Week 10: Cardiovascular Flashcards
What are the two laws that describe the resistance and pressure gradient needed for the CV system to function?
Ohm’s law: pressure gradient
Poiseuille’s law: resistance
What is the most important variable that determines the flow of the CV system?
radius of the blood vessels
How do you calculate: stroke volume, cardiac output, ejection fraction and MAP?
Stroke volume = EDV - ESV
Cardiac output = HR x SV
Ejection fraction = SV/EDV
MAP = CO x TPR
Define edema, what are the major causes (4)
accumulation of excess fluid in the interstitial space
Causes:
Heart failure: increased hydrostatic pressure as fluid accumulates from fluid backup
Increased hydrostatic pressure: increased arterial or venous pressure or arterial dilation
Decreased osmotic pressure: decreased plasma proteins or increased permeability to proteins
Obstruction: lymph failure
What is the role of the lymphatic system (3)
- function to maintain BV
- important in defense and fat absorption
- Return excess fluid from the interstitium to the circulatory system through vein-like vessels
Define lymphedema
excessive accumulation of lymph due to damaged or obstructed lymph vessels
Define acute lymphangitis
acute inflammation of lymph vessels; lymphadenitis if nodes are involved
What is the role of the venous system? What is important to maintain venous return?
- return blood to the heart through low-resistance blood conduits
- maintain blood pressure
How do: sympathetic stimulation; skeletal muscle pump; and respiratory pump help maintain venous return?
Sympathetic stimulation: contracts smooth muscle to raise venous pressure
Skeletal muscle pump: muscle contraction constricts veins and raises venous pressure
Respiratory pump: during inspiration, thoracic cavity expands, reducing pressure in the R atrium at the same time that abdominal pressure increases, helping generate a pressure gradient to drive blood return to the heart
How does digitalis work to help with CV function?
inhibits Na-K-ATPase, increased NA to exchange with Ca2 - increases intracellular Ca2
Strengthens contractions
How does nitroglycerin work to help with CV function?
increases vasodilation and increases blood flow to the heart
How do calcium channel blockers work to help with CV function?
disrupt the movement of calcium through calcium channels, relaxes blood vessels
How do beta-adrenergic antagonists work to help with CV function?
Reduces myocardial oxygen demands + Increase ventricular filling by relaxing the obstructing muscle. Reduces contractility and heart rate
How do ACE inhibitors work to help with CV function?
reduce afterload through vasodilation, by blocking the formation of Angiotensin II
How do diuretics work to help with CV function?
reduce fluid retention
Define hyperlipidemia, what is an associated disease that increases r/f CVD?
- lipids collect in the blood normally transported by proteins
- atherosclerosis
Which form of hyperlipidemia may have a genetic basis? Which form is associated with lifestyle choices - obesity, sedentary lifestyle, etc.?
- primary
2. secondary
Chylomicrons: percentage of triglycerides/protein; where are they synthesized?
80-90% triglycerides, very little protein 2%
Synthesized in small intestine as part of fat reabsorption process
Very-low density lipoproteins (VLDL): percentage of triglycerides/cholesterol/protein
55-65% triglycerides, 10% cholesterol and 5-10% protein
Low-density lipoproteins (LDL): percentage of triglycerides/cholesterol/protein; what is this the main carrier of?
Is this considered “good” or “bad” cholesterol?
- 10% triglycerides, 50% cholesterol, 25% protein
- Cholesterol
- Bad as it carries more cholesterol
High-density lipoproteins (LDL): percentage of triglycerides/cholesterol/protein; What is the major role of this lipoprotein?
Is this considered “good” or “bad” cholesterol?
- 5% triglycerides, 20% cholesterol, 50% protein
- reverse carrier, brings cholesterol from tissues to liver, allows body to recycle cholesterol
- Good cholesterol - carries less cholesterol
Where are LDL/HDL synthesized and released?
Liver
Ideal levels of LDL, HDL, total cholesterol, triglycerides
What level does LDL get to to be classified as hypercholesterolemia?
LDL < 100mg/dL HDL > 40-60 mg/dL Total cholesterol < 200mg/dL Triglycerides < 10-150mg/dL Hypocholesteremia = LDL 70-130mg/dL
How do the following agents help lower lipids: Statins, sequestrants, absorption inhibitors, fibrates, niacin/nicotinic acid, omega-3 supplements
Statins: prevent liver from manufacturing cholesterol
Sequestrants: prevent body from absorbing cholesterol
absorption inhibitors: limit body’s absorption of cholesterol
Fibrates: decrease synthesis of VLDL by liver, stimulate triglyceride clearance
Niacin/nicotinic acid: blocks synthesis and release of VLDLs from liver, reduces VLDL and LDL level, increase HDL concentrations
omega-3 supplements: decreases rate at which the liver synthesizes triglycerides
Define atherosclerosis, risk factors, patho, consequences on CV function
series of arterial disorders that have degenerative changes in arteries, leading to a decrease in blood flow through blood vessels
Key risk factors: hypercholesteremia, hypertension, smoking (nicotine promotes vasoconstriction), obesity, diabetes (sugar attach to proteins that are associated with changes), sedentary lifestyle
Pathogenesis: deposition of lipids leads to decrease in radius, eventual occlusion of blood flow and hypertrophy of vessels, loss of elasticity
Consequences on CV function: CAD, TIAs, CVAs, renal stenosis, arterial occlusive disease
Define aneurysm, where do they typically form? Risk factors, major concern
- change in dilation of blood vessel wall, can lead to rupture and bleeding
- aorta
- Underlying risk factors: congenital defects, trauma, infection, atherosclerosis that leads to hypertension
- Major concern: massive blood loss particularly if aneurysm present in a large vessel