Histology and Physiology Flashcards
What are the physiological functions of skeletal muscle?
Maintenance of posture
Purposeful movement in relation to external environment
Respiratory movements
Heat production
Contribution to whole body metabolism
Describe skeletal muscle and its innervation
Striated and innervated by somatic nervous system
Describe cardiac muscle and its innervation
Striated and innervated by autonomic nervous system
Describe smooth muscle and its innervation
Unstriated and innervated by autonomic nervous system.
What is the neurotransmitter at the neuromuscular junction?
Acetylcholine
What is the motor unit of the skeletal muscles?
A single alpha motor neuron and all the skeletal muscle it innervates
What determines the number of muscle fibres per motor unit?
Depends on the functions served by the muscle. Muscles with fine movements have fewer fibres per motor unit.
What does skeletal muscle consist of?
Parallel muscle fibres bundled by connective tissue. Fibres usually extend the length of the muscle.
Describe skeletal muscle histologically?
It is striated, unbranched and multinucleated.
Where are the nuclei in skeletal muscle?
At the periphery of the fibre just under the cell membrane (in muscle cells this is the sarcolemma)
What are bundles of fibres called?
Fascicles
What is the name of the tissue that surrounds the muscle?
Epimysium
What is the name of the tissue around a single fascicle?
Perimysium
What is the name of tissue around a single muscle fibre?
Endomysium
What are the units of contraction of a muscle cell?
Sarcomeres
Where does the sarcomere extend from and to?
Extends from one Z line to another
Describe Type I Skeletal muscle
Relatively slow contracting fibres that depend on oxidative metabolism. They have abundant mitochondria and myoglobin, are resistant to fatigue and produce relatively less force.
Describe Type IIa Skeletal muscle
intermediate between the other two types. They are relatively fast contracting but are also reasonably resistant to fatigue. They are relatively uncommon.
Describe Type IIb skeletal muscle.
fast contracting fibres that depend on anaerobic metabolism. They have few mitochondria and less myoglobin than Type I fibres. They fatigue relatively easily and produce relatively greater force.
Describe bone.
Rigid, non-permeable.
Cells within the bone must eb nourished by blood vessels that pervade the tissue
Explain the composition of bone.
65% bioapatite
23% collagen
10% water
2% non-collagen proteins
What is the diaphysis and what is it made of?
The shaft of the bone. Made up of dense cortical bone as an outer shell.
What is the epiphyses and what is it made of?
The ends of the bone are made up of cancellous or trabecular bone
