Cardiovascular System - Fung Flashcards
What are the layers of a blood vessel?
- the tunica intima
- the tunica media
- the tunica adventitia
How are the layers of a blood vessel related to the heart?
The major blood vessels that connect to the heart are continuous with the heart.
- the intima becomes endocardium
- the media is made up of cardiac myocytes
- the adventitia becomes epicardium
What two characteristics of the heart are most important in heart pathology?
- cardiac weight
2. ventricular wall thickness
What is the average weight of a female heart?
250-300 grams
What is the average weight of a male heart?
300-350 grams
What is the typical thickness of the ventricular wall in females?
0.3-0.5 cm
What is the typical thickness of the ventricular wall in males?
1.3-1.5 cm
How is cardiac muscle different from striated muscle?
It has centrally located nuclei.
Describe the functions of vascular endothelial cells?
- maintain non-thrombogenic blood-tissue interface
- modulate vascular resistance
- metabolize hormones
- regulate inflammation
- regulate cell growth
Describe the function of smooth vascular smooth muscle cells?
- synthesize collagen, elastin and proteoglycans
2. produce growth factors and cytokines
What are the components of of vascular extracellular matrix?
- elastin
- collagen
- gycosaminoglycans
What are the two types of arteries?
- elastic arteries
2. muscular arteries
What layer of vasculature contain smooth muscle cells?
The tunica media
Which cells of vasculature are responsible for homeostasis of the vessel?
The endothelial cells.
Does an artery have more smooth muscle in it’s tunica media?
Yes. Arteries have to work under higher pressure than veins.
What is the vasa vasorum and why do we need it?
The vasa vasorum are tiny blood vessels that supply other larger vessels. We need them because nutrients and oxygen can only diffuse so far. The vasa vasorum supplies part of the tunica media and the tunica adventitia.
Which types of vessels have more elastic tissue?
Elastic arteries.
Do muscular arteries have elastic tissue?
Yes. They have elastic tissue in the internal and external elastic lamina. They have less elastic tissue than elastic arteries.
Give a couple examples of elastic arteries.
- aorta
2. common carotids
Give a couple examples of muscular arteries.
- radial artery
2. femoral artery
What are the two types of vascular systems?
- blood vascular system
2. lymph vascular system
Do lymph vessels have muscular walls?
No. Lymph moves due to contraction of surrounding muscle.
Where does gas and nutrient exchange take place?
Capillaries.
Veins are not very muscular. How do they get blood back to the heart?
Contraction of skeletal muscle helps blood flow back to heart and one way valves keep the blood from flowing backwards.
Most cardiovascular disease results from….?
“a complex interplay of genetics and environmental factors that disrupt networks of genes and signaling pathways that control morphogenesis, myocyte survival and response to injury, biochemical stress responses, contractility or electrical conduction”
What are the six mechanisms of cardiac dysfunction?
- failure of pump
- obstruction of flow
- regurgitant flow
- shunted flow
- disorders of cardiac conduction
- rupture of the heart or a major blood vessel
Cardiovascular disease is most commonly related to what?
Atherosclerosis.
Describe the stereotypical response of blood vessels to injury.
- recruitment of smooth muscle cells or smooth muscle precursor cells to the tunica intima
- smooth muscle cells undergo mitosis and proliferation
- elaboration of smooth muscle cell extracellular matrix
- inflammation
Endothelial cell loss or dysfunction does what…?
Stimulates smooth muscle cell growth and extracellular matrix synthesis leading to intimal thickening.
What is hypertension?
Sustained increased blood pressure associated with increased risks.
Sustained increased blood pressure is associated with risk of…?
- atherosclerosis
- hypertensive heart disease
- multi-infarct dementia
- aortic dissection
- renal failure
What is the normal blood pressure range?
less than 120/less than 80 mmHg
What is prehypertension?
