Muscle tissue histology

Question 1

Skeletal muscle?

Answer 1

• attached to the skeleton

- involved in such things as limb movement

Question 2

Smooth muscle?

Answer 2

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

Question 3

Cardiac muscle?

Answer 3

-makes up the bulk of the walls of the heart.- myocardium

Question 4

What are skeletal and cardiac muscles made up of?

Answer 4

striated muscle- composed of light and dark bands

Question 5

What are the involuntary muscle?

Answer 5

cardiac and smooth muscle as they are controlled by the ANS which means they are not consciously controlled.

Question 6

What is the voluntary muscle?

Answer 6

skeletal muscle

• controlled by the somatic nervous system
• its voluntary as its contractions are under conscious control

Question 7

what are the skeletal muscle fibre composed off ?

Answer 7

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

Question 8

what are muscle cells held together by ?

Answer 8

muscle cells are held together by connective tissue elements which also transmit the blood supply to the muscle cells

Question 9

what structures will you see when looking at muscle cells under microscope?

Answer 9

muscle cells are highly innervated so you will see blood vessels, connective and nervous tissue

Question 10

what is the function of 6 extraocular muscles of the eye ?

Answer 10

they serve to move the eye in various direction

Question 11

where are the 6 extraocular muscles located ?

Answer 11

they attach to the skull posteriorly and insert into the sclera of the eye anteriroly

Question 12

what is the function of orbicularis occuli?

Answer 12

facial muscle that encircles the eye and its contraction results in eye closure

Question 13

what os function of levator palpebrae superioris ?

Answer 13

raises the eyelid

Question 14

what is the advantage of skeletal muscles being striated ?

Answer 14

they have more forceful contraction

Question 15

what is the size of skeletal muscle ?

Answer 15

3-4 cm length

up to 150 um wide

Question 16

when viewing skeletal muscle cells longitudinally

what are the white spaces and blue fragments?

Answer 16

. white space- blood vessel

. blue fragment- nuclei

Question 17

what other structures do you see when viewing skeletal muscle cells longitudinally?

Answer 17

. nervous tissue

. proteins ( actin and myosin )

Question 18

where is the nuclei on skeletal muscle ?

Answer 18

.several nuclei pushed to the edge of cell at the periphery of the cell

Question 19

do skeletal muscle branch ?

Answer 19

. no

. cardiac muscles branch so faster conduction of action potential through out the heart

Question 20

what is myofibril?

Answer 20

Made of series of end to end sarcomeres

Question 21

What is the relationship between a myofibril and a muscle fibre?

Answer 21

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

Question 22

What is meant by the epimysium, perimysium and endomysium?

Answer 22

. 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 )

Question 23

Why does the muscle no longer appear striated in a transverse section?

Answer 23

planar section same orientation as striations – striations no longer perpendicular to planar sections

Question 24

what are the small holes in skeletal muscles- in transverse section?

Answer 24

blood vessel

Question 25

Do all the muscle fibres in this tissue look the same?

Answer 25

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.

Question 26

what is the shape of smooth muscle ?

Answer 26

spindle-shaped cells

Question 27

what is the size of smooth muscle ?

Answer 27

20-500 um

5 um wide

Question 28

Apart from size and the lack of striations, how else does a smooth muscle cell differ morphologically from a skeletal muscle fibre?

Answer 28

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

Question 29

Physiologically, how does smooth muscle compare to skeletal muscle?

Answer 29

Skeletal muscle is under voluntary control whereas smooth muscle is under involuntary control

Question 30

What advantages does smooth muscle have over skeletal muscle?

Answer 30

• 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

Question 31

What is the function of oesophageal smooth muscle?

Answer 31

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

Question 32

What type of epithelium lines the oesophagus?

Answer 32

Stratified squamous epithelium

Question 33

Why do arteries have a smooth muscle component?

Answer 33

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

Question 34

What is the function of the ciliary body?

Answer 34

Change shape of the lens in the eye during accommodation to help with the focusing.

Question 35

How do you view longitudinal sections?

Answer 35

low power in microscope

Question 36

How do you view transverse sections?

Answer 36

High power in microscope