Lecture 8

Question 1

Arteriosclerosis

Answer 1

Term used for a group of disorders all having in common a hardening and a loss of elasticity of arteries

Question 2

What are the 3 main disorders of arteriosclerosis?

Answer 2

• Atherosclerosis
• Mönckeberg’s medial calcification
• Arteriolosclerosis

Question 3

What is the general structure of blood vessels wall?

Answer 3

• Tunica Intima (thin innermost
  layer) - endothelium lines all vessels
• Tunica Media (thickest central layer)
• Tunica Adventitia (thin outermost layer)

Question 4

Atherosclerosis

Answer 4

• Greatest killer in Western world
• Disorder in tunica intima
• Condition where plaque, composed of fats, cholesterol and other substances, builds up in walls of arteries, leading to hardening and narrowing.

Question 5

What does atherosclerosis contribute to?

Answer 5

Development of:
- ischaemic heart
- cerebrovascular disease
- peripheral vascular disease

Question 6

What does atherosclerosis affect?

Answer 6

Large and medium-sized elastic arteries

Question 7

Risk factors of atherosclerosis:

Answer 7

Multifactorial
- Hypertension
- Smoking
- Diabetes mellitus
- Genetics
- High levels of blood lipids
- Male
- Age
- Insulin resistance
- Diet
- Obesity

Question 8

Classification of atherosclerosis

Answer 8

Type I: adaptive intimal thickening

Type II: fatty streak

Type III: transitional or intermediate lesions

Type IV: advanced plaques

Type V: fibroatheroma or atheroma with thick fibrous cap;

Type VI: complicated plaques with surface defects, and/or hematoma-haemorrhage, and/or thrombosis

Question 8

What is the initial cellular event in atherosclerosis?

Answer 8

Monocytes adhere to the arterial wall, migrate into the intima, and transform into macrophages.

Question 9

What happens after monocytes migrate into the intima in atherosclerosis?

Answer 9

Macrophages engulf lipoproteins, becoming foam cells, and smooth muscle cells migrate from the media to the intima.

Question 10

How do foam cells contribute to plaque formation?

Answer 10

Foam cells accumulate, forming fatty streaks that can evolve into more advanced plaques if hypercholesterolemia persists.

Question 11

What role do smooth muscle cells play in plaque maturation?

Answer 11

They proliferate, transform into myofibroblasts, and produce collagen and matrix, stabilizing the plaque.

Question 12

What are the two types of mature atheromatous plaques?

Answer 12

Solidly fibrotic plaques and plaques with a soft lipid core.

Question 13

What vascular changes occur around mature plaques?

Answer 13

New small blood vessels form around the plaque to supply nutrients.

Question 14

What vessels are affected in atherosclerosis?

Answer 14

• Descending thoracic and abdominal aorta
• Coronary arteries
• Femoral/popliteal arteries
• Internal carotid arteries
• Circle of willis

Question 15

Fate of Plaque atherosclerosis

Answer 15

The atheroma may eventually undergo one of four changes, which is called complicated atherosclerosis
1. Calcification
2. Cholesterol emboli
3. Superimposed thrombi
4. Haemorrhage

Question 16

Complicated atherosclerosis calcification

Answer 16

Plaques frequently undergo patchy or massive, and arteries are hardened.

This is known as dystrophic calcification as it occurs at
sites of chronic tissue damage.

Question 17

Complicated atherosclerosis cholesterol emboli

Answer 17

Expanding plaques may lead to overstretching and rupture of the fibrous cap (plaque roof) weakened by released hydrolytic enzymes from inflammatory cells,

Debris are discharge into the bloodstream

Question 18

Complicated Atherosclerosis superimposed thrombi

Answer 18

May develop, because platelets
readily adhere to exposed
thrombogenic lipid-rich material;

Further narrow the lumen and may cause complete blockage.

Question 19

Complicated atherosclerosis haemorrhage

Answer 19

Newly formed blood vessels around the plaque are relatively fragile and may rupture, leading to sudden plaque expansion and rupture

Question 20

Clinical effects of atherosclerosis - Intermittent ischaemic effects

Answer 20

A narrowing of arterial lumen -> reduced blood flow to their area of distribution. May present as:
- Angina pectoris
- Intermittent claudication
- Impairment of mental function

Question 21

Clinical effects of atherosclerosis - Thrombosis, embolism, infarction

Answer 21

Acute occlusion of vessels causes ischaemia and anoxia. May present as:
- Myocardial infarction
- Cerebral infarcts (stroke)
- Gangrene of limbs

Question 22

Clinical effects of atherosclerosis - Aneurysm

Answer 22

Weakend tunica media of arteries balloons outwards

Question 23

Causes of death in advanced atheroma

Answer 23

Most common:
- Myocardial infarction
- cerebral infarction

Less common:
- Rupture of aneurysms causing haemorrhage
- heart failure
- Gangrene

Question 24

Arteriosclerosis

Answer 24

- Most commonly associated with systemic hypertension - Also seen in elderly people with normal BP - affects arterioles and small arteries within many tissues

Question 25

What is hyaline arteriolosclerosis, and what causes it?

Answer 25

Caused by injury to the arteriole wall → thickening with smooth muscle cells and elastin. Vessel wall degenerates → fibrinoid necrosis → narrowed lumen. Arteriole wall becomes eosinophilic and amorphous → "hyaline arteriolosclerosis" (glass-like appearance). Ischemia from narrowed vessels leads to tissue degeneration.

Question 26

Types of arteriosclerosis

Answer 26

Either benign or malignant in nature

Question 27

Benign nephrosclerosis

Answer 27

Refers to the process of benign arteriolosclerosis involving the kidneys * Glomeruli, as well as arterioles, undergo progressive hyalinisation

Question 28

Malignant nephrosclerosis

Answer 28

* Seen in malignant hypertension *thickening of the walls * This triggers the renin-angiotensin pathway, with further narrowing of the vessels -> Impaired Renal function

Question 29

What is Monckeberg’s medial calcification, and who does it affect?

Answer 29

Idiopathic arterial disease affecting both males and females equally. Rare before age 50–55. Primarily involves medium-sized muscular arteries (e.g., femoral, tibial, ulnar, radial, coronary)

Question 30

What are the pathological changes seen in Monckeberg’s medial calcification?

Answer 30

Degeneration and necrosis of medial smooth muscle, followed by dystrophic calcification. Calcification forms plate-like deposits within the arterial wall. The tunica intima remains intact, and the lumen stays open, preventing ischemia unless atheroma is also present.

Question 31

What are the clinical features and vascular effects of Monckeberg’s medial calcification?

Answer 31

Affected arteries lose their ability to dilate and constrict effectively. Typically asymptomatic with minimal clinical signs. Ischemia only occurs if atheroma coexists.