Lecture 4: CV Pathophysiology II Flashcards
(44 cards)
CO = ?
HR * SV
What is a normal MAP?
100 mmHg
factors that increase heartrate
positive chronotropic effect
factors that decrease heartrate
negative chronotropic effect
factors that increase contractility
positive inotropic effect
factors that decrease contractility
negative inotropic effect
increased EDV leads to increased SV
Frank-Sterling mechanism
stretching of muscle cells allows more actin/myosin cross bridges to form, causing more tension and increasing contractility
length-tension relationship
the degree of stretch of the muscle prior to contraction
preload
What does increasing EDV do to the preload?
increases it
What does hypertension do the contractility and SV?
decreases both (heart must pump against higher arterial pressure)
the load that the heart must pump against
afterload
Which receptors monitor BP?
venous, atrial, and arterial baroreceptors
What are some problems that can arise with the electrical system of the heart?
- SA node irregularities
- AV blocks
- abnormal activation of SNS or PNS
- atrial fibrillation
What are some problems that can arise with the cardiac muscle of the heart?
- unable to relax or expand
- unable to generate sufficient force to eject blood
What are some of the problems that can arise with venous return (preload)?
- central venous pressure too low due to abnormal vasodilation
- low blood volume
- high blood volume (kidney reacting to heart failure)
What are some of the problems that can arise with afterload?
- stiffening of large arteries with age (arteriosclerosis)
- increase in resistance in smaller arteries
How does the filtrate in the glomerulus compare to plasma?
its much lower in concentration of proteins
What are some factors that alter GFR?
- changes in MAP
- contraction of renal arteries
How does contraction of afferent and efferent arterioles affect GFR?
- contraction of AFFERENT decreases GFR by decreasing pressure
- contraction of EFFERENT increases GFR by increasing pressure
when the macula densa cells in the nephron detect a change in Na+/Cl- levels and triggers vasodilation/vasoconstriction of the afferent arteriole to compensate
tubuloglomerular feedback
Describe the differences of sodium and water reabsorption across the nephron.
proximal tubule - 65-75% of sodium reabsorbed; water follows
loop of Henle - 15-20% of sodium reabsorbed (only sodium)
distal tubule - variable; controlled by aldosterone and ADH
What are the most important sensors of BP?
- carotid baroreceptors
- juxtaglomerular apparatus
- macula densa
What is the pathway for renin?
juxtaglomerular apparatus –> renin + angiotensinogen (from liver) –> angiotensin I + ACE (on endothelial cells) –> angiotensin II