Muscle Flashcards
What connects cardiac muscle cells?
intercalated discs
What is the cell membrane of a muscle cell called?
Sarcolemma
What does muscle arise from?
Mesoderm
What are the stem cells of skeletal muscle called?
Satellite cells
What is epimysium?
Dense connective tissue that surrounds the entire muscle
What is perimysium?
Connective tissue that surrounds fasicles
What is endomysium?
Connective tissue that surrounds myofibers
What causes the appearance of striation in skeletal and cardiac muscle?
Alternating I-bands and A-bands of sarcomeres
What are the regulatory proteins on actin?
- Tropomyosin
- Troponin
What does Titin do?
Connects myosin to the Z-disc, looks like a spring
What does myomesin do?
-connects myosin to the M-line
What does nebulin do?
it is a spacer/linker protein between actin
What does creatine kinase do?
- it is the source of emergency high energy in muscle cells
- Transfers phosphate groups form phosphocreatine to ADP
What holds cardiac muscle cells together at the intercalated discs?
-desmosomes
What are the stem cells of smooth muscle called?
-Pericytes
What are Dihydropyridine receptors?
- Voltage receptor
- Changes shape to activate Ryanodine
What are ryanodine receptors?
- Ca2+ release channels in SR
- Stimulated by confirmation change in Dihydropyiridine
What catalyzes the relaxation of skeletal muscle?
Smooth ER calcium ATPase (SERCA)
how does EC coupling work in cardiac muscle?
- Extracellular Ca2+ enters cell via DHP receptor
- Increase in [Ca]i causes RYR receptors to open
- Calcium induced calcium release (CICR)
How do cardiac muscle cells relax?
- Ca pumpted into SR by SERCA
- Ca/Na antiporter on sarcolemma
What do smooth muscle cells use instead of troponin?
Calmodulin (CaM)
What makes up the motor unit?
- Nerve
- Neuromuscular Junction
- Muscle
Type 1 Skeletal muscle fibers
- Slow, sustained force generation
- Use aerobic oxidative metabolism
- RED
Type 2 Skeletal muscle fibers
- Fast, but unsustained force generation
- anaerobic glycolytic
What happens when the baseline cytoplasmic calcium concentration of cardiac muscle cells is increased?
-Increased force of contraction
when is the Active tension of muscle cells at its maximal value?
When the overlap of actin and myosin is maximal, when the most potential interactions of myosin heads and actin occur
What is preload?
- isometric tension generation at a given length
- Want to optimize in cardiac patients
What do cardiac glycosides (Digitalis) do?
inhibit Na-k ATPase, causing a decreased Na gradient in cardiac muscle cells. Leads to an increased amount of intracellular Ca, because Na/Ca antiporter is impaired
What generates afterload for cardiac muscle cells?
Increased blood pressure
What takes the place of T-tubules in smooth muscle cells?
Caveolae
What is a myocardial scar?
- Cardiac muscle does not have satellite cells, so it cannot regenerate
- Damaged areas are normally replaced by proliferating fibroblasts and growth of connective tissue, forming myocardial scars
