Tissue Structure and Function (Wk 3)

Question 1

What are the classification of different type of connective tissue?

Answer 1

Fibrous -> Collagenous / Elastic

Fibro-cellular -> Areolar (loose) / Adispose -> White / Brown

Matrical (hard) -> Cartilage -> Hyaline (Glassy) / Elastic / Fibro-Cartilage

Matrical (hard) -> Bone -> Cancellous (spongy) / Compact (corticol).

Question 2

What is the structure of cartilage and how is it formed?

Answer 2

Structure: Chondroblasts (secrete the matrix). Contains proteoglycans, GAGs, Collagen Type II, elastin & water.

Chondrocytes (trapped within cartilage to maintain it).

Formation:

Young animals: intersitial growth where chondroblasts are laid down derived from messenchyme cells which undergo mitosis and lay down matrix and fibres. Chrondroblasts are trapped in lacunae of mature cartilage (clusters of 2-4 cells) and come chondrocytes.

Appositional Growth: Perichondrium growth. Cells differentiate to chondroblasts, divide and lay down matrix, to become trapped in laccunae and then chondrocytes within mature cartilage. This new cartilage expands outwards.

Question 3

How does the structure of Fibrous Elastic connective tissue link to its function with regards to a ligament in transverse cross section?

Answer 3

Ligament connects bone to bone and has elastic recoil, functioning to reposition bone.

Elastin fibres allow for recoil.

Fibres taper, thus different size in transverse cross section.

Question 4

How does the structure of Fribro-Cellular Aerolar (loose) connective tissue link to its function when rat subcutaneous tissue is stretched on a slide?

Answer 4

Thinner areas display individual collagen and elastic fibres.

Thicker parts display small nerves, arterioles, branching capillaries and thin walled venules.

Question 5

How does the structure of Fribro-Cellular Aerolar (loose) connective tissue link to its function when rat subcutaneous tissue is stretched on a slide?

How can elastin fibres, fibroblasts, artierole, capillaries, and venules be identified on such a specimen?

Answer 5

Thinner areas display individual collagen and elastic fibres.

Thicker parts display small nerves, arterioles, branching capillaries and thin walled venules.

Elastin: criss-cross fibres, may be branching or coiled if unattached
Fibroblasts: nuclei
Arteriole: Smooth muscle bands
Capillaries: thin walled
Venule: Absence of bands

Question 6

How does the structure of Fribro-Cellular white adipose connective tissue link to its function with regards to a lymph node?

Answer 6

Structure: Appears as mesh; which are fibres giving structure to adipose cells. Nb. Lipid is lost in preparation.

Function: Fat lipid storage, cushioning for delicate structures, for example, a lymph node and it’s surrounding nerves and blood vessels.

Question 7

What do fibres and the matrix give cartilage? How are different types of cartilage determined?

Answer 7

Fibres and Matrix give cartilage solid yet flexible consistency.

Different types of fibres in the matrix give rise to the differnt types of cartilage.

Question 8

What are Messenchyme Cells?

Answer 8

Mesenchyme is a type of animal tissue comprised of loose cells embedded in a mesh of proteins and fluid, called the extracellular matrix. … Mesenchyme directly gives rise to most of the body’s connective tissues, from bones and cartilage to the lymphatic and circulatory systems.

Question 9

Does articular cartilage have perichondrium? How does this impact on function?

Answer 9

No, cannot regenerate.

Question 10

How does the structure of Matrical connective tissue link to its function with regards to

1. Hyaline (trachea)
2. Elastic (larynx)
3. Fibrocartialge (vertebral disc)

Answer 10

Hyaline: trachea. Hyaline provides structure to airway, trachealis muscle contracts and relaxes to open and close. Perichondrial surface of outer hyaline is appositional growth; beginning with chrondroblasts, becoming chondrocyte clusters trapped within laccunae of mature cartilage.

Elastic: dense meshwork of larynx, stretch and recoil.

Fibrocartilage: dense layers of collagen fibres with chondrocytes present.

Question 11

Describe intramembranous and endochondral formation of Bone

Answer 11

Intermembranous: eg. Mandible: “membrane” bone form without cartilage. Mesenchyme replaced by bone:

1. Mesenchymal cells differentiate into osteoblasts which secrete osteoid
2. Oteoids become mineralised (multiple centres of ossification).

Endochondrial: epiphyseal growth plate:

1. Primary cancellous bone, osteoblasts lay down bone on calcified cartilage ->
2. hypertrophy and calcification ->
3. maturing ->
4. proliferating ->
5. Resting

Question 12

Describe the structure and locations of different types of Bone.

Answer 12

Periosteum - outer bone
Oseton
Outer circumferential lamella
Inner circumerential lamella 
Haversian [vertical] and Volkmann [horizontal][ canals
Lacuna (smaller than haversian canal)
Endosteum
Inner circumferential lamellae, surrounding the medullary and trabecular where bone marrow produces new red blood cells.

Question 13

What is the difference between the Haversian and Walkmans canal?

Answer 13

Haversian runs centrally within lamellae.

Volkmann’s run vertically to the Haversian’s canal.

Question 14

What is Haversian remodelling?

Answer 14

New osteons (secondary) growing in compact bone; taking over and then another osteon growing etc. Structure of bone remodels due to stresses put on bone.