Tissues
Definition- group of similar cells that
together perform a specialized function
 Histology- study of tissues
 Basic types

– Epithelial- covers body surfaces, lines cavities,
organs, ducts, and forms glands
– Connective- protection, supports body, binds
organs together, stores energy as fat,
produces immunity
– Muscle- movement
– Nervous- initiates and transmits impulses that
coordinate body activity
Epithelial tissue
Consist of closely packed cells, little
intercellular fluid
 Single or multiple layers
 Avascular- no blood vessels
 Have nerve supply
 High turn over rate- constantly making
more
 Functions

– Protection, filtration, lubrication, secretion, digestion,
absorption, transportation, excretion, sensory receptors,
reproduction
 Simple-
single layer found where
transport is needed
 Stratified- 2+ layers used for
protection
 Psuedostratified- one layer but looks
like more
 Squamous-
flat and attached
together like tiles
 Cubiodal- cube or hexagonal shape
– Produce secretions (sweat, enzymes)
– Can absorb- intestinal tract
Simple Squamous
Simple cuboidal
Stratified squamous
Stratified cuboidal
 Columnar-
tall and cylindrical
– Protection of underlying tissue
– Specialized for secretion and absorption
 Transitional
– Vary in shape
– Flat to columnar due to stretching
Stratified columnar
Simple columnar
Transitional
Pseudostratified
columnar
Glandular Epithelium
Functions for secretions- cells lie below
outer epithelium
 Endocrine- ductless- hormones
 Exocrine- secreted into ducts- mucous,
sweat, oil, digestive enzymes

Connective Tissue
 Most
abundant tissue in the body
 All connective tissue comes from
embryonic mesenchyme
– Stem cells
Connective Tissue Proper
 Intercellular
material and matrix
– Hyaluronic acid
 Viscous,
slippery substance that binds cells
– Chondroitin sulfate
 Provides
support and adhesiveness in
cartilage, bone, skin, and blood vessels
Loose (areolar) tissue

Most widely distributed
Location- widespread- mucous membranes, around blood

Fibrous

vessels and nerves, subcutaneous
– Collagenous (white)


Tough, resistant to pulling
Made of collagen
– Elastic (yellow)

Smaller, provides strength, skin, blood vessels, and lungs
– 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
Cells

Fibroblasts- most numerous, especially active

Macrophages- large and function to engulf
in repair
bacteria and cellular debris by phagocytosis
Plasma cells- secrete antibodies- immunity
 Melanocytes- pigmented cells below deepest

layer of skin- produce melanin

Mast cells- produce heparin (anti-coagulant)
and histamine- a chemical that dilates small
blood vessels during inflammation
Adipose tissue


Cells called
adipocytes- fat
storage
Shape
– Signet ring shaped

Location
– Subcutaneous

Functions
– Good insulation, energy
reserve, protection of
internal organs
 Dense
collagenous tissue
– More numerous cells and thicker fibers
– Location: muscles, ligaments, tendons
– Functions: provide elasticity
 Elastic
tissue
– Structure: freely branched fibersstretch and snap back
– Location: muscles, ligaments, tendons
– Function: allow for elasticity

Cartilage- no blood vessels or nerves
(except in the perichondrium- tissue
around carilage)
– Characteristics
 Dense
network of collagen and chondroitin sulfate
 Resistant
 strong
– Types
 Hyaline-
gristle- bluish white color, shiny, most
abundant
– Found in embryonic skeleton (exclusively)
– Found on end of long bones and costal
 Fibrocartilage
– Found in matrix to give strength
– Bundles of collagen fibers
 Elastic
– Threadlike network for elasticity
Hyaline cartilage
Elastic Cartilage
Cartilage from the external ear
Osseous tissue (bone)
 Skeletal
system- basic unit called an
osteon- made of:
– Lamellae
 Concentric
rings of hard matrix- calcium
– Lacunae
 Spaces
between lamellae- has Haversian
canal- contains blood vessels and nerves
Vascular tissue (blood)
 Connective
tissue
 Plasma- mostly water with dissolved
substances (nutrients, wastes,
enzymes, hormones, respiratory
gasses)
– Erythrocytes- red blood cells
– Leucocytes (WBC)- phagocytes,
immunity
– Platelets- clotting
Other tissues
 Muscle
tissue- highly specialized cells
for contraction
– Smooth- walls of internal organs
(hollow)- involuntary- non striated
– Cardiac- wall of heart- involuntarystriated- 1 nucleus
– Skeletal- striated- voluntary- fibers are
cylindrical and striated- multiple nuclei
Smooth muscle
Skeletal muscle
Cardiac muscle
 Nerve
tissue
– Consists of neurons
– Neurons
 Calls
that receive stimuli and convert to
impulse- carry impulses to other nerves,
muscles, or glands
– Dendrites- converging branches that take impulse
to cell body
– Axons- long, single strand that conduct impulses
AWAY from cell body
– Neuroglea
 Cells
for protection and support of neurons
 DO NOT CONDUCT
 Common sites of tumors
 Membranes
– Mucous- line cavities that open to the outside
world
– Serous- line cavities that do not open to
outside, cover organs, produce serous fluid
– Synovial- line freely moving joints, not open to
outside