L3 connective tissues

How is connective tissue distributed in the body?

Abundant and widely distributed

Where is connective tissue found?

Makes up part of every organ in the body

How are connective tissue cells arranged?

Cells are separated from each other by extracellular matrix (ECM)

What are the three main classes of connective tissue?

• Connective tissue proper

• Supporting connective tissues

• Fluid connective tissue

What functions does connective tissue perform?

• Connection (tendons, ligaments)

• Support (bones, cartilage)

• Enclosing/protection (capsules, bones)

• Separation (sheaths)

• Cushioning/insulation (adipose tissue)

• Storage (adipose tissue)

• Transportation (blood)

What is the germ layer origin of connective tissue?

Embryonic mesoderm

What are connective tissues composed of?

• Cells

• Extracellular matrix (ECM)

How does this differ from other primary tissues?

Other primary tissues are composed mainly of cells

What types of resident cells are found in connective tissue?

• Blasts – create the ECM

• Cytes – maintain the ECM

• Clasts – break down the ECM

Give examples of bone and cartilage cells.

• Osteoblasts / Chondroblasts – create

• Osteocytes / Chondrocytes – maintain

• Osteoclasts / Chondroclasts – break down

What other cell types are found in connective tissue?

• Adipose cells (adipocytes)

• Mast cells (mastocytes)

• Macrophages (phagocytes)

• White blood cells (leukocytes)

• Lymphocytes

• Undifferentiated mesenchymal stem cells

What is the ECM composed of?

• Ground substance

• Extracellular protein fibres

What do the properties of the ECM allow connective tissue to do?

Bear weight and withstand tension and trauma

What remains after a heart is de-cellularised?

Only the ECM scaffold

Why is an ECM scaffold useful?

Useful in artificial tissue and organ regeneration

Why is recellularising with a patient’s own cells beneficial?

Eliminates adverse immune responses and is better than a donor heart

What is ground substance?

: A gel-like fluid that fills the space between cells

What does ground substance contain?

• Water

• Two main groups of soluble proteins

What are the two main groups of soluble proteins in ground substance?

• Cell adhesion proteins

• Proteoglycans

What are cell adhesion proteins?

Connective tissue glue

Give examples of cell adhesion proteins.

• Fibronectin

• Osteonectin

• Chondronectin

What are proteoglycans?

Macromolecules with a protein core to which glycosaminoglycans (GAGs) are attached

What is attached to the protein core of a proteoglycan?

Glycosaminoglycans (GAGs)

What properties does this proteoglycan arrangement confer?

• High viscosity

• Low compressibility

Why is low compressibility useful?

Good for joints

How does GAG content affect ground substance

The higher the GAG content, the more viscous the fluid

List the important glycosaminoglycans (GAGs).

• Hyaluronic acid

• Chondroitin sulfate

• Heparan sulfate

• Dermatan sulfate

• Keratan sulfate

What is the function of connective tissue fibres?

Provide support

What are the three types of fibres?

• Collagen

• Elastic

• Reticular

What are key features of collagen fibres?

• Most abundant (6% body weight)

• Created by fibroblasts

• Rope-like structure requiring vitamin C

What are the main collagen types listed? and how many types are there?

• Type I – most abundant (tendons, ligaments)

• Type II – cartilage

• Type III – reticular fibres

25 types

What are the characteristics of elastic fibres?

• Long and thin

• Contain elastin

• Secreted by fibroblasts

• Form branching networks

Where are elastic fibres found?

Lungs and blood vessel walls

What are reticular fibres?

• Short, fine fibres

• Type III collagen

• Form branching networks

Where are reticular fibres abundant?

Liver, spleen, lymph nodes

What components make up connective tissue?

connective tissue proper, supporting connective tissue and fluid connective tissue

what are the parts of connective tissue and what makes them up?

what are the parts of supporting connective tissue and what makes them up?

what are the parts of fluid connectuve tissue and what makes them up?

what are some examples of loose connective tissue proper?

areolar. adipose and reticular

what are some examples of dense connective tissue proper?

regular collagenous and regular elastic, irregular collagenous and irregular elastic

What components make up connective tissue?

• Cells

• Extracellular matrix (ground substance + fibres)

What is connective tissue classification based on?

Physical properties

What are the three main classes?

Proper, supporting, fluid

What causes scurvy?

Vitamin C deficiency leading to defective collagen fibres

What causes Marfan’s syndrome?

Defective elastic fibres due to abnormal fibrillin-1

What causes pulmonary emphysema?

Destruction of elastic tissue from increased elastase activity

What is fibrosis?

formation of excess fibrous connective tissue

What is confluent fibrosis?

Scarring that obliterates normal tissue architecture

Where is bone marrow found?

Central cavity of large bones and spaces of spongy bone

What does bone marrow produce?

• Red blood cells

• White blood cells

• Platelets

• Lymphocytes

as you become a adult what areas no longer produce blood in the bone marrow?

arms apart from elbow and shoudlder and hand. and legs apart from hip, knee and feet.

What is leukaemia?

High numbers of immature or abnormal white blood cells

What treatments are listed for leukemia?

• Radiotherapy

• Chemotherapy

• Bone marrow transplant