Skeletal Muscle Structure and Function Flashcards
What are the 3 types of muscle
Skeletal
Cardiac
Smooth
Where can you find smooth muscle
contractile cells of the viscera and blood vessels
Describe the appearance of smooth muscle
No Striations
Spindle shaped
Central nucleus
What does contraction cause to happen to the cell
shorten and round up
What does calcium from the ECF bind to in smooth muscle
Calmodulin
What activates myosin heads to bind to actin
calmodulin
What 3 things regulate smooth muscle contraction
Autonomic Nervous System
Hormones
Local physiological conditions
nothing is under voluntary control
What happens to smooth muscle in asthma
Smooth muscle proliferates and contracts airways
What is Leiomyoma
A benign smooth muscle neoplasm
Describe the appearance of cardiac muscle
Striations - actin and myosin in regular arrangement
Central nucleus
Long branched cardiac fibres formed by linking cardiac muscle cells end to end
Intercalated disks connect cells, these are specialised junctional systems
Why can’t cardiac muscle regenerate after damage
It has no stem cells
Contraction of cardiac muscle is similar to skeletal muscle, what controls its contraction
Autonomic control of cardiac muscle
Describe the appearance of skeletal muscle
Striated - actin + myosin in regular arrangement
Multinucleated fibres - many individual cells fused together
Fibres 10cm in length
nucleus peripheral
contains stem cells for repair
What is a sarcomere made up of
Parallel interdigitating thick and thin myofilaments.
Thick = myosin
Thin = actin
What is a sarcolemma in skeletal muscle
Muscle cell plasma membrane
What are T-Tubules
These are extensions of the sarcolemma that extend transversely into the muscle cell and surround each myofibril at the junction of A and I bands
How are the myosin binding sites revealed
Calcium binding to troponin = conformational change and this removes tropomyosin from the binding site
What is the role of a T-Tubule
They carry the depolarisation of the muscle fibre membrane into the muscle fibre
Where is calcium released from in the muscle cell and where does it bind to
Released from sarcoplasmic reticulum and binds to troponin
After myosin binding site exposure how does skeletal muscle contract
Myosin binds and hydrolyses ATP and change the shape of the myosin head
Stored energy is released and ADP and inorganic phosphate
This myosin head pulls the actin and contracts the muscle
Myosin then lets go of actin and allows muscle relaxation
Upon muscle damage what repairs the muscle if the sarcolemma is intact
Satellite cells activate and repair muscle
Upon muscle damage what repairs the muscle if the sarcolemma is damaged
region of damage is replaced with fibrocollagenous tissue
What type is slow twitch and what is fast twitch
type 1 = slow
type 2 = fast
