Download INTEGUMENTARY SYSTEM

HISTOLOGY
THE STUDY OF TISSUES
GENERAL
Tissue = Cells with similar structure &
function organized into groups or layers
Four major types:
- Epithelial (Covers or lines surfaces, found
in glands)
- Connective (Binds & supports body parts)
- Muscle (Movement)
- Nervous (Detects changes & transmits info.)
CHARACTERISTICS OF
EPITHELIAL TISSUE
Covers all body surfaces inside & out
Many tightly packed cells, usually
arranged into layers
Free surface & basement membrane
Functions: protection, absorption,
sensation, secretion
High rate of cell division (healing)
Avascular (rely on diffusion)
Epithelial Cell Surface May be variously modified
CLASSIFICATION OF
EPITHELIAL TISSUE
 Layers
- Simple (one layer)
- Stratified (>1 layer; Note: only cells at
surface have characteristic shape)
 Shapes
- Squamous (thinnest, if simple)
- Cuboidal
- Columnar
- Transitional (changes shape)
CONNECTIVE TISSUE GENERAL
Few cells widely spaced in non-living
matrix
Matrix may be fibrous, solid, semi-solid,
fluid
Largest % of tissue by weight; found in all
body parts
Binds, protects, supports, transports,
storage, insulation
May be vascular
CONNECTIVE TISSUE GENERAL
Fibroblast
- Most common cell
- Secretes fibers
* Collagen – strong, flexible, structural
* Elastic – stretch & recoil
* Reticular – highly branched, supportive
Differs in type, amount, and arrangement
of fibers in matrix
Loose or dense; regular or irregular
MUSCLE TISSUE
Contract, provide movement
3 types based on location, morphology, &
function:
- Skeletal (attached to bones; voluntary
movement)
- Smooth (hollow organs; moves
substances through organs)
- Cardiac (heart; moves blood)
NERVOUS TISSUE
Rapidly regulates & coordinates body
functions
Brain, spinal cord, nerves
2 types of cells:
- Neuron (nerve cell)
* Most specialized cell in body
* Generates & transmits nerve impulses
- Neuroglia (“nerve glue”)
* Assist neurons (bind, protect, supply)
Hollow Organs
Substances pass through
Wall is composed of 3-4 layers
Lumen is term for inner space
Septum (internal wall) may subdivide
lumen
E.g. digestive organs, urinary tract, blood
vessels, ducts
Solid Organs
Outer Cortex
Deeper Medulla
May require internal support
Parenchyma is functional tissue; stroma
is supportive/filler tissue (usually deeper)
E.g. brain, spleen, kidney