TISSUES

Body Tissues Tissue is a group of cells that have similar

structure and that function together as a unit. A nonliving material, called the intercellular

matrix, fills the spaces between the cells. The intercellular matrix may contain special

substances such as salts and fibers that are unique to a specific tissue and gives that tissue distinctive characteristics.

TISSUE TYPES

EpithelialConnectiveMuscleNervous

Epithelial TissueEpithelial tissues are widespread

throughout the body. They form the covering of all body

surfaces, line body cavities and hollow organs, and are the major tissue in glands.

They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.

Epithelial Tissue continued…….

The cells in epithelial tissue are tightly packed together with very little intercellular matrix.

Because the tissues form coverings and linings, the cells have one free surface that is not in contact with other cells.

Opposite the free surface, the cells are attached to underlying connective tissue by a non-cellular basement membrane. This membrane is a mixture of carbohydrates and proteins secreted by the epithelial and connective tissue cells.

Epithelial cells may be squamous, cuboidal, or columnar in shape and may be arranged in single or multiple layers.

SIMPLE MEANS

Single Layer

STRATIFIED MEANS

Several Layers

PSEUDOSTRATIFIED MEANSHas only one layer of cells, but some cells fail to reach the surface, which gives the tissues a multi-layered APPEARANCE

TYPES OF CELL SHAPESSquamous- flattened and scale-likeCuboidal- cube-shaped when viewed in cross section

Columnar- tall and cylindricalTransitional- have a combination of shapes and are found where there is a great degree of distention or expansion (lungs, stomach)

TYPES OF EPITHELIAL TISSUES

Simple SquamousSimple CuboidalSimple ColumnarStratified SquamousStratified CuboidalStratified ColumnarGlandular Epithelium

SIMPLE SQUAMOUS

A single layer of flat, scale-like cells resembling a tiled floor.

LOCATION: Line the heart, line blood vessels and lymph vessels and form the walls of capillaries (endothelium)

FUNCTION: filtration and diffusionForms the epithelium of serous membranes (mesothelium)

SIMPLE CUBOIDAL

Cube-shapedLOCATION: lining surface of ovaries, lens of eye, retina, kidneys, gland ducts

FUNCTION: secretion and absorption

SIMPLE COLUMNARRectangular shapedTwo types: ciliated and nonciliated.The nonciliated type lines the digestive tract, the gallbladder, and gland ducts

The ciliated type is found in the upper respiratory tract, uterus, and spinal cord

FUNCTION: secretion, absorption and protection

GOBLET CELLS

Are interspersed among columnar cells and secrete mucus that:Lubricates the intestinal wallCarries foreign particles that have been inhaled to the throat where they can be swallowed and eliminated

Simple Columnar

In the small intestines, the plasma membranes of these cells are folded into microvilli, which aid in food absorption

STRATIFIED SQUAMOUSNear the surface of the skin these cells have a flat appearance; in deeper skin they vary in shape from cuboidal to columnar

LOCATION: esophagus, lining of skin, entrances into the body

FUNCTION: protectionTwo types: nonkeratinized and keratinized

NONKERATINIZED

Found on wet surfaces exposed to wear and tear, not functioning as absorptive surfaces (lining of mouth, tongue, esophagus, vagina)

KERATINIZED

Contain keratin, a waterproof protein resistant to friction- tough layer

LOCATION:-skin,hair and nails

STRATIFIED CUBOIDALRareLOCATION: sweat glands, conjunctiva of the eye, pharynx, epiglottis, urethra

FUNCTION: protection

STRATIFIED COLUMNARRareLOCATION: milk ducts in mammary glands

FUNCTION: protection and absorption

GLANDULAR EPITHELIUM

Composed of glands that secrete various products into the body. A gland may be only one cell or a group of cells that secrete substances into ducts, onto surfaces, or into the blood. Exocrine glands Endocrine glands

EXOCRINE GLANDS

Secrete their products (mucous, sweat, oil, wax, digestive enzymes) into ducts or onto a free surface. Examples are sweat glands, salivary glands, and goblet cells

TYPES OF EXOCRINE GLANDSHolocrineMerocrineApocrine

HOLOCRINE

Accumulate a secretory product in the cytoplasm and die releasing the product (sebaceous gland).

MEROCRINE

Form a secretory product and discharge it from the cell. Cells do not die (salivary glands)

APOCRINE

Accumulate the secretory product at the apical end (tip end), and then the end pinches off. The cell repairs itself and repeats the process (mammary glands)

ENDOCRINE GLANDS

Ductless and release their products (hormones) directly into the blood (Hormones are chemicals that regulate various physiological functions)

Connective TissueIntroduction: Connective tissue is a widely spread tissue in

body It support, binds, protect organs It has cellular and extracellular component Cellular for defenses Extra cellular for support and protection

Constitution of Connective Tissue Cells Extracellular Matrix

Cells in Connective Tissue Fibroblasts Macrophages Plasma cells Mast cells Fat Cells (Adipocytes) Pigment cells

Fibroblasts Large cells with branching processes that

form new fibers and matrix – They are called fibrocytes when mature Helpful in tissue repair as they form

granulation tissueMacrophages WBCs capable of engulfing bacteria and

cellular debris- derived from monocytes (a type of White Blood Cell)

They are working as Phagocytosis

Plasma cells Give rise to antibodies, which attack

antigens that enter the body (Plasma cells arise from lymphocytes.)

