Muscle Tisue (Structure & Function)

Question 1

What is Myalgia?

Answer 1

Muscle pain

Question 2

What s Myasthenia?

Answer 2

Weakness of the muscles

Question 3

What is a myocardium?

Answer 3

Any muscular component of the heart

Question 4

What is myopathy?

Answer 4

Any disease of the muscles

Question 5

What is myoclonus?

Answer 5

A sudden spasm of the muscles

Question 6

List the two types of striated muscles.

Answer 6

Skeletal

Cardiac

Question 7

State the type of non-striated muscle.

Answer 7

Smooth muscle

Question 8

List some features of skeletal muscle.

Answer 8

Myoglobin present
Striated
Voluntary control
Direct nerve-muscle communication

Question 9

List some features of cardiac muscle.

Answer 9

Myoglboin present
Involuntary control
Indirect nerve-muscle communication
Striated

Question 10

List some features of smooth muscle.

Answer 10

Myoglobin is absent
Involuntary control
No direct nerve-muscle communication

Question 11

What is myoglobin and what its role in a muscle?

Answer 11

It’s a red protein that is structurally similar to a single subunit of heamoglobin

It stores O2 giving it up to working striated muscles

Heamoglobin gives O2 up to myoglobin, esp at low pH

Question 12

What happens when striated muscle dies (in terms of myoglobin) and what damage can this cause?

Answer 12

When the muscle dies (muscle necrosis) myoglobin is released into the bloodstream (myoglobinuria)

Kidneys remove it from the blood into the urine, the urge becomes tea-coloured.

May damage the kidneys if it builds up

Question 13

What is the outer membrane of a muscle cell called?

Answer 13

The sarcolemma

Question 14

What is the cytoplasm of a muscle cell called?

Answer 14

The sarcoplasm

Question 15

What is a sarcosome?

Answer 15

Another word for a muscle cells mitochondrion.

Question 16

What is the smooth endoplasmic reticulum called in a muscle cell and what does it hold?

Answer 16

It’s called the sarcoplasmic reticulum and it holds Ca2+ ions

Question 17

What does movement depend on in skeletal muscle?

Answer 17

Movement depends on the direction of muscle fibres contraction .

Question 18

What is a muscle origin?

Answer 18

Usual proximal to the insertion point (closer to the body than insertion point)

Doesn’t move during contraction

Tension is created here
Usually into bone or something sturdy

Question 19

What is a muscle insertion point?

Answer 19

Usually distal to origin (further from the body than origin)

May move during contraction (elbow moves = insertion, shoulder still = origin)

Where movement is created in contraction

Can be into bone, tendon or connective tissue

Question 20

What are extrinsic muscle attached to?

Answer 20

They attach to bone or cartilage

Eg(allow tongue to stick out, In and move side to side,)

Question 21

What is unusual about intrinsic muscles?

Answer 21

They are not attached to bone

Eg( allow tongue to Shante shape not position, aid swallowing)

Question 22

What are skeletal muscle fascicles surrounded by?

Answer 22

Each separate fascicles surrounded by perimysium (a form of connective tissue carrying nerves and blood vessels)

Question 23

Hw does blood supply to muscles correlate to muscle thickness?

Answer 23

Thick fibres require more blood.

Thin fibres require less blood.

Question 24

Describe the relative thickness of ACtin and MYosin and how they’d appear in microscopy.

Answer 24

Actin is the thinner filament so appears as the lighter section in microscopy.

The opposite is true for myosin

Question 25

What are the 3 types of striated muscle cells?

Answer 25

Slow twitch, fast twitch and intermediate

Question 26

Why is slow twitch fibres darker on a stain?

Answer 26

As they contain more myoglobin and mitochondria (to maintain energy for longer)

Question 27

Look at fibres twitch types table in PowerPoint

Answer 27

Y

Question 28

Describe the structure of cardiac muscle fibres.

Answer 28

Striated Centrally positioned nuclei (1/2 per cell), with glycogen around them Intercalated discs Branching fibres

Question 29

What are ANP and BNP?

Answer 29

Peptides released by ANP=atria, BNP=ventricles during heart failure. They reduce arterial pressure by decreasing blood volume and systemic vascular resistance ANP released in congestive heart failure BNP released in left ventricular hypertrophy and mitral valve disease

Question 30

What is cell hypertrophy?

Answer 30

When the number of cells remain the same but they all grow in size individually - tissue grows

Question 31

What is cel hyperplasia?

Answer 31

When the cells remain the same in size but they multiply in number - tissue grows

Question 32

What is the role of purkinje fibres and describe their cellular make-up.

Answer 32

They conduct action potentials rapidly eneabling ventricles to contract in synchronous manner. Have abundant glycogen (good conduction), sparse microfibrils and extensive gap junction sites.

Question 33

Describe the structure of smooth muscle cells

Answer 33

Spindle shaped (fusiform) Single central large nucleus No striations, sarcomeres or T tubules Can be stretched substantially ``` Form sheets, bundles or layers of thousands of cells Numerous caseload (cavelike invagination that sample external environ) ```

Question 34

What does smooth muscle contraction rely upon? And describe it compared to other muscular contraction.

Answer 34

Depends upon actin-myosin interactions Contraction is slower, more sustained and requires less ATP than other muscles May remain contracted for hours or days

Question 35

Due to smooth muscles involuntary nature it ca contribute to a number of conditions list some..

Answer 35

``` High BP (primary hypertension) Dysmenorrhea (painful menstruation) Asthma Abnormal gut mobility (IBS) Incontinence ```

Question 36

How do smooth muscle initiate contraction?

Answer 36

Innervated by autonomic nervous system fibres. They release neurotransmitters from varicosities into a wide synaptic cleft

Question 37

How do skeletal muscles repair?

Answer 37

The regenerate by the mitotic activity of satellite cells, so hyperplasia follows muscle injury. Satellite cells can also fuse with existing muscle cells to increase mass. (Hypertrophy)

Question 38

Can cardiac muscle regenerate?

Answer 38

Adult cardiac muscles are incapable of regeneration. After damage fibroblasts invade, divide and lay scar tissue

Question 39

How do smooth muscle cells regenerate? Give a prevalent example,

Answer 39

They retain their mitotic activity so can form new muscle cells Evident in pregnant uterus where muscle wall becomes thicker by hypertrophy and hyperplasia.