Systemic circulation

Question 1

What are vessels arranged in?

Answer 1

Parallel and series

Question 2

What problems does the parallel circuitry of veins cause?

Answer 2

Implications in resistance, flow and pressure in blood vessels

Question 3

Which of the vessels has the greatest total cross sectional area?

Answer 3

Capillaries

Question 4

Which of the vessels carries the majority of blood volume?

Answer 4

Veins

Question 5

Does velocity of blood flow increase with increased total cross sectional area?

Answer 5

No

Question 6

Where is blood flow the slowest?

Answer 6

Capillaries

Question 7

What are the 3 distinct layers of blood vessel walls?

Answer 7

1) Tunica adventitia (connective tissue - collagen fibres)
2) Tunica media
(smooth muscle and elastin)
3) Tunica intima
endothelium (squamous)

Question 8

What are some examples of elastic arteries?

Answer 8

Aorta and major branches

Question 9

What are features of elastic arteries?

Answer 9

• Large diameter, slow resistance pathways

- Large amounts of elastin in tunica media, withstand and smooth out large pressure fluctuations

Question 10

What do muscular arteries do?

Answer 10

Deliver blood to specific organs

Question 11

What are features of muscular arteries?

Answer 11

• Small diameter
• Less elastin and more smooth muscle in the tunica media
• More active in vasoconstriction

Question 12

What do arterioles do?

Answer 12

Deliver blood to capillary beds

Question 13

What type of muscle is the arteriole almost all made up of?

Answer 13

Smooth

Question 14

What does arteriole diameter regulate?

Answer 14

Blood flow to capillary beds and responds to neural stimuli and local chemical influences

Question 15

What are the two basic types of capillaries?

Answer 15

Continuous and fenestrated

Question 16

What are features of continuous capillaries?

Answer 16

Tight junctions between epithelial cells

Intercellular clefts exist

Question 17

What are features of fenestrated capillaries?

Answer 17

• Some endothelial cells have oval pores or fenestrations
• Much more permeable to fluids and small solutes
• Found where active absorption or filtrate formation occurs (small intestine, kidney)

Question 18

What are the interweaving networks between capillaries called?

Answer 18

Capillary beds

Question 19

What is blood flow through capillary beds termed as?

Answer 19

Microcirculation

Question 20

What is the vascular shunt that bypasses true capillaries called?
(true capillaries are actual exchange vessels)

Answer 20

Metarteriole

Question 21

What is capillary flow regulated by? (Hint - it is a ring of smooth muscle fibres)

Answer 21

Precapillary sphincter

Question 22

What carries blood from the capillaries to the heart?

Answer 22

Venules - formed when capillaries unite

Question 23

What does the wall of smaller venules consist solely of?

Answer 23

Endothelium

Question 24

What do larger venules possess?

Answer 24

Sparse tunica media and tunica adventitia

Question 25

What distincts veins from arteries?

Answer 25

Walls are thinner and lumens larger than those of corresponding arteries

Question 26

What is systemic blood pressure?

Answer 26

Fluid driven through circuit of closed vessels operating under pressure

Question 27

What does blood flow along?

Answer 27

Pressure gradient - higher pressure closer to the pump

Question 28

How does pressure result?

Answer 28

When flow is opposed by resistance

Question 29

Where is systemic blood pressure the greatest?

Answer 29

The aorta

Question 30

Where is systemic blood pressure the lowest?

Answer 30

Right atrium

Question 31

Where does the steepest drop in systemic blood pressure occur?

Answer 31

Arterioles

Question 32

What does arterial blood pressure reflect?

Answer 32

1) Compliance of elastic arteries near the heart | 2) Volume of blood being forced into these arteries at a particular point in time

Question 33

What is the highest arterial pressure?

Answer 33

Systolic pressure

Question 34

What is the lowest arterial pressure?

Answer 34

Diastolic pressure

Question 35

How do you measure blood pressure?

Answer 35

Sphygmomanometry - cuff is inflated to a pressure above systolic blood pressure and diastolic pressure so the smooth laminar blood flow through occluded artery is interrupted, resulting in Korotkoff sounds.

Question 36

When does the beginning and end of Korotkoff sounds start?

Answer 36

Beginning - systolic | End - diastolic

Question 37

Is capillary blood pressure higher at the arterial end or venous end?

Answer 37

Arterial

Question 38

Why is capillary pressure very important?

Answer 38

Must be low otherwise the fragile walls will rupture | Must be closely controlled to regulate the extent of filtration of solute into interstitial space

Question 39

Is venous pressure steady in the cardiac cycle?

Answer 39

Yes

Question 40

Why can't venous blood returned to the heart be at the same rate as the heart pumping blood into the systemic arterial system?

Answer 40

Venous pressure normally too low

Question 41

What are the factors influencing venous return?

Answer 41

respiratory pump | skeletal muscle pump

Question 42

What does inspiration do to influence venous return?

Answer 42

Inspiration increases abdominal pressure, compresses abdominal veins. Venous valves prevent back flow of blood and forces blood towards the heart Inspiration decreases thoracic pressure - veins expand, aiding the movement of blood towards the right atrium

Question 43

How do skeletal muscles propel blood towards the heart?

Answer 43

Contract and compress the deep veins, valves distal to point of compression are closed by back flowing blood

Question 44

True or false - the greatest total cross sectional area occurs at the level of the muscular arteries

Answer 44

False

Question 45

True or false - at any point in time most of the blood is located in vessels at the venous side of the circulation

Answer 45

True

Question 46

True of false - the velocity of blood flow is greatest in the capillaries and venules

Answer 46

False

Question 47

True or false - the wall of the aorta contains more elastin and less smooth muscle than the wall of an arteriole

Answer 47

True

Question 48

True or false - the elastic arteries are less distensible and may vasoconstrict to a greater extent than muscular arteries

Answer 48

False