Histology

Question 1

Where in a muscle fibre is the nucleus located?

Answer 1

Nuclei are at the periphery of the fibre

under the cell membrane (sarcolemma)

Question 2

Describe the difference between the three types of connective tissue found in muscle

Answer 2

Epimysium - surrounds the muscle as a whole

Perimysium - around a single fascicle

Endomysium. - around a single muscle fibre

Question 3

Describe the main differences between cartilage and bone

Answer 3

CARTILAGE:
Semi-rigid and Deformable
Permeable
Avascular
Cells nourished by diffusion through the extracellular matrix.

BONE:
Rigid
Not Permeable
Cells within the bone must be nourished by blood vessels that pervade the tissue.

Question 4

What cells make up cartilage?

Answer 4

chondrocytes

chondroblasts when immature

Question 5

Where can chondrocytes specifically be found?

Answer 5

space in the extracellular matrix = LACUNA

Question 6

What do chondrocytes do to the extracellular matrix around them?

Answer 6

secrete and maintain the extracellular matrix around them

Question 7

What components are found in the extracellular matrix of hyaline cartilage

Answer 7

75% water
25% organic material.
- 60% Type II collagen
- 40% proteoglycan

Question 8

Describe the main differences between Hyaline, Elastic and Fibrocartilage

Answer 8

Hyaline cartilage = blue-white in colour and translucent

Elastic cartilage = Light yellow in colour.
- The elastic fibres makes flexible

Fibrocartilage = white

• Hybrid between tendon and hyaline cartilage
• bands of densely packed Type 1 Collagen and rows of chondrocytes surrounded by little cartilagenous ECM

Question 9

Give examples of where hyaline cartilage is commonly found

Answer 9

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

Question 10

What are the main functions of bone?

Answer 10

Support  
  Levers for effective movement.
  Protection of internal organs (e.g. cranium, ribs)
  Calcium store
  Haemopoiesis

Question 11

Describe the basic make up of bone

Answer 11

65% bioapatite (a form of calcium phosphate)
23% collagen
10% water
2% non-collagen proteins

Question 12

What two types of bone can be recognised in a longitudinal section through a long bone?

Answer 12

Outer shell of dense cortical bone makes up the shaft (diaphysis)

Cancellous or trabecular bone occupies the ends of the bone (the epiphyses)

Question 13

What are the names given to the two types of canal carrying blood vessels in bone?

Answer 13

Haversian canal = supplies vessels that give vascular supply to osteocytes

Volkmanns canal = carries vessels transversely which branch into Haversian canals

Question 14

What is the main difference between cortical and trabecular bone?

Answer 14

presence of spaces (marrow cavities) adjacent to trabecular bone

Question 15

Why does trabecular bone generally lack Haversian canals?

Answer 15

the struts are thin

=> the osteocytes can survive from contact with the blood vessels in marrow spaces

Question 16

What are the main types of bone cells?

Answer 16

Osteoprogenitor cells
Osteoblasts 
Osteocytes
Osteoclasts
.

Question 17

What is the function of Osteoprogenitor cells and where are they found?

Answer 17

• located on bone surfaces

- function as a pool of reserve osteoblasts

Question 18

What is the main function of Osteoblasts?

Answer 18

• bone forming cells

- found on the surface of developing bone

Question 19

What type of bone cell is an Osteocyte?

Answer 19

bone cell trapped within the bone matrix

Question 20

Describe the appearance, location and function of osteoclasts

Answer 20

• large multinucleated cells
• found on the surface of bone
• responsible for bone resorption

Question 21

What do osteoblasts secrete?

Answer 21

collagen
glycosaminoglycans (GAGs)
proteoglycans
and organic components of the matrix

This is collectively termed OSTEOID

Question 22

What happens to osteoid secreted by osteoblasts over a period of time?

Answer 22

It becomes mineralized over time in the extracellular space

Question 23

What is woven bone?

Answer 23

During development/following a break

Bone has collagen fibres are laid down in a haphazard fashion rather than in one direction