Blood Pressure

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

Which units are used to measure blood pressure?

Answer 3

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

Question 4

Define blood pressure?

Answer 4

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

Question 5

What is the flow rate of blood?

Answer 5

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

Question 6

Flow is directly proportional to…

Answer 6

… pressure gradient

Question 7

Flow is inversely proportional to …

Answer 7

… vascular resistance.

Question 8

What is vascular resistance?

Answer 8

Frictional force that opposes the flow of a fluid

Question 9

Increased resistance =

Answer 9

decreased flow rate

Question 10

decreased resistance =

Answer 10

increased flow rate

Question 11

How can the body compensate for increased
resistance?

Answer 11

Heart works harder to achieve a larger
pressure gradient

Question 12

the flow rate of blood through a vessel is…

Answer 12

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

Question 13

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

Answer 13

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

Question 14

the flow rate of blood is inversely proportional to …

Answer 14

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

Question 15

flow rate of blood through a vessel =

Answer 15

pressure gradient / resistance of blood vessel.

Question 16

What causes resistance to blood flow?

Answer 16

1. Blood viscosity
2. Vessel dimensions

Question 17

What is blood viscosity?

Answer 17

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

Question 18

What causes resistance to blood flow?

Answer 18

2. Vessel dimensions
   Length
   Radius

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

‘rubbing against arterial walls.

Question 19

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

Answer 19

increased resistance - flow decreases.

Question 20

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

Answer 20

decreased resistance. Flow increases

Question 21

Slight change in the radius of a vessel =

Answer 21

notable change in flow

Question 22

Poiseuille law

Answer 22

Flow = pi x pressure gradient x radius^4

/

8 x viscosity x length

Question 23

Resistance is inversely proportional to…

Answer 23

… the fourth power of the
radius

Question 24

Doubling the radius reduces resistance to…

Answer 24

1/6th its orginal value

Question 25

flow is…

Answer 25

… 16 fold

Question 26

What is pulse pressure?

Answer 26

PP = systolic pressure – diastolic pressure (DP)

in simple terms

Question 27

Pulse pressure represents…

Answer 27

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

Question 28

MAP = clinically defined as

Answer 28

Perfusion pressure

Question 29

MAP is normally between…

Answer 29

70 to 110 mmHg

Question 30

If MAP falls significantly…

Answer 30

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

Question 31

cross sectional area is related to…

Answer 31

… velocity

Question 32

velocity is inversely proportional to …

Answer 32

… cross sectional area.

Question 33

what is cardiac output?

Answer 33

volume of blood pumped by the heart

Question 34

Cardiac output (CO) = ?

Answer 34

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

Question 35

What is peripheral resistance?

Answer 35

resistance of arteries and
arterioles to blood flow

Question 36

What results in changes in blood pressure?

Answer 36

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