PGY 412 EXAM 2 QUESTIONS AND ACCURATE
ANSWERS
Pulmonary Circuit - answer Low Pressure Circuit
Volume dependent
Venous side
Defined by "Preload"- highly dependent upon venous return (VR)
CO from right side of the heart is the 'pulmonary' blood flow
Systemic Circuit - answer High Pressure
Pressure Dependent
Arterial side
Defined by "afterload"- highly dependent upon cardiac output (CO)
CO from left side of the heart is 'systemic' blood flow
Heart Histology: Pericardium - answer AKA 'Epicardium'
Outer, Fibrous sac with small amount of fluid within the pericardial space- helps muscle
to contract smoothly
3 layers with potential space
Heart Histology: Endocardium - answer Continuous with the 'endothelium' of vessels
and with the valves
Simple squamous epithelium
Connective tissue (BM)
-Attaches to Myocardium
All valves open and closed based upon - answer Passive movement due to pressure
differences
,Papillary muscles & Chordae Tendineae - answer Prevent prolapse of AV-valves during
systole
Pericardium layers - answer *Fibrous
*Serous (simple squamous)- parietal pericardium
-Space-
*Serous- visceral layer
Heart Histology: Myocardium - answer Cardiac muscle
-Central nuclei
-Syncytium arrangement
-Thickest layer
-Connective tissue
-Adipose
-Involuntary
-Gap Junctions
Blood Flow through Cardiovascular System - answer IVC/SVC > RA > Tricuspid Valve >
RV > Pulmonary Semilunar valve > Pulmonary Trunk > Pulmonary Artery > Lungs >
Pulmonary Veins > LA > Bicuspid Valve > LV > Aortic Semilunar Valve > Aorta > Arteries
> Capillaries > Veins > IVC/SVC
The ability of the heart to eject blood during a heartbeat is a function of 3 factors -
answer * Amount of cardiac filling (preload)
* Strength of contraction (contractility)
*Pressure against which it ejects blood (afterload)
Systole - answer The period when the ventricle is contracting and ejection of blood
occurs
Diastole - answer The period when the ventricle is relaxing, and filling occursj
,What factors improve the heart as a pump - answer *Increasing Preload
*Increasing Contractility
*Decreasing Afterload
What factors diminish heart as a pump - answer *Decrease preload
*Decrease contractility
*Increase afterload
Preload (Starling's Law) - answer *Up to a point, the heart pumps more when it is filled
more during diastole
*Increased ventricular 'filling' adds 'stretch' on the ventricular muscle, resulting in
greater contraction (up to a point of diminished returns)
*Called 'starlings law'
*At some point, excess stretch stops increasing output and eventually decreases it.
Define: Preload - answer Volume of blood in ventricles just before contraction- volume
dependent
*Can be expressed as: EDV, end-diastolic pressure, stretch on sarcomeres
*Often synonymous with 'EDV' which is related to RA pressure and VR.
Preload is increased with: - answer *Increased VR
*Increased EDV
*Fluid retention
*Hypervolemia
*Heart Failure
*Regurgitation of cardiac valves
*Excessive venoconstriction (alpha-1)
, *Increase stretch on the ventricular m.
