Download Types of Tissues

Tissue
• A tissue is a group of similar cells, that function
together to carry out specialised activities
There are four types
1. Epithelial tissue
2. Connective tissue
3. Muscular tissue
4. Nervous tissue
1
Epithelial Tissue
•
•
•
•
•
Makes up 3% of your body weight
They don’t move
They don’t send messages
Their cells are all touching one another
Of all tissues, they are the most widely varied
in structure and function
2
Locations of Epithelial Tissues
• Covers the body (epidermis)
• Found on the inside of hollow organs and the
outside of all organs
• Found above a connective tissue layer (epi =
above)
• Lines the cavities, tubes, ducts, and blood
vessels inside the body
3
Epithelial Anatomy
• Apical surface – upper surface that is free or exposed
to the “exterior”
• Basal surface – attached surface (below)
• Microvilli – small fingerlike extensions that increase
the surface area allowing for more work to be done
4
Functions of Epithelial Tissue
– Protects from physical & chemical injury
– Protects against microbial infection
– Contains nerve endings which respond to
stimuli
– Filters, secretes & reabsorbs materials
– Secretes fluids to lubricate joints
5
Types of Epithelial Membranes
• Mucous or mucosa– lining of tubes; moistens
and protects from enzymes (stomach, trachea,
and vagina)
• Serous or serosa – outside of organs; lubricates
(all thoracic, abdominal and pelvic organs)
• Cutaneous or skin – body surface; protection
• Synovial – synovial joints; lines and protects
synovial cavities (elbow, knee, hip, etc.)
6
General Features of Epithelial Tissue
1. The cells are arranged in continuous sheets  single
or continuous layers.
2. Have an apical surface exposed to a body cavity,
lining of an internal organ or the exterior of the body;
lateral surface facing adjacent cells on either side,
basal surface which are the deepest layers of the cell
3. Lack blood vessels  get nutrients by diffusion.
4. They have a nerve supply.
5. They have a high capacity for renewal by cell division.
7
8
Arrangement of cells in layers
Simple epithelium
• Is a single layer of cells that functions in
diffusion, osmosis, filtration, secretion and
absorption.
• Secretion is the production and release of
mucus, sweat or enzymes.
• Absorption is the intake of fluids or other
substances such as digested food from the
intestinal tract
9
Arrangement of cells in layers
Stratified epithelium (stratum = layer)
• Consists of two or more layers of cells that
protect underlying tissues in locations where
there is considerable wear and tear
10
Three Basic Shapes
• Squamous – like scales, or
pancakes (“being squashed like a
pancake”)
• Cuboidal – looks like cubes
• Columnar – longer and look like
columns
11
Squamous Epithelium
• Simple – one cell thick
• Forms solid layer of cells
which line blood vessels,
body cavities and covers
organs in body cavities
• Stratified – multiple layers
• Forms epidermis
12
Simple Squamous
Epithelium
• Found in parts of the body where filtration
(kidneys) or diffusion (lungs) are priority
processes.
• Simple squamous epithelium that lines the
heart & blood vessels is known as
endothelium.
13
Simple Squamous
14
Simple cuboidal epithelium
• Found in organs such as the thyroid gland and
kidneys.
• Performs the functions of secretion and
absorption.
15
Cuboidal Epithelium
Cuboid Cells
• Simple – one cell thick
Duct
• Roughly cube shaped
• Line ducts in kidneys
Cuboid Cells
where re-absorption and
secretion activities take
place.
Duct
16
Simple Cuboidal
17
Columnar Epithelium
• Simple – one cell thick
• Column shaped (long and
narrow)
• Lines digestive tract
where re-absorption &
secretion occurs.
18
Simple columnar epithelium
• There are ciliated and non ciliated
Non ciliated:
• Those with microvilli  increase the surface area of
the plasma membrane.
=increasing the rate of absorption of the cell.
• Goblet cells  secret mucus
• Mucus serves as a lubricant for the lining of the
digestive and respiratory tract.
• It helps trap dust entering the respiratory tract.
• Prevents destruction of the stomach lining by acid
secreted by the stomach.
19
Nonciliated Simple Columnar
20
Simple columnar epithelium
Ciliated simple columnar epithelium
• Contain cells with cilia at their apical surface.
• In some parts of the upper respiratory tract
mucus secreted by the goblet cells forms a film
over the respiratory surface that traps inhaled
foreign particles.
