Lecture 10 - Connective Tissue

Question 1

Name some of the cells of connective tissue

Answer 1

Fibroblasts, Chondrocytes, Osteocytes, Osteoblasts, Osteoclasts, Adipocytes, Stem cells, Bone marrow etc.

Question 2

What are the products of CT cells?

Answer 2

Fibres, ground substance, wax and gel like substances

Question 3

What 3 things are CTs made or structurally?

Answer 3

Cells, fibres and ground substance

Question 4

Describe some of the functions of CT.

Answer 4

Binding and support - Skin, lungs etc.

Protecting - Bone, fat

Insulation - Fat

Storage - Bone marrow storing cells, fat storing energy

Transport - Blood and interstitium

Tissue Separation - Fascia/tendons

Question 5

What are the two types of connective tissue and their subdivisions

Answer 5

Loose CT - Areolar tissue “little space”
Eg. Lamina Propria, basal lamina

Dense CT - Fibrous/collagenous tissue:

Irregular - fibres run in all directions
Regular - Fibres run parallel to one another

Question 6

Loose CT - Name the type of cells and the fibres present in loose CT

Also name the functions

Answer 6

Fibroblasts, macrophages, mast cells

Collagen and elastic

They hold fluid vessels, acts as packaging around organs, holds everything in place generally

Question 7

Function of fibroblasts

Answer 7

Fibroblasts produce fibres which are present in extracellular matrix aka ground substance

Can mature into myofibroblasts that contain actin for wound contraction

Question 8

Function of macrophages

Answer 8

Present during local inflammation especially, they phagocyte debris and foreign material

Antigen presenting cells too for T cells

Question 9

Mast Cells

Answer 9

Contain abundant granules of histamine, heparin and other substances

Present near blood vessels but not in CNS

Coated with IgE which bind to allergens, which then release these granules in the cells

Question 10

White Fat Cells vs Brown Fat Cells

Answer 10

Unilocular vs Multilocular

Normal levels of mitochondria vs Brown cells having LARGE no of mitochondria

Contributes to brown cells being better energy store and insulator

White adipose lipid breakdown is slow so not used to generate heat (shiver instead)

Brown cells used to generate heat via oxidative phosphorylation and lipid breakdown

Question 11

Describe the 4 types of collagen

Answer 11

Collagen I - 90% of all collagen, fibrils becomes fibres and fibre bundles, tendons, skin dermis, organ capsules etc.

Collagen II - Fibrils dont form fibres (hyaline and elastin cartilage)

Collagen III - Reticulin (muscle and nerve cells)

Collagen IV - Unique, present in basal lamina

Question 12

Pathogens that enter via epithelia can be treated by cells in the CT of the basal lamina, gland CT and around blood vessels. Causes CT to swell and then return to normal size

Answer 12

.

Question 13

2 examples of where loose CT is

Answer 13

Submucosa of the colon

Superficial layer of dermis

Question 14

What is ground substance?

Answer 14

Viscous, clear substance composed of proteoglycans binded to glycosaminoglycans

Forms a hydrated gel that allows rapid diffusion and resists compression

Example of GAG is hyaluronic acid, binds to PG via a link protein to form hydrophilic macromolecules

Present in cartilage

Question 15

Differentiate Irregular from Regular dense CT

Answer 15

Both contain fibroblasts

I : Collagen I fibres in all directions resists stress in all directions

Eg. deep dermis, submucosa of intestine

R : Parallel, one direction of stress resistance

Eg. Tendons, ligaments

Question 16

Look at histology of regular and irregular from lecture and describe them

Answer 16

.

Question 17

What causes the mechanical strength of the myotendinous joint?

Answer 17

Muscle fibres connect with tendon collagen bundles

Collagen passes from tendon to muscle and interacts w collagen fibres coating muscle

Question 18

Tendon anatomy

Answer 18

70% Collagen I
30% Collagen III (reticulum)

30% collagen
2% elastin
68% water

Question 19

What type of CT is in ligaments?

Answer 19

Regular dense CT
Parallel collagen fibres
Fibres undulate

Wrapped in loose CT to make fascicles

Between fascicles are ground substance

Question 20

What is fascia?

Answer 20

Connective tissue consisting of 3 types: Superficial, deep or visceral/parietal

Made of fibrous CT, bundles of collagen parallel to one another

Resist unidirectional tension forces

Question 21

Why do we need Vitamin C?

Answer 21

Vitamin C hydroxylates proline and lysine

This leads to form procollagen, which is secreted out of cell and forms collagen outside the cell

Without Vitamin C, cannot form collagen, leading to diseases such as scurvy

Question 22

What is scurvy?

Answer 22

Lack of vitamin C

Leads to thin collagen aggregating to create thick areas and thinner areas of collagen

Leads to gum disease, bruising, bleeding, poor wound healing

Question 23

Marfan’s syndrome

Answer 23

Autosomal doninant disorder

Expression of Fibrillin I affected, abnormal elastic tissue

Leads to arachnodactyly, abnormally tall, frequent joint dislocation, catastrophic aortic rupture

Question 24

Describe structure of elastin fibres

Answer 24

Elastin enfolds and surrounded by fibrillin microfibrils

Occurs in most CT

Important in lungs, artery walls, dermis etc.

Eg. tunica Intima, Tunica Media, Tunica externa

ELASTIN CANNOT BE REPLACED IN ADULTHOOD (smoking)

Question 25

Osteogenesis Imperfecta

Answer 25

“Brittle bone disease”

Due to mutated collagen fibres that do not knit together or not produced enough

Results in:

Weakened bones
Short stature
Blue sclera
Hearing loss
Hypermobility
Poor teeth