Chapter 5
Tissues
Intercellular Connections
• Individual cells connect to form tissues 3
ways:
– Tight junctions- prevents permeability of ions
through junction.
– Desmosome- adhesion between cells in
spots. Allows from some permeability.
– Gap junctions- cytoplasms of adjacent cells
are connected through transport proteins.
• Ions can pass freely through cells.
Intercellular Connections
Tissue Types
A tissue is a group of cells with a common
structure & function
The human body is composed of four main
tissue types:
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1.
2.
3.
4.
Epithelial
Connective
Muscle
Nerve
Epithelial Tissue
Epithelial Tissue
Characteristics

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Always has a free (apical) surface
exposed to outside or open space.
Lacks blood vessels
Readily divide and replicate
Has a basement membrane to anchor
underlying tissue

Between epithelial and connective tissue
Functions

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Covers body surfaces
Makes up glands
Protects
Absorbs
Secretes
Excretes
Classified by Shape
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Squamous – flattened cells
Cuboidal – cube-shaped
Columnar – tall, column-shaped
Classified by Shape
May occur in layers:
 Simple – 1 layer of cells
 Stratified – 2 or more layers
 Pseudostratified – appears to be
layered, but is not
 Example – simple cuboidal
 Example – stratified columnar
Examples of Epithelial
Tissue
s
Simple Squamous- Thin, flattened cells.
Allow for diffusion and filtration. Line air sacs of
lungs and walls of capillaries.
Simple cuboidal-single layer of cube
shaped cells. Lines follicles of thyroid gland,
kidneys and ducts of certain glands. Used for
secretion and absorption
Simple columnar- single layer of
elongated cells. Can contain cilia, used for protection
and absorption in digestive tract. Can contain goblet
cells.
Stratified squamous- Layers of
squamous cells. Make up epidermis and line cavities
exposed to external environment. Outer layer die and
accumulate keratin.
Stratified columnar- Several layers of
columnar cells overlying cuboidal cells near the
basement membrane. Found in male reprod. System
and pharynx
Pseudostratified ciliated
columnar- Appear stratified but are not. Often
contain cilia and goblet cells which secrete mucus.
Line respiratory passages.
Pseudostratified ciliated columnar
w/goblet cells- Line Respiratory passages to trap
unwanted particles
Transitional tissue- Changes in
response to change in tension (stretching). Line
urinary bladder and urethra. Larger cells at surface,
smaller cells deeper.
Glandular Epithelium
• Specialized to secrete substances
• Usually glands are lined w/cuboidal or
columnar epithelium
• Those that secrete substances into ducts
that open onto a surface are exocrine
glands (salivary, oil glands, etc.)
• Those that secrete into tissues or blood
are endocrine glands (pituitary)
Classifying Glands by Structure
• Simple- does not branch off before
reaching secretory portion
• Compound- duct that does branch before
secretory portion.
Classifying Glands by Type of
Secretions
3 types:
•
•
•
•
• No loss of cytoplasm
in secretions
• Ex. – pancreas
Small portions of cells
in secretions
Ex. – mammary glands
Classifying by Secretions
• Secretions w/entire cells filled w/secretory
products; ex. – sebaceous (oil) glands
Connective Tissue
Functions
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1.
2.
3.
4.
5.
connects
supports
protects
provides framework
fills spaces
Functions
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6. stores fat
7. produces blood cells
8. protects against infection
9. transports nutrients
10.helps repair damaged tissue
Characteristics
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1. Consists of cells in a matrix
(intercellular material)
2. Cells some distance apart
3. Most can divide
4. Good blood supply
Types of Fibers:
1.
collagenous – composed of collagen
(protein); have great tensile strength;
slightly
elastic;
compose
bones,
tendons &
ligaments
Types of Fibers - continued

elastic – composed of elastin (protein);
very elastic but weaker; compose vocal
cords & air passages of lungs
Types of Fibers - continued
Reticular – composed of very fine
collagenous
fibers.
 Form
support
network.

Types of Cells
1. Fixed cells – stay in one place &
have stable numbers; 2 types:

fibroblasts – large & star-shaped;
most prevalent
Types of Cells - continued

mast cells – may release heparin (for
blood clotting) &
histamines (promotes
allergic reactions &
inflammation);
usually located near
blood vessel walls
Types of Cells - continued
2. Wandering cells –

macrophages –
travel through
body; numbers
change in
response to
infection;
scavengers
(Purple cells – macrophages,
Green cells – T-lymphocytes)
Examples of Connective
Tissue
Areolar tissue- binds the skin to
underlying organs and under epithelium to provide
bloodflow. Binds and protects. A- fibroblast, Bcollagen, C- elastin
Adipose tissue- connective tissue
composed of fats, cushion joints and provide
insulation. A- nuclei, B- fat globules
Regular dense connectivestrong fibers bind body parts together. Found in
ligaments and tendons. Poor blood supply so slow
healing. A- fibroblasts. B- collagen and elastin
Irregular dense connectivedisorganized and strong. Found in the dermis
Hyaline cartilage- Most common, found
on ends of bones, nose cavity and supporting rings of
resp. system. A- chondrocytes, B- Matrix (fine collagen
fibers), C- Lacunae
Fibrocartilage- tough tissue containing
collagenous fibers. Shock absorbers between
vertebrae and pubic girdle. A- Chondrocyte, BCollagen fibers
Elastic cartilage- flexible cartilage make
up ears and larynx. Used for flexible support. Achondrocytes, B- elastin, C- Lacunae
Blood – platelets, found in plasma. Used for
blood clotting
Blood – red cells & white cell
Red- used for transport, white- immunity
Elastic connective- allows for
stretching, found in attachments between vertebrae. Aelastic fibers
Reticular connective- walls of liver
and spleen. Used for support.
Bone- A- central canal (contains blood vessels)
B- Canaliculi- minute tubes allow for movement
between cells.
Bone- D- Lamellae (layers of osetocytes), Costeocytes (Bone Cells)
Muscle & Nerve Tissue
Muscle Tissue
3 types:
 Skeletal- Attached to bone and controlled by
conscious effort (Voluntary).
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Used for movement
Striated
Long and thin with multiple nuclei
Muscle Tissue Cont.

Smooth- lacks striations found in
skeletal, used for involuntary
movements

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Ex- move food through digestive tract
Cardiac- striated muscle found only in
the heart

At intercellular junction contain intercalated
discs.

Allows for heart to contract as one unit
3 Types of Muscle Tissue
Smooth muscle- B- nucleus
Skeletal muscle- A- striations, B- nucleus
Cardiac muscle- A- Intercalated discs, Bcell
Nervous Tissue
• Found in the brain, spinal cord and
peripheral nerves.
• Cells called neurons
– Responsible for transmitting nervous impulses
to muscles and glands.
• Also include neuroglia cells (support cells)
– Support the function of the neurons
Nerve tissue – A- neuron, B- Axon, Cneuroglia