L85- Physiology of hypertension 1 Flashcards
what is happens to the valves when isovolumetric ventricular contraction happens?
they close
when does isovolumetric ventricular contraction occur?
during systole
what is happens to the valves when isovolumetric ventricular relaxation happens?
they are closed
when does isovolumetric ventricular relaxation occur?
during diastole
how is actin and myosin involved in a contraction?
- myosin cross bridge attaches to the acts myofilament.
- myosin head pivots and bends as I pulls on he actin filament sliding it toward the M line.
- As new ATP ATTACHES TO THE MYOSIN HEAD THE CROSS BRIDGES DETACHES.
- as ATP is split into ADP and Pi cocking of the myosin head occurs.
where does calcium bind to in cardiac muscles to stimulate a contraction?
troponin
what factors affect cardiac output?
heart rate and stroke volume
what is preload?
volume of blood in ventricles at the end of diastole (end diastolic pressure)
what is after load?
resistance left ventricles must overcome to circulate blood
what is venous return?
return of blood to the heart via veins
what does venous return control?
end-diastolic volume
what happens to venous return during inhalation for the respiratory pump?
- thoracic cavity expands
- pressure in plural cavities drop
- pulls air into lungs
- also pulls blood into IVC and R atrium from smaller veins in abdominal cavity
what happens to venous return during exhalation for the respiratory pump?
- pressure in pleural cavities rise
- pushes blood into R atrium
- important during heavy exercise
