CPRS 23: Control of Heart Flashcards
What is equal to the end diastolic volume - end systolic volume
Stroke volume
In cardiac conducting cells
opening of which channel causes slow influx of the funny current of Na+
HCN channels
Why is the signal delayed in AV node
allow time for the ventricles to finish blood-filling before contraction can occur
Parasympathetic Control of Heart Rate is referred to as Negative Chronotropism.
Which neurotransmitter is binding to which receptors?
How can it achieve the purpose? 3 ways
- Threshold
- Slope of Phase 4 (Slow down the _______ current influx)
- Repolarization (Open more ______ channels to increase repolarization)
Ach binding to M2 Muscarinic Receptors
How can it achieve the purpose? 3 ways
- make threshold more positive
- Slow down the funny current influx, reduce the slope of phase 4
- Open GIRK channels to increase repolarization to make the max diastolic potential more negative
Sympathetic Control of Heart Rate is referred to as Positive Chronotropism.
Which neurotransmitter is binding to which receptors?
How can it achieve the purpose? 3 ways
- Threshold
- Slope of Phase 4
- Increase rate of sequestration by ________
- Increase rate of dissociation of Ca2+ from __________, which is for Ca2+ binding, speeding up relaxation
NE/E binding to Beta-1 adrenergic receptors
How can it achieve the purpose? 3 ways
- make threshold more negative
- Increase the funny current influx, increase the slope of phase 4
- Increase rate of sequestration by SERCA2a
- Increase rate of dissociation of Ca2+ from Troponin C, which is for Ca2+ binding, speeding up relaxation
Cardiac Muscle Contraction
- Action potential enters, Ca2+ enters the cell through ________ Ca2+ channel
- Calcium ions in cytoplasm stimulates the ________ receptors to release more calcium from the __________, which is called _____________
- Action potential enters, Ca2+ enters the cell through L-type Ca2+ channel
- Calcium ions in cytoplasm stimulates the ryanodine receptors to release more calcium from the SR, which is called calcium-induced-calcium release
Cardiac Muscle Relaxation
- Ca2+ is sequestered by _______ (Calcium ion ATPase) back to the SR
- Ca2+ exits sacromere by _________ and ________ (2 channels)
Cardiac Muscle Relaxation
- Ca2+ is sequestered by SERCA2a (Calcium ion ATPase) back to the SR
- Ca2+ exits sacromere by Sodium Calcium exchanger and Na/K ATPase (2 channels)
Refer to the Pressure Volume Loop on CPRS 23 notes
A (Lower left corner) => B => C => D => E => F
The graph is Left ventricular pressure against Left Ventricular Volume
Where is End-systolic volume Where is End-diastolic volume When does Mitral Valve Open When does Mitral Valve Close When does Aortic Valve Open When does Aortic Valve Close
Refer to the Pressure Volume Loop on CPRS 23 notes
A (Lower left corner) => B => C => D => E => F
The graph is Left ventricular pressure against Left Ventricular Volume
Where is End-systolic volume: A Where is End-diastolic volume: C When does Mitral Valve Open: A When does Mitral Valve Close: C When does Aortic Valve Open: D When does Aortic Valve Close: F
Refer to the Pressure Volume Loop on CPRS 23 notes
A (Lower left corner) => B => C => D => E => F
The graph is Left ventricular pressure against Left Ventricular Volume
Which period corresponds to ventricular filling
Which period corresponds to isovolumetric contraction
Which period corresponds to ventricular ejection
Which period corresponds to isovolumetric relaxation
Refer to the Pressure Volume Loop on CPRS 23 notes
A (Lower left corner) => B => C => D => E => F
The graph is Left ventricular pressure against Left Ventricular Volume
Which period corresponds to ventricular filling: ABC
Which period corresponds to isovolumetric contraction: CD
Which period corresponds to ventricular ejection: DEF
Which period corresponds to isovolumetric relaxation: FA
Consider Ventricular Preload
- Increase in preload will lead to increased _____________,
- By SV=EDV-ESV, Stroke volume will _______
- Increase in stretching of ventricles means increase in preload
Consider Ventricular Preload
- Increase in preload will lead to increased end-diastolic volume,
- By SV=EDV-ESV, Stroke volume will increase
Suggest to refer to diagram on CPRS 23
Name certain factors that increases ventricular preload
- Venous return
- Ventricular filling
- Heart rate
- Ventricular inotropy
- Atrial inotropy
- Outflow resistance
- Ventricular compliance
- Muscle Damage
Name certain factors that increases ventricular preload
- Venous return increases
- Ventricular filling increases
- Heart rate decreases (more time filling)
- Ventricular inotropy decreases (less blood squeezed out)
- Atrial inotropy increases (more blood squeezed from atrium to ventricles)
- Outflow resistance increases (more blood retained)
- Ventricular compliance increases (=increase the ability for the ventricles to be stretched)
- Muscle Damage decreases (Less infarction, less fibrosis => Reduce elasticity => Increase stretching)
(If the Q gives something opposite to this, = the situation of afterload)
Afterload is the force opposing the ejection of the blood by the left ventricle
Major contributor of afterload is _________
Increase in afterload will lead to an ______ in end systolic volume, by SV=EDV-ESV, Stroke volume _______.
Afterload is the force opposing the ejection of the blood by the left ventricle
Major contributor of afterload is aortic pressure
Increase in afterload will lead to an increase in end systolic volume, by SV=EDV-ESV, Stroke volume decreases.
Suggest to refer to diagram on CPRS 23
Preload and Afterload combined
Increased preload …
Increased afterload …
(Homeostatis concept)
Increased preload ... Increase SV Increase aortic pressure Increase afterload Decrease SV
Increased afterload …
Decrease SV
Increase preload
Increase SV
