ANIM2051 Chapter Notes - Chapter 7 (ed. 2): Loose Connective Tissue, White Adipose Tissue, Ultimate Tensile Strength
ANIM2051 – Anatomy and Physiology
WEEK 3
TEXTBOOK PAGES 199-122
Connective tissue; found everywhere in the body and represents the most abundant type of tissue
type by weight.
- Derived from mesoderm and composed primarily of nonliving extra-cellular matrix
- Is vascularised
Loose connective tissue and adipose connective tissue possess good blood supply whereas denser
connective tissue is poorly vascularised.
All connective tissue composed of; extracellular fibres, ground substance and cells.
- Mixture of fibre and ground substance is called the extracellular matrix
- Variation in these two mean connective tissue takes on different qualities
The ground substance in connective tissue is an amorphorus, homogenous material that ranges in
texture from a liquid, gel or solid. It is the medium in which cells exchange nutrients and waste with
the bloodstream, acts as a shock absorber and the thick texture works as an effective obstacle for
invading microorganisms.
Connective tissue fibres; collagenous, reticular and elastic.
Collagenous; strong, thick strands composed of collagen, a structural protein. They are organised
into discrete bundles of long, parallel fibrils. They possess tensile strength which allows them to
resist pulling forces and are found in tendons and ligaments. They are known as the white fibres.
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Reticular; composed of collagen but not thick. Thin, delicate and branched in complicated networks.
They provide support for highly cellular organs such as endocrine glands, lymph nodes, spleen, bone
marrow and liver.
Elastic; composed primarily of elastin. They are branched and form complicated networks but lack
tensile strength. They are composed of bunches of fibrils and stretch like a rubber band because
they are coiled. They occur in tissues prone to stretching such as vocal cords, lungs, skin and blood
vessel walls. They are sometimes referred to as the yellow fibres.
Major Cell Types
Fixed Cells
- Fibroblast; large, irregularly shaped cells which manufacture and secrete fibres and ground
substance
Each type of connective tissue is characterized by a predominant fibroblast (cartilage contains
chondroblasts, bone contains osteoblasts and connective tissue contains fibroblasts).
Adipose cells are fat cells!
- Reticular cells; flat, star shaped cells with log reachig ars that touch other cells, forig
netlike connections. They are involved in the immune response and manufacture of reticular
fibres.
Wandering Cells
Leukocytes, mast cells and macrophages.
- Leukocytes (white blood cells); found in blood and move into connective tissue in large
numbers when infection arises. They can squeeze through the walls of tiny blood vessels to
enter the surrounding tissue (dispedesis)
- Mast cells; oval cells that contain histamine and heparin, which initiate an inflammatory
respone. Found near blood vessels, they burst open when invaders are near and release
granules.
- Macrophages engulf microbes, dead cells and debris.
TEXTBOOK PAGES 122-129
In general, connective tissue is divided into two broad categories: connective tissue proper and
specialised connective tissue.
Connective tissue proper
- Contains every subtype of tissue except bone, cartilage and blood
- Two subclasses: loose connective tissue (areolar, adipose and reticular) and dense
connective tissue (dense regular, dense irregular and elastic)
Loose connective tissue
Areolar tissue; tangle of fibres and cells suspended in a thick translucent ground substance. It
appears relaxed with a myriad of round and star shaped cells placed amongst crisscrossing fibres.
Means small, open space. Acts as packing material to support and cushion organs and other delicate
structures, surrounds every organ; forms the subcutaneous layer that connects skin to muscle and is
present in all mucous membranes. Moderately elastic but tears easily.
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Document Summary
Connective tissue; found everywhere in the body and represents the most abundant type of tissue type by weight. Derived from mesoderm and composed primarily of nonliving extra-cellular matrix. Loose connective tissue and adipose connective tissue possess good blood supply whereas denser connective tissue is poorly vascularised. All connective tissue composed of; extracellular fibres, ground substance and cells. Mixture of fibre and ground substance is called the extracellular matrix. Variation in these two mean connective tissue takes on different qualities. The ground substance in connective tissue is an amorphorus, homogenous material that ranges in texture from a liquid, gel or solid. It is the medium in which cells exchange nutrients and waste with the bloodstream, acts as a shock absorber and the thick texture works as an effective obstacle for invading microorganisms. Collagenous; strong, thick strands composed of collagen, a structural protein. They are organised into discrete bundles of long, parallel fibrils.
