Chapter 3 Cells and Tissues
Chapter 3 Cells and Tissues
Chapter 3 Cells and Tissues
Body Tissues
HISTOLOGY – the study of tissues
Tissues - Groups of cells with similar structure and function
Four primary types:
Epithelial tissue (epithelium)
o Locations: body coverings, body linings, and glandular tissue
o Functions: protection, absorption, filtration, and secretion
o Characteristics:
Cells fit closely together and often form sheets
The apical surface is the free surface of the tissue
The lower surface of the epithelium rests on a basement membrane
Avascular (no blood supply)
Regenerate easily if well nourished
o Classification
Number of cell layers
Simple – one layer
Stratified – more than one layer
Shape of cells
Squamous – flattened
Cuboidal – cube-shaped
Columnar – column-like
Simple Epithelia
o Simple Squamous
Single layer of flat cells
Locations: (usually forms membranes)
Lines body cavities
Lines lungs and capillaries
Functions in diffusion, filtration, or secretion in membranes
o Simple Cuboidal
Single layer of cube-like cells
Locations:
Common in glands and their ducts
Forms walls of kidney tubules
Covers the ovaries
Functions in secretion and absorption; ciliated types propel mucus or reproductive
o Simple Columnar
Single layer of tall cells
Often includes mucus-producing goblet cells
Locations: lines digestive tract
Functions in secretion and absorption; ciliated types propel mucus or reproductive
cells
o Pseudostratified Columnar
Single layer, but some cells are shorter than others
Often looks like a double layer of cells but all cells rest on the basement membrane
Location: respiratory tract, where it is ciliated
Functions in absorption or secretion
Stratified Epithelia
o Stratified Squamous
Cells at the apical surface are flattened
Functions as a protective covering where friction is common
Locations: lining of the skin, mouth, and esophagus
o Stratified Cuboidal
Two layers of cuboidal cells
functions in protection
o Stratified Columnar
Surface cells are columnar
Cells underneath vary in size and shape
Functions in protection
o Stratified Cuboidal and Columnar
Rare in human body
Found mainly in ducts of large glands
o Transitional Epithelium
Composed of modified stratified squamous epithelium
Shape of cells depends upon the amount of stretching
Functions in stretching and the ability to return to normal shape
Locations: lines organs of the urinary system
Glandular Epithelium
o Gland
One or more cells responsible for secreting a particular product
Secretions contain protein molecules in an aqueous (water-based) fluid
Two major gland types
Endocrine Gland
Ductless since secretions diffuse into blood vessels
All secretion are hormones
Exocrine Gland
Secretions empty through ducts to the epithelial surface
Include sweat and oil glands
Connective tissue
o Found everywhere in the body
o Includes the most abundant and widely distributed tissues
Functions
Binds body tissues together
Supports the body
Provides protection
o Characteristics
Variations in blood supply
Some tissue types are well vascularized
Some have a poor blood supply or are avascular
Extracellular matrix
Non-living material that surrounds living cells
Two main elements
Ground substance – mostly water along with adhesion proteins and
polysaccharide molecules
Fibers - produced by the cells
Three types
Collagen (white) fibers
Elastic (yellow) fibers
Reticular fibers
o Types
Bone (osseous tissue)
Composed of:
Bone cells in lacunae (cavities)
Hard matrix of calcium salts
Large numbers of collagen fibers
Functions: Protect and support the body
Hyaline Cartilage
Most common type of cartilage
Composed of:
Abundant collagen fibers and rubbery matrix
Locations: Larynx and entire fetal skeleton prior to birth
Functions: More flexible skeletal element than bone
Elastic Cartilage
Provides elasticity
Location: Supports the external ear
Fibrocartilage
Highly compressible
Locations: Forms cushion-like discs between vertebrae
Dense Connective Tissue (dense fibrous tissue)
Main matrix element is collagen fiber
Fibroblasts are cells that make fibers
Locations:
Tendons – attach skeletal muscle to bone
Ligaments – attach bone to bone at joints
Dermis – lower layers of the skin
Loose Connective Tissue Types
Areolar tissue
Most widely distributed connective tissue
Soft, pliable tissue like “cobwebs”
Functions as a packing tissue
Contains all fiber types
Can soak up excess fluid (causes edema)
Adipose tissue
Matrix is an areolar tissue in which fat globules predominate
Many cells contain large lipid deposits
Functions
Insulates the body
Protects some organs
Serves as a site of fuel storage
Reticular connective tissue
Delicate network of interwoven fibers
Locations:
Forms stroma (internal supporting network) of lymphoid
organs: lymph nodes, spleen, and bone marrow
Blood (vascular tissue)
Blood cells surrounded by fluid matrix called blood plasma
Fibers are visible during clotting
Functions: Transport vehicle for materials
Muscle tissue
o Function is to produce movement
Three types
Skeletal Muscle
Under voluntary muscle
Contracts to pull on bones or skin
Produces gross body movements or facial expressions
Characteristics of cardiac muscle cells
Striated
Multinucleate (more than one nucleus)
Long, cylindrical cells
Cardiac Muscle
Under involuntary control
Found only in the heart
Function is to pump
Characteristics of cardiac muscle cells
Striated
One nucleus per cell
Cells are attached to other cardiac muscle cells at intercalated disks
Smooth Muscle
Under involuntary muscle
Found in walls of hollow organs such as stomach, uterus, and blood vessels
Characteristics of smooth muscle
No visible striations
One nucleus per cell
Spindle-shaped cells
Nervous tissue
o Composed of neurons and nerve support cells
o Functions is to send impulses to other areas of the body
Irritability
Conductivity
o Support cells called neuralgia insulate, protect, and support neurons