Tissue (Biology)

Tissue– Are group of cells performing same function.

Animal Tissue:

*epithelial- A type of tissue where cells are closely arranged with each other.

-Simple squamous- made up of flat like and scale like or polygonal cells. Made up of 1 thick cell of these cells, found in capillaries, alveoli, glomeruli.

-stratified squamous- Forms at the outermost layer of the skin, inner lining of mouth, esophagus

-Simple cuboidal- cube like cells. Cells comprising thyroid gland and kidney tubules, ovaries, lining of nephrons, thyroid.

-stratified cuboidal- Found in sweat glands, salivary glands and mammary glands.

-Simple columnar- associated with the linings of digestive tract functioning for absorption and secretion. Stomach, large intestine, small intestine.

-Pseudo stratified Columnar- tissue may appear stratified creating illusions on the condition. All cells originated in the base. Found in male reproductive organ.


Connective Tissue

*Loose connective tissue- consists of fibroblasts (secretes fibers that are deposited in the tissue matrix). Found beneath the dermis of skin, underneath epithelial tissues, mucous membranes of digestive, respiratory and urogenital tracts.

*Dense connective tissue- Made up of dense collagenous fibers in bundles and arranged in parallel fashion.

-Tendon- connects muscles to bones

-Ligament- connects bone to bone

*Cartilage- has cells known as chondrocytes (lodged in spaces known as lacunae)

-does not have blood supply

-has three types based on type of extracellular matrix

~hyaline cartilage- matrix: transparent and made up of type II collagen and chondroitin sulfate. This tissue makes up tracheal rings, nasal septum, costal cartilages and epiphyseal cartilages.

~elastic cartilage- made up of bundles of elastin fibers. Can be found in epiglottis and pinnae.

~fibrocartilage- has an extracellular matrix with dense bundles of collagenous fibers. Found in pubic symphisis and intervertebral discs.

-Bone- a connective tissue made up of bone cells (osteocytes) made up of inorganic component, calcium hydroxyapatite and organic component of collagen fibers. Basic unit of bone tissue is the haversian system. Blood vessels and nerves supply bone cells through haversian canal. Volkman’s canal arises from haversian canal.

Canaliculi are minute and microscopic canals that carry nutrients to individual bone cell.

-Bones have calcified matrix.


Muscular Tissue

*Skeletal muscle tissue- attached to bones. Muscle fiber is characteristically striated with alternating light (isotopic) and dark (anisotropic) bands. The thin actin molecules are associated with light band while the thicker myosin molecules are oriented at the dark band.

Muscle fiber is multinucleate (synctium) has contractile unit termed as sarcomere.

Cardiac muscle- muscle tissue of the heart

*striated & has involuntary function. The muscle fibers are branch and provided with links (intercalated disks) between them.

Smooth muscle- also known as visceral muscle tissue. Spindle shaped with a singular nucleus and involuntary in action. Main contracting tissue of visceral organs (e.g. digestive tract, uterus, urinary bladder and blood vessels)

~peristaltic movement- movement due to the contraction of smooth muscles.


Blood Tissue – extracellular matrix of a blood tissue is plasma. Plasma (where vitamins and minerals are lodged). Comprised with:

`Red blood cells- (erythrocytes) appear as biconcave. No nucleus at maturity. Produced by erythropietic organ. Life span is from 120-127 days after that it will be destroyed by spleen. Has hemoglobin (red protein pigment which carries oxygen and carbon dioxide.

`White blood cells- (leucocytes)

Agranulocytes (no granules)

.lymphocytes-cells divided into two types: (B-cells; production of antibodies, T-cellsl cell mediated immunity)

.Monocytes- in tissues, the cell are functioning as phagocytes

Granulocytes- have granules

.neutrophils- have 3-5 lobed nucleus. Considered primary combatant in infection. Cells engulf bacteria.

.eosinophils- cells have horse shoe shaped nucleus. Have ability to destroy parasites.

.Basophils- release histamine once stimulated. Histamine is responsible for allergic reaction.

*blood platelets (thrombocytes) irregular cells for blood clotting.



P.S. This is a reviewer for the tissues lesson. Credits for the picture  http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AnimalTissues.html


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