CVS 1: Cardiovascular System Flashcards
Functions of the CVS
- Transport:
1. Respiratory - O2 & CO2
2. Nutritive - digestion products to liver & nutrients to tissues
3. Excretory - metabolic wastes to kidneys - Regulation:
1. Hormonal - hormones from glands to target tissues
2. Temp - divert blood to cool/warm body
3. Protection - blood clotting
4. Immune - wbcs & antibodies
What side of the heart supplies the pulmonary circuit
The right heart
(pulmonary artery)
T/F?: does the right heart supply the systemic circuit
No
The systemic circuit is supplied by the left heart
(aorta)
what does contraction of heart allow
pushes blood out of heart into vasculature
what does relaxation allow
allows heart to fill with blood
what drives blood flow
Pressure gradient
T/F? blood moves from area of lower pressure to area of higher pressure
False
Blood moves from area of higher pressure to area of lower pressure
T/F? atria contract after ventricles
False
Atrial contraction precedes ventricular contraction
where does blood flow to when ventricles contract
arteries - pulmonary artery takes blood to lungs, aorta takes blood to rest of body
T/F? Av valves open during ventricular contraction
False.
AV valves open during atrial contraction - allow blood to flow only from atria to the ventricles
where are the semilunar valves located
origin of aorta & pulmonary artery
T/F? semilunar valves open during ventricular contraction
True.
allow blood flow only from ventricles to arteries
T/F? myocardial cells are connected by intercalated discs
true.
these intercalated discs contain gap junctions. connection forms complex network.
what are gap junctions
fluid filled channels that allow action potentials to spread from cell to cell
what is used to initiate contraction of myocardial cells
extracellular Ca2+ rather than intracellular Ca2+ (intracellular stores in sarcoplasmic reticulum)
what cells trigger the cuntraction of cardiac muscle
autorhythmic / pacemaker cells
how are APs generated & spread into myocardial cells
cell membranes spontaneously depolarise & generate APs - generates contraction of cardiac muscle
what happens at threshold
at -50mV (threshold) fast Ca2+ and Na+ channels open.
spontaneous membrane depolarisation occurs (influx of Ca2+ and Na+ causes inside of cell to depolarise & become less negative).
action potential is generated.
T/F?: threshold is -60mV
False.
threshold is -50mV
what happens at peak depolarisation (+20mV)
- K+ channels open, K+ ions leave the cell (rapid efflux)
- membrane repolarisation occurs (inside of cell once again more neg than outside)
- fast Na+ and Ca2+ channels close
what causes the opening of voltage gated Na+ channels
the arrival of AP at contractile myocardial cell opens Na+ channels & causes rapid depolarisation
what does the inward movement of extracellular Ca2+ during depolarisation also cause
also opens Ca2+ channels on the sarcoplasmic reticulum, triggers contraction in an identical mechanism to skeletal muscle
why is the length of an AP much longer in myocardial cell than in skeletal muscle cell
due to plateau phase in myocardial cells
what sets the rate of depolarisation in the contractile myocardial cells
the rate of depolarisation in the SA node
