Lecture 9 Cardiovascular Flashcards
what causes blood to move throughout the circulatory system
- pressure differences throughout the circulatory system
- pressure higher in aorta and decreases to almost 0 in vena cava
2 parts of the heart
- right = pulmonary, left = systemic
4 chambers of the heat and general role
2 atria that receive blood
2 ventricle that pump blood out of heart
- left atria receives unoxygenated blood
- left ventricle pumps blood to lungs / pulmonary circulation
- right atria receives oxygenated blood from lungs
- right ventricle pumps oxygenated blood to the body
2 types of valves, total of 4 valves
- AV = atrioventricular - connects atria and ventricles
- semilunar = goes from ventricles to arteries
- AV = tricuspid in right heart and bicuspid aka mitral in left heart
- semilunar = pulmonary valve in right heart and aortic valve in left heart
part of heart that separates chambers
fibrous skeleton
- atria attached on top and ventricles attached to the bottom
venous return meaning
unoxygenated blood that is returning to the heart through the superior and inferior vena cava
describe flow of blood through the circulatory system (entire flow)
vena cava –> right atria –> tricuspid valve –> right ventricle –> pulmonary valve –> pulmonary arteries –> lungs and pulmonary capillaries and alveoli –> gas exchange and oxygenation –> pulmonary veins –> left atria –> mitral valve –> left ventricle –> aortic valve
describe the relationship between resistance, pressure, and radius of the lumen
- smaller radius –> increased resistance and pressure
- blood has to work harder if pressure and resistance are high
which ventricle does more work and why
- left ventricle works harder because blood pressure in systemic circulation is higher than that of pulmonary circulation
describe how hypertension can lead to congestive heart failure
hypertension –> increased system blood pressure –> left ventricle has to work harder –> thickening of left ventricle heart muscle –> cavity of left ventricle becomes smaller –> not enough blood being pumped
effect of exercise on cardiovascular system (blood pressure)
- decreased systemic bp so heart doesnt have to work as hard
eversion aka prolapsing of valves
- valves flip out the opposite way
what causes valves to open
changes in blood pressure
- when bp is higher downstream then upstream valves open
papillary muscle
prevent valves from prolapsing
chorda tendinea
tendons that connect valves and papillary muscle
3 names for valves that can become prolapsed
regurgitative, incompetent, insufficient
systole vs diastole
systole = contraction of ventricles diastole = relaxation of ventricles
end diastolic volume
volume in ventricles after relaxation when it fills with blood
end systolic volume
volume in ventricle after contraction when blood gets pushed out
stroke volume and 2 representations
end diastolic volume - end systolic volume
- how much blood as ejected
- percent = amount ejected / end diastolic volume
isovolumteric contraction
- ventricles are contraction and AV valve is closed but semilunar valves have not yet opened
- no change in volume
isovolumetric relaxation
- semilunar valves have closed and AV valves are still closed but are about to open
- ventricles are relaxing
describe flow / 5 parts of the heart beat
1 = isovolumetric contraction - ventricles being to contract and pressure rises but semilunar valves not yet open 2 = ventricle contraction and semilunar valves open = blood is ejected 3 = isovolumetric relaxation - AV and semilunar valves are closed, ventricles are relaxed 4 = passive filling of ventricles due to pressure differences 5 = atria contract to fill ventricles
what causes sounds of the heart
lub = closing of AV valves dub = closing of semilunar valves
heart murmur definition
- abnormal heart sounds caused by abnormal flow of blood in heart
2 causes of heart murmurs (just list them)
- congenital = born with
- rheumatic fever
rheumatic fever
- antibodies made in response to strep end up binding to valves and causing autoimmune response
systolic vs diastolic murmur and sound order
systolic = lub shhh dub diastolic = lub dub shhh
mitral valve prolapse - what type of murmur
- mitral valves evert/prolapse when closed
- systolic because mitral/AV valves are closed during ventricle contraction
mitral stenosis - meaning and what type of murmur
- calcification of valves preventing them from opening fully
- diastolic because AV / mitral valve open during ventricle relaxation when it is filling with blood
septum description
separates right and left heart, thicker between ventricles
congenital septal defect
hole in the septum, may close after birth but if not causes shunting of blood from one side of heart to the other
gap junctions of myocardial cells
allow electricity to pass from one cell to another
can electrical activity pass from chamber to chamber directly? why?
