Diversity of Cells Flashcards
What is the definition of a tissue?
A group of cells in close proximity, organised to perform one or more specific functions.
Describe an epithelial tissue.
Covers surfaces of the body or line hollow organs, as well as forming many glands.
They occur as sheets of cells (highly cellular) and vary widely in size, shape, orientation and function.
Provides protective boundaries through specialised junctions between connective tissues and free surfaces (internal organs, lining of body cavities, exterior surface of the body, tubes and ducts).
What are the characteristics of epithelial cells?
Highly cellular, functions as receptors, form a barrier, minimal ECM, avascular, innervated.
What are the three different types of epithelial tissue structure?
Squamous, cuboidal and columnar.
Describe the characteristics of a squamous tissue structure.
Cells are flattened, keratinized/ nonkeratinized, involved in protection and diffusion, found in capillary walls and skin.
Describe the characteristics of a cuboidal tissue structure.
Cells are cube shaped, form tubes in the nephrons of kidneys, involved in secretion and absorption.
Describe the characteristics of a columnar tissue structure.
Cells are rectangular, cilia often present, involved in absorption, secretion, protection and lubrication, form the inner lining of the gut tube.
Describe the 3 different types of layers that exist for epithelial tissue organisation.
Simple- one layer of cells.
Stratified- two or more layers of cells.
Pseudostratified- simple epithelia that appear to be stratified when viewed in cross section though they are only one layer.
Describe connective tissue.
Most abundant tissue type in the body that consists of cells and an ECM (ground substance and protein fibres).
Ground substance is an amorphous, space occupying material composed of large unbranched polysaccharide molecules known as glycoaminoglycans (GAGs), most of which are bound to protein cores to form glycoproteins.
Originates from mesenchyme (loosely organised embryonic tissue featuring elongated cells in a viscous ground substance).
What are the 3 types of connective tissue fibres?
Collagen fibres, reticular fibres and elastic fibres.
Describe collagen fibres.
Most abundant, high tensile strength and flexible.
Subunits- collagen fibrils (appear striated).
Describe reticular fibres.
Thinner than collagen fibres, found in extensive networks.
Provide structural support and framework.
Describe elastic fibres.
Thinner than collagen, able to return to their original shape.
What are the 3 classifications of connective tissue?
Proper connective tissue, dense connective tissue and specialised connective tissue.
Describe proper connective tissue.
Include loose connective tissue, often referred to as areolar tissue, and dense connective tissue. Loose connective tissue consists of thin, loosely arranged collagen fibres in a viscous ground substance.
What can dense connective tissue be further classified as?
Dense regular connective tissue and dense irregular connective tissue.
Describe dense regular connective tissue.
DRCT makes up tendons and ligaments. Fibres densely packed and organised in parallel to create a strong tissue capable of withstanding the pull of muscle and bone on movement.
Describe dense irregular connective tissue.
DICT contains abundant fibres but lacks directionality. High number of fibres to provide strength, disorganised pattern of fibres allows for flexibility. Associated with hollow organs of the digestive tract.
Provide examples of specialised connective tissue.
Adipose cells, bone tissue, blood and cartilage.
What are the characteristics of muscle tissue?
Extensible, elastic, contractile and organised into bundles.
What are the 3 types of muscle tissue?
Skeletal, cardiac and smooth.
Describe skeletal muscle.
Rapid and strong contraction; large, cylindrical, elongated cells; syncytium; peripheral and ovoid nuclei; striated; present in voluntary skeletal muscles.
Describe cardiac muscle.
Strong contraction; striated; single and centrally located nucleus, connected by gap junctions and intercalated discs; syncytium; found in the myocardium.
Describe smooth muscle.
Weak and slow contractions; spindle shaped cells; single and central nucleus; non-striated; found in involuntary muscles.
