Fung: Cardiovascular System Flashcards
Which ventricle is thicker, right or left?
left ventricle
**1.3-1.5cm vs 0.3-0.5cm (right ventricle)
T/F: Males’ hearts have greater mass than female hearts by about 50gm
True
Describe the three layers of the heart tissue
- Intima (endocardium lined by endothelial cells)
- media (myocardium made up of smooth muscle cells)
- adventitia (epicardium)
What are some features of cardiac muscle?
striated
centrally located nuclei
intercalated discs
Describe blood flow through the heart beginning with deoxygenated blood entering the right atrium via the superior vena cava.
superior vena cava –> right atrium –> tricuspid valve –> right ventricle –> pulmonary circulation (picks up O2) –> enters left atrium –> through mitral valve to left ventricle –> out the aortic valve and aorta to the systemic circulation
What connects the papillary muscles to the mitral and tricuspid valves?
chordae tendinae
Describe the pathway of electrical conduction through the heart
SA node –> AV node –> Bundle of HIS –> Purkinje fibers
Which arteries are responsible for supplying blood to the heart tissue itself?
the right and left coronary arteries come off of the aorta to supply the cardiac tissue with nutrients; the left coronary artery divides immediately into the left circumflex artery and the left anterior descending artery. The right coronary artery does not divide immediately, but then does diverge into the right marginal artery and the posterior descending artery
What are the three main components of vascular structure?
endothelial cells
smooth muscle cells
extracellular matrix
What are some functions of the vascular endothelial cells?
maintain non-thrombotic state modulate vascular resistance metabolize hormones regulate inflammation regulate cell growth
What are some functions of vascular smooth muscle cells?
proliferate when stimulated
synthesize collagen, elastin, proteoglycans
increase growth factors and cytokines
What makes up the extracellular matrix of the blood vessels?
elastin
collagen
GAGs
In which vessels, arteries or veins, is there a thicker media layer?
arteries handle blood under a lot more pressure, so they have a much thicker media
In what layer of the blood vessel is the vasa vasorum located? What does it do?
in the adventitia - it’s the blood supply for the blood vessels themselves
How are muscular arteries different from elastic arteries?
muscular arteries have less elastin and require less recoil; muscular arteries have an internal (between intima and media) and external elastic lamina (between media and adventitia)
How do veins differ from arteries?
they are not as thick (thinner media)
they move blood via contraction of skeletal muscle
contain valves
no adventitia
Three types of arteries?
elastic arteries (ex: aorta, brachiocephalic) muscular arteries (ex: radial, femoral) arterioles
Cadiovascular disease can be caused by six different mechanisms. Name as many as you can.
failure of the pump obstruction to flow regurgitant flow shunted flow disorders of cardiac conduction rupture of heart or major blood vessel
The stereotypical response in cardiovascular disease involves loss or dysfunction of (blank) which stimulates (blank) cell growth and ECM deposition leading to (blank)
endothelial cells; smooth muscle cells; intimal thickening
Explain how the juxtaglomerular apparatus of the kidney regulates blood pressure
The juxtaglomerular apparatus is located near the renal glomerulus; it senses how much blood is passing through the kidney. When it senses low blood pressure, the kidney releases RENIN. Renin causes angiotensinogen to be converted to angiotensin I in the liver. Ang I is converted to Ang II in the lungs, which causes the adrenal gland to release aldosterone. Aldosterone causes increased resorption of Na+ which increases blood volume.
What is released from the heart in response to high blood pressure?
atrial natriuretic peptide
What is normal blood pressure? What BP, systolic and diastolic, is considered prehypertension? What BP is considered malignant hypertension?
120/80mgHg
120/80 - 140/90mgHg
200/120mmHg
What is essential hypertension? What can cause it?
hypertension with no real known cause; 90% of HTN is essential hypertension
single gene defects, polymorphisms, vascular problems (structural changes), environmental factors (obesity, stress, diet)
10% of hypertension is secondary hypertension. What kinds of things can cause secondary hypertension?
renal disease (renal artery stenosis)
endocrine problems
cardiovascular problems
neurologic problems
What is hyaline arteriosclerosis? In what disease state does it occur?
Hyaline arteriosclerosis occurs in essential benign hypertension and diabetes. It is the deposition of protein into the vessel walls of arterioles, which creates pink hyaline. Causes end organ ischemia, glomerular scarring, and can cause chronic renal failure when it presents around the arterioles in the kidney.
What is hyperplastic arteriosclerosis? What disease state is it associated with?
Hyperplastic arteriosclerosis is associated with malignant hypertension. It is the proliferation of smooth muscle cells around the arterioles, especially those of the kidney. Forms onion-like appearance.
**Can cause end organ ischemia.
Causes flea-bitten appearance of kidney.
What makes up an atheroma? What can happen when atheromas protrude into the vessel lumen?
