Muscle Tissues Flashcards
What is epimysium?
Fibrous elastic tissue that surrounds a muscle
What is endomysium?
Loose connective tissue that surrounds each muscle cell/muscle fibre
What is perimysium
Surrounds. A bundle of muscle fibres eg a fascicles
In skeletal muscles , are nuclei central or peripheral ?
Peripheral
What are the three different types of muscle fibres ?
1) slow twitch
2) fast twitch
3 intermediate twitch
What type of respiration do Type 1( slow twitch) , Type 2A and type 2b ( fast twitch) fibres undergo?
Type 1 and type 2A- aerobic which means they have many mitochondria , many cytochromes , have a rich capillary supply
Type 2B - anaerobic - which means they have few cytochromes, few mitchondria , poor capillary supply
What colour do each muscle fibres appear ?
Slow twitch - red ( high myoglobin levels)
Type 2A - red to pink ( high myoglobin levels)
Type 2B - white
What type of activity would you expect to use type 1 fibres ?
Endurance type
What type of activity would you expect type 2B to be used?
- strength activities
What does slow oxidative mean and what type of fibres produce ATP through this method?
- type 1
- produce many ATP through oxidative phosphorylation
- 36 mol / glucose ATP to allow low power contractions over long periods.
What does fast oxidative glycolytic fibres mean?
- produce ATP through aerobic and anaerobic respiration.
- type 2A fibres use this
What fibres use fast glycolytic ?
Type 2B - generate ATP through anaerobic respiration , produce lactate.
- generate ATP at a slow rate.
What are a few similarities between cardiac muscles and skeletal muscles ?
- both striated
- contraction mechanisms are the same
What are a few differences between cardiac and skeletal muscle?
- cardiac have intercalated discs which have low electrical resistance.
- cardiac are involuntary whereas skeletal are voluntary
- cardiac are uninucleated whereas skeletal are multinucleated.
- in skeletal muscles , nuclei are peripheral whereas in cardiac they are central
- in cardiac muscles , there is only one type of contractile cell- this being the cardiomyocyte.
How does the heart conduct electricity ?
1) action potentials are originated at the SAN in the right atria. This is sent across the atria causing them to contract. There is a non-conducting collagen fibre which prevents ventricles from contracting at this point.
2) action potentials are sent to the AVN .
3) action potentials then travel slowly across the AV bundle , then to bundle of his
4) then descends to Apex - then to purkyne fibres which conduct action potentials RAPIDLY
What are a few characteristics of purkyne fibres ?
- they conDuct electricity very quickly
2) have large cells
3) lots of glycogen
4) have extensive gap junctions to let ions pass through quickly .
What are a few characteristics of smooth muscles ?
- non striated
- involuntary
- uninucleated
- spindle shaped
- no sarcomeres , no T tubules
- nuclei are in the centre
- contraction is slower , requires less ATP
What would you expect from a TEM u,trastructure of smooth muscle ?
- fewer mitochondria
- gap junctions formCa2+ to enter
- caveolae
What are a few examples of where smooth muscle is found ?
- gut
- respiratory tract
- reproductive and urinary systems
What are a few illnesses that smooth muscle is responsible for ?
- asthma
- painful menstruations
- high blood pressure
- abnormal gut mobility eg diorreah and constipation
Is muscle repair possible in skeletal muscle ?
- muscle cells themselves cannot divide , but satellite cells which are a type of stem cells can divide by mitosis resulting in hyperplasia .
- they can also fuse with existing skeletal muscles cells to increase muscle mass ( hypertrophy)
Is muscle repair possible in cardiac muscle ?
- only on children , not adults
- in adults , fibroblasts invade and divide and lay down scar tissue
-
Can smooth muscle repair itself ?
Yes , they retain their mitotic ability , for example during pregnancy muscle wall expands and in asthma.
Where in the body would you find many type 1 muscle fibres ?
Postural muscles such as those in the spine and neck.
Where would you find type 2A muscle fibres ?
- muscles of the arms
What do,our does the endomysium and perimysium stain with trichrome?
Blue/cyan
What donintercalated discs comprise of ?
Gap junctions
Desmosomes
Fascia adherens
What is the role of calveoli on the sarcolemma surface of smooth muscle cells ?
- constantly sample the external environment and use the contents to initiate some forms of contraction.
Why are purkyne cells usually stained pale white ?
- high glycogen content
Where is the sinoatrial node located ?
- in the wall of the heart (myocardium) of the right atrium , in a region called sinus venarum.
During skeletal muscle damage what components would be found in blood ?
- tropnin C , I, T
- creatine kinase
- K+ ( because high intracellular concentration)
During cardiac muscle damage an increase of what components would be found in blood ?
k+
- troponin I
- creatine kinase
In smooth muscle damage , what components would be found in the blood
k+ only
