Transcript Tissues and Membranes

Tissues and Membranes
Anatomy chapter 5
Body Tissues
• A tissue is a group of cells that have similar
structures and that function together as a unit.
• Histology – the microscopic study of tissues.
• There are 4 main tissue types in the body:
Epithelial
Muscle
Connective
Nervous
Tissue types
EPITHELIAL TISSUE
Epithelial Tissue
• Widespread throughout the body
•
•
•
•
Cover body surfaces
Line body cavities
Major tissue in glands
It always has a free surface – exposed to the
outside or to open space internally
• Jobs include protection, secretion, absorption,
filtration, diffusion, and sensory reception
Epithelial Tissue types
Epithelial tissue
• Tightly packed cells – very little intercellular
matrix (the substance between cells)
• Cells are attached to underlying tissue by the
basement membrane, which is nonliving.
• The basement membrane is a mixture of
carbohydrates and proteins.
Basement membrane
The epithelial cells above receive their nutrients by
diffusion from the blood vessels in the underlying tissues.
Epithelial tissue
• Are avascular – which means they have no
blood supply directly.
• Reproduce quickly (divide readily)
• Are classified according to cell shape and
number of layers in the tissue.
Epithelial types
Squamous cells are flat;
the nuclei are broad and
thin.
Cuboidal – cubelike, the
nuclei are spherical and
centrally located.
Columnar – are tall and
narrow, nuclei are usually
near the base
Simple squamous epithelium
• A single layer of thin,
flat cells that fit closely
together.
• Alveoli in lungs
• Capillary walls
• Tissue is damaged
easily.
Simple squamous
Simple Cuboidal Epithelium
• A single layer of cube
shaped cells.
• Linings of many glands
• Lining of kidney
tubules
• Absorption and
secretion
Simple Cuboidal
Simple Columnar Epithelium
• Single layer of cells
that are taller than they
are wide.
• Lining the stomach and
intestines, also lines the
uterus
• Secretes digestive
enzymes, absorbs
nutrients
Simple columnar
Simple columnar
• Where absorption is
necessary, these cells
may have microvilli.
• Goblet cells secrete
mucus.
• Cilia may be present
Pseudostratified Columnar
Epithelium
• Appears to have multiple
layers, but it really does
not.
• All cells attached to
basement membrane.
• Commonly have cilia
• Usually in respiratory
and male reproductive
tract.
Pseudostratifed Columnar
Stratified Squamous Epithelium
• The most common type
of layered epithelium.
• Many layers of cells.
• Cuboidal at the
basement membrane,
become thinner near the
surface.
Stratified Squamous
Stratified Squamous
• Cells at the basement membrane undergo
mitosis.
• The cells die as they are pushed further from
the basement membrane.
• Outer layer of skin
• As skin cells age, they accumulate keratin (a
protein) and then harden and die.
Stratified Cuboidal Epithelium
• Two or three layers of
cuboidal cells that form
a lining of the lumen.
• More protection than 1
layer.
• Lines sweat, salivary
and mammary glands,
also the pancreas
Stratified Columnar Epithelium
• Several layers of cells.
• Superficial layer are
columnar, basal layers
are cuboidal.
• Found in the pharynx,
also in the male urethra.
Transitional Epithelium
• A specialized type of tissue with several
layers, but can be stretched in response to
tension.
• The lining of the bladder is an example.
Transitional epithelium
Glandular epithelium
• Consists of cells that are specialized to
produce and secrete substances.
• Lies deep (underneath) epithelium that cover
and line parts of the body.
• Exocrine glands secrete their products onto a
free surface via a duct.
Types of glandular epithelium
• Simple tubular – the
ducts have no branches.
• The gland and duct
merge with no change
in diameter.
Types of glandular epithelium
• Compound acinar
• Has branches
(compound)
• Has sacs (acinar)
• This type is also called
alveolar
Gland classified by mode of
secretion
• Merocrine glands – use exocytosis, no
cytoplasm is lost. Example: salivary glands
• Apocrine glands – Product accumulates in an
area of the gland, then is pinched off – a small
portion of the cell is lost. Example: sweat
glands
• Holocrine – the entire cell ruptures, releasing
products. Example: Oil (sebaceous) glands
CONNECTIVE TISSUE
Connective tissue
• Binds structures together
• Form a framework and support for organs and
the body.
• Store fat
• Transport substances
• Protect against disease and repair tissue
damage.
Connective tissue
• Cells can reproduce, but not as quickly as
epithelial tissue.
• Three types of fibers embedded in
intercellular matrix – collagenous fibers,
elastic fibers and reticular fibers.
• Many cell types in connective tissue. Most
common are mast cells, macrophages, and
fibroblasts
Connective tissue cells
• Fibroblasts – Most common. Large cells
secrete proteins into the extracellular matrix.
• Macrophages – Originate as white blood cells
and carry on phagocytosis. Can move about
• Mast Cells – Large cells usually near blood
vessels. They release heparin and histamine.
Fibers
• Collagenous fibers – thick threads of the protein
collagen. Grouped in bundles. Flexible but only
slightly elastic. Important parts of ligaments and
tendons.
• Elastic – composed of the protein elastin. Weaker
than collagenous, but stretch easily. Vocal cords.
• Reticular – Very thin collagenous fibers. Highly
branched and form a supporting network in organs
like the spleen
Types of connective tissue
•
•
•
•
•
•
•
Loose connective tissue
Adipose tissue
Elastic connective tissue
Dense fibrous connective tissue
Cartilage
Bone
Blood
Loose connective tissue
Loose connective tissue
• Also called areolar CT
• Packing material in the
body
• Attaches skin to
underlying tissue, fills
spaces between
muscles.
