Lab 11 - Muscle Histology

Question 1

What can muscle tissue be divided into

Answer 1

Skeletal muscle
Smooth muscle
Cardiac muscle

Question 2

What is skeletal muscle

Answer 2

Attached to skeleton, involved in such things as limb movement

Question 3

What is smooth muscle

Answer 3

Located in the hollow organs of the body such as blood vessels, and the ‘tubes’ of the respiratory & digestive system.

Question 4

What is cardiac muscle

Answer 4

Makes up bulk of walls of the heart ( myocardium )

Question 5

What does skeletal and cardiac muscle look like under the microscope

Answer 5

Light and dark bands

Question 6

Are skeletal and cardiac muscle striated or non striated

Answer 6

Striated

Question 7

What can striated muscles do

Answer 7

Generate a lot of force quickly

Question 8

Properties of smooth muscle

Answer 8

• Less forceful

- Lacks striations

Question 9

What muscles innervated by ANS

Answer 9

Smooth and cardiac
Their contractions cannot be consciously controlled.
Invoulantary muscle

Question 10

What muscle is innervated by Somatic NS

Answer 10

Skeletal
Contractions are under conscious control.
Voluntary

Question 11

What are muscles composed of

Answer 11

Number of individual muscle cells

Question 12

What are muscle cells referred to as

Answer 12

Muscle fibres - elongated

Question 13

Properties of muscle fibres

Answer 13

• Filled with cytoplasm (sarcoplasm) and are enclosed by a plasma membrane (the ‘sarcolemma’).
• Contain all the usual organelles (mitochondria, nucleus etc.
• Much of the cell is filled with the contractile proteins (myofilaments) actin and myosin.

Question 14

Properties of muscle cells

Answer 14

• Held together by connective tissue elements, which also transmit the blood supply to the muscle cells
• Heavily innervated - so when you look at muscle tissue under the microscope you will see blood vessels, connective and nervous tissue

Question 15

How many groups of skeletal muscle are associated with the eye

Answer 15

2

Question 16

6 extraocular muscles

Answer 16

• Attach to the skull posteriorly and insert into the sclera of the eye anteriorly
• They serve to move the eye in various directions

Question 17

What does skeletal muscle do in terms of the eye

Answer 17

Raising and lowering the eyelids

e. g. orbicularis occuli is a facial muscle that, encircles the eye and its contraction results in eye closure.
e. g. levator palpebrae superioris, raises the eyelid. - located above the eye

Question 18

What is the advantage of skeletal muscles being striated rather than smooth

Answer 18

Have more forceful contractions

Question 19

What are the dimensions of skeletal muscle cells

Answer 19

Can be very long (3-4 cm) and relatively wide (up to 150mm).
= LARGE AND MULTINUCLEATE

Question 20

What is levator palpebrae superioris muscles stained with

Answer 20

Toluidine blue

Question 21

What are the white spaces shown in extraocular muscle

Answer 21

Blood vessels

Question 22

What are the blue fragments shown in extraocular muscle

Answer 22

Nuclei

Question 23

What are other structures in extraocular muscle

Answer 23

Axons

Myelin

Question 24

What is the bulk of a skeletal muscle cells’ interior occupied by and what does this result in

Answer 24

The contractile proteins, actin and myosin

Consequently the nuclei and other intracellular organelles are pushed to the edge of the cell against the sarcolemma.

Question 25

Identify the nuclei and the location of the other organelles in skeletal muscle cel

Answer 25

Pushed to the edge of the cells. Straited skeletal muscle - more than one nuclei per cell

Question 26

Do the fibres branch in skeletal muscle

Answer 26

No

Question 27

How are microfilaments arranged in skeletal muscle

Answer 27

(actin and myosin) are arranged in an orderly overlapping manner into sarcomeres (

Question 28

What is a myofibril

Answer 28

Made of series of end to end sarcomeres

Question 29

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

Answer 29

Myofibrils run the entire length of the muscle fiber and many myofibrils are found in a muscle fiber

Question 30

What is longitudinal axis

Answer 30

Along axis of the cell

Question 31

What is transverse section

Answer 31

Cross section - fibres coming towards you out of the page

Question 32

How are fibres of many skeletal muscles such as superior oblique arranged

Answer 32

Bundled together in fascicles

Question 33

What is epimysium

Answer 33

Surrounds the entire muscle | The interstitial connective tissue of muscle is subdivided into the epimysium

Question 34

What is perimusium

Answer 34

Sheath of connective tissue that groups muscle fibers into bundles

Question 35

What is endomysium

Answer 35

Connective tissue that surrounds each muscle fiber

Question 36

Why does the muscle under higher power no longer appear striated

Answer 36

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

Question 37

What are the small holes in the muscle fibres

Answer 37

Blood vessels

Question 38

Do all muscle fibres look the same in skeletal muscle

Answer 38

- 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. - Nuclei to the edges .

Question 39

Properties of smooth muscles fibres

Answer 39

- Contain far less actin and myosin, and these contractile proteins are randomly arranged inside the cell, which accounts for its lack of regular striations. - Smooth muscle tissue is found in the walls of glands and of hollow structures within the body (i.e, the digestive, respiratory, urinogenital & vascular systems), the movements of which are not under voluntary control. - Spindle shaped cells

Question 40

What is dimension of smooth muscle cells

Answer 40

Much smaller (only 20-500 mm long) and thinner (~5 mm wide)

Question 41

What is the function of ciliary muscle?

Answer 41

Change the shape of the lens in the eye to help with focusing

Question 42

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

Answer 42

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 43

Physiologically, how does smooth muscle compare to skeletal muscle

Answer 43

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

Question 44

What advantages does smooth muscle have over skeletal muscle?

Answer 44

- 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 45

- 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

Answer 45

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 46

What type of epithelium lines the oesophagus?

Answer 46

Stratified squamous epithelium

Question 47

What determines amount of artery surrounding smooth muscle

Answer 47

Type of artery

Question 48

Property of veins

Answer 48

- Generally have less muscle in their tunica media = Walls are usually thinner

Question 49

Why do arteries have a smooth muscle component?

Answer 49

This is because they have to carry pumped blood away from the heart to all the organs and tissues that need the oxygenated blood. Maintain and control blood pressure