Blood Pressure 1

Question 1

Degree of constriction
experienced by a blood
vessel relative to…

Answer 1

… its maximally dilated state.

Question 2

What is vascular smooth muscle?

Answer 2

vascular tone (vascular tonus).

Question 3

Pre-capillary sphincters + Blood vessel smooth muscle =

Answer 3

major control of blood flow and blood pressure locally

Question 4

mean diameter and mean wall thickness of artery?

Answer 4

diameter = 4.0 mm
wall thickness = 1.0 mm

Question 5

mean diameter and mean wall thickness of arterioles?

Answer 5

diameter = 30.0 um
wall thickness = 6.0um

Question 6

mean diameter and mean wall thickness of capillarys

Answer 6

diameter = 8.0 um
wall thickness = 0.5 um

Question 7

mean diameter and mean wall thickness of venules?

Answer 7

diameter = 20.0 um
wall thickness = 1.0 um

Question 8

mean diameter and mean wall thickness of vein?

Answer 8

diameter = 5.0 mm
wall thickness = 0.5 mm

Question 9

Which units are used to measure blood pressure?

Answer 9

1. Bar
2. PSI (pound per square inch)
3. mm Hg – millimetre of mercury

Question 10

Define blood pressure?

Answer 10

pressure exerted by circulating blood upon the walls of blood vessels. Force applied to the vessel walls.

Question 11

What is the flow rate of blood?

Answer 11

volume of blood flowing through a specific vessel – or organ – over a period of time (for example, L/min, mL/s, etc.)

Question 12

Flow is directly proportional to…

Answer 12

… pressure gradient

Question 13

Flow is inversely proportional to …

Answer 13

… vascular resistance.

Question 14

What is vascular resistance?

Answer 14

Frictional force that opposes the flow of a fluid

Question 15

Increased resistance =

Answer 15

decreased flow rate

Question 16

decreased resistance =

Answer 16

increased flow rate

Question 17

How can the body compensate for increased
resistance?

Answer 17

Heart works harder to achieve a larger
pressure gradient

Question 18

the flow rate of blood through a vessel is…

Answer 18

… the volume of blood passing thorugh per unit of time.

Question 19

the flow rate of blood thorugh a vessel is directly proportional to…

Answer 19

… the pressure gradient (as the pressure gradient increases, flow rate increases.

Question 20

the flow rate of blood is inversely proportional to …

Answer 20

… vascular resistance (as resistance increases, flow rate decreases).

Question 21

flow rate of blood through a vessel =

Answer 21

pressure gradient / resistance of blood vessel.

Question 22

What causes resistance to blood flow?

Answer 22

1. Blood viscosity
2. Vessel dimensions

Question 23

What is blood viscosity?

Answer 23

The ‘thicker’ a liquid, the more viscous it is

Question 24

What causes resistance to blood flow?

Answer 24

2. Vessel dimensions
   Length
   Radius

Blood ‘rubbing’ - the greater the contact area = the greater the ressitance

‘rubbing against arterial walls.

Question 25

More blood in contact with the walls of a narrow vessel =

Answer 25

increased resistance - flow decreases.

Question 26

Less blood in contact with the walls of a wide vessel =

Answer 26

decreased resistance. Flow increases

Question 27

Slight change in the radius of a vessel =

Answer 27

notable change in flow

Question 28

Poiseuille law

Answer 28

Flow = pi x pressure gradient x radius^4 / 8 x viscosity x length

Question 29

Resistance is inversely proportional to...

Answer 29

... the fourth power of the radius

Question 30

Doubling the radius reduces resistance to...

Answer 30

1/6th its orginal value

Question 31

flow is...

Answer 31

... 16 fold

Question 32

What is pulse pressure?

Answer 32

PP = systolic pressure – diastolic pressure (DP) in simple terms

Question 33

Pulse pressure represents...

Answer 33

It represents the force that the heart generates each time it contracts (Amount of pressure required to create the feeling of a pulse)

Question 34

MAP = clinically defined as

Answer 34

Perfusion pressure

Question 35

MAP is normally between...

Answer 35

70 to 110 mmHg

Question 36

If MAP falls significantly...

Answer 36

organ will not receive enough blood flow -> resulting in ischemia.

Question 37

cross sectional area is related to...

Answer 37

... velocity

Question 38

velocity is inversely proportional to ...

Answer 38

... cross sectional area.

Question 39

what is cardiac output?

Answer 39

volume of blood pumped by the heart

Question 40

Cardiac output (CO) = ?

Answer 40

CO = Heart Rate X Ventricle Stroke Volume = dm3/min, L/min

Question 41

What is peripheral resistance?

Answer 41

resistance of arteries and arterioles to blood flow

Question 42

What results in changes in blood pressure?

Answer 42

Any factor causing a change in cardiac output or peripheral resistance will result in a change in blood pressure.

Question 43

Factors affecting heart rate?

Answer 43

o2 and co2 Phyiscal activity Hct Symp and paraymp activity body comp drugs dehydration adrenaline adn other hormones adenosine and caffeine pH electrolytes prostaglandins

Question 44

Factors affecting heart rate (HR)?

Answer 44

Autonomic innervation Hormones fitness levels age

Question 45

What factors affect stroke volume?

Answer 45

Heart size Fitness levels gender contratility duration of contraction preload (EDV) Afterload (resistance)

Question 46

How to calculate stroke volume?

Answer 46

Stroke volume (SV) = EDV - ESV

Question 47

How to calculate cardiac output?

Answer 47

Cardiac output (CO) = HR x SV

Question 48

What is vascular compliance?

Answer 48

Ability of a blood vessel wall to expand and contract passively with changes in pressure.

Question 49

whats vascular compliance?

Answer 49

Ability of a blood vessel wall to expand and contract passively with changes in pressure

Question 50

What is aortic aneurysm a result of?

Answer 50

of increased total peripheral resistance.

Question 51

An increase in cardiac output leads to...

Answer 51

...an increase in the volume of blood contained in the aorta and an increase in mean arterial pressure when total peripheral resistance remains the same

Question 52

a constant cardiac output leads to...

Answer 52

... an increase in the volume of blood contained in the aorta and an increase in mean arterial pressure when total peripheral resistance increases.

Question 54

aortic aneurysms have a limited...

Answer 54

...vascular compliance

Question 55

aortic aneurysm affect on aorta?

Answer 55

Enlargement (dilatation) of the aorta to greater than 1.5 times normal size.

Question 56

Aortic aneurysm is often...

Answer 56

...asymptomatic -> high risk of death

Question 57

what are some occasional symptoms of aneurysms?

Answer 57

Occasionally, abdominal, back, or leg pain.

Question 58

Aortic aneurysm most commonly located in...

Answer 58

... abdominal aorta, but can be located in the thoracic aorta.

Question 59

describe the distribution of blood within the circulation?

Answer 59

the greatest volume found in venous vasculature, where 70-80% of blood is found. FOr this reason, veins are referred to as capacitance vessels. The relative volume of blood between arterial and venous sides of the circulation can vary considerably depending upon total blood volume, intravascular pressures, and vascular compliance.

Question 61

blood distribution values?

Answer 61

vein = 65% arteries = 13% arterioles = 2% capilleries = 5% central blood volume = 15%

Question 62

what is central blood volume (CBV)?

Answer 62

Central blood volume (CBV) = blood in heart cavities + lungs + central arterial tree.

Question 63

CBV increased during ...

Answer 63

... sympathetic stimulation