Heart Part 1, UTHSC Fall 2022 D2 Pathology
Heart weight
• Varies with body height and weight, 0.4-0.5% of body
• Female: ~250 to 320 g, male: ~300 to 360 g
Epicardial surface
• Smooth and glistening
• Epicardial fat
Thickness of the free wall
• Right ventricle: 0.3 to 0.5 cm
• Left ventricle: 1.3 to 1.5 cm
Increase in cardiac weight/size = Cardiomegaly
• Hypertrophy
• Dilation
What is the path of blood through the heart?
Right Atrium, Tricuspid, Right Ventricle, Pulmonic valve, Pulmonary artery, Lungs,
Pulmonary veins, Left Atrium, Bicuspid (Mitral) Valve, Left Ventricle, Aortic valve, Aorta
what do cardiac myocytes use almost exclusively for energy needs?
oxidative phosphorylation
Myocardium extremely vulnerable to
ischemia
what are the four major arteries that supply blood to the heart muscles?
1. left main coronary artery
2. right coronary artery
3. left anterior descending artery
4. left circumferential artery
what are the three layers of the heart wall?
epicardium, myocardium, endocardium
Endocardium
endothelial cells over connective tissue
Myocardium
cardiac muscle
Epicardium
connective tissue with blood vessels and nerve fibers, covered by layer of mesothelial
cells
T/F the epicardium is part of the pericardium
True
what powers the heart's pumping?
due to coordinated contraction and relaxation of the cardiac myocytes
what is the effector unit of cardiac muscle?
myofibrils
what are the subunits to myofibrils?
actin, myosin, and other regulatory proteins
Cardiac Structure/Myocardium Histology
- Striated appearance
- Pale pink intercalated disks as intercellular junction for coordinated beating of cardiac
myocytes
, Cardiac Structure/Valves
- As extensions of endocardium, maintain unidirectional blood flow
- Function depends on the mobility, pliability, and structural integrity of the leaflets or
cusps
- Leaflets in tricuspid and mitral; cusps in the semilunar valves (aortic and pulmonary)
- Tri-layered architecture
what are the three major pathological changes to heart valves?
- Damage to collagen that weakens the leaflets → mitral valve prolaps
- Nodular calcification beginning in interstitial cells → calcific aortic stenosis
- Fibrotic thickening → rheumatic heart disease
Cardiac Stem Cells
- Increasing evidence of presence stem cells in mammalian myocardium, although it is
classically considered as a permanent cell population.
- 5-10% of normal atrial cellularity , but 1∕100,000 cells in normal ventricle
- Cardiac stem cells with very slow rate of proliferation
Congestive Heart Failure
- A common, usually progressive condition with a poor prognosis
- In CHF heart is unable to pump blood at a rate sufficient to metabolic demands of the
tissues.
Congestive Heart Failure stats
In US, 5 million individuals (2% of the population) affected each year, causes 300,000
death/year
what is a common end stage of many forms of chronic heart disease?
Congestive Heart Failure
what is one way the heart will change to help maintain arterial pressure and organ
perfusion?
myocardial hypertrophy
Cardiac Hypertrophy Pathophysiology and Progression to Heart Failure
1. Pressure (systemic hypertension) or Volume overload (aortic stenosis
2. Increase in mechanical work
3. Myocyte adaptation
4. Increase in size (hypertrophy) of myocyte
5. Increase in size and weight of the heart
what is the result of Myocyte hypertrophy not being accompanied by a
proportional increase in capillary numbers?
- weak blood supply for hypertrophied heart while oxygen consumption is elevated
- More vulnerability of hypertrophied heart to ischemia-related decompensation
- Cardiac failure
what is the result of hypertension on the vascular system?
Pressure overload
what is the result of Valvular Disease on the vascular system?
Pressure and/or volume overload
what is the result of Myocardial infarction on the vascular system?
Regional dysfunction with volume overload
what do Hypertension, Valvular Disease, and Myocardial infarction lead to in the
heart?