Blood pressure between 120-139/ 80-89 mm Hg
What is the blood pressure range for hypertension?
greater than 140/greater than 89 mm Hg
What is the blood pressure range associated with malignant hypertension?
greater than 200/ greater than 120 mm Hg
What are some broad categories of causes of essential hypertension?
- single gene defects
- polymorphisms
- vascular - vasoconstricion, structural changes
- environmental factors
Single gene defects that cause essential hypertension are usually involved in what functions?
- aldosterone
- metabolism
- sodium reabsorption
Polymorphisms associated with essential hypertension are usually involved with what systems?
- angiotensinogen locus
- angiotensin receptor locus
- renin-angiotensin system
What are some environmental factors associated with essential hypertension?
- diet
- stress
- obesity
- smoking
- physical inactivity
Most commonly, the cause of essential hypertension is what?
Idiopathic
What are systems that if effected could cause secondary hypertension?
- renal system
- endocrine system
- cardiovascular system
- neurologic system
What kinds of conditions affecting the renal system could lead to secondary hypertension?
- acute glomerulonephritis
- chronic renal disease
- polycystic disease
- renal artery stenosis
- renal vasculitis
- renin-producing tumors
What kinds of conditions affecting the endocrine system could lead to secondary hypertension?
- adrenocortical dysfunction
- exogenous hormones
- pheochromocytoma
- acromegaly
- hypothyroidism
- hyperthyroidism
- pregnancy-induced
What kinds of conditions affecting the cardiovascular system can lead to secondary hypertension?
- coarctation of the aorta
- polyarteritis nodosa
- increased vascular volume
- increased cardiac output
- rigidity of aorta
What kinds of conditions affecting the neurologic system can lead to secondary hypertension?
- psychogenic
- increased intracranial pressure
- sleep apnea
- acute stress
Hyperplastic arteriosclerosis is associated with what type of hypertension?
Malignant hypertension.
What are atheromas?
Raised lesions that protrude into a vessel lumen. They consist of a sod yellow core of lipid and are covered by a fibrous cap.
What does a fibrous cap consist of?
- smooth muscle cells
- macrophages
- foam cells
- lymphocytes
- collagen
- elastin
- proteoglycans
- they are also neovascularized
What does the necrotic center of an atheroma consist of?
- cell debris
- cholesterol crystals
- foam cells
- calcium
Atheromas can cause…..?
- obstruction of blood flow
- they can rupture and cause vessel thrombosis
- can lead to formation of an aneurysm
Does atherosclerosis start in childhood?
Yes.
What is one consequence of an atheroma?
Because they protrude out from the vessel wall and into the lumen, they increase the distance with which nutrients have to diffuse to get to the layers of the vessel wall.
What are the constitutional risk factors for atherosclerosis?
- age
- gender (male)
- genetics
What are the modifiable risk factors for atherosclerosis?
- hyperlipidemia
- hypertension
- smoking
- diabetes
What are some other risk factors for atherosclerosis?
- inflammation
- hyperhomocysteinemia
- metabolic syndrome
- Lipoprotein A
- hemostatic factors
- sedentary life style
- Type A personality/stress
- obesity
What is the response to injury hypothesis of athersclerosis?
This theory states that atherosclerosis is a chronic inflammatory and healing response to arterial wall and endothelial injury.
What are the steps leading to atherosclerosis according to the injury response hypothesis?
- endothelial injury
- lipoprotein accumulation
- monocyte adhesion and formation of foam cells
- platelet adhesion
- smooth muscle cell recruitment
- smooth muscle cell proliferation and ECM production
- lipid accumulation
What are the two main causes of endothelial injury?
- hemodynamic disturbances
2. hyperlipidemia
What are some ways that endothelium can be injured?
- mechanical denudation
- immune complex deposition
- irradiation
- chemicals
What are some things that can cause endothelial dysfunction?