Mast cells Produce heparin, which prevents blood

from clotting in the vessels. Also produce histamine and serotonin

(which dilate blood vessels) Mast cells develop from basophils.

Fat cells Cells are filled with Globule of fat Ring shaped They produce and store fat

Extra Cellular Matrix Collagenous- white fibers –

Most numerous and widely distributed Present in ligaments, tendon and aponeuroses very tough and resistant, composed of the protein collagen

Elastic- yellow fibers- Less compare to collagen fibers Seen in arteries and ligament flava Made up of fibroblast smaller and more elastic, may stretch up to 50% of their length

Reticular fibers- These are fine reticular fibers, Present in lymphoid organs collagen and glycoprotein, provide support and strength in

areolar matrix

Ground Substance Non fibrous Element It is like get containing high amount of Water Main substance is Hyaluronic Acid

Types of Connective Tissue1. Ordinary connective tissue

A. Irregular connective tissue1. Loose connective tissue2. Dense irregular connective tissue3. Adipose tissue

B. Regular connective tissue

2. Special connective tissueA. Mucoid tissueB. Pigmented connective tissueC. BoneD. Cartilage

Loose connective tissue Most extensively distributed in body Made of thin collagen and Elastin fibers Have all type of cell except reticular cells It is present at eyelid, penis, scrotum, muscle,

blood vessels, nerves It permit considerable movement between the

parts it bounds

Dense irregular tissue It found at the places where there is extensive

stress It contain high amount of collagen fibers with

few fibroblasts It is found in dermis, sheets of muscles,

vessels, nerves, periosteum, perichondrium

Adipose Tissue This tissue made of Large amount of Fat cells. Have “signet ring” (class ring) shape where

cell’s nucleus and cytoplasm are pushed to the edge of cell

Two types White and Brown

Brown Makes up 20 to 25

percent of body weight

Location – Supporting the Kidney, Eyes, between Muscle fibers, under the skin,

Function – as thermal insulator

Abundant in new born

When it is metabolized it produces more heat and less energy

Less in adults

White

Mucoid Tissue It’s an embryonic type of connective tissue It forms umbilical cord It is made of fine meshwork of collagen fibers Cells are fibroblastPigmented tissue Present in Choroid and Lamina fusca of the

sclera of eye

Function of connective tissue1. As a packing Material, as it provides a

supporting matrix2. It forms restraining mechanism of body like

retinacula, pulley etc3. Forms deep fascia4. Helps in repairing injuries, by help of

fibroblasts5. Macrophages in defense

CARTILAGE Can endure a lot of stress Has no blood vessels or nerves, except for

perichondrium, which covers the surface Strength is due to collagenous fibers Resilience is due to chondroitin sulfate Cartilage cells are called chondrocytes

(chondroblasts) and sit in shallow cavities called lacuna

TYPES OF CARTILAGE Hyaline Fibrocartilage Elastic

Hyaline cartilage Most dense type (gristle) Most abundant LOCATION:

Ends of long bones and forms the costal cartilage at the ventral ends of the ribs

Found in the nose, larynx, trachea, and bronchi

Fibrocartilage Strength and rigidity LOCATION:

Symphysis pubis, intervertebral discs, and menisci (protective sac) of the knee

Elastic cartilage Chondrocytes are thread-like network of

elastic fibers Location:

Epiglottis, pinnae (outer ear), Eustachian tubes (inner ear)

OSSEOUS TISSUE (BONE) Together with cartilage forms the skeletal

system Contains abundant matrix. Osteoblasts produce bone matrix. Bone tissue consists of many repeating

units of OSTEONS (Haversian Systems).

OSTEON Osteon Consists of

Haversian canal- runs through the bone matrix; contains blood vessels and nerves

Lamellae- concentric rings of hard intercellular matrix

Lacunae- small cavities in the matrix where “osteocells” (cytes, blasts, clasts) are found

Osteocytes- mature bone cells that have lost the ability to produce new bone tissue

Canaliculi Minute canals radiating throughout the

matrix- nutrients enter the osteocytes and cell wastes are removed through these canals

ADULT CONNECTIVE TISSUEConnective tissue proper is composed of a fluid- like intercellular material and fibroblasts. The intercelluar matrix is in large amount,The fibroblasts secrete the intercellular material (matrix)

Cartilage (3 types)Osseous tissue (1 types)Vascular tissue (blood)

