Pressure and flow in arteries and veins

Question 1

Define systolic pressure, diastolic pressure and pulse pressure.

Answer 1

systolic pressure is when the heart is contracting and pumping blood around body
diastolic pressure is when heart is relaxing
pulse pressure is systolic minus diastolic

Question 2

• Explain the origin of the Korotkoff sounds and their use.

Answer 2

silence, tapping, thumping, muffled, silence

Question 3

• Illustrate the changes in the aortic pressure wave as it passes through the vascular tree.

Answer 3

ventricular contraction- semilunar valve opens and blood is ejected from ventricles and flows into arteries. aorta and arteries expand and store pressure in elastic walls
ventricular relaxation- isovolumetric ventricular relaxation, semilunar valve shuts preventing back flow into ventricle and elastic recoil sends blood forward into rest of circulatory system

Question 4

Illustrate the changes in blood velocity and total cross-sectional area of the vessels throughout the vasculature.

Answer 4

If cross sectional area is low then velocity needs to be high to get all the blood through for example the aorta.
Higest velocity in the aorta and lowest in the capillaries as there are lots of them

Question 5

how does gravity effect flow of blood in veins

Answer 5

1. gravity- doesn’t effect driving pressure from arteries to veins but does cause venous distension in legs. Lower EDV, Preload, SV, CO, MAP. causes venous collapse in neck

Question 6

Describe the mechanisms that prevent blood clotting in vessels.

Answer 6

1.endothelium forms a physical barrier to stop platelets coming into contact with collagen which will inhibit platelet aggregation
2. produces prostacyclin and nitric oxide which inhibit platelet aggregation
3. Stop thrombin production by producing tissue factor pathway inhibitor
4.produces thrombomodulin and heparin which inactivates thrombin
5. secretes tissue plasminogen activator which converts plasminogen to plasmin and digests clots

Question 7

what is the oscillatory blood pressure measurement

Answer 7

1. turbulent blood flow sets up vibrations in blood vessel wall
2. tranducser monitors these vibrations
3. maximum vibrations occur at mean arterial pressure
4. algorithm estimates diastolic and systolic

Question 8

what is pressure in the arteries effected by

Answer 8

stroke volume, velocity of ejection, elasticity of arteries, TPR from arteries to arterioles

Question 9

skeletal muscle pump

Answer 9

2. skeletal muscle pump- rhythmic contraction increases venous return and EDV. when muscle contracts it squeezes veins and venues and pushes blood in both directions back to heart and back to feet.

Question 10

respiratory pump

Answer 10

3. respiratory pump- increased Respiratory rate and depth increases venous return and EDV

Question 11

venomotor tone

Answer 11

4. venomotor tone- state of contraction of smooth muscle surrounding venues and veins. mobilises capacitance and increases EDV

Question 12

systematic filling pressure

Answer 12

pressure created by ventricles and transmitted through vascular tree to the veins

Question 13

how are clots formed

Answer 13

when blood vessels are damaged the platelets have access to collagen in the basement membrane. Platelets will become activated and stick to basement membrane forming a fibrin clot. platelets act as bricks and fibrin is the mortar