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Flashcards in Integration of cardiovascular mechanisms Deck (48)
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1

Factors which influence MAP?

Heart Rate
Stroke Volume
Systemic vascular resistance

2

Main site of systemic vascular resistance?

Arterioles

3

Components of cardiovascular system?

Heart - pump
Arteries - passageway of blood from heart to tissues
Arterioles - major resistance vessels
Capillaries - Site of gas exchange, nutrients and water between blood and tissues
Veins - Contains most of blood volume during rest - passageways of blood from tissues to heart

4

What must venous return provide?

The heart with sufficient blood to pump

5

Name for veins?

Capacitance vessels

6

How is HR mainly regulated?

Autonomic nervous system

7

How is SV mainly regulated?

Preload
Myocardial contactility
Afterload

8

CO equation=

CO= HR x SV

9

How can MAP be estimated?

DBP + 1/3 pulse pressure

10

How is systemic vascular resistance regulated?

By vascular smooth muscles

11

What does contraction of vascular smooth muscles cause?

Vasoconstriction and decreases SVR and MAP

12

What are vascular smooth muscles controlled by?

Intrinsic and extrinsic mechanisms

13

What is resistance to blood flow directly proportional tp?

Blood viscosity and length of blood vessel

14

What is resistance to blood flow inversely proportional to?

Radius of blood vessel to the power of 4

15

Resistance to flow equation?

R proportional to n.l/r^4
n=blood viscosity
L= length of blood vessel
r= radius of blood vessel
R= resistance to flow

16

What does extrinsic control of vascular smooth muscle involve?

Nerves and hormones

17

If we constrict muscle in arterioles what happens?

Increases resistance and decreases flow

18

What are vascular smooth muscles supplies by?

Sympathetic nerve fibers

19

Vascular smooth muscle neurotransmitter and receptor it works on?

Noradrenaline
acts on alpha receptors

20

Vasomotor tone?

Vascular smooth muscle partially constructed at rest

21

Control of vascular smooth muscles via hormones?

Adrenaline
Organ specific
Depends on predominant type of receptor

22

What does adrenaline acting on alpha receptors cause?

Vasoconstriction

23

What causes vasodilation?

Adrenaline acting on beta 2 receptors

24

Where are alpha receptors predominantly found?

Skin
Gut
Kidney arterioles

25

What receptor is found on cardiac and skeletal muscle arterioles?

Beta2 receptors

26

Other hormones which extrinsically affect vascular smooth muscle control?

Angiotensin 2- causes vasoconstriction
Antidiuretic hormone- causes vasoconstriction

27

What do local metabolic changes within an organ influence?

Contraction of arteriolar smooth muscles

28

What factors causes relaxation of arteriolar smooth muscles?

Vasodilation
Metabolic hyperaemia

29

What do other local chemicals released within an organ influence? and when are they released

Contraction of arterial and arteriolar smooth muscles
Following a tissue injury or inflammation

30

Examples of humoral agents which cause contraction of arteriolar smooth muscles resulting in vasoconstriction?

Serotonin
Thromboxane A2
Leukotrienes
Endothelin