Adipose tissue
• Better known as fat
• Cells can take up fat
and release it at a later
date.
• Acts as a cushion for
the body, insulator for
heat.
Reticular connective tissue
Dense Fibrous Connective Tissue
• Closely packed parallel
bundles of collagenous
fibers.
• Make up tendons and
ligaments
Elastic Connective Tissue
• Closely packed elastic
fibers.
• Yields easily to pulling
force.
• Vocal cords and
vertebral ligaments
Cartilage
•
•
•
•
Has an abundant matrix – solid, yet flexible
Cartilage cells are called chondrocytes
Heals slowly – no direct blood supply
Protects underlying tissues, supports
structures, and is a framework
3 types: hyaline, fibrocartilage, and elastic
Hyaline cartilage
Hyaline: most common
type
Found at the end of long
bones
Most of the fetal skeleton
is made of this before it
is replaced by bone
Fibrocartilage
• Abundance of strong
collagenous fibers.
• Acts as shock absorber
• Found in between
vertebrae and between
the bones in the knee
joint.
Elastic Cartilage
• Much more flexible
than hyaline or
fibrocartilage.
• Found in outer ear.
Bone
• Most rigid connective
tissue
• Arranged in concentric
rings
• Form a framework for
body, and attach
muscles
Bone tissue
Blood
•
•
•
•
•
Unique because it has a liquid matrix.
Erythrocytes – red blood cells
Leukocytes – white blood cells
Plasma – liquid matrix
Platelets – fragment of a cell in the bone
marrow.
Blood
Blood components
•
•
•
•
Red blood cells
White blood cells
Platelets
Plasma – plasma is 95% water
• Other 5% is salts, nutrients, hormones, and
proteins.
Web sites
• Goto
http://msjensen.cehd.umn.edu/default.asp
• Click on image bank and review some images
of types of tissue
• Click on self-test and choose a test to take.
Use your notes and identify tissue types and
structures.
MUSCLE TISSUE
Muscle Tissue
• Made up of cells that have an ability to
shorten or contract to produce movement.
• Highly cellular – good blood supply
• Arranged usually in bundles or layers.
• 3 types: skeletal, cardiac, and smooth
Types of muscle tissue
Skeletal muscle
• What we usually think
of as “muscle”
• 40% of body weight
• Fibers are long and
cylindrical with many
nuclei
• Cell has a striated
appearance.
Skeletal muscle
• Muscle fibers are
collected into bundles
and wrapped in
connective tissue.
• Skeletal muscle is
voluntary
Smooth muscle
• Found in the walls of
hollow body organs –
stomach, intestines, etc.
• Lacks striations
• Also called involuntary
muscle
Cardiac muscle
• Found only in the heart
wall.
• Look similar to striated
muscle
• One nucleus per cell
• Involuntary contraction
NERVOUS TISSUE
Nervous tissue
• Found in brain, spinal cord and nerves
• Responsible for coordinating and controlling
body activities.
• Communicates by way of electrical nerve
impulses.
• Nerve cells - neurons
Neurons
INFLAMMATION AND TISSUE
REPAIR
Inflammation
• A defense mechanism that attempts to contain
tissue injury and prepare for healing.
• Symptoms: redness, swelling, heat, pain.
• It is a beneficial process, even though it may
be painful.
Inflammatory process
• Blood vessels dilate, become more permeable
• Increased blood flow to area
• Fluid and WBC’s leave vessels and go into
tissue space. WBCs engulf debris and
bacteria.
• Fluid dilutes toxins and contains clotting
proteins.
Tissue Repair
Regeneration
Fibrosis
• Replacement of destroyed
tissue by proliferation of
identical cells.
• Occurs only in tissues that
can undergo mitosis
• Skeletal muscle, cardiac
muscle, and nerve tissue
cannot regenerate.
• Replacement of destroyed
tissue by fibrous (scar)
tissue
• Collagen fibers form the
basis of the scar.
• Immature scar tissue is
called granulation tissue.
• Scar may be visible or not
depending on the severity of
the wound.
BODY MEMBRANES
Body Membranes
• Thin sheets of tissue that cover the body, line
body cavities, cover organs, and line the
cavities in hollow organs.
• Skin is a membrane
• Membranes may be epithelial or connective
tissue.
Epithelial membranes
Mucous membranes
Serous membranes
• Epithelial tissue that is
attached to loose connective
tissue.
• Line the body cavities that
open to the outside
• Examples: digestive tract,
respiratory, excretory, and
reproductive tracts.
• Line body cavities that do
not open directly to the
outside.
• Thin layer of loose
connective tissue covered by
a layer of simple squamous
epithelium.
• Covered by a thin layer of
serous fluid.
Mucous membranes
Serous membranes
Connective tissue membranes
Synovial membranes
Meninges
• Line the cavities of the
freely moveable joints, like
the shoulder, elbow and
knee.
• They secrete synovial fluid
into the joint cavity, which
lubricates the cartilage.
• Connective tissue coverings
around the brain and spinal
cord.
• Provide protection.
• Meningitis is inflammation
of the meninges.
Synovial membranes
Meninges
Meninges
Cell communication
• Interactions between cells are vital to the
function of other cells, tissues, and organs.
• All cells are signaled to survive and carry out
homeostasis (maintenance of a constant
internal state).
• All cells need energy to carry out functions.
Methods of cell communication
• Most common way that cells communicate is
by chemical means.
• Hormones
• Signal receptors (like a lock and key)
• Proteins
Specific examples of hormone
communication
•
•
•
•
Cell division
Immune response
Production of enzymes or proteins
Blood clotting
Other methods of cell
communication
• Cell to cell contact
• Electrical impulses (SA node in the heart,
axons in the nervous system)