**Anything that forces blood back to the heart, or increases VR or Venous Volume
Preload is decreased with: - answer *Low venous tone
*Hypovolemia
- Dizzy, vision trouble, weak, tachycardia, retain fluid- not making urine to be excreted
*Dehydration
An increase in EDV will _________ stroke volume - answer Increase
Contractility - answer the ability of the heart to contract at a given preload (EDV)
AKA 'Inotropism' or 'Inotropy'
*Intrinsic ability of cardiac muscle to generate force at a given EDV or muscle length
At a cellular level, 'contractility' is related to: - answer **Intracellular Ca++ levels
- Reflects amount of Ca++ released from SR
- Contractility strength is directly tied to Ca++ concentration in ICF
- Positive inotropic agents increase Ca++ release from SR
-Increased Ca++ released/ minute results in increased tension
Positive Inotropic effectors: - answer **Cause an increase in contractility (myocardial
squeeze)
- Beta- 1 agonists cause a faster HR, and increase contractility (via Ca++)
- Beta-2 agonists cause increased contractility
-Digitalis works by inhibiting the Na/K pump, and increasing ICF Ca++ levels
Negative Inotropic effectors: - answer **Produce a decrease in contractility
-Parasympathetic stimulation via muscarinic (M2) receptors
-Beta receptor antagonist (Beta blocker)
ANSWERS
Pulmonary Circuit - answer Low Pressure Circuit
Volume dependent
Venous side
Defined by "Preload"- highly dependent upon venous return (VR)
CO from right side of the heart is the 'pulmonary' blood flow
Systemic Circuit - answer High Pressure
Pressure Dependent
Arterial side
Defined by "afterload"- highly dependent upon cardiac output (CO)
CO from left side of the heart is 'systemic' blood flow
Heart Histology: Pericardium - answer AKA 'Epicardium'
Outer, Fibrous sac with small amount of fluid within the pericardial space- helps muscle
to contract smoothly
3 layers with potential space
Heart Histology: Endocardium - answer Continuous with the 'endothelium' of vessels
and with the valves
Simple squamous epithelium
Connective tissue (BM)
-Attaches to Myocardium
All valves open and closed based upon - answer Passive movement due to pressure
differences
,Papillary muscles & Chordae Tendineae - answer Prevent prolapse of AV-valves during
systole
Pericardium layers - answer *Fibrous
*Serous (simple squamous)- parietal pericardium
-Space-
*Serous- visceral layer
Heart Histology: Myocardium - answer Cardiac muscle
-Central nuclei
-Syncytium arrangement
-Thickest layer
-Connective tissue
-Adipose
-Involuntary
-Gap Junctions
Blood Flow through Cardiovascular System - answer IVC/SVC > RA > Tricuspid Valve >
RV > Pulmonary Semilunar valve > Pulmonary Trunk > Pulmonary Artery > Lungs >
Pulmonary Veins > LA > Bicuspid Valve > LV > Aortic Semilunar Valve > Aorta > Arteries
> Capillaries > Veins > IVC/SVC
The ability of the heart to eject blood during a heartbeat is a function of 3 factors -
answer * Amount of cardiac filling (preload)
* Strength of contraction (contractility)
*Pressure against which it ejects blood (afterload)
Systole - answer The period when the ventricle is contracting and ejection of blood
occurs
Diastole - answer The period when the ventricle is relaxing, and filling occursj
,What factors improve the heart as a pump - answer *Increasing Preload
*Increasing Contractility
*Decreasing Afterload
What factors diminish heart as a pump - answer *Decrease preload
*Decrease contractility
*Increase afterload
Preload (Starling's Law) - answer *Up to a point, the heart pumps more when it is filled
more during diastole
*Increased ventricular 'filling' adds 'stretch' on the ventricular muscle, resulting in
greater contraction (up to a point of diminished returns)
*Called 'starlings law'
*At some point, excess stretch stops increasing output and eventually decreases it.
Define: Preload - answer Volume of blood in ventricles just before contraction- volume
dependent
*Can be expressed as: EDV, end-diastolic pressure, stretch on sarcomeres
*Often synonymous with 'EDV' which is related to RA pressure and VR.
Preload is increased with: - answer *Increased VR
*Increased EDV
*Fluid retention
*Hypervolemia
*Heart Failure
*Regurgitation of cardiac valves
*Excessive venoconstriction (alpha-1)
, *Increase stretch on the ventricular m.
**Anything that forces blood back to the heart, or increases VR or Venous Volume
Preload is decreased with: - answer *Low venous tone
*Hypovolemia
- Dizzy, vision trouble, weak, tachycardia, retain fluid- not making urine to be excreted
*Dehydration
An increase in EDV will _________ stroke volume - answer Increase
Contractility - answer the ability of the heart to contract at a given preload (EDV)
AKA 'Inotropism' or 'Inotropy'
*Intrinsic ability of cardiac muscle to generate force at a given EDV or muscle length
At a cellular level, 'contractility' is related to: - answer **Intracellular Ca++ levels
- Reflects amount of Ca++ released from SR
- Contractility strength is directly tied to Ca++ concentration in ICF
- Positive inotropic agents increase Ca++ release from SR
-Increased Ca++ released/ minute results in increased tension
Positive Inotropic effectors: - answer **Cause an increase in contractility (myocardial
squeeze)
- Beta- 1 agonists cause a faster HR, and increase contractility (via Ca++)
- Beta-2 agonists cause increased contractility
-Digitalis works by inhibiting the Na/K pump, and increasing ICF Ca++ levels
Negative Inotropic effectors: - answer **Produce a decrease in contractility
-Parasympathetic stimulation via muscarinic (M2) receptors
-Beta receptor antagonist (Beta blocker)
