Heart Tissue Flashcards
Week 5
Structures of the heart
- pericardium
- cardiac muscle
- fibrous ring
- coronary vessels
- valves
- neural tissue:
- SA node
- AV node
- Purkinje fibers
Layers of the heart
endocardium -> myocardium -> epicardium -> visceral layer of serous pericardium -> pericardial cavity -> parietal layer of serous pericardium -> fibrous pericardium -> adipose tissue
Parietal pericardium
Simple squamous epithelium covering dense regular connective tissue
Serous/visceral pericardium
- Simple squamous epithelium covering:
- Loose connective tissue
- Secretes pericardial fluid
Pericarditis
- Inflammation of the pericardium
Cause: - viral infection (typically)
- bacterial infection like tuberculosis, uremic pericarditis, following a heart attack, cancer, autoimmune disorders, and chest trauma
Symptoms: - sharp/stabbing chest pain (quickly) in the middle/left side of chest
Fibrinous Pericarditis
- Visceral pericardium infiltrated by the fibrinous exudate: fibrin strands and leukocytes
- Vascular congestion is also present
- myocardium has no changes
Cardiac muscle
L:
- Only found in the heart, very end of vena cava, pulmonary veins
V:
- Rounded central nuclei
- Associated mitochondria, glycogen granules
- Intercalated discs:
- adherens juctions, desmosomes, gap junctions
- similar to skeletal muscle
- slight delay between excitation of muscle and contraction
Fibrous Rings of the Heart
Function:
- Skeleton of the heart
- attachment point for cardiac muscle and the fibrous AV? valves and semilunar valves
Components:
- primarily a fibrous dense irregular CT covered by muscle, CT, and epithelium
- serous pericardium (out); endocardium (in)
Atrioventricular septum
- Chambers and valves lined by endocardium
- Dense fibrous irregular CT extends from septum into fibrous region of the valves
Coronary circulation
Video
Myocardial infarct
- block in artery starving muscles of O2
- symptoms: referred pain, heart attacks
New: - leads to cell death,
inflammation
Granulation phase: - 1-3 weeks
- granules
Old phase: - 3-6 weeks
- granulation phase then scar tissue
- loss of function
- need bypass or stint
Myocardial infarct (necrosis phase)
cardiomyocyte cell death
<1 day
Myocardial infarct (neutrophilic infiltrate)
infiltration of neutrophils and macrophages - clear cellular debris
Myocardial granulation
1-3 weeks
organizing granulation tissue
begin to see scar tissue
Myocardial infarct (scar)
weeks to months
- irregular areas of virtually acellular, dense connective tissue (scar tissue)