Histology of Muscle, Cartilage and Bone

Question 1

What are 3 main features of skeletal muscles

Answer 1

Straited
Unbranched
Multinucleate

Question 2

What are the periphery of skeletal muscle fibres

Answer 2

Nuclei (just under cell membrane)

Question 3

What is another name for the cell membrane that encloses each muscle cell

Answer 3

Sarcolemma

Question 4

Skeletal muscle fibres are grouped into bundles called what?

Answer 4

fascicles

Question 5

What is the name of the connective tissue that surrounds the muscle as a whole called?

Answer 5

Epimysium

Question 6

What is the name of the connective tissue around a single fascicle called

Answer 6

Perimysium

Question 7

What is the name of the connective tissue around a single muscle fibre called?

Answer 7

Endomysium

Question 8

Describe the diameter of skeletal muscle fibres

Answer 8

Consistent and very little variation

Question 9

What aer the unit of contraction of muscle cells

Answer 9

Sarcomeres

Question 10

Sarcomeres are placed end to end to form what in a typical muscle cell

Answer 10

Myofirbril

Question 11

What type of filaments are anchored at the z disc?

Answer 11

Actin filaments

Question 12

Why do skeletal muscles appear striated?

Answer 12

The sarcomeres in the myofibrils with their alternating dark and light bands are held in registry with one another across the fibre. I.e. the Z disks in the sarcomere of one myofibril will be aligned with the Z disks of the sarcomeres in the surrounding myofibrils.

Question 13

Why do skeletal muscles and cardiac muscles look different even though they are both striated

Answer 13

The accuracy in cardiac muscles is not as good as it is in skeletal muscles

Question 14

What does a motor unit consist of

Answer 14

1 motor neurone and all of the muscle fibres that it innervates

Question 15

Describe the control of movement based on the number of muscle fibres in a motor unit

Answer 15

The fewer the number of muscle fibres in a motor unit, the fibre the control of movement

Question 16

What does the axon of the motor neurone do as it nears its termination

Answer 16

It branches

Question 17

What does each axon branch end in ?

Answer 17

A special type of synapse called the neuromuscular junction

Question 18

How often is a muscle fibre touched?

Answer 18

Only once, regardless of its size

Question 19

How many types of skeletal muscle are there?

What is the difference between these

Answer 19

3

Based on differences in the biochemistry, morphology and physiology of the fibres

Question 20

Describe Type 1 skeletal muscle

Answer 20

relatively slowly contracting fibres that depend on oxidative metabolism.
Abundant mitochondria and are resisitant to fatigue
Red fibres
Great force but slow contracting
High conc. of myoglobin

Question 21

Describe type IIa skeletal muscle

Answer 21

Intermediate between type I and TypeIIB
Relatively fast congtracting but are also reasonably resistant to fatigue
Uncommon fibres

Question 22

Describe type IIb skeletal muscle

Answer 22

Fast contracting fibres that depend on anaerobic metabolism 
Few mitochondria
Fatigue relatively easily 
Produce great force 
Called white fibres 
Low myoglobin

Question 23

What stain can be used to determine the different types of skeletal muscle

Answer 23

Succinate dehydrogenase stain

Question 24

List some of the features of cartilage

Answer 24

Semi-rigid and deformable
Permeable
Avascular
Cells nourished by diffusion through the extracellular matrix

Question 25

List some features of bone

Answer 25

Rigid Not permeable Cells within the bone must be nourished by the blood vessels that pervade the tissue

Question 26

What are cells gound in cartilage called

Answer 26

Chondrocytes (chondroblasts when immature)

Question 27

Where do chondrocytes live

Answer 27

Within a space in the extracellular matrix termed a lacuna

Question 28

What do chondrocytes do?

Answer 28

they are active cells which not only secrete but also maintain the extracellular matrix around them

Question 29

What is the most common form of cartilage

Answer 29

Extracellular Matrix in Cartilage (hyaline)

Question 30

What is ECM made from

Answer 30

75% water and 25% organic material

Question 31

What type of collagen is found in most connective tissues?

Answer 31

Type 1

Question 32

What does Type II collagen form

Answer 32

A 3-meshwork

Question 33

Describe the colour of Hyaline cartilage

Answer 33

Blue-white in colour and translucent

Question 34

Descibe the colour of Elastic cartilage

Answer 34

Light yellow in colour

Question 35

What makes elastic cartilage flexible

Answer 35

The addition of elastic fibres

Question 36

Describe the colour of fibrocartilage

Answer 36

Appears White

Question 37

What type of cartialge contains bands of densely packed type 1 collagen interleaved with rows of chondrocytes surrounded by small amounts of cartilaggenous ECM?

Answer 37

Fibrocartilage

Question 38

Where is hyaline cartilage found?

Answer 38

``` Articular surfaces Tracheal rings Costal cartilage Epiphyseal growth plates Precursor in fetus to many bones ```

Question 39

What are 5 functions of bone

Answer 39

``` Support Levers for effective movement Protection of internal organs Calcium sotre (more than 95%) Haemopoiesis (blood cell production) ```

Question 40

What is the main composition of one

Answer 40

Mineral (calcium hydroxyapatite crystals)

Question 41

What makes up the shaft (diaphysis) of long bones

Answer 41

An outer shell of dense cortical bone

Question 42

What occupies the ends of the bone (epiphyses)

Answer 42

Cancellous or trabecular bone

Question 43

What is the main difference between bone cells and the matrix

Answer 43

The presence of spaces adjacent to trabecular bone (marrow cavities)

Question 44

What is the name given to living cells in bone

Answer 44

Osteocytes

Question 45

What is the term given to the lines that are often visible surrounding the osteon

Answer 45

Cement lines

Question 46

What is the purpose of osteoprogenitor cells and where are they located?

Answer 46

Serve as a pool of reserve osteoblasts located on bone surfaces - e.g. under the periosteum

Question 47

What are osteoblasts and where are they located

Answer 47

Bone forming cells found on the surface of developing bone

Question 48

What are osteocytes

Answer 48

A bone cell trapped within the bone matrix

Question 49

What are osteoclasts

Answer 49

Large, multinucleated cells | They are found on the surface of bone and are responsible for bone resorption

Question 50

Where are osteoclasts believed to be derived from?

Answer 50

THe macrophage lineage of cells

Question 51

What 4 things doe osteoblases secrete which are all colectively termed osteoid

Answer 51

Collagen Glycosaminoglycans (GAGs) Proteoglycans Other organic components of the matrix

Question 52

Why does the bone that is laid down during devlopment of following a break differ from normal lamella bone

Answer 52

Because rather than having collagen fibres orientated all in one direction, the collagen fibres are laid down in a haphazard fashion. This is called woven bone

Question 53

What is the main difference between woven and lamellar bone

Answer 53

Woven is not as strong as lamellar bone

Question 54

What happens to woven bone over time

Answer 54

It is broken down by osteoclasts and reformed by new osteoblasts