Structure and Function of Cells and Tissues – BIOM1004/1904

Connective Tissue Part 1

Dr Louise Dunford

Learning outcomes

• Define the four types of tissue in the human body

• Describe the composition of connective tissue

• Understand the variation in types of connective tissue

• Identify histological images from different types of connective tissue

Four Types of Tissue

• Muscle

• Nervous

• Epithelial

• Connective

Four Types of Tissue

Muscle:

• Body movement• Specialised for contraction

Nervous:

• Transmit messages• Electrical impulses

Four Types of Tissue

Epithelial:

ProtectionSecretion & absorption

Connective:

Supports, connects and separates tissues & organs

Why?

©Doulou

Types of Connective Tissue

Connective Tissue

All images © Eraxion

Connective Tissue

• Provides structural and metabolic support for other tissues and organs throughout the body

• Far more diverse than muscle, nervous and epithelial tissue

• Made up of cells, fibres, and ground substance

Cells

• Connective tissue generally has a low cell density

• Most common are fibroblasts; secrete extra-cellular matrix (ECM) in most tissues

• Chondrocytes (cartilage) & osteocytes (bone) secrete ECM

©Altogen.com

©Wellcome Images

Cells

• Immune cells – e.g. mast cells, tissue macrophages, all white blood cells, antibody-secreting plasma cells

• Adipocytes – storage and metabolism of fat

Fibres

• Extra cellular matrix (ECM) is made up of organised bundles of fibrous proteins and ‘ground substance’

• Fibres of connective tissue• Collagen• Elastin

Fibres: Collagen

• Most abundant protein in the human body; 27 types of collagen

• Type I – dermis of skin, tendons, ligaments, bone

• Type III – ‘reticulin’; liver, bone marrow, lymphoid organs

• Type IV – basement membranes

Fibres: Elastin

• Arranged as fibres or discontinuous sheets

• Properties: stretching and elastic recoil

• Skin, lung, blood vessels, bladder

©Martin Luther University

Ground Tissue

• Amorphous transparent material – semi-fluid gel

• Mixture of long, unbranched polysaccharide chains – glycosaminoglycans (GAGs)

• Associated with tissue fluid – mediates passage of molecules through the tissue

Types of connective tissue

• Loose connective tissue

• Dense connective tissue

• Elastic connective tissue

• Reticular connective tissue

• Adipose tissue

• Cartilage

• Bone

• Blood

Loose Connective Tissue

Collagen fibres

Elastin fibresNuclei of fibroblasts

Location: everywhere; support and elasticitye.g. subcutaneous tissue; around nerves, blood vessels, muscles

Function: support; reservoir for fluid & salts

Dense Connective Tissue

Collagen fibres

Nuclei of fibroblasts

Location: Tendons, ligaments, dermis of skin

Function: support; transmission of mechanical forces

Elastic Connective Tissue

Elastic fibres

Location: lung tissue, large arteries, skin, bladder

Function: confers elasticity

Reticular Connective Tissue

Reticular fibres

Location: Framework of liver, lymph nodes, spleen

Function: support

Adipose Tissue

Location: subcutaneous layer, pads around some organs

Function: support, insulation, energy storage

Nuclei

Lipid droplets

Cartilage

Location: ends of bones, ear, oesophagus

Function: flexible support

Chondrocytes

Lacuna

Bone

LacunaeLocation: skeletal structure

Function: support, protection, calcium reservoir

Haversian canal

Blood

Location: blood vessels, heart

Function: transport of nutrients, oxygen, hormones, waste

Neutrophil

Lymphocyte

Red blood cells

Quiz

1. Bone

2. Reticular connective tissue

3. Cartilage

4. Adipose tissue

5. Dense connective tissue

Resources

Stevens, A. & Lowe, J. Human Histology. 3rd edition, Gower/Mosby, (2004)  Young, B. & Heath, J.W. Wheater’s Functional Histology. 5th edition, Churchill-Livingstone (2008)

For some fantastic images of cells, fibres etc:http://wellcomeimages.org/Orhttp://www.biologyimagelibrary.com/home

Learning outcomes

Next time: Connective Tissue Part 2

• Define the four types of tissue in the human body

• Describe the composition of connective tissue

• Understand the variation in types of connective tissue

• Identify histological images from different types of connective tissue