• The cilia move the foreign particles towards
the throat where it can be coughed up
swallowed or spit out.
21
Ciliated Simple Columnar
22
Stratified epithelium
Stratified squamous epithelium
• Cells in the apical layer are flat.
• The basal (deepest) cells continuously
undergo cell division.
• The cells are pushed upwards towards the
surface.
• At the apical layer the cells die  replaced by
cells emerging from the basal cells.
23
Stratified Squamous Epithelium
24
Connective Tissue
• Protects and supports the body and its organs
together, stores energy reserves as fat &
provides immunity
Examples:
• Cartilage
• Bone tissue
• Liquid connective tissue (blood tissue)
• Adipose tissue
25
Connective Tissue
• Binds together, supports and strengthens
other body tissues
• Protects and insulates internal organs
• Compartmentalizes structures such as skeletal
muscle
• The major transport system within the body
• Site of stored energy reserves
• Main site of immune responses
26
General Features of Connective Tissue
• 2 basic parts:
– Cells and Matrix
• Matrix – material between widely spaced cells
– Consists of protein fibers and ground substance
27
General Features of Connective Tissue
• Does not occur on free surfaces
• Has a nerve supply (except cartilage)
• Highly Vascular (except cartilage and tendons)
28
Connective Tissue
29
Adipose tissue
• Has cells called adipocytes.
• They are specialised for the storage of
triglycerides (fats).
• Adipose tissue is a good insulator and can
reduce heat loss through the skin.
30
Adipose tissue
• It is a major energy source.
• It protects various organs.
• As the amount of adipose tissue increases
with weight gain new blood vessels form.
• Thus an obese person has more blood vessels
than a lean person.
• A situation that can cause high blood pressure
since the heart has to work harder.
31
Adipose Tissue
32
Connective Tissue Matrix – Fibers
• Strengthens and supports connective tissue
– Collagen Fibers
• Strong, resist pulling forces, flexible
• Made of the protein collagen which is the most
abundant protein in your body
– Elastic Fibers
• Smaller in diameter than collagen fibers, branch to
form network
• Made of the protein elastin
33
Muscular Tissue
• Generates the physical force needed to make
body structures move.
34
MUSCLE TISSUE
• Abundant, dense tissue
– 40-50% of body weight
• High metabolic activity
– high energy use/output;
– O2 consumption;
– CO2 production
35
Functions of Muscle Tissue
• Produce movement by contracting
– Locomotion & manipulation
– Movement of blood, food, urine, etc through hollow
organs
• Maintenance of posture
• Stabilize joints
– so that other muscles can produce movement or maintain
posture
• Heat production
– Maintenance of body temperature.
36
Three Kinds of Muscle Tissue
• Skeletal muscle:
– Striated, usu. voluntary, attached to skeleton
• Cardiac muscle:
– Striated, involuntary, walls of heart
• Smooth muscle:
– Non-striated, involuntary, wrapping of hollow organs
– Stomach, intestines, arteries, bladder, vas deferens,
uterus, etc.
37
Muscle Tissue Types
 Skeletal muscle
 Can be controlled
voluntarily
 Cells attach to
connective tissue
 Cells are striated
 Cells have more than
one nucleus
38
Muscle Tissue Types
 Cardiac muscle
 Found only in the
heart
 Function is to pump
blood (involuntary)
 Cells attached to
other cardiac muscle
cells at intercalated
disks
 Cells are striated
 One nucleus per cell
39
Muscle Tissue Types
 Smooth muscle
 Involuntary muscle
 Surrounds hollow
organs
 Attached to other
smooth muscle cells
 No visible striations
 One nucleus per cell
40
Nervous Tissue
• Detects changes inside and outside the body
and initiates and transmits nerve impulses
that coordinate body activities to help
maintain homeostasis.
41
Nervous Tissue
 Neurons and
nerve support
cells
 Function is to
send impulses to
other areas of
the body
 Irritability
 Conductivity
42
Tissue Repair
 Regeneration
 Replacement of destroyed tissue by the
same kind of cells
 Fibrosis
 Repair by dense fibrous connective tissue
(scar tissue)
43
Regeneration of Tissues
 Tissues that regenerate easily
 Epithelial tissue
 Fibrous connective tissue and bone
 Tissues that regenerate poorly
 Skeletal muscle
 Tissues that are replaced largely with scar
tissue
 Cardiac muscle
 Nervous tissue within the brain and spinal cord
44