8.1 Muscle Flashcards
What is the sarcolemma?
The outer membrane of a muscle cell
What is the sarcoplasm?
The cytoplasm of a muscle cell
What is the sacroplasmic reticulum?
The sarcoplasmic reticulum is the smooth endoplasmic reticulum of a muscle cell. It plays a role in stocking calcium
What are the 3 types of muscle we find in the body?
Skeletal, cardiac and smooth
Which muscle types are Striated?
Skeletal and cardiac
What muscle type is non-striated?
Smooth
Which muscle type has the longest cells? How do we explain this?
Skeletal because the individual cells span the whole length of the muscle.
Which type is muscle has multiple peripheral nuclei?
Skeletal
Which muscle type has spindle shaped cells?
Smooth
Which muscle type has cells that have branched ends?
Cardiac
At what speed to contractions occur in the various muscle types?
Skeletal: rapid and forceful
Cardiac: variable
Smooth slow, sustained and rythmic
What are the 3 different types of fiber that one finds in skeletal muscle and what differentiates them?
Red fibers - small and many mitochondria, rich vascularization, rich myoglobin, responsable for slower, repetitive weaker contraction! eg. postural back muscles
Intermediate fibres
White fibres - bigger, few mitochondria, poor vascularization, poor myoglobin, responsable for stronger and faster contraction. eg. extraocular and finger muscles.
What is myoglobin?
Myoglobin is a red protein containing haem, which functions as an oxygen storing molecule, providing oxygen to the working muscles.
Present in Skeletal and Cardiac muscle but NOT in smooth muscle!
Haemoglobin gives up oxygen to myoglobin especially when pH is low (i.e. in metabolically active tissues, where CO2 is produced)
A muscle cell is also the muscle…
fibre
Between fibres, cells, there is…
endomysium
the entier muscle is covered in a sheath called…
epimysium
Fibers are grouped into…
fascicules
Between muscle fascicules there is…
perimysium
What is epimysium?
The outer sheath surrounding a muscle
What is a muscle fascicule?
It is a group of muscle cells (and cells are fibres)
what is endomysium?
endomysium separates individual muscle cells (or fibres)
what is perimysium and what does it contain?
permysium separates muscle fascicules, it is connective tissue carrying nerves and blood vessels.
If going from cell to muscle, what is the hierachy?
Cell = fiber Endomysium Fascicule Perimysium Muscle Epimysium
Extrinsic vs intrinsic muscles?
Extrinsic muscles have insertions onto bone or cartilage
Intrinsic muscles are not attached to the bone, they are within the muscle, and enable it to changes shape, but not “position”
What is a sarcomere?
Sacromeres are the basic unit of striated muscle tissue. They are composed of Thick filaments made of myosin and thin filaments that are made of actin.
Myosin has a long fibrous tail and a globular haed that binds to actin. The myosin head also binds to ATP, source of energy fore msucle movement. Myosin can only binds to actin when the binding sites are exposed by calcium ions. ie need calcium for muscle movement.
Sacromeres habe a banded appearance.
What is the banding pattern of sarcomeres explained? I.e. What do each bands contain?
A sarcomere is delimited by 2 Z bands.
Then, moving towards center of the sarcomere we have the I bands, they are composed of actin.
Then, enter the A band, that spans all over the center of the sarcomere. The A band is made up of overlapping actin and myosin.
The A band also contains a central H zone, the H zone is made up only of Myosin.
The A band is the same length as 1 whole myosin filament.
Within H the is the M line.
ZI(A(H(M)H)A)IZ
Which bands of sarcomeres change during contraction?
I bands shortens
H bands shortens
A bands stays the SAME!
What is atrophy?
atrophy is when destruction overides replacement, resulting in loss of msucle
What is hypertrophy?
when replacement overides destruction
