Skeletal Muscle- Histology

Question 1

Describe the development of muscle?

Answer 1

• Myoblasts align and fuse together to form myotubes.
• Myotubes synthesize the proteins to make myofilaments
• Part of the myoblast population does not fuse and remains mesenchymal cells called satellite cells.

Question 2

What do satellite cells do?

Answer 2

•Satellite cells proliferate and produce new muscle fibres following muscle injury.

Question 3

Name the 3 types of tissues?

Answer 3

Skeletal
Cardiac
Smooth

Question 4

What are the 3 properties that muscles are bases on?

Answer 4

Voluntary or involuntary contractions
Striated
Location

Question 5

Define Skeletal muscle?

Answer 5

Skeletal muscle (striated) - voluntary muscle. Involved in moving and stabilising bones and other structures.

Question 6

Define Cardiac muscle?

Answer 6

Cardiac muscle (striated) - involuntary l muscle that forms most of the walls of the heart.

Question 7

Define smooth muscle?

Answer 7

Smooth muscle (not striated)- involuntary muscle that forms part of the walls of most vessels and hollow organs. Moving substances through them by pulsations or peristaltic contractions.

Question 8

Define type 1 fibres

Answer 8

rich blood supply and use oxygen to release energy. More resistant to fatigue.

Question 9

Define type 2 fibres

Answer 9

fast twitch fibres

Question 10

Whats the difference between Type 2a and Type 2b Fibres?

Answer 10

Type IIa – a hybrid of type I and type II. Respire aerobically, resulting in resistance to fatigue, but can also hydrolyse ATP quickly using aerobic and anaerobic metabolism.

•Type IIb – anaerobic, extracting energy from organic molecules in cells. Lots of energy produced rapidly, but fatigue quickly.

Question 11

How much mass does skeletal muscle make up?

Answer 11

40%

Question 12

What is the longest muscle in the body?

Answer 12

Sartorius

Question 13

What is the smallest muscle in the body?

Answer 13

Stapedius

Question 14

What os the biggest muscle in the body?

Answer 14

Gluteus maximus

Question 15

What are the 2 attachments in skeletal muscle?

Answer 15

Origin- attachment that moves the least

Insertion- attachment that moves the most

Question 16

How are Skeletal muscle joined to bone?

Answer 16

Skeletal muscle are joined to bone by tough connective tissue called tendons.

Question 17

What are the 4 functions of skeletal muscle?

Answer 17

Skeletal Muscle
Maintenance of posture
Support of soft tissues
Thermoregualtion

Question 18

Define a prime mover?

Answer 18

Muscle with the major repsonsibilty for certain movement

Question 19

Define an antagonist?

Answer 19

Muscles that opposes or reverses a prime mover.

Question 20

Define Synergist?

Answer 20

Muscles that aids a prime mover in a movement.

Question 21

Describe a flat muscle?

Answer 21

Have parallel fibre often with an aponeurosis

Question 22

Describe a pennate muscle?

Answer 22

Feather like deltoid

Question 23

Describe a fusiform muscle?

Answer 23

Spindle shaped with thick belly and tapered end

Question 24

Describe convergent muscles?

Answer 24

Arise from a broad area and converge to form a single tendon

Question 25

Describe quadrant muscles?

Answer 25

is equal muscles

Question 26

Describe circular muscles

Answer 26

Eyelids

Question 27

Describe Multiheaded muscles?

Answer 27

More than one head like biceps brachaii

Question 28

What are the large multinucleate cells in skeletal muscle?

Answer 28

They’re fused myoblasts surrounded by loose connective tissue containing collagen and elastin fibres which merge into the tendon at the site of muscle attachment.

Question 29

Define the structure of a skeletal muscle?

Answer 29

• Endomysium around single muscle fibre
• Perimysium around a fascicle (bundle of fibres)
• Epimysium covers the entire skeletal muscle
• Epimysium blends into a connective tissue attachment

Question 30

How do neurological impulses work in the skeletal muscle?

Answer 30

Impulses travel from the precentral gyrus nerves that supply muscles by releasing acetylcholine

Question 31

Explain how the skeletal muscle contracts?

Answer 31

Each muscle fibre contain hundred of myofibrils
Each myofibril is made up of actin and myosin
Myosin filaments use ATP to walk along the actin filaments using cross bridges.
This pulls the actin filaments closer together bringing the Z lines closer together shortening the sarcomere
They contract by pulling never pushing

Question 32

What filaments are anchored to z lines

Answer 32

Actin

Question 33

Define reflexive contraction?

Answer 33

Although skeletal muscles are referred to as voluntary, certain aspects are automatic

Question 34

Define tonic contraction?

Answer 34

Even when relaxed the muscles are slightly contracted.
This slight contraction does not produce movement but gives the muscles firmness. Assisting stability of joints and the maintenance of posture, while keeping the muscle ready to respond to appropriate stimuli.

Question 35

Define the 2 types of phasic contraction?

Answer 35

Isotonic
Muscle changes length in relationship to production of movement
There are 2 types concentric and eccentric contractions.

Isometric
Muscle length remains the same.

Question 36

Name some properties of cardiac muscle

Answer 36

Never fatigues 
Striated in appearance 
Heart
Single Nucleus 
Regulated intrinsically

Question 37

How does the heart act as a pacemaker?

Answer 37

An impulse conducting system composed of specialised cardiac muscle fibres.

Question 38

Name some properties of smooth muscle?

Answer 38

Fatigues slowly
Forms large part of the middle layer of wall blood vessels
Found in the skin forming arrector pilli muscles of hair and eyeball
CVS
Digestive system and urinary tract
Non strained, no sarcomeres and contains actin and myosin

Question 39

Define myositis

Answer 39

Autoimmune inflammatory disease of muscle skin, lungs and heart.
Breathing and swallowing is effective

Question 40

What is the primary treatment for myositis?

Answer 40

Steroids and DMARDS and in more severe cases, the biological therapy of rituximab is used.