PHRM 100 Lecture 9: APPP 9: The Cardiovascular System
9. Cardiovascular System
Kidneys play an important role in BP regulation:
- Releases renin: Angiotensinogen → Angiotensin I (inactive)
-ACE: Angiotensin I → Angiotensin II (powerful vasoconstrictor) → Aldosterone
-Aldosterone: sodium retention → water retention → increase BP
Myocardial infarction
- Heart cannot repair itself with cardiomyocytes; but with fibroblast
- Fibroblast: no contractile or ability to contract
- Subsequent tissue below blood clot dies = heart failure
NOTE heart muscle does not regenerate
Inotropic agents – increase force of contraction e.g. Digoxin (Entresto is not but useful)
Ions responsible for electrical current: Na+, K+, Ca2+
The Heart
Septum: divides right and left ventricles
Pericardium: chamber with fluid
that protect heart (reduce resistance and from overfilling)
Bicuspid valve (Mitral valve): AV valve between left atrium and ventricle
Semilunar valve = pulmonary valve / aortic valve
Papillary muscle: holds valve in place
The Artery
Endothelial cells: initial contact with blood
Arterial intima: contains collagen and proteoglycans
Internal elastic lamina: prevents smooth muscle from moving into intima
Media: smooth muscle cells
Adventitia: small blood vessels that supply blood to blood vessels themselves
Electrical activity of the heart
SA node (60-100 beats/min)
- generator of electrical activity – controls HR
- short current duration
AV node (40-60 beats/min)
Bachmann bundle: takes electrical activity across the atrium
Depolarizing: makes inside more positive (Na+, Ca2+ moves in)
Repolarizing: brings membrane potential back to normal (K+ moves out)
