1. TISSUES

2. TYPES OF TISSUE
A tissue is a group of similar cells that function together to perform a specialized activity (differentiation).
Histology is the study of tissues.
The major types of tissues are: Epithelial, Connective, Muscular, and Nervous.

3. Epithelial Tissue
Is the only tissue that is constantly regenerated in large amounts.
The 2 types of epithelium are: Lining and Glandular.
Epithelium contains very little intracellular material and is avascular (no blood supply)

4. General features of Epithelium
Consist of closely packed cells.
Contain a free surface open to body cavities, lining of organs, or exterior of body.
Avascular
Do not have a nerve supply.
High regeneration rate.

5. Function of Epithelium
Protection
Secretion
Absorption
Excretion
Sensory Reception
Reproduction

6. Covering and Lining Epithelium
Classified by Shape: squamous, cuboidal, columnar, or transitional.
Classified by Arrangement of layer: simple, stratified, or pseudostratified. Some epithelium also contain cilia and/or secrete mucous.

7. Simple Squamous
Simple squamous epithelium functions to diffuse gases and movement of fluid via osmosis.
Location: lines heart, lymph nodes, abdominal cavity, and serous secretions.
Main function is Filtration and absorption.

8. Simple Squamous Epithelium

9. Simple Squamous Epithelium

10. Simple Squamous

11. Simple Cuboidal
Secretes tears and saliva and absorbs water in kidney tubules.
Location: covers ovaries, lines kidney tubules, eye lens, and retina.
Function: secretion and absorption.

12. Simple Cuboidal

13. Simple Cuboidal

14. Simple Cuboidal

16. Simple Columnar
May have microvilli, which serve to increase surface area or goblet cells to secrete mucous.
Location: lines GI tract, stomach excretory ducts or glands, gallbladder.
Function: secretion and absorption.

17. Simple Columnar

18. Ciliated Columnar

19. Simple Ciliated Columnar
Lines respiratory tract, uterine tubes, and uterus.
Moves mucous by ciliary action

20. Stratified Squamous
Contain protein called keratin and serves as a protective barrier against microbes and water. (keratinization)
Lines the mouth, tongue, esophagus, vagina, and outer layers of skin.
Function: Protection

21. Stratified Squamous

24. Stratified Cuboidal
Rare type of epithelium, serves as a protective layer.
Comprises ducts of sweat glands, conjunctiva of eye, pharynx, and male urethra.
Function: Protection

28. Stratified Columnar Lines male urethra.
Function: Protection and Secretion.

31. Goblet Cells

32. Transitional Epithelium
Found in organs which have to expand.
Acts to prevent organ rupture.
Lines urinary bladder, urethra, and ureter tubes.

36. Pseudostratified Columnar
Serves as functional structure for ducts and tubes throughout the body and provides for movement of materials.
Lines large excretory ducts, epididymis,male urethra, eustachian tubes, male reproductive tract.

40. Glandular Epithelium Principal function is Secretion.
A gland consist of one cell or a group of cells, highly specialized for secretions into ducts, onto surfaces, and into the blood.
Exocrine glands secret products which empty onto external or internal surfaces. Ex: sweat glands, salivary glands, and digestive tract glands.

41. Glandular
Endocrine glands: are ductless, release hormones, and secrete their products directly into the blood circulation.
Examples: pituitary gland and adrenal glands.

42. Connective Tissue Most abundant tissue in the body.
Highly vascular (blood supply)
Contains a variety of cells with a large amount of intracellular matrix.
Functions: protection, support, binding, and storage.

43. General Features of Connective Tissue
Consists of 3 basic elements: cells, ground substance, and fibers.
The 3 components together form the Matrix.
Do not generally occur on free surfaces.
Contains a nerve supply; except cartilage.

44. General Features Cont….
Highly vascular; except for cartilage.
The matrix can be gelatinous, fibrous, or calcified.

45. Connective Tissue Cells
Fibroblasts – generate the protein fibers.
Macrophages – destroy foreign invaders, similar to a white blood cell
Plasma cells – generate and form matrix for red blood cells.
Mast cells – generate histamine in response to allergens or tissue injury

46. Connective Tissue Matrix
Matrix gives unique characteristics to each tissue type.
Contains protein fibers embedded into fluid, gel, or solid Ground Substance.
Fibers include: Collagen, Elastic, and Reticular.

47. Fibers Cont…..
Collagen – very tough and resist pulling. Arranged into bundles for strength. Most abundant fiber in body. Made up of protein.
Elastic – smaller and thinner than collagen. Made up of the protein elastin which provides strength and elasticity.
Reticular – comprised of collagen and glycoproteins, provides strength to support blood vessels.

48. Classification of Connective Tissue
Embryonic Tissue – found in developing fetus. Includes Mesenchyme and Mucous connective.
Adult Tissue – includes Loose, Adipose, Dense, Elastic, and Reticular.
Osseous (bone) and Vascular (blood) are specialized connective tissues.

49. Embryonic
Mesenchyme – stem cells which differentiate to form all connective tissues.

50. Mucous Connective

51. Areolar Location: around organs, dermis, subcutaneous layer.
Function: strength, elesticity, and support.

52. Adipose Location: subcutaneous, heart, kidneys, bones, joints.
Function: heat loss reduction, support, protection, store energy (fat).

54. Collagenous
Location: tendons, ligaments, heart, bone, liver, lymph nodes.
Function: support and attachment.

56. Elastic Location: lungs, arteries, trachea, bronchi, and vocal cords.
Function: stretching.

58. Reticular Location: liver, spleen, lymph nodes.
Function: forms stroma and basal laminae of organs.

60. Hyaline Cartilage
Location: Ends of long bones, larynx, bronchi, and embryonic skeleton.
Function: movement at joints, support, flexibility.

62. Fibrocartilage
Location: joints between hips, intervertebral disc, and knees.
Function: support and fusion.

64. Elastic Cartilage
Location: epiglottis, external ear, and eustachian tubes.
Function: Support and shape.

66. Osseous Tissue (bone) Forms structure and frame of body.
Functional unit is called an osteon or haversian system.

67. Vascular Tissue (blood)
Made up of erythrocytes (red), leukocytes (white), and thrombocytes (platlets).

68. Muscle Tissue
Specialized tissue which contracts, provides movement, maintains posture, and produces heat.
3 Types: Skeletal (attached to bone),
Cardiac (heart) and Smooth or Visceral found in organs.
Skeletal and Cardiac are striated, while smooth is non-striated.

69. Muscle Tissue Cont…
Smooth and Cardiac are involuntary controlled by the brain without thinking about it.
Skeletal is voluntary. You think the movement then it happens.

71. Nervous Tissue
Specializes in electrical conduction to send signals throughout the body.
Neuron – nervous cell made up of 3 parts: Dendrites, Cell body, and axon.
Neuroglia (glia) – support cells that help neurons function.

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