So, an atheroma is a mass or plaque of degenerative tissue in the tunica intima of blood vessels; obstruction of blood flow, rupture of vessel wall, formation of aneurysm
Consist of raised lesions with a soft, yellow, core of lipid covered with a fibrous cap
atherosclerotic plaque
What are two main causes of endothelial dysfunction leading to atherosclerosis?
- hemodynamic disturbances - plaques occur in areas of disturbed, turbulent flow, like ostia of exiting vessels or branch points of vessles
- hyperlipidemia - most plaques are made up of cholesterol and cholesterol esters; lowering serum cholesterol can decrease rate of atherosclerosis
What happens to smooth muscle cells in the media during arthersclerosis?
these cells migrate into the intima and begin proliferating due to chemokines and growth factors produces
What are some non-modifiable risks for atherosclerosis?
What are some modifiable risks?
age gender (females more protected) genetics (ex: familial hypercholesterolemia); hyperlipidemia hypertension smokers diabetes
a chronic inflammatory and healing response to arterial wall and endothelial injury
atherosclerosis
List some of the pathologic events in formation of atheromas
endothelial injury
lipid accumulation in intima
monocyte adhesion and formation of foam cells (LDL eaten by macrophages)
smooth muscle cell recruitment to intima
smooth muscle cell proliferation, and ECM deposition
How does a fatty streak become an atheroma?
endothelial cell injury, lipids accumulate, lipids are oxidized and eaten by macrophages to form foam cells, T cell recruited, smooth muscle cells also recruited, ECM deposited, etc.
Becomes a mature atheroma when it develops a fibrous cap.
What are some major consequences of atherosclerosis?
Myocardial infarction (plaque rupture with thrombosis)
Cerebral infarction
Aortic aneurysms (weakening of vessel wall)
Stenosis of medium sized vessels –> Peripheral vascular disease (claudication), angina, ischemic bowel disease
How do atheromas evolve?
they undergo acute plaque changes; for example, an atheroma with a weak fibrous cap can rupture and release its thrombogenic contents. Or, the atheromas can grow so much that they almost completely occlude the vessel
an imbalance between the supply and demand of the heart for oxygenated blood; frequently referred to as coronary artery disease
myocardial ischemia
What causes ischemic heart disease?
> 90% obstructive atherosclerotic lesions in the coronary arteries
coronary emoboli
blockage of coronary arteries
severe hypotension
Paroxysmal and recurrent attacks of substernal and precordial chest discomfort
Caused by transient myocardial ischemia that falls short of inducing myocyte necrosis
angina pectoris
What is stable angina? What causes it? What can relieve this type of angina?
it is chest pain following physical activity, emotional excitement, or increased cardiac workload; it is caused by an imbalance or perfusion relative to oxygen demand; relieved by rest or vasodilators
What causes prinzmetal angina? What can relieve this type of angina?
coronary artery spasm that is NOT related to physical activity, heart rate, or blood pressure
ex: cocaine abuse
can be relieved by vasodilators or Ca+ channel blockers
What is unstable angina? What is it caused by?
a pattern of increasingly frequent pain of prolonged duration that occurs even a low levels of activity or at rest; caused by acute plaque change with superimposed thrombosis/embolism or vasospasm
This type of angina is seen in artery occlusion of 90% or greater and is a warning sign of impending acute MI
unstable angina
Death of cardiac muscle due to prolonged severe ischemia
myocardial infarction
What is the typical sequence of an MI? What happens first?
acute change of an atheromatous plaque exposes the thrombogenic contents; platelets adhere to the exposed plaque and degranulate; tissue factor activates the coag cascade which adds to the bulk of the thrombus; eventually, the thrombus completely occludes the lumen of the vessel
What are some things that can cause an MI NOT related to coronary vascular pathology?
vasospasm due to cocaine or platelets aggregating
emboli
ischemia without atherosclerosis or thrombus formation (ex: vasculitis, severe hypotension or amyloid deposition)
How long is heart tissue viable after an MI? In other words, what is the time period for “reversible injury” during an MI?
for 20-30 minutes of ischemia, the injury is reversible; after this time period, myocytes begin necrosing and necrosis will be complete within 6 hours
Myocardial ischemia proceeds from the (blank) outward
endocardium
Necrosis involves the full thickness
Associated with chronic atherosclerosis, acute plaque change
ST elevation infarcts
transmural infarction
Necrosis limited to inner 1/3 of ventricular wall
Due to any reduction in coronary flow
Non-ST elevation infarcts
subendocardial infarction
If the left anterior descending artery is occluded, which portions of the heart may become ischemic?
apex
anterior wall of left ventricle
anterior 2/3 of ventricular septum
If the right coronary artery is occluded, what portions of the heart may become ischemic?
posterior 1/3 of septum
right ventricle wall
posterobasal wall of left ventricle