TISSUES AND MEMBRANESCHAPTER 6Joe 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:areolaradiposereticular

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 TISSUEReticular 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 TISSUEDense 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 TISSUESupporting 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 TISSUEBlood 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 TISSUEMuscle 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 MUSCLECardiac 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

MEMBRANESMembranes:

Thin sheets of tissue that cover surfaces, line body cavities and surround organs.

Classified as epithelial or connective tissue.

MEMBRANESEpithelial 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 MEMBRANESMucous 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 MEMBRANESSerous 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 MEMBRANESThree 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 MEMBRANESPericardium 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.