cardiology physiology Flashcards
what will inhibition of COX 2 cause
platelet aggregation. allowing the reaction to happen causes physiological inhibition of aggregation
what are the precursor to RBCs and when will they be raised?
reticulocytes, raised in normocytic anaemias (lower in the other two) or haemolytic anaemia and in bleeding.
what will cause peripheral arteriodilation
CO2, hypoxia, adenosine, H+, ANP
what surrounds capillaries
pericytes
what do baroreceptors do?
quickly increase angiotensin levels when not stimulated, when stretched, they decrease angiotensin levels
list the stages in the cardiac cycle
diastole (atrial filling then ventricular contraction then diastase); atrial contraction; closing of mitral and tricuspid valves; isovolumic contraction; rapid then reduced ejection; closing of semilunar valves (2nd heart sound)
describe the route of blood in the foetal circulation
from placenta>umbilical vein>ductus venosus (some to liver)>right atrium>foramen ovale>left atrium>left ventricle>aorta. If in right atrium>pulmonary artery>ductus arteriosus>aorta.
what day does the heart start beating
day 22
describe the cardiac action potential
0 inward Na depolarises
1 initial repolarisation K out and Na stops going in
2 plateau, K out and Ca in
3 repolarisation lots of K out
4 resting potential, K slowly goes back in
what is the PR interval
the time it takes for the action potential to reach the AV node
what is the ST segment
ventricular depolarisation period
what is the T wave
ventricular repolarisation
define pre load
end diastolic volume
define afterload
the aortic pressure against the left ventricle
what joins myocytes
intercalated discs
what is ANP
atrial natrietic peptide, excreted mostly by RA to decrease sodium and water by inhibiting renin
what are heart muscle cells
involuntary striated
what does the baroreceptor reflex do?
increases CO and causes vasoconstriction in muscles and the GI tract. receptors are in the carotid sinus
what does histamine do to blood vessels
dilates arteries and contricts veins>oedema
which layer of blood vessels contains autonomic nerves that control the smooth muscle?
the adventitia
what will decreased renal perfusion cause
renin release to increase BP by reabsorption, intake and vasoconstriction
what happens to the blood that enters the heart in the foetal circulation?
goes through the ductus arterioles, which is distal to the brachiocephalic trunk and left carotid/subclavian
what kind of structural defect can occur after an MI?
VSD
what structural abnormalities can lead to Eisenmenger’s syndrome
ASD
VSD
patent ductus arteriosus
TOF
what makes up tetralogy of fallot?
VSD, aorta overriding VSD, pulmonary stenosis and right ventricular hypertrophy
what do you need to be careful of before cardiac surgery in someone with a structural defect?
Eisenmenger’s, surgery will kill because the defect is RL so it’s relieving the high pressure in the right
what is classic of TOF on XR?
boot shaped heart
how is VSD treated?
it may close by itself so treated with diuretics and beta blockers (rate control)
what are the normal parameters for heart rate?
60-100
what happens on inspiration to the heart rate?
parasympathetic tone decreases so the heart rate increases
what can cause bradycardia?
hypothermia, hypothyroidism, cholestatic jaundice, raised ICP, anti-arrythmic drugs, ischaemia or fibrosis of the SAN, neurally mediated syndromes
give some causes of heart block
infiltration, infection (Chagas’, Lyme, endocarditis), digoxin, beta blockers, SLE, cardiac surgery
features of RBBB
V1-tall late R waves
I V6-deep S waves
what will left postero-inferior hemiblock look like?
right axis deviation
what is Wolff Parkinson White a type of?
AVRT (bundle of Kent)
