the peripheral flow then becomes low resistant with continuous flow throughout systole and diastole

16
Q

What are 3 sources of peripheral resistance?

A
  1. Blood viscosity
  2. Blood vessel diameter
    - radius
  3. Total vessel length
17
Q

Blood viscosity

A

Is a measure of the resistance of blood to flow

18
Q

What is an example of a biophysical property? (2)

A
  1. Thickness of blood

2. Stickiness of blood

19
Q

What does viscosity determine? (4)

A
  1. Friction against vessel walls
  2. Rate of venous return
  3. Work required to pump the heart
  4. How much oxygen is transported to tissues and organs
20
Q

What is blood viscosity affected by? (9)

A
  1. Hypertension
  2. Cholesterol and triglycerides
    - LDL and HDL
  3. Diabetes
  4. Obesity
  5. Cigarette smoking
  6. Male gender
  7. Aging
  8. Temperature
  9. Anemia
21
Q

When does blood viscosity increase?

A

As blood is more hemoconcentrated

- as red blood cell concentration increases

22
Q

When does blood viscosity decrease?

A

As blood is more diluted

- red blood cell concentration decreases

23
Q

Hemodilute

A

Blood will flow more readily

- thinner

24
Q

Hemoconcentrated

A

Blood will flow more steadily

- thicker

25
Q

Hematocrit

A

Is the percentage of red cells in the total blood volume

26
Q

What does hematocrit affect?

A

The bloods viscosity

- therefore the resistance to flow

27
Q

What does it mean if the blood is more viscous? (2)

A
  1. The greater the resistance it encounters

2. The higher the blood pressure

28
Q

When can the hematocrit increase? (2)

A
  1. More red blood cells

2. Less plasma in the blood

29
Q

When can the hematocrit decrease? (2)

A
  1. Fewer red blood cells

2. More plasma

30
Q

What is blood strongly dependent on?

A

Hematocrit

31
Q

Polycythemia

A

Is a condition of abnormal elevation in red cell hematocrit causing higher blood viscosity

32
Q

What does polycythemia do? (3)

A
  1. Increases the resistance to flow
  2. Increases the work of the heart
  3. Can impair organ perfusion
33
Q

What does anemia cause? (2)

A
  1. Low hematocrit

2. Reduced blood viscosity