True/False
The first heart sound is due to the SL valves closing.
False
AV valves
What are the RMPs of nodal cells and contractile cells?
Nodal cell: ~-60 mv
Contractile cell: -90 mv
Describe the first phase of the cardiac cycle.
Atrial relaxation and ventricular filling
80% of blood drains into ventricles
What are the values for normal HR, CO, EDV, SV, and ESV?
75 bpm
5 L
130, 70, 60 ml
Define arterial anastomosis.
Connected arteries that provide two ways of serving a certain body tissue
CO/SV=HR
True
Why does the AP in contractile cells need to be so long?
To give time for the muscle to fully contract and relax before the next depolarization.
This allows Ca to flood into sarcoplasm and bind to troponin, cause the contraction, and then be pumped back out so that the muscle relaxes. Then depolarization occurs and more Ca floods in.
Describe the second phase of the cardiac cycle. Include corresponding part of EKG.
Atrial contraction and ventricular filling
SA node fires, atria squish last 20% of blood into ventricles
P wave
What is afterload? Describe its effect on SV.
Peripheral/arterial resistance
Decreases SV
List 2 characteristics of myocardial cells that enable them to meet the heart's high energy demands.
25% of cell volume is mitochondria
Cells are able to metabolize FAs, glucose, lactic acid, AAs, ketone bodies
Functions aerobically
Cardiomegaly is the inward growth of heart walls.
False
This is hypertrophic cardiomyopathy.
Cardiomegaly is overall hypertrophy of heart due to high BP.
In nodal cells, Ca channels bring the voltage from ___ mv to ____ mv.
-40 to slightly above zero
Describe the third phase of cardiac cycle. Include EKG.
Isovolumic contraction
No change in blood volume, AV valves close, ventricular contraction
QRS wave
Describe the Frank Starling effect. List 2 factors that affect it.
Effect: more stretch means more optimal overlap
1. Venous return
-muscle pump, blood volume
2. Filling time
List 2 functions of the fibrous skeleton.
Insulates electrical activity
Prevents electrical signals from travelling between the ventricles
Provides supportive rings to anchor the heart valves
Provides structural support
Nodal cells have slow Na channels and fast Ca channels while contractile cells have fast Na channels and slow Ca channels.
Contractile channels need slow Ca channels for voltage plateau (these are the ones that work with K channels to create long AP)
In contractile cells, Na channels bring the MP from __ mv to __ mv.
-90 to +30
Describe the fourth phase of the cardiac cycle. Include EKG.
Ventricular ejection
ventricular plateau, ST segment
What are positive and negative inotropic agents?
Alter amount of Ca in sarcoplasm available for cross-bridge formation. Affect contractility.
Positive: NE, EPI, TH
Negative: excess H+, extracellular K+, Ca channel blockers
What is the foramen ovale in the fetal heart? What it is in an adult heart?
The opening that connects the atria
Becomes the fossa ovalis after birth
The PNS alters HR and contractility.
False
SNS
PNS only goes to nodal cells (HR only)
What is junctional rhythm? This is a type of cardiac ________.
cardiac arrhythmia
Describe fifth phase of cardiac cycle.
Isovolumic relaxation
SL valves close
What are positive and negative chronotropic agents?
Affect HR
+: cause more rapid depolarization by letting in more Ca (NE, EPI from SNS, caffeine, nicotine, etc.)
-: cause hyperpolarization by letting out K (Ach from PNS, beta blockers (block beta adrenergic receptors for NE, EPI)
Describe two types of edemas resulting from congestive heart failure.
Left ventricle impairment>>pulmonary edema
Right ventricle impairment >>systemic edema