Heart weight
• Varies with body height and weight, 0.4-0.5% of body
• Female: ~250 to 320 g, male: ~300 to 360 g
Epicardial surface
• Smooth and glistening
• Epicardial fat
Thickness of the free wall
• Right ventricle: 0.3 to 0.5 cm
• Left ventricle: 1.3 to 1.5 cm
Increase in cardiac weight/size = Cardiomegaly
• Hypertrophy
• Dilation
What is the path of blood through the heart?
Right Atrium, Tricuspid, Right Ventricle, Pulmonic valve, Pulmonary artery, Lungs,
Pulmonary veins, Left Atrium, Bicuspid (Mitral) Valve, Left Ventricle, Aortic valve, Aorta
what do cardiac myocytes use almost exclusively for energy needs?
oxidative phosphorylation
Myocardium extremely vulnerable to
ischemia
what are the four major arteries that supply blood to the heart muscles?
1. left main coronary artery
2. right coronary artery
3. left anterior descending artery
4. left circumferential artery
what are the three layers of the heart wall?
epicardium, myocardium, endocardium
Endocardium
endothelial cells over connective tissue
Myocardium
cardiac muscle
Epicardium
connective tissue with blood vessels and nerve fibers, covered by layer of mesothelial
cells
T/F the epicardium is part of the pericardium
True
what powers the heart's pumping?
due to coordinated contraction and relaxation of the cardiac myocytes
what is the effector unit of cardiac muscle?
myofibrils
what are the subunits to myofibrils?
actin, myosin, and other regulatory proteins
Cardiac Structure/Myocardium Histology
- Striated appearance
- Pale pink intercalated disks as intercellular junction for coordinated beating of cardiac
myocytes
, Cardiac Structure/Valves
- As extensions of endocardium, maintain unidirectional blood flow
- Function depends on the mobility, pliability, and structural integrity of the leaflets or
cusps
- Leaflets in tricuspid and mitral; cusps in the semilunar valves (aortic and pulmonary)
- Tri-layered architecture
what are the three major pathological changes to heart valves?
- Damage to collagen that weakens the leaflets → mitral valve prolaps
- Nodular calcification beginning in interstitial cells → calcific aortic stenosis
- Fibrotic thickening → rheumatic heart disease
Cardiac Stem Cells
- Increasing evidence of presence stem cells in mammalian myocardium, although it is
classically considered as a permanent cell population.
- 5-10% of normal atrial cellularity , but 1∕100,000 cells in normal ventricle
- Cardiac stem cells with very slow rate of proliferation
Congestive Heart Failure
- A common, usually progressive condition with a poor prognosis
- In CHF heart is unable to pump blood at a rate sufficient to metabolic demands of the
tissues.
Congestive Heart Failure stats
In US, 5 million individuals (2% of the population) affected each year, causes 300,000
death/year
what is a common end stage of many forms of chronic heart disease?
Congestive Heart Failure
what is one way the heart will change to help maintain arterial pressure and organ
perfusion?
myocardial hypertrophy
Cardiac Hypertrophy Pathophysiology and Progression to Heart Failure
1. Pressure (systemic hypertension) or Volume overload (aortic stenosis
2. Increase in mechanical work
3. Myocyte adaptation
4. Increase in size (hypertrophy) of myocyte
5. Increase in size and weight of the heart
what is the result of Myocyte hypertrophy not being accompanied by a
proportional increase in capillary numbers?
- weak blood supply for hypertrophied heart while oxygen consumption is elevated
- More vulnerability of hypertrophied heart to ischemia-related decompensation
- Cardiac failure
what is the result of hypertension on the vascular system?
Pressure overload
what is the result of Valvular Disease on the vascular system?
Pressure and/or volume overload
what is the result of Myocardial infarction on the vascular system?
Regional dysfunction with volume overload
what do Hypertension, Valvular Disease, and Myocardial infarction lead to in the
heart?
