I.
Tissue
A. Definition – group of similar cells and their
intercellular substance that performs a
specialized function
B. Histology – study of tissues
C. Basic types of tissue in humans
1. epithelial – tissue that covers body surfaces,
lines body cavities, hollow organs, ducts, and
forms glands
2. connective – protects, supports the body, its
organs, binds organs together, stores energy
reserves as fat, and produces immunity
3. muscle – movement tissue
4.nervous – initiates and transmits nerve
impulses that coordinate body activity
II. Epithelial Tissue
A. Characteristics
1. consists largely of closely packed cells with
little intercellular fluid
2. arranged in single or multiple layers
3. avascular – without blood vessels
4.have a nerve supply
5. high mitotic rate – healing/renewal
6.function for protection, filtration,
lubrication, secretion, digestion, absorption,
transportation, excretion, sensory receptors,
and reproduction
B. Arrangement of layers
1. simple – single later of cells found in areas
where passive and active transport are
needed
2. stratified – two or more layers used for
protection of underlying tissue in areas of
wear & tear
3. pseudostratified – one layer of a mixture of
cell shapes – looks multi-layered
C. Cell shapes
1. squamous – flat and attached together like
tiles
2. cuboidal – cube or hexagonal shape
- produce secretions (sweat, enzymes)
- can absorb – intestinal tract
3. columnar – tall and cylindrical – protection
of underlying tissue – specialized for
secretion and absorption, - can have cilia
4.transitional – cells vary in shape
- flat to columnar due to stretching of the
tissue
D.Layers and shapes – basis for classification of
tissue
1. simple – squamous, cuboidal, columar
2. stratified – squamous, cuboidal, columnar,
transitional
3. pseudostratified –columnar epithelium
E. Glandular epithelium – functions for secretions
- cells lie below outer epithelium
1. endocrine – ductless glands – hormones
2. exocrine – secreted into ducts – mucous,
sweat, oil, digestive enzymes
III. Connective Tissue – most abundant tissue in the
body – (embryonic is mesenchyme – all connective
tissues come from this)
A. Connective tissue proper – intercellular material
and matrix –hyaluronic acid – vicous, slippery
substance that binds cells –
- chondroitin sulfate - provides support
and adhesiveness in cartilage, bone, skin,
and blood vessels
B. Loose (areolar) tissue - most widely distributed
1. Fibrous
a. collagenous - (white), tough, resistant to
pulling, made of collagen
b.elastic – (yellow), smaller, provides
strength, skin, blood vessels, and lungs
c. reticular – thin – immature collagen –
collagen coated with glyco-protein –
supports walls of blood vessels, nerve cells,
and smooth cells – forms stroma –
framework of spleen and lymph nodes
2. Cells
a. fibroblasts – most numerous especially
active in repair
b.macrophages – large and function to engulf
bacteria and cellular debris by phagocytosis
c. plasma cells – secrete antibodies –
immunity
d.melanocytes – pigmented cells below the
deepest layer of skin – produce melanin
e. mast cells – produce heparin(anti coagulant) and histamine – a chemical that
dialates small blood vessels during
inflammation
3. Location – widespread - (mucous membranes),
around blood vessels, and nerves, subcutaneous
B. Adipose tissue – tissue composed of cells called
adipocytes – fat storage
1. shape – signet ring shaped
2. subcutaneous – location
3. functions - good insulation, energy reserve,
protection of internal organs
C. Dense collagenous tissue – more numerous cells
and thicker fibers
1. locations – muscles, ligaments, tendons
2. functions – provide elasticity
D.Elastic tissue
1. structure – freely branched fibers
–
stretch and snap back
2. location – muscles, ligaments, tendons
3. function – allow for elasticity
E. Cartilage – no blood vessels or nerves except in
the perichondrium – tissue around cartilage
1. characteristics
a. dense network of collagin and chondroitin
sulfate
b.resilient
c. strong
2. types
a. hyaline – gristle – bluish white color, shiny
substance, - most abundant
- found in embryonic skeleton (exclusively)
- found on the end of long bones and costal
region
b. fibrocartilage
- found in matrix to give strength
- bundles of collagin fibers
- threadlike network for elasticity
d.elastic
 threadlike network for elasticity
F. Osseous tissue (bone) – skeletal system – basic
unit is osteon – composed of:
1. lamellae – concentric rings of hard matrix calcium
2. lacunae – spaces between lamellae – has
Haversian canal – contains blood vessels and
nerves
G. Vascular tissue (blood) – connective tissue –
plasma – mostly H2O with dissolved substances
such as nutrients, wasts, enzymes, hormones,
respiratory gasses (O2, CO2)
1. erythrocytes – red blood cells
2. leucocytes – phagocytosis, immunity
3. platelets - clotting
IV. Other tissue
A. membranes (pg 95)
B. muscle tissue – high specialized cells for
contraction
1. smooth – walls of internal organs (hollow) –
involuntary – non striated
2. cardiac – wall of heart – involuntary –
striated – 1 nucleus
3. skeletal – striated, voluntary, fibers are
cylindrical and striated – multiple nucleus
C. nerve tissue
- consists of neurons
1. neurons – cells that receive stimulus and
convert to impulse, as well as carry
impulses to other nerves, muscles or
glands.
a. Dendrites – converging branches the
take the impulse towards the cell body
b. Axons – long, single strand that
conducts impulses away from the cell
body
2. neuroglea - cells for protection and
support of neurons
a. they do not conduct
b. common site of tumors