Physiology: Pressure and Flow of Arteries and Veins

Question 1

What is method of measuring arterial pressure?

Answer 1

Auscultation of the Korotkoff sounds using a sphyhmomanometer and stethoscope

Question 2

When is systolic and diastolic pressure when measuring with a sphygmomanometer?

Answer 2

The pressure at which there is a tapping sound systolic

The first pressure where there is silence after tapping is diastolic

Question 3

What are some of the advantage of measuring arterial pressure using a sphygmomanometer?

Answer 3

Cheap

non-invasive

Question 4

What are some of the disadvantage of measuring arterial pressure using a sphygmomanometer?

Answer 4

Needs care to be accurate

Discontinuous

Question 5

What is the function of elastic arteries?

Answer 5

Acts as pressure reservoirs to dampen down the pressure variations

Question 6

What are pressure waves affected by?

Answer 6

Velocity of the ejection
SV
Elasticity of the heart
Total Peripheral Resistance

Question 7

What is a normal arterial pressure?

Answer 7

120/80 mmHg

Question 8

What happens to pressure of the vessels once blood passes through the arteries through to the veins?

Answer 8

The pressure decreases as it travels through the body

Question 9

What is the forces driving blood through the veins into the R atrium?

Answer 9

Systemic Filling Force

Question 10

What is the relation in velocity of blood in the Aorta, Vena Cava and Capillaries?

Answer 10

The blood flow is fastest in the aorta and the Vena Cava but slowest in the capillaries

Question 11

What is the pressure drop through the arteries?

Answer 11

95mmHg to 90mmHg as there is a low resistance conduit

Question 12

What is the pressure drop through the arterioles?

Answer 12

90mmHg to 40mmHg as they are the resistance vessels

Question 13

Why is it good that the pressure is already low at the capillaries?

Answer 13

As they are thin walled for efficient gas exchange

Question 14

What is the comparison between systemic and pulmonary pressure?

Answer 14

Pulmonary pressure is a 5th of systemic pressure

Question 15

What vessel has the highest total cross sectional area of lumen?

Answer 15

Capillaries

Question 16

Describe the physiology of the veins?

Answer 16

Pressure is low

Vessels are distensible and collapsible

Question 17

What factors effect the pressure of veins?

Answer 17

Gravity
Skeletal muscle pump
Respiratory pump
Venomotor tone 
Systemic filling Pressure

Question 18

How does gravity effect the pressure of the veins?

Answer 18

If an individual is lying down then the presssure is all equal when compared to when the individual is standing up.
The pressure is lower in the head and higher in the lower vessels ie in the feet
Has no effect driving force from arteries to veins

Question 19

What can Jugular Venous Height show?

Answer 19

The CVP

If the pressure outside the vessel is lower than inside the vessel the height of the JVP may be high

Question 20

How does skeletal muscle pump affect venous pressure?

Answer 20

Contraction of skeletal muscle when is being worked causes an increase in venous pressure and therefore increase in venous return

Question 21

How does the respiratory muscle pump affect venous pressure?

Answer 21

Inspiration causes a reduction of thoracic pressure and an increase in abdominal pressure causing an increase in venous return. It is the opposite for expiration

Question 22

How does Venomotor tone affect venous pressure?

Answer 22

The contraction of smooth muscle around the vein causes a contol of venous return

Question 23

What is the systemic filling pressure?

Answer 23

Pressure created by the ventricles and is transmitted through the vascular tree

Question 24

Why is blood flowing slowly through vessels dangerous?

Answer 24

There is a chance that the blood is able to clot

Question 25

What does clotting involve?

Answer 25

Platelets aggregating together to form a platelet plug.

Fibrinogen is converted into Fibrin by Thrombin and the Fibrin form a clot

Question 26

What are some anti-clotting mechanisms seen in the endothelium?

Answer 26

Blood is unable to contact collagen 
Prostacyclin and NO
Tissue Factor Pathway Inhibitor (TFPI)
Thrombomodulin
Heparin 
Tissue plasminogen activator (t-PA)

Question 27

Why does blood not touching collagen prevent clotting?

Answer 27

As the platelets are unable to aggregate

Question 28

How does prostacyclin and NO prevent clotting?

Answer 28

Inhibits the platelets binding together

Question 29

How does TFPI prevent clotting?

Answer 29

Stops the production of thrombin

Question 30

How does thrombomodulin prevent clotting?

Answer 30

inactivates thrombin by binding to it

Question 31

How does heparin prevent clotting?

Answer 31

inactivates thrombin

Question 32

How does t-PA prevent clotting?

Answer 32

Activates plasminogen which digests clot