5. Muscle Tissue Flashcards
What are the features of Cardiac muscle?
Branched cylindrical cells One centrally located nucleus Intercalated discs Striations Small fibre length, large diameter
What are the characteristics of smooth muscle?
Fusiform shaped
One central nucleus
Non-striated (Smooth)
Small diameter, medium length
What are the characteristics of skeletal muscle?
Long, cylindrical shape
Many peripheral nuclei
Striated
Very large diameter and length
How is cardiac muscle contracted/relaxed?
Built in pacemaker causes autorhythmicity. Can be affected by NTs and hormones
What regulates the contraction of smooth muscle?
ANS and Endocrine system
Some autorhythmicity, such as in GI tract
What is the function of fascia? Where is it located?
A CT that surrounds skeletal muscle/muscle groups. Forms compartments
What are the layers present in skeletal muscle?
Endomysium - surrounds individual muscle fibres (cells)
Perimysium - surrounds fascicles (formed by groups of muscle fibres)
Epimysium - surrounds whole muscle, blends with tendons
Satellite cells found between endomysium and muscle cell
What innervates skeletal muscle fibres?
Somatic motor neurones
Axons branch to supply several fibres
What is a motor unit?
The neurone plus all the skeletal muscle fibres it stimulates
How do skeletal muscle cells develop?
By the fusion of myoblasts
What are myofibrils and what do they look like?
1-2 um Cylindrical structures composed of sarcomeres filling the sarcoplasm of muscles. Appear striated due to light (thin) and dark (thick) bands
What are the bands and discs in a sarcomere composed of?
I band - primarily actin - least dense
A band - myosin - most dense
Z discs - bands marking sarcomeres borders
M line - middle of sarcomere
Describe two types of muscle atrophy
Disuse atrophy - reduced nerve impulses to muscle
Denervation atrophy - nerve supply cut
What is a characteristic symptom of muscular dystrophy?
Atrophy around oral cavity or hypertrophy of muscles around mouth