no! due to fibrous skeleton and septum
pacemaker cells
cells that can generate their own AP
HCN channels - what type, where found, when open, and meaning of HCN
Na+ VGIC channels
- found in pacemaker cells only
- H = hyperpolarization, CN = cAMP increases their frequency of AP
- open during hyperpolarization causing pacemaker potential and pacemaker cell to reach threshold
affect of sympathetic system on pacemaker cells (entire flow)
sympathetic –> epi/norepi from adrenal medulla –> bind to excitatory beta 1 adrenergic receptor –>
describe all stages of AP for pacemaker cells
Na+ entering HCN causes pacemaker potential a spontaneous graded depoalrization –> Ca2+ enters VGIC channels causing steep depolarization –> K+ exits cause steep repolarization and hyperpolarization –> HCN channels open
SA node - regular rate, location, and affect of parasympathetic
- 100 bpm
- right atria
- parasympathetic Ach onto M2 muscarinic receptors, K+ exit causes hyperpolarization and decrease in heart rate
atropine mechanism and effect on SA node
- M2 antagonist, decreases affect of parasympathetic on heart
- increases heart rate
AV node - normal rate, location
- 40-60 bpm
- right atria
- slower then SA node so never generates its own AP, always depolarized by the SA node
AV bundle - alternate name, function
- bundle of His
- brings AP from SA node and right atria down septum and to bottom of the heart
- splits off into left and right bundle branch and Purkinje fibers on the right
Purkinje fibers
- branch off from right bundle branch of AV bundle
- also has pacemaker cells 15-40 bpm
sinus rhythm
- heart rate is determined by SA node
ectopic pacemaker
heart rate is determined by some node other than SA - AV node or Purkinje fibers, abnormal
flow of electricity through heart
right atria –> left atria (both atria contract) –> travels down bundle of His to bottom of heart –> travels up heart and both ventricle contract while both atria relax (and repolarize)
EKG function
measure electrical activity fo the heart
P wave
atria depolarize
QRS complex
ventricle depolarize
T wave
ventricle repolarize
myocardial cell RMP
-90 (instead of -70)
plateau phase - what is it and what is the cause
Ca2+ entering cell makes absolute refractory period longer by keep cell depolarized for a longer period of time
importance of plateau phase / long refractory period
- gives heart contraction a chance to finish before next AP is generated
- if plateau phase was not present back to back AP could be generated and heart would not relax and refill with blood = tetany
excitation-contraction coupling meaning and flow
- excitation of heart muscles causes their contraction
- excitation / stimulus –> Ca2+ enters cells –> Ca2+ released from SR (storage inside cell) –> Ca2+ wave occurs –> Ca2+ binds to troponin and causes muscle contraction
caffeine effect on heart and mechanism
- inhibits the enzyme that breaks down cAMP
- mimics epi/norepi which increases cAMP and speed of HCN opening = increase in heart rate
sympathetic/sympathoadrenal and parasympathetic effect on pacemaker cells (2 flows)
- sympathoadrenal: epi/norepi from adrenal medulla –> beta 1 adrenergic receptors –> increase in cAMP –> HCN channels open faster –> increased heart rate
- parasympathetic: Ach onto M2 muscarinic –> K+ channels open and K+ exits causing hyperpolarization –> heart rate decreased
blood pressure in pulmonary circulation, aorta, and venous return
arterial = 100-120mmHg pulmonar = 15 mmHg venous = 0-10 mmHg
problem if pressure in pulmonary system was too high
if pressure too high blood would be squeezed out of capillaries and fill alveoli
passive vs active filling and percentages
- passive = AV valves open, pressure difference moves blood, 90% of filling
- active = atria contract, 10% of ventricle filling
pacemaker potential
spontaneous graded potential caused by HCN channels opening and Na+ entering
