Lecture 17 Flashcards
Give the muscle related words and their meanings?
Myopathy= muscle disease
Myasthenia= muscle weakness
Myoclonus= muscle spasm
Myocardium= muscular component of heart
Myalgia= muscle pain
What characterises smooth muscle?
It is not striated and has no nerve to muscle communication
What is myoglobin?
Red protein similar to a single haemoglobin subunit. At low pH haemoglobin will give oxygen to myoglobin.
When striated muscle dies (necrosis)myoglobin is release into bloodstream known as myoglobinuria (after marathon with no training). Causes renal damage and removed by kidney to I’ve tea coloured urine.
Explain muscle cell component terminology?
Sarcolemma- outer membrane of muscle cell
Sarcoplasm- cytoplasm of muscle cell
Sarcomere- contraction unit in striated muscle
Sarcosome- mitochondrion in muscle
Sarcoplasmic reticulum- smooth endoplasmic reticulum of muscle
Difference between endomysium, perimysium and epimysium?
Endomysium found between fibres, perimysium found around fascicles and epimysium found surrounding muscle
What’s the difference between the origin and the insertion?
Origin is fixed at the tendon while the insertion moves with contraction
What is the difference between intrinsic and extrinsic muscle?
Intrinsic for example would be within the tongue and would allow it to change shape for swallowing etc. Extrinsic muscles would retract it or move it from side to side
How is skeletal muscle structured
Myofibrils in a muscle cell or fibre surrounded by an endomysium and many of these make a fascicle surrounded by a perimysium and many of these make a muscle surrounded by an epimysium
What is a myofibril made of?
Actin and myosin filaments
What is a sarcomere?
Part of a myofibirl that forms the basic unit of striated muscle tissue
Can you label the zones of a sarcomere?
See lecture
What are T tubules?
Extension of sarcolemma that project into skeletal and cardiac muscle
Where are sarcosomes located
Between the myofibrils and have peripherally positioned nuclei
Where is a sarcomere measured form?
Z band to z band
What types of muscle fibres are there
Fast, slow and intermediate
What are the types of slow and fast twitch fibres
Slow type 1 oxidative
Fast type 2A oxidative
Fast type 2B glycolytic
How to tell muscle fibre types from each other?
1a red, 2A red to pink 2B pale
2B glycolytic fibres used for strength training sprinting etc
How to easily identify cardiac muscle?
Intercalated disks and branching
Some differences between skeletal and cardiac muscle?
Nuclei central in cardiac peripheral in skeletal
Cardiomyocytes communicate through gap junctions in T tubules
What hormones does the heart produce?
Atrial nuturietic factor and brain-type naturietic factor. Released during heart failure to make pumping easier by reducing vascular resistance
Hypertrophy vs hyperplasia?
Hypertrophy is an increase in cell size hyperplasia is an increase in cell number
Atrophy vs hypertrophy
Atrophy cells smaller hypertrophy cells larger
Function of Purkinje fibres?
Rapid signal transduction which enables ventricles to contact in a synchronous manner
Smooth muscle?
Tapered ends and spindle shaped
Slower and sustained contraction
Can be stretched
Single large nucleus that is central
Clinical relevance of smooth muscle?
Involuntary and so can be hard to control eg high blood pressure asthma etc
How are smooth muscle cells innvervated?
Autonomic nervous system sends signal to varicosities which release neurotransmitter into synaptic cleft
How to identify smooth muscle?
Long flat cells with long and flat nuclei when relaxed
Mature muscle repair?
Skeletal- cannot divide but satellite cells can go through mitosis to make more muscle cells- hyperplasia
Cardiac- cannot regenerate, fibroblasts lay down scar tissue
Smooth- can regenerate eg endometrium
Where would you find fast and slow contracting muscle fibres?
Fast in eye, slow in back
