TISSUES AND MEMBRANES
CHAPTER 6
Joe Pistack MS/ED
TISSUES
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Tissues-groups of cells that are similar to each
other in structure and function.
Four Major types: epithelial
connective
nervous
muscular
Histology- the study of tissues.
EPITHELIAL TISSUE
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Also called epithelium.
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Forms large continuous sheets.
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Helps form skin and covers entire outer surface
of the body.
Line most of the inner cavities such as the
mouth, respiratory tract, reproductive tract.
EPITHELIAL TISSUE
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Primarily concerned with:
protection
absorption
filtration
secretion
Abundant in organs such as digestive tract.
Forms glands that secrete a variety of hormones
and enzymes.
EPITHELIAL TISSUE
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Characteristics:
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Forms continuous sheets.
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Cells fit together snugly like tiles.
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Has two surfaces, one surface is always
unattached , like the skin or lining of the mouth.
Under surface attaches to basement membrane
(very thin material that anchors epithelium to
underlying structures).
EPITHELIAL TISSUE
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Avascular-has no blood supply.
Nourished from blood supply from underlying
connective tissue. (able to repair and regenerate
quickly).
EPITHELIAL TISSUE
EPITHELIAL TISSUE
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Classified-according to shape and number of
layers.
Three Shapes:
squamous
cuboidal
columnar
CLASSIFICATION
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Squamous epithelium-cells are thin and flat like
fish scales.
Cuboidal epithelium-cells are cubelike, look like
dice.
Columnar epithelium-cells are tall and narrow,
look like columns.
Epithelial cells-arranged in layers.
CLASSIFICATION

Simple epithelium-one layer.
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Stratified epithelium-two or more layers.
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Shape and number of layers are used to describe
types of epithelium.
CLASSIFICATION OF EPITHELIAL TISSUE
SIMPLE EPITHELIA
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One layer of cells. Layer is thin.
Concerned primarily with the movement, or
transport of various substances across the
membranes from one compartment to another.
Simple squamous epithelium-single layer with an
underlying basement membrane.
Found where substances move by rapid diffusion
or filtration.
SIMPLE SQUAMOUS EPITHELIUM
SIMPLE SQUAMOUS EPITHELIUM
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Found in the walls of capillaries-(the smallest
blood vessels).
Eg.-the walls of the alveoli-(air sacs of the lungs).
The tissue allows the rapid diffusion of oxygen
from alveoli into the blood.
SIMPLE CUBOIDAL EPITHELIUM
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Single layer of cells resting on a basement
membrane.
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Cuboidal in shape.
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Found in glands and kidney tubules.
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Functions in the transport and secretion of
various substances.
SIMPLE CUBOIDAL EPITHELIUM
SIMPLE COLUMNAR EPITHELIUM
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Single layer of columnar cells resting on its
basement membrane.
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Tall, tightly packed cells.
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Line the entire length of the digestive tract.
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Play a major role in absorption of the products of
digestion.
Goblet cells-modified columnar cells that produce
mucous.
SIMPLE COLUMNAR EPITHELIUM
PSEUDOSTRATIFIED COLUMNAR
EPITHELIUM
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Single layer of columnar cells.
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Cells are irregular shaped, appear multilayered.
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Pseudostratified means falsely stratified.
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Function is to facilitate absorption and secretion.
PSEUDOSTRATIFIED COLUMNAR
EPITHELIUM
STRATIFIED EPITHELIA
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Multilayered, stronger than simple epithelia.
Function-protective function for tissues exposed
to everyday wear and tear.
Found in the mouth, esophagus, and skin.
TRANSITIONAL EPITHELIUM
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Found primarily in organs that need to stretch
such as the bladder.
Transitional because the cells slide past one
another when tissue is stretched.
GLANDULAR EPITHELIA
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Function-secretion.
Two types of glands:
1. exocrine
2. endocrine
Exocrine glands-contain ducts or tiny tubes into
which the exocrine secretions are released before
reaching the body surfaces or body cavities.
Ducts carry the exocrine secretions outside the
body.
GLANDULAR EPITHELIA
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Exocrine secretions include; mucous, sweat,
saliva, and digestive enzymes.
Eg. Sweat flows from the sweat glands through
ducts onto the surface of the skin for evaporation.
EXOCRINE GLAND
ENDOCRINE GLAND
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Secrete hormones, such as insulin.
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Do not have ducts, called ductless glands.
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Because endocrine glands are ductless, hormones
are secreted directly into the blood.
