Histology

Question 0

What is the appearance of hyaline cartilage? What fibres is it made from and where is it found?

Answer 0

It is translucent, made from collagen type II and is found in major air pipes, articulating surfaces and foetal skeleton.

Question 1

What are the three types of cartilage?

Answer 1

Hyaline, Elastic and Fibrocartilage

Question 2

What does elastic cartilage look like? What fibres and where is it found?

Answer 2

It appears yellowish, made of elastic fibres and found in external ear and epiglottis.

Question 3

What does Fibrocartilage look like? What is it made of and where is it found?

Answer 3

White. It’s made of dense CT and hyaline with collagen type I fibres. Found in pubic symphysis and intervertebral disks.

Question 4

What cartilage has rows of chondrocytes?

Answer 4

Fibrocartilage

Question 5

Name 3 functions of cartilage.

Answer 5

1. Shock absorber
2. Protection of articulating surfaces
3. Temporary skeleton for foetus

Question 6

Name three things that make up composition of cartilage?

Answer 6

1. Perichondrium
2. Cartilage cells
3. Cartilage ECM

Question 7

What is perichondrium?

Answer 7

It is a CT layer surrounding cartilage, made of collagen type I fibres and fibroblasts on the outside with cartilage progenitor cells on the inside. It is vascular and contains nerves and lymphatics too.

Question 8

Name three types of cartilage cell.

Answer 8

1. Chondroprogenitor cells
   Stem cells which line inner Perichondrium.
2. Chondroblasts
   More differentiated, oval cells inbetween perichondrium and ECM. They secrete ECM.
3. Chondrocytes
   Large round mature cells which lie in lacunae and maintain surrounding ECM. Less active

Question 9

What is interstitial growth?

Answer 9

It is growth of cartilage ECM from within. It happens only in the young at epiphyseal growth plate and is due to proliferation of chondrocytes which form nests, expanding the matrix.

Question 10

What is appositional growth?

Answer 10

Proliferation of chondroprogenitor cells which mature into highly active chondroblasts which secrete ECM and causes outer margin of cartilage to grow in adults.

Question 11

What 4 things is bone made of?

Answer 11

1. Periosteum
2. Endosteum
3. Bone matrix (ECM)
4. Bone cells

Question 12

What is periosteum?

Answer 12

Layer of dense CT that covers bone, containing bone stem cells. Important for bone growth and repair and is a site of anchorage to muscle, tendons and ligaments.

Question 13

What is endosteum?

Answer 13

Layer of bone stem and forming cells lining bone cavities. Important for bone growth, remodelling and repair.

Question 14

What is bone matrix made of?

Answer 14

30% osteoid.. Collagen type I in ground substance.

70% inorganic minerals.. Hydroxyapatite crystals. Binds to osteoid to mineralise it.

Question 15

What are the 4 types of bone cells?

Answer 15

1. Osteoprogenitor cells
2. Osteoblasts
3. Osteocytes
4. Osteoclasts

Question 16

Osteoprogenitor cells?

Answer 16

Stem cells in periosteum which differentiate into osteoblasts.

Question 17

Osteoblasts?

Answer 17

They secrete osteoid and mineralise it. Found in periosteum and endosteum and like osteoprogenitor cells, are much more active in the young.

Question 18

What do osteocytes do?

Answer 18

They are mature osteoblasts which maintain surrounding matrix. Neighbouring osteocytes communicate via gap junctions.

Question 19

What are osteoclasts?

Answer 19

Large multinucleate cells derived from monocytes and macrophages In marrow. They are bone resorbing cells which secrete acids and proteolytic enzymes in Howship’s lacunae.
PTH stimulates activity. Calcitonin inhibits.

Question 20

Two types of bone.

Answer 20

Woven (immature) and lamellar (mature)