Cardiovascular II

Question 1

describe post capillary venules

Answer 1

• capillaries –> postcapillary venules –> veins
• high endothelial venules (cuboidal cells)
  
  • HEV: high endothelial vessels
• loosest ZO (zona occludens)
  
  • allows for migration of leukocytes

Question 2

explain the homing effect

Answer 2

• significance of HEV: the vessels are ports of entry for lymphocytes into lymphatic organ (lymph node), which is defined as the homing effect

Question 3

describe valves in veins

Answer 3

• valves in veins = folds of t. intima, supported by fibro-elastic CT
• these prevent the back flow of blood, as they drain the blood towards the heart against gravity

Question 4

describe a large (muscular) vein

Answer 4

• tunica media: circularly arranged smooth muscles + CT
• t. adventitia: longitudinal smooth muscle bundles
  
  • allows for continuous milking of blood towards the heart against gravity

Question 5

describe hypertension

Answer 5

• can cause damage to smaller blood vessels by scarring, hardening, narrowing of blood vessels and eventually become less elastic
• 3 characteristic changes in muscular artery:
  
  • symmetrical hypertrophy of the muscular t. media
  • extensive reduplication of the internal elastic lamina
  • fibrotic thickening of the t. intima
• all changes lead to reduction in diameter of the lumen

Question 6

describe atherosclerosis

Answer 6

• lesions of the t. intima called atheroma (or fibro fatty plaques) that protrude into and obstruct the vascular lumen
  
  • also weakening of the underlying t. media