Muscle tissue histology Flashcards
Skeletal muscle?
- attached to the skeleton
- involved in such things as limb movement
Smooth muscle?
which is located in the hollow organs of the body such as blood vessels, and the ‘tubes’ of the respiratory & digestive system. -less striations hence less contractions . less actin and myosin -single nucleus -spindle shaped cells
Cardiac muscle?
-makes up the bulk of the walls of the heart.- myocardium
What are skeletal and cardiac muscles made up of?
striated muscle- composed of light and dark bands
What are the involuntary muscle?
cardiac and smooth muscle as they are controlled by the ANS which means they are not consciously controlled.
What is the voluntary muscle?
skeletal muscle
- controlled by the somatic nervous system
- its voluntary as its contractions are under conscious control
what are the skeletal muscle fibre composed off ?
they are made of elongated cells ( fibres ) they filled with sarcoplasm and are enclosed by sarcolemma and contain the usual organelles mitochondria , nucleus and myofilaments actin and myosin
-Nuclei lie in the periphery of the cell
what are muscle cells held together by ?
muscle cells are held together by connective tissue elements which also transmit the blood supply to the muscle cells
what structures will you see when looking at muscle cells under microscope?
muscle cells are highly innervated so you will see blood vessels, connective and nervous tissue
what is the function of 6 extraocular muscles of the eye ?
they serve to move the eye in various direction
where are the 6 extraocular muscles located ?
they attach to the skull posteriorly and insert into the sclera of the eye anteriroly
what is the function of orbicularis occuli?
facial muscle that encircles the eye and its contraction results in eye closure
what os function of levator palpebrae superioris ?
raises the eyelid
what is the advantage of skeletal muscles being striated ?
they have more forceful contraction
what is the size of skeletal muscle ?
3-4 cm length
up to 150 um wide
when viewing skeletal muscle cells longitudinally
what are the white spaces and blue fragments?
. white space- blood vessel
. blue fragment- nuclei
what other structures do you see when viewing skeletal muscle cells longitudinally?
. nervous tissue
. proteins ( actin and myosin )
where is the nuclei on skeletal muscle ?
.several nuclei pushed to the edge of cell at the periphery of the cell
do skeletal muscle branch ?
. no
. cardiac muscles branch so faster conduction of action potential through out the heart
what is myofibril?
Made of series of end to end sarcomeres
What is the relationship between a myofibril and a muscle fibre?
Myofibrils run the entire length of the muscle fibre and many myofibrils are found in a muscle fibre.
Transverse section- be able to see them on the outside/edge
What is meant by the epimysium, perimysium and endomysium?
. fibres are grouped into fascicles and surrounded by connective tissue perimysium
. several fascicles make up the whole muscle which is surrounded by epimysium
. endomysium (connective tissue that surrounds each muscle fibre )
Why does the muscle no longer appear striated in a transverse section?
planar section same orientation as striations – striations no longer perpendicular to planar sections
what are the small holes in skeletal muscles- in transverse section?
blood vessel
Do all the muscle fibres in this tissue look the same?
No- have slightly different densities- are in different states, depends where you cut through – straight through plane (Actin or myosin)- every muscle fibre wouldn’t have the same number of myofibrils.
what is the shape of smooth muscle ?
spindle-shaped cells
what is the size of smooth muscle ?
20-500 um
5 um wide
Apart from size and the lack of striations, how else does a smooth muscle cell differ morphologically from a skeletal muscle fibre?
Smooth muscle – single nucleus
Skeletal muscle fibres are cylindrical, multinucleated, striated, and under voluntary control. Smooth muscle cells are spindle shaped, have a single, centrally located nucleus, and lack striations. They are called involuntary muscles
Physiologically, how does smooth muscle compare to skeletal muscle?
Skeletal muscle is under voluntary control whereas smooth muscle is under involuntary control
What advantages does smooth muscle have over skeletal muscle?
- It uses less energy (which is good as smooth muscle is continuously active) - energy efficient
- Ones does not want to generate a lot of force
What is the function of oesophageal smooth muscle?
The strong wave-like motions of the smooth muscle in the esophagus carry the food to the stomach, where it is churned into a liquid mixture called chyme
What type of epithelium lines the oesophagus?
Stratified squamous epithelium
Why do arteries have a smooth muscle component?
This is because they must carry pumped blood away from the heart to all the organs and tissues that need the oxygenated blood. Maintain and control blood pressure
What is the function of the ciliary body?
Change shape of the lens in the eye during accommodation to help with the focusing.
How do you view longitudinal sections?
low power in microscope
How do you view transverse sections?
High power in microscope