Blood then carries the hormone to the site of
action.
CONNECTIVE TISSUE
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Connects or binds parts of the body together.
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Most abundant of the four types of tissue.
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Widely distributed throughout the body.
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Found in blood, under the skin, in bone and
around many organs.
Other functions, support, protection, fat storage,
and transport of substances.
CONNECTIVE TISSUE
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Although different types of connective tissue do not resemble each
other closely they do share two characteristics:
1. Most connective tissue have a good blood supply except
ligaments, tendons, and cartilage.
2. All connective tissues have an abundance of intercellular
matrix.
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Intracellular matrix-material that makes the types of tissues so
different
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Within connective tissue are fibers made of protein. They are:

Different types-collagen, elastin, and reticular fibers.
1. Collagen- strong and flexible not easily stretched
2. Elastin- very strong but stretchy
3. Reticular- like collagen but finer and smaller
TYPES OF CONNECTIVE TISSUE
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Different Types:
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Loose connective tissue
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Dense fibrous connective tissue
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Cartilage
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Bone
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Liquid connective tissue (blood & lymph)
TYPES OF CONNECTIVE TISSUE
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Loose connective tissue:
contains fibers that are loosely arranged
around cells.
Three types of connective tissue:
areolar
adipose
reticular
TYPES OF LOOSE CONNECTIVE TISSUE
Areolar Tissue:
 Made up of collagen and elastin fibers in a gellike intercellular matrix.
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Surrounds, protects, and cushions many of the
organs.
Acts like “tissue glue” holds the organs in
position.
TYPES OF CONNECTIVE TISSUE
Adipose Tissue:
 Type of loose connective tissue.
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Stores fat
Forms the tissue layer underlying the skin
(subcutaneous).
Insulates the body from extremes of outside
temperature.
TYPES OF CONNECTIVE TISSUE
Reticular connective tissue:
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Network of delicately interwoven cells and
reticular fibers.
Forms the internal framework for lymphoid
tissue such as the spleen, lymph nodes, and bone
marrow.
TYPES OF CONNECTIVE TISSUE
Dense fibrous connective tissue:
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Composed of an intercellular matrix that
contains many collagen and elastic fibers.
Fibers form strong, supporting structures such as
tendons, ligaments, capsules and fascia.
DENSE FIBROUS CONNECTIVE TISSUE
Supporting structures:
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Tendons-cordlike structures composed of dense
fibrous connective tissue that attach muscle to bone.
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Ligaments-dense fibrous connective tissue that cross
joints and attach bones to each other.
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Capsules-dense fiber forms tough capsules around
such organs as the kidney and liver.
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Fascia-dense fibrous connective tissue that forms
bands or sheets to cover muscle, blood vessels and
nerves.
TYPES OF CONNECTIVE TISSUE
Cartilage:
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Formed by chondrocytes or cartilage cells.
Cartilage secrete a protein-containing
intercellular matrix that is firm, smooth and
flexible
Perichondrium-layer of connective tissue that
covers cartilage, carries blood vessel supply to the
cartilage.
TYPES OF CARTILAGE
Three types of cartilage:
 Hyaline cartilage
 Elastic cartilage
 Fibrocartilage
Hyaline cartilage is found in in the: larynx or voicebox, ends of
long bones and joints, the nose and the area between the
breastbone and the ribs.
Elastic cartilage is found in the external ear and larynx
Fibrocartilage is found in the intervertebral discs, pads in the
knee joint, and in the pubic bone
TYPES OF CONNECTIVE TISSUE
Bone Tissue (osseous tissue):
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Bone cells are called osteocytes.
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Bone cells secrete an intercellular matrix that
includes, collagen, calcium salts, and other minerals.
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Bone acts as a storage site for mineral salts,
especially calcium
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Collagen provides flexibility and strength, and the
mineral containing matrix as a whole makes the bone
tissue hard.
The hardness enables protection of organs such as the
brain.
OSTEOPOROSIS
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Occurs when mineralization of bone tissue is
diminished.
Bone is weakened and tends to break easily.
Adequate intake of dietary calcium is essential
for strong bones.
Calcium is needed throughout the life cycle.
Estrogen encourages the deposition of calcium in
bone tissue.
OSTEOPOROSIS
TYPES OF CONNECTIVE TISSUE
Blood and Lymph:
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Two types of connective tissue that have a watery
intercellular matrix.
Form a liquid connective tissue.
Blood consists of blood cells surrounded by a fluid
matrix called plasma.