FUNCTION OF CONNECTIVE TISSUE

Bindings ProtectionTransportInsulation

CONNECTIVE TISSUE PROPERAreolarAdiposeDense connective Elastic connective tissueReticular connective tissue

AREOLAR TISSUE

Loose ordinaryAbundant in humans, consists of various types of fibers and cells embedded in the matrix

The matrix contains of hyaluronic acid, which serves to help the passage of nutrients in and out of cells

Locations

Under the skin Between the musclesSupport the blood vessels and nerves

Digestive canal

FIBERS IN AREOLAR TISSUECollagenous- white fibers - very tough and resistant, composed of the protein collagen

Elastic- yellow fibers- smaller and more elastic, may stretch up to 50% of their length

Reticular fibers- collagen and glycoprotein, provide support and strength in areolar matrix

CELLS IN AREOLAR MATRIX

FibroblastsMacrophagesPlasma cellsMast cells

FIBROBLASTS

Large cells with branching processes that form new fibers and matrix –

They are called fibrocytes when mature

Helpful in tissue repair as they form granulation tissue

MACROPHAGES

WBCs capable of engulfing bacteria and cellular debris- derived from monocytes (a type of White Blood Cell)

They are working as Phagocytosis

PLASMA CELLS

Give rise to antibodies, which attack antigens that enter the body (Plasma cells arise from lymphocytes.)

MAST CELLS

Produce heparin, which prevents blood from clotting in the vessels. Also produce histamine and serotonin (which dilate blood vessels) Mast cells develop from basophils.

ADIPOSE TISSUE

Have “signet ring” (class ring) shape where cell’s nucleus and cytoplasm are pushed to the edge of cell

Two typesWhite and Brown

WHITE ADIPOSE TISSUE

Makes up 20 to 25 percent of body weight

Location – Supporting the Kidney, Eyes, between Muscle fibers, under the skin,

Function – as thermal insulator

BROWN ADIPOSE TISSUE

Abundant in new bornWhen it is metabolized it produces more heat and less energy

Less in adults

DENSE CONNECTIVE TISSUE

Has a closer, more dense packing of fibers than areolar and less matrix IrregularRegular

IRREGULAR DENSE CONNECTIVE TISSUETensions are exerted in various directions- the bundle fibers are interwoven without regular orientation

Forms fasciae, ligaments, periosteum of bone, perichondrium of cartilage (protective covering around the surface of cartilage)

REGULAR DENSE CONNECTIVE TISSUEAdapted for tension in one direction. Fibers have an orderly, parallel arrangement

ELASTIC CONNECTIVE TISSUEFreely - branching elastic fibers giving tissue a yellow color.

Fibroblasts are present between fibers.

Can stretch and snap back into place

LOCATION: larynx, arteries, trachea, bronchial tubes, lungs

FIBROUS TISSUE

Its bundles of collagen fibers with small matrix

LOCATION:- ligaments, periosteum, outer coverings of Brain, Kidney, muscle facia

RETICULAR CONNECTIVE TISSUEFUNCTION: Consists of interlacing reticular fibers that support organs (forms the stroma, or framework of organs)

VASCULAR TISSUE-BLOOD Picks up O2 from the lungs, nutrients

from the digestive tract, hormones from the endocrine glands, and enzymes and transports them to cells

Picks up wastes (CO2, urea) from cells and carries them to the lungs, kidneys, or sweat glands for expulsion

Erythrocytes (RBCs), Leukocytes (WBCs) and Thrombocytes (platelets)

MUSCLE TISSUE

FUNCTION: contractionProvides means for motion, maintenance of posture and heat production

3 TYPES Skeletal Cardiac Smooth

SKELETAL Voluntary muscle; attached to and

moves the skeleton Myofibrils are contractile units - give

muscle striated appearance Cells are multinucleated and

cylindrical Each cell is surrounded by sarcolemma (plasma membrane)

The cytoplasm is called sarcoplasm

CARDIAC MUSCLE Forms the bulk of the heart

(involuntary muscle) Striated with quadrangular (square)

fibers which branch - forming networks

Uninucleated Muscle fibers are separated from each

other by transverse thickenings of the sarcolemma called intercalated discs

SMOOTH MUSCLE Involuntary muscle Found in the walls of hollow internal

structures (vessels, stomach, bladder, small intestines)

Non-striated, uninucleated, pointed at both ends (Canoe or cigar – shaped nucleus)

NERVOUS TISSUE

FUNCTION: pick up and transmit stimuli (conduction)

Two components Neurons (nerve cells) Neuroglia (support cells)

NEURONSConduct nervous impulses to other neurons, muscles, or glands

3 main parts Dendrites: receive impulses from other

neurons Cell body (Perikaryon, or soma):

contains the nucleus and other organelles

Axon: carries impulse away from a cell body

NEUROGLIA Smaller cells that protect and support

the larger neurons

THE END