Blood vessels

Question 1

Name layers of blood vessels from superficial to deep

Answer 1

1. Tunica externa (adventitia): CT
2. Tunica media: smooth muscles involve in vasoconstrict+dilate
3. Tunica intima: endothelium, basement membrane (+ fenestrated)

Question 2

Diff. b/w elastic artery & muscular artery. Provide E.g of each

Answer 2

• Elastic: elastic tiss. - expand & recoil to conduct pressure. E.g. aorta, major branches
• Muscular: thick walls - vasoconstrict+dilate&raquo_space; distribute blood. E.g. Med. size arteries

Question 3

Diff. b/w tunics in arteries & veins (tunics)

Answer 3

• Externa: a) thin. v) thick
• Media: a) thick = Elastic tiss. + smooth muscle. v) thin = smooth muscle
• Intima: v) valves

Question 4

Arteries (& types) vs arteriole

Answer 4

Arteries: Large in size
- Elastic: elastic tiss; conduct pressure = blood travels
- Muscular: thick muscle wall; vasoconstrict+dilate = distribute blood
Arterioles: small size = R wall layers

Question 5

Venules vs. veins

Answer 5

Venules: small diameter (after capillary)
Veins: large lumen + thin walls, valves. More smooth muscle than venules

Question 6

Capillaries & function

Answer 6

• Small vessels
• endothelial cells on basement memb. + loose CT
  » where rapid exchange of nutrients takes place

Question 7

Function of arteries & veins

Answer 7

A): takes blood away from <3 in systemic circ. = elastic & muscular walls to withstand Hi kpa
V): takes blood towards <3 from sys. circ. = large lumen (Hi compliance) + valves (prevent back flow bc low kpa)

Question 8

3 structural types of capillaries (include location)

Answer 8

• Continous: no gaps b/w endothelial cells. E.g. muscle, skin
• Fenestrated: Highly permeable. E.g. kidney, endocrine glands
• Sinusoids: large diameter & fenestrae. e.g. liver, bone marrow, spleen

Question 9

Proportion of blood found in various parts of cardiovascular sys?

Answer 9

• Syst. circ.: 84%
• heart chambers: 7%
• Pulmonary vessels: 9%

Question 10

What parameters make blood flow?

Answer 10

1. blood flow = pressure diff.

2. resistance ≠ blood flow

Question 11

How does vessel diameter influence blood flow?

Answer 11

• flow = vessel diameter*
• Big Diameter = lo resistance = Hi flow
• Sml diameter = Hi resistance = lo flow

Question 12

How does blood viscosity influence blood flow?

Answer 12

flow ≠ blood viscosity
Hi Viscosity = lo flow
Lo viscosity = Hi flow

Question 13

Intrinsic (local) control vs extrinsic control

Answer 13

• Intrinsic: blood flow = metabolic needs of tissues

- Extrinsic: maintain pressure

Question 14

How blood vessel controlled intrinsically? (3)

Answer 14

1. Local metabolic factors: flow = metabolic needs. Vasodilate bc increase CO2, H+, K+, NO, temperature, adenosine, & decrease O2
2. Local vasoactive substances: dilate: histamine. constrict: leokotrienes
3. Myogenic control: stretch in walls of b.vessel (+ve stretch = v.constrict )

Question 15

How blood vessel controlled extrinsically? (2)

Answer 15

1. Neural factor: sympathetic adrenergic vasoconstrictor fibres from vasomotor centre in MO control vasomotor tone (except in brain & <3)
2. Hormonal factor: nor+adrenaline = v.constrict; adrenaline = v.dilate

Question 16

Laminar vs turbulent flow

Answer 16

• Laminar: streamlined flow (when diameter is consistent throughout length)
• Turbulent: turbulence created by interruption of diameter => sounds

Question 17

List long term mechanisms

Answer 17

1. Direct renal mechanisms: conserve or lose body fluid through urine to maintain MAP
2. Indirect hormonal control: RAA system

Question 18

What is responsible for the short term and long term MAP control mechanisms

Answer 18

Short: Neural reflex and hormones
Long: Renal control of blood volume

Question 19

List the short term MAP control mechanisms

Answer 19

1. Baroreceptor reflex: detect increase of decrease in MAP
2. Hormonal influence: nor+adrenaline, antiogensin II & ADH
3. Chemoreceptors reflex: affect MAP if decrease in pH or increas of CO2
4. HIgher CNS centres: control cardiovascular center bc emotions
5. CNS ischaemic response: loss of blood => vasoconstriction to increase MAP