Epithelial: Is made of cells arranged in a continuous sheet with one or more layers, has apical & basal surfaces.
A basement membrane is the attachment between the basal surface of the cell & the underlying connective tissue.
Two types of epithelial tissues: (1) Covering & lining epithelia and (2) Glandular Epithelium.
The number of cell layers & the shape of the cells in the top layer can classify epithelium.
Simple Epithelium - one cell layer
Stratified epithelium - two or more cell layers
Pseudostratified Columnar Epithelium - When cells of an epithelial tissue are all anchored to the basement Membrane but not all cells reach the apical surface.
Glandular Epithelium – (1) Endocrine: Release hormones directly into the blood stream and (2) Exocrine - Secrete into ducts.
Connective: contains many different cell types including: fibroblasts, macrophages, mast cells, and adipocytes.
Connective Tissue Matrix is made of two materials: ground substance - proteins and polysaccharides, fiber – reticular, collagen and elastic.
Classification of Connective Tissue:
oose Connective - fibers & many cell types in gelatinous matrix, found in skin, & surrounding blood vessels, nerves, and organs.
Dense Connective - Bundles of parallel collagen fibers& fibroblasts, found in tendons& ligaments.
Cartilage - Cartilage is made of collagen & elastin fibers embedded in a matrix glycoprotein & cells called chondrocytes, which was found in small spaces.
Cartilage has three subtypes:
Hyaline cartilage – Weakest, most abundant type, Found at end of long bones, & structures like the ear and nose,
Elastic cartilage- maintains shape, branching elastic fibers distinguish it from hyaline and
Fibrous Cartilage - Strongest type, has dense collagen & little matrix, found in pelvis, skull & vertebral discs.
Muscle: is divided into 3 categories, skeletal, cardiac and smooth.
Skeletal Muscle – voluntary, striated, striations perpendicular to the muscle fibers and it is mainly found attached to bones.
Cardiac Muscle – involuntary, striated, branched and has intercalated discs
Smooth Muscle – involuntary, nonstriated, spindle shaped and is found in blood vessels & the GI tract.
Nervous: Consists of only two cell types in the central nervous system (CNS) & peripheral nervous system (PNS):
Neurons - Cells that convert stimuli into electrical impulses to the brain, and Neuroglia – supportive cells.
Neurons – are made up of cell body, axon and dendrites. There are 3 types of neurons:
Motor Neuron – carry impulses from CNS to muscles and glands,
Interneuron - interpret input from sensory neurons and end responses to motor neurons
Sensory Neuron – receive information from environment and transmit to CNS.
Neuroglia – is made up of astrocytes, oligodendrocytes, ependymal cells and microglia in the CNS, and schwann cells and satellite cells in the PNS.
Development: All tissues of the body develop from the three primary germ cell layers that form the embryo:
Mesoderm – develops into epithelial tissue, connective tissue and muscle tissue.
Ectoderm - develops into nervous tissue and epithelial tissue.
Endoderm – develops into epithelial tissue.
Cell Junctions:
Tight Junctions - Form a seal between cells, define apical and basal sides of an epithelial cell
Gap Junctions - An open junction between two cells, which allows ions, & small molecules to pass freely between the cells.
Adherens Junctions - Link actin cytoskeletal elements in two cells.
Desmosomes - Link keratin filaments in adjoining cells and resist shearing forces.
Hemidesmosomes - Anchor keratin fibers in epithelial cells to the basement membrane through integrin anchors.
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"Title" Tutorial Summary :
This tutorial covers the four main types of tissue in the human body. It also includes a description of the anatomical location of those tissues within the body.
All 4 types of tissue originate from 3 primary layers in the developing human embryo. There are a number of cell junctions used by the various tissue types for contact with surrounding cells and the basement membrane, communication and for structural integrity.
Tutorial Features:
Specific Tutorial Features:
A detailed description of the epithelial tissue in the body is presented including a histological description, subtype classification and location within organs and glands and the function.
Series Features:
Concept map showing inter-connections of new concepts in this tutorial and those previously introduced.
Definition slides introduce terms as they are needed.
Visual representation of concepts
Examples given throughout to illustrate how the concepts apply.
A concise summary is given at the conclusion of the tutorial.
"Title" Topic List:
The four types of tissue in the human body: A tissue is a group of cells that is from similar embryological origin and is specialized for a particular function. Four types: epithelial, connective, muscle and nervous.
