TISSUES AND MEMBRANES

CHAPTER 6 Joe Pistack MS/ED

TISSUES

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

Also called epithelium.

Forms large continuous sheets.

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

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

Characteristics:

Forms continuous sheets.

Cells fit together snugly like tiles.

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

Avascular-has no blood supply.

Nourished from blood supply from underlying

connective tissue. (able to repair and regenerate

quickly).

EPITHELIAL TISSUE

EPITHELIAL TISSUE

Classified-according to shape and number of

layers.

Three Shapes: squamous

cuboidal

columnar

CLASSIFICATION

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.

Stratified epithelium-two or more layers.

Shape and number of layers are used to describe

types of epithelium.

CLASSIFICATION OF EPITHELIAL TISSUE

SIMPLE EPITHELIA

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

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

Single layer of cells resting on a basement

membrane.

Cuboidal in shape.

Found in glands and kidney tubules.

Functions in the transport and secretion of

various substances.

SIMPLE CUBOIDAL EPITHELIUM

SIMPLE COLUMNAR EPITHELIUM

Single layer of columnar cells resting on its basement membrane.

Tall, tightly packed cells.

Line the entire length of the digestive tract.

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

Single layer of columnar cells.

Cells are irregular shaped, appear multilayered.

Pseudostratified means falsely stratified.

Function is to facilitate absorption and secretion.

PSEUDOSTRATIFIED COLUMNAR

EPITHELIUM

STRATIFIED EPITHELIA

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

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

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

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

Secrete hormones, such as insulin.

Do not have ducts, called ductless glands.

Because endocrine glands are ductless, hormones

are secreted directly into the blood.

Blood then carries the hormone to the site of

action.

CONNECTIVE TISSUE

Connects or binds parts of the body together.

Most abundant of the four types of tissue.

Widely distributed throughout the body.

Found in blood, under the skin, in bone and

around many organs.

Other functions, support, protection, fat storage,

and transport of substances.

CONNECTIVE TISSUE

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.

Intracellular matrix-material that makes the types of tissues so different

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

Different Types:

Loose connective tissue

Dense fibrous connective tissue

Cartilage

Bone

Liquid connective tissue (blood & lymph)

TYPES OF CONNECTIVE TISSUE

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 gel-

like intercellular matrix.

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.

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:

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:

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:

Tendons-cordlike structures composed of dense fibrous connective tissue that attach muscle to bone.

Ligaments-dense fibrous connective tissue that cross joints and attach bones to each other.

Capsules-dense fiber forms tough capsules around such organs as the kidney and liver.

Fascia-dense fibrous connective tissue that forms bands or sheets to cover muscle, blood vessels and nerves.

TYPES OF CONNECTIVE TISSUE

Cartilage:

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):

Bone cells are called osteocytes.

Bone cells secrete an intercellular matrix that includes, collagen, calcium salts, and other minerals.

Bone acts as a storage site for mineral salts, especially calcium

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

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:

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:

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.

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:

Generally attached to bones.

Appears to be striped or striated.

Moves the muscle, maintains posture, and

stabilizes the joints.

SKELETAL MUSCLE

SMOOTH MUSCLE

Smooth Muscle:

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:

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

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

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:

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.

Include: digestive, urinary, reproductive, and

respiratory tracts.

Mucous membranes secrete mucous.

Mucous keeps the membranes moist and

lubricated.

SEROUS MEMBRANES

Serous membranes:

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.

SEROUS MEMBRANES

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:

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:

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

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.