Vascular System and Vessels

Question 1

Tunics of Blood Vessel Walls

Answer 1

1. Tunica Intima:
   - innermost: flattened epithelial cells supported by delicate connective tissues
   - capillaries only have tunica intima and base membrane
2. Tunica Media
   - middle layer - mainly smooth muscle
   - variable thickness
3. Tunica Adventitia
   - outermost layer made of connective tissue

Question 2

Types of Arteries

Answer 2

1. Large, elastic
   - many elastic layers to allow for smooth blood flow
2. Medium Muscular
   - circular smooth muscle fibres that are capable of vasoconstriction
3. Small arteries and arterioles
   - narrow lumina, thick smooth muscle walls

Question 3

What is the clinical importance of pulsatile arterial blood flow

Answer 3

Blood spurting out = elastic/muscular artery severed (reflects systole and diastole

Blood seeping out = blood from veins

Question 4

Anastomeses

Answer 4

links b/w arteries that provide detours for blood flow if usual pathway is obstructed (collateral flow)

Question 5

End arteries

Answer 5

no anastomoses

Question 6

Veins

Answer 6

more abundant than arteries

1. Venules and small veins
   - drain capillary beds and unite to form venus plexuses
   - small amount of smooth muscle
   - no elasticity
2. Medium veins
   - drain venus plexuses and accompany medium arteries
   - contain valves
3. Large veins
   - wide bundles of longitudinal smooth muscles

Question 7

Valves

Answer 7

cusps of folded endothelium located distal to entry of major tributary to prevent backflow of venous blood

Question 8

Neurovascular supply of a vessel

Answer 8

• contractions occur in tunica media

- modulated by vasomotor nerves (SNS)

Question 9

Venus Return vis vascular venous pump

Answer 9

vascular venus pump = a result of the arrangement of venae comitantes:
- connective tissue resists expansion therefore arterial pulsation compresses blood in veins and valves direct flow proximally

Venus flow returns –> atria due to:

• blood pressure
• contraction of skeletal muscle
• respiratory oscillation of intrathoracic pressure

Question 10

Venous Return via Musculovenous Pump

Answer 10

main method

- expansion of contraction muscles is limited by fascia –> compresses veins around muscle and pushes blood superiorly

Question 11

Venous Return via Thoracic Venous Pump

Answer 11

double pump mechanism linked to respiration

During inspiration:
- diaphragm descends –> IVC empties and SVC fills up

During expiration:
- diaphragm ascends –> IVC fills up and SVC shortens

Question 12

Organisation of lymphatic vascular system

Answer 12

superficial (under epithelium) drains –> deep lymph capillaries (in reticular dermal layer) –> lymphatics (larger with valves) –> veins

lymphatic vessels have 3 tunis like blood vessels, but thinner walls

Question 13

Lymph drainage

Answer 13

facilitated by pulsatile movements due to smooth muscle contractions in the tunica media

Question 14

Lymphatic trunks and ducts

Answer 14

Thoracic Duct: all lymph from LEFT side of body and left bottom half

Right Thoracic Duct: drains lymph from RIGHT HEAD, NECK UPPER LIMB, THORAC, UPPER ABDO

ducts drain –> venous system at neck where internal jugular joins subclavian vein