Body's muscle: Skeletal, cardiac & smooth Flashcards
What are the three different types of muscle tissue
smooth, cardiac and skeletal muscle
What are the functions of skeletal muscle
Locomotion: requires contraction of muscle fibres (cells)
Contractile proteins (myofilaments) arranged as myofibrils
Describe the microstructure of skeletal muscle
Elongated, multinucleated cells
Peripheral nuclei
Grouped into bundles called fascicles
Surrounded by connective tissue
Epimysium
Perimysium
Endomysium
Basement membrane is continuous with Endomysium
Sarcolemma is the muscle fiber’s cell membrane
Sarcoplasm is the fiber’s cytoplasm
Note the Satellite cells – allow skeletal muscle to regenerate
What are the two types of myofilaments
Actin and myosin
Describe the contraction control
ACT neurotransmitter passes the nerve impulse across the gaps from the motor end plate to the muscle fiber = the neuromuscular junction
Impulse spreads into the sarcolemma (cell membrane) and into T tubules, perpendicular extensions
Sarcoplasmic reticulum is a smooth endoplasmic reticulum in muscle whose function is to store and release Ca when needed
State the different types of muscle fibre arrangement
Flat (parallel)
Pennate
Fusiform
Quadrate
Circular
Multiheaded (bellied)
Whats the difference in muscle generation between the different types of muscle
Skeletal muscle- satellite cells
Cardiac muscle- Incapable (fibrosis)
Smooth muscle- limited (cell division)
Describe the function of cardiac muscle
Function: continuous rhythmic contractions to pump blood from the heart
Describe cardiac muscle
Continuous into adjacent portions of the great vessels
Intrinsically generated contractions modified by the autonomic nervous system (ANS)
Parasympathetic (via Vagus nerve) decreases HR
Sympathetic increases HR
Describe the microstructure of cardiac muscle
Central nuclei Branching pattern Cells connected by intercalated discs Myofibrils less defined No defined connective tissue layer
Describe the intercalated discs?
Fascia adhesions (Desmosomes allow coordination of contraction)
Gap junctions (allow fast conduction and dissemination of Action Potential)
Describe the function of smooth muscle
slow sustained contractions to move contents through viscera
Describe smooth muscle
Low force
Contractions may be rhythmic or wave like
Stimulated by:
Autonomic NS
Hormones
Describe the microstructure of smooth muscle
Spindle shaped
Single central nuclei
Branching pattern
Contractile proteins not arranged as myofibrils/sacromeres
Proteins criss-cross and anchor to focal densities
Cells run parallel to force of contraction
Has a supporting network of connective tissue
Describe muscle disorders
Muscular dystrophies: group of genetic diseases causing progressive muscle weakness
Cardiomyopathies:
deterioration in heart muscle function – range of reasons
