1. Tissues Chapter 5

2. Tissues A tissue is a group of similar cells that are specialized for a particular function. Histology – the study of tissues The Immortal Life of Henrietta Lacks

3. Four Principal Types of Tissues: Epithelial –covering and lining; glands Connective – protects and supports, binds organs together, stores energy, and provides immunity Muscle – movement Nervous –transmits impulses that coordinate body activities

4. Epithelial Tissue Characteristics Closely packed cells with little extracellular material between cells Epithelial cells are arranged in continuous sheets, in single or multiple layers

5. Epithelial Tissue Characteristics Avascular, meaning no blood vessels. Attached firmly to nearby connective tissue by means of the basement membrane. Has a good nerve supply

6. Epithelial Tissue Characteristics Constant cell division since it is subject to wear and tear. Epithelial tissue functions include: protection, filtration, secretion, absorption, excretion, transportation **Epithelium is named for its cell shape and number of layers

8. Covering and Lining Epithelium Epithelial layers are arranged as: Simple epithelium (one layer) Stratified epithelium (several layers) Pseudostratified epithelium (one layer that looks like several) nuclei at different level; not all cells reach the surface*** *** cells that do have cilia or secrete mucus.

9. Number of Layers Simple Stratified Pseudostratified Transitional*

10. Cell Shapes Squamous (flat) for diffusion Cuboidal (cubelike) - produce secretions and function in absorption Columnar (rectangular) - protect underlying tissue, may have cilia, secretion or absorption. Transitional (variable) - change in shape from flat to columnar due to distention, expansion or movement of body parts.

11. Cell Shapes

12. Classification is by number of layers and cell shape (top layer) Simple squamous epithelium - 1. single layer of flat cells. 2. found in heart, blood vessels, lungs, and kidneys. 3. Diffusion, osmosis, and filtration

15. Classification is by number of layers and cell shape (top layer) Simple cuboidal epithelium - 1. single layer of cube-shaped cells. 2. found in ovaries, glands, and kidneys 3. secretion and absorption ***(cuboidal - think glands!)

17. Classification is by number of layers and cell shape (top layer) Simple columnar epithelium comes in two forms: with or without cilia Simple columnar epithelium - 1. a single layer 2. lines the digestive tract from the stomach to the anus

18. Classification is by number of layers and cell shape (top layer) 3. Functions - secretion, absorption, protection, and movement 4. Special feature - can have cilia and Goblet cells that secrete mucus

20. Classification is by number of layers and cell shape (top layer) Pseudostratified columnar epithelium 1. Has only one layer but looks like it has many layers. (Some cells do not reach the surface.) 2. Lines passages of respiratory system 3. Functions - secretion and movement 4. Pseudostratified ciliated - has cilia and goblet cells

22. Stratified Epithelial Tissue Has at least two layers of cells. Named by shape of the cells in the superficial layer. Stratified squamous epithelium – 1. several layers of cells (Top layer has flattened cells.) 2. Found in skin, mouth, vagina, and throat 3. Function - protection 4. keratin - protein found in outer layer of skin. Waterproofs skin

24. Stratified Epithelial Tissue Stratified cuboidal epithelium - 1. consists of several layers (Top layer is cube-shaped) 2. Found in ducts of glands (sweat, mammary, etc) 3. Function is mainly protection. 4. Fairly rare

26. Stratified Epithelial Tissue Stratified columnar epithelium - 1. several layers of cells (Top layer is rectangular.) 2. Found in male vas deferens & urethra, pharynx 3. Functions in protection & secretion 4. Also uncommon

28. Stratified Epithelial Tissue Transitional epithelium 1. Has many layers 2. Found in the urinary bladder & urethra 3. Function - expansion or stretching (distention)

33. Glandular Epithelium A gland is a single cell or a mass of epithelial cells adapted for secretion. There are two types depending on how the cells release the substances they produce: exocrine glands and endocrine glands

34. Glandular Epithelium OUTOUT OF INTO

35. Glandular Epithelium Exocrine glands secrete product out of ducts or directly onto a free surface. Secretions include mucus, sweat, oil, ear wax, saliva, and digestive enzymes.

36. Glandular Epithelium Classification of exocrine glands : Holocrine - whole cell disintegrates (example - sebaceous glands) Apocrine glands - a portion of cell pinched off. Cell repairs itself. (example - mammary glands) Merocrine - substance secreted by going through cell membrane (exocytosis). (example - salivary glands)

40. Glandular Epithelium Endocrine glands - “ductless glands” discharge their secretions into the bloodstream. secretions - hormones, which regulate many bodily functions.