TYPES OF CONNECTIVE TISSUE
NERVOUS TISSUE
Nervous Tissue:
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Makes up the brain, spinal cord, and nerves.
Consists of two types of cells: neurons and
neuroglia.
Neurons-nerve cells that transmit electrical
signals to and from the brain and spinal cord.
Neuroglia-cells that support and take care of
neurons.
MUSCLE TISSUE
Muscle tissue:
 Composed of cells that shorten, or contract.
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Cause movement of body part by shortening and
contracting.
Three types of muscle tissue are:
 Skeletal (striated)
 Smooth (non-striated)
 Cardiac
SKELETAL MUSCLE
Skeletal Muscle:
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Generally attached to bones.
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Appears to be striped or striated.
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Moves the muscle, maintains posture, and
stabilizes the joints.
SKELETAL MUSCLE
SMOOTH MUSCLE
Smooth Muscle:
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Generally found in the walls of the viscera or organs
such as the stomach, intestines and urinary bladder.
Also found in tubes, such as breathing passages and
blood vessels.
Function is related to the organ in which it is found.
As an example, stomach muscle help to churn
food, bladder muscles help to expel urine.
SMOOTH MUSCLE
CARDIAC MUSCLE
Cardiac Muscle:
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Found only in the heart.
Functions to pump blood into a vast network of
blood vessels.
Cardiac muscle fibers are long branching cell
that fit together tightly at junctions.
Arrangement promotes rapid conduction of
electrical signals throughout the heart.
CARDIAC MUSCLE
MUSCLE TISSUE
TISSUE REPAIR
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Two types of tissue repair:
1. regeneration-replacement of tissue by cells
that are identical to the original cells.
2. fibrosis-replacement of injured tissue by the
formation of fibrous connective tissue or scar
tissue.
TISSUE REPAIR
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Pressure ulcer-(bedsore) formerly known as a decubitus ulcer
Ulcer that is caused by an interruption of the blood supply to
the tissue.
Decubitus comes from the Latin word meaning to lie down.
Caused by the weight of the body on the skin overlying a
boney area. E.g.. Elbow, heel, hip, sacrum.
Weight of the body compresses the blood vessels, cutting off
the supply, tissues are deprived, tissue dies, forming an ulcer.
Keloid Scar - excessive fibrosis at an injury site
DECUBITUS ULCERS
MEMBRANES
Membranes:
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Thin sheets of tissue that cover surfaces, line
body cavities and surround organs.
Classified as epithelial or connective tissue.
MEMBRANES
Epithelial membranes:
 Includes the cutaneous membrane (skin), mucous
membranes, and the serous membranes.
Cutaneous membranes:
 The outer layer of the skin (epidermis) is
stratified squamous epithelium.
 The underlying layer (dermis) is composed of
fibrous connective tissue.
MUCOUS MEMBRANES
Mucous membranes:
 Line all body cavities open to the exterior.
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Include: digestive, urinary, reproductive, and
respiratory tracts.
Mucous membranes secrete mucous.
Mucous keeps the membranes moist and
lubricated.
SEROUS MEMBRANES
Serous membranes:
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Line the ventral body cavities, which do not open
to the exterior.
Parietal layer-part of the membrane that lines
the walls of the cavity.
Visceral layer-part of the membrane that covers
the outside of an organ.
SEROUS MEMBRANES
Three serous membranes:
 Pleurae-found in the thoracic cavity.
Parietal pleura-line the walls of the thoracic cavity.
 Visceral pleura-cover each lung.
 Pleural cavity-space between the pleural layers.
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SEROUS MEMBRANES
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Pleurisy-inflammation of the pleura
and a decrease in serous fluid.
Inflamed and dry pleura membranes slide past
one another during breathing movements.
Patient experiences pain.
SEROUS MEMBRANES
Pericardium membranes:
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Found in the thoracic cavity and partially
surrounds the heart.
Parietal and visceral pericardium offers a
slinglike support to the heart.
Pericardial cavity-space between the pericardial
membranes.
SEROUS MEMBRANES
Peritoneum Membrane:
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Found within the abdominal cavity.
Parietal peritoneum lines its walls and the
visceral peritoneum covers the abdominal organs.
Peritonitis-infection in the abdominal cavity, can
be life threatening.
AS YOU AGE
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Tissues consist of cells, cellular aging alters the
tissues formed by the cells.
Collagen and elastin decrease in connective
tissue, tissues become stiffer, less efficient in
functioning.
Tissue atrophy causes a decrease in the mass of
most organs.