Chapter 11: Blood vessels

Question 1

Which two underlying mechanisms is the basis of all vascular diseases?

Answer 1

1) Narrowing (stenosis)

2) Weakening of vessel walls

Question 2

Which three layers does blood vessels consist of?

Answer 2

1) the intima - a single layer of endothelial cells plus basement membrane and underlying thin layer of ECM. The internal elastic membrane separates this from media.
2) The media - Smooth muscle layers - more in arteries than in veins. A lot of elastin in elastic arteries.
3) the adventitia - separated from the media by external elastic lamina. Loose connective tissue with nerve fibers and blood supply.

Question 3

arteries on a scale:

Answer 3

1) elastic eg aorta
2) muscular arteries
3) arterioles

Question 4

What is intimal thickening?

Answer 4

When vascular injury induces smooth muscle cells to divide and ECM to increase causing a thickening of the vessel wall in the intima - dependent on endothelial cells in the intima.

Question 5

What is renin?

Answer 5

Proteolytic enzyme, secreted by juxtaglomerualr cells in the liver when: 1) low BP in afferent arteriole 2) high amount of cathecolamines. Cleaves plasma angiotensin to angiotensin 1. This is celaved by ACE to angiotensin II. This increases vascular contraction, stimulates Na resorption and increases aldosterone production.

Question 6

Causes of secondary hypertension:

Answer 6

1) renovascualr hypertension - caused by occlusion of renal arterioles - aldosterone production increases.
2) genes involved in sodium reseorption or aldosterone breakdown or synthesis.

Question 7

What is the difference between secondary and essential hypertension?

Answer 7

Secondary has a defineable source while essential has not.

Question 8

Causes of essential hypertension:

Answer 8

1) genetic factors
2) Reduced renal sodium secretion
3) Vasoconstrictive influences
4) environmental factors.

Question 9

What is arteriosclerosis?

Answer 9

Hardening of arteries - all arteries.

Question 10

What are the different forms of arteriosclerosis?

Answer 10

1) arteriolosclerosis - in arterioles and capillaries.
2) monckberg medial sclerosis - calcification of medial muscular layer in muscular arteries.
3) atherosclerosis.

Question 11

Name some of the risk nonmodifiable factors for atherosclerosis:

Answer 11

1) Genetic
2) Age - older is worse
3) Gender - men are worse off (before menopause)

Question 12

Name some of the modifiable risk factors for atherosclerosis:

Answer 12

1) Hyperlipidemia (hypercholesterolemia)
2) Hypertension
3) cigarette smoking
4) Diabetes mellitus

(Others)

5) inflammation (C-reactive protein in particular)
6) increased levels of homecysteine in the serum
7) metabolic disorder
8) lipoprotein a
9) Factors affect hemostasis

Question 13

Describe the pathogenesis of atherosclerosis:

Answer 13

1) endothelial injury
2) accumulation of lipoproteins
3) Monocyte adhesion to epithelium
4) platelet adhesion
5) factor release
6) Smooth muscle cell proliferation, ECM making and recruitment of t-cells
7) Lipid accumulation

Question 14

What are the two most important underlying reasons for endothelial injury?

Answer 14

1) Hemodynamic disturbances - turbular flow - laminar flow leads to gene expression which is supressing.
2) increased LDL, decreased HDL, increased lipoprotein a

Question 15

How does inflammation affect atherosclerosis?

Answer 15

Cholesterol is recognized as foreign antigen and leads to macrophage and lymphocyte activation and recruitment.

Macrophages secrete ROS whicch further activates LDL-cholesterol as well as growth factors promoting smooth muscle cell growt etc.

Question 16

What are fatty streaks?

Answer 16

streaks which starts small and become around 1 cm long. They are made up of lipid filled foamy macrophages.

Question 17

Features that are responsible for clinical manifestations:

Answer 17

1) stenosis can occlude vessel lumen and prevent nutrients and oxygen
2) Acute plaque change (rupture, erosion, hemorrage)
3) thrombosis
4) vasoconstriction

Question 18

What is an aneurysm?

Answer 18

A local abnormal dilation of the blod vessel.

Question 19

What is the general pathogenesis of an aneurysm?

Answer 19

When the structure or integrity of the connective tissue in the vessels get compromised.

Question 20

What are some of the major causes of aneurysm pathogenesis?

Answer 20

1) poor quality of connective tissue (eg marfans syndrome)
2) Inflammation alters equilibrium of collagen synthesis/degradation eg MMPs.
3) Vascular wall is weakened by lack of smooth muscle cells (eg lack of oxygen as a product of lack of oxygen)

The two most important are hypertension and atherosclerosis.

Question 21

What is an AAA?

Answer 21

Aortic abdominal aneurysm. Mostly from atherosclerosis.

Question 22

What is an aortic dissection?

Answer 22

Blood fills the media as a result of a weakening of the aortic vessel wall. Almost always from hypertension.