Lecture 26 - Vascular System and Vessels

Question 1

Understand the layered structure of vessels and describe how these layers differ between arteries, veins and lymphatic vessels

Answer 1

o There are 3 types of blood vessels: arteries, veins and capillaries
o All blood vessels have 3 layers (tunics) surrounding the lumen
o Veins have thinner tunics and larger lumen
o Blood leaves heart under high pressure via arteries, then travels through capillary beds, finally distributing to vessel arterioles that return O2 rich blood to capillaries.
o Layers of blood vessel walls
 Tunica intima
 Tunica media
 Tunica adventitia

Question 2

Name the types of arteries and arterial branches and understand their structural components

Answer 2

Large elastic arteries (conducting)
 Many elastic layers, resulting in smooth flow of blood
 Near the heart, aorta and its major branches
Medium muscular arteries (distributing)
 Circular smooth muscle fibres, capable of vasoconstriction + blood flow regulation
 Majority of named arteries
Small arteries and arterioles
 Narrow lumina, thick smooth muscle walls
 Flow into capillary beds tonus regulates arterial pressure in vascular system

Question 3

Describe the functional role of anastomoses

Answer 3

o Links between arteries or between arterioles
o Provide potential detours for blood flow if usual pathway is obstructed

Question 4

Describe the anatomical components of veins and venous tributaries

Answer 4

o 80% of blood occupies veins
o Return low O2 blood from capillary beds to heart and are more abundant than arteries
o Veins have valves than enforce unidirectional blood flow from distal proximal

Question 5

Understand the principles of venous return including the thoracic and Musculo venous pump

Answer 5

Vascular venous pumps
- Result of arrangement of venae comitantes
- Connective tissue resist expansion, arterial pulsation compresses blood in veins, valves direct flow proximally
Musculovenous pump
- Main method of venous return from limbs
- Expansion of contracting muscles limited by fascia
- Muscles contraction ‘milks’ blood superiorly
Thoracic venous pump
- Double pump mechanism linked to respiration Descent of diaphragm during inspiration shorten IVC (emptying it) and lengthens SVC (filling it)
- In expiration diaphragm ascends, SVC shortens and empties, IVC lengthens and fills

Question 6

Describe the principles of neurovascular supply of a vessel

Answer 6

o Vascular smooth muscle has tone (continuous partial contraction)
o Modulated by visceral motor nerves – vasomotor nerves from neigh boring peripheral nerves
o Almost exclusively part of sympathetic nervous system

Question 7

Understand the functional role of lymph vessels and lymph nodes

Answer 7

Clears interstitial spaces of surplus fluid, leaked plasma proteins, cellular debris, returns lymphocytes from lymph organs to blood

Question 8

Name the major sites of lymph nodes and other lymphoid tissues

Answer 8

o Pericranial ring (base of head)
o Tracheal nodes
o Inguinal nodes
o Femoral nodes
o Deep nodes
o Axillary nodes
o Cervical nodes

Question 9

Describe the principles of lymph flow and the neurovascular supply of lymph vessels

Answer 9

o Like blood vessels have 3 tunics
o Thinner walled than veins
o Lymph drainage facilitated by smooth muscle contractile waves