Lecture 1 Flashcards
Effective circulating volume (ECV) =
- volume sensed by baroreceptor system which is available for perfusion.
Primary energy source of the heart
(non-stress scenario):
- Free fatty acid
- β-oxidation
- oxidative phosphorylation
- ATP
Secondary energy source of the heart
(stress scenario):
- Glucose
- Glycolysis
- Oxidative phosphorylation
- ATP
Heart source of energy in non-stress and in stress:
- Non-stress: Free fatty acids
- Stress: Glucose
The predominant differences between cardiac muscle and skeletal muscle:
-
cardiac muscle has:
- chronic work load
- high reliance on extracellular calcium
Type of calcium channels expressed in cardiac myocytes:
-
Type-L calcium channels.
- Calcium enters myocytes through these channels to allow for cross-bridge cycling/contraction.
The two pathways in which an action potential in the heart can cause an influx of calcium into the sarcolemma of a myocyte:
- Extracellular: Type L Ca2+ channels
- Intracellular: T-tubules (DHPR and RyR)

The two sources of calcium for cardiac myocytes:
- Extracellular:
- enter sarcolemma via Type-L Ca2+ channels.
- Intracellular:
- enter sarcolemma via T-tubules (DHPRs and RyRs).
Phospholamban:
- protein phosphorylated by PKA.
- Unphosphorylated state: inhibits SERCA.
- Phosphorylated state: SERCA activated.
Process of cardiomyocyte relaxation:
- Phospholamban phosphorylated; SERCA channels activated.
- Calcium efflux via SERCA channels and NCX ATPases.
What two structures are utilized by cardiomyocytes to cause calcium efflux from the sarcolemma and relaxation?
- SERCA channels
- NCX ATPase
- secondary active transporter
- sodium-calcium exchanger
Creatinine kinase function:
- enzyme
- converts creatine to phosphocreatine and ADP.
- phosphocreatine + ADP = ATP.
Creatinine kinase expressed in myocardium:
CK-MB; “cardiac-specific CK.”
- rises beginning around 3-8 h post-injury.
- returns to normal within 48-72 h post-injury.
Troponins expressed in myocardium:
cTnI and cTnT
- cardiac troponin I (cTnI)
- cardiac troponin T (cTnT)
- rise within around 3-4 h post-injury.
- return to normal over 10-14 d post-injury.
What cardiac-specific markers increase in blood plasma levels post-myocardium injury?
- CK-MB (creatinine kinase)
- cTnI (cardiac troponin I)
- cTnT (cardiac troponin T)
Diastole characteristics (4):
- Phase of ventricular filling
- Myocardium relaxed
- Low intraventricular pressure
- Lowest arterial BP
The two values associated with diastole:
- End diastolic pressure (EDP)
- End diastolic volume (EDV)
Systole characteristics (4):
- Phase of ventricular emptying
- Myocardium contracting
- Highest intraventricular pressure
- Highest arterial BP
The two values associated with systole:
- End systolic pressure (ESP)
- End systolic volume (ESV)
When does the lowest arterial BP occur?
diastole
When does the highest arterial BP occur?
systole
Cardiac output (CO) =
CO = SV X HR
- (stroke volume X heart rate)
- SV = EDV - ESV
Stroke volume (SV) =
SV = EDV - ESV
(end diastolic volume - end systolic volume)
What are end diastolic volume (EDV) and end systolic volume (ESV)?
- EDV = left ventricle volume after diastole (filling).
- ESV = left ventricle volume after systole (emptying).
- SV = EDV - ESV