- hemodynamic disturbances
- hypercholesterolemia
- hypertension
- smoking
- infectious agents
- homocysteine
Where do atherosclerotic plaques tend to occur?
At areas of disturbed blood flow or areas of hemodynamic disturbance. Including - branch points, ostia of exiting vessels, and the posterior wall of the abdominal aorta.
What type of blood flow is protective against atherosclerosis?
Non-turbulent, laminar flow.
What are the dominant types of lipids in atherosclerotic plaques?
- cholesterol
2. cholesterol esters
Describe the relationship between lipids and atherosclerosis.
- Genetic hyperlipoproteinemia is associated with accelerated atherosclerosis
- DM and hypothyroidism is associated with hypercholesterolemia
- Lowering serum cholesterol slows the rate of atherosclerosis
What affect does lipid accumulation have on vessels?
It reduces their ability to dilate. Hyperlipidemia increases ROS production which then accelerates decay of nitric oxide so that vessels cannot vasodilate very well.
Lipid accumulation increases the production of what type of cells?
Foam cells. The ROS’s oxidize LDL which is then ingested by macrophages through a scavenger receptor. Also, oxidized LDL increases release of growth factors, cytokines and chemokines that lead to monocyte recruitment.
LDL is cytotoxic to what?
Endothelial cells and smooth muscle cells of the vessel wall. This injures the endothelium and leads to plaque formation.
Atherosclerotic lesions cause what?
Chronic inflammation with T-cell proliferation. It also leads to release of chemokines and growth factors that promote smooth muscle cell proliferation and ECM synthesis.
What are the major consequences of atherosclerosis?
- MI
- cerebral infarction
- aortic aneurysm
- peripheral vascular disease
Atheroma’s project into the lumen of a vessels and cause….?
Stenosis.
What percentage of stenosis of a vessel is critical and causes chronically decreased perfusion?
70%
Chronically decreased perfusion leads to…..?
- bowel ischemia
- chronic ischemic heart disease
- ischemic encephalopathy
- intermittent claudication
Unstable atherosclerotic plaques can undergo what changes?
- they can rupture, fissure, erode or ulcerate
- if any of the above happen then thrombogenic plaque contents or the thrombogenic sub endothelial basement membrane is exposed to blood and can lead to thrombus formation
- plaques can also hemorrhage
Describe the progression of atherosclerosis.
Pre-clinical phase - usually younger age:
1. lesion prone areas start to form fatty streaks or undergo endothelial injury or dysfunction
2. endothelial injury/dysfunction leads to formation of plaques
3. over time plaques remodel and grow and may become unstable
Clinical phase - usually middle age to elderly:
1. plaques/atheroma’s begin to cause clinical symptoms
2. They can cause thrombosis, emboli and vessel wall weakening leading to aneurysm and rupture
3. atheroma’s can rupture, erode, hemorrhage leading to thrombus formation and occlusion
4. atheroma’s can grow and cause critical stenosis
Describe ischemic heart disease.
This term is a generic designation for a group of pathologically related syndromes resulting from myocardial ischemia.
What is myocardial ischemia?
An imbalance between the supply and demand of the heart for oxygenated blood.
Ischemic heart disease is also called what?
Coronary artery disease.
Ischemic heart disease results from what?
- a greater than 90% obstructive atherosclerotic lesion in the coronary arteries
- coronary emboli
- blockage of coronary arteries
- severe hypotension
What are some results of ischemic heart disease?
- tachycardia
- myocardial hypertrophy
- hypoxemia
Name some ischemic heart diseases?
- angina pectoris
- MI
- chronic ischemic heart disease with heart failure
- sudden cardiac death (usually due to arrythmias)
Describe angina pectoris.
- Paroxysmal and recurrent attacks of substernal and precordial chest discomfort
- Caused by transient myocardial ischemia that falls short of inducing myocyte necrosis
What are the variants of angina pectoris?
- stable (most common)
- prinzmetal
- unstable (crescendo)