Epithelium. Four primary tissue types:

Transcription

1 Epithelium Four primary tissue types: Epithelial (covering) Connective (support) Nervous (control) Muscular (movement) Smooth muscle Cardiac muscle Skeletal muscle 1

2 Epithelial Tissue Features Epithelial tissues always have an apical and basal surface. Avascular with no direct blood supply; nutrients must diffuse. Epithelial tissues have a high capacity for regeneration. Cells are in close contact with each other with little or no intercellular space between them. May have junctions for both attachment and communication. Always resting on a basement membrane Classified based on: Number of layers: 1 layer = simple 1 layer irregularly shaped= pseudostratified >1 layer = stratified >1 layer of similar cells = transitional Shape of the cells of outermost layer: Flat: Squamous Square, round, cubical: Cuboidal Tall: Columnar 2

3 Simple Squamous Epithelium Thin single cell layer attached to a basement membrane Simple squamous: with flattened nuclei. Present in the alveoli of lungs, Kidneys, Lining of visceral organs and all blood vessels. Function: selective diffusion, filtration absorption or secretion. Mesothelium: simple squamous that lines body cavities and cover organs. Endothelium: simple squamous that lines the inside of blood vessels and capillaries. 3

4 Simple Cuboidal Epithelium Simple cuboidal: with central rounded nuclei. Present in liver, pancreas, acini of glands, lines small ducts and tubules of kidney. Function: excretory, secretory or absorptive. 4

5 Simple Columnar Epithelium Simple columnar: with basal oval nuclei. Present in the absorptive surfaces (intestine); secretory surfaces (stomach); lining gall bladder (absorbs water). Simple Columnar Epithelium (cont d) 5

6 Pseudostratified Columnar Epithelium Pseudostratified columnar ciliated: nuclei disposed at different levels; basal cells do not extend to surface; Present in larger airways of respiratory system (trachea, bronchi). Function: to trap and remove unwanted particles from the respiratory tract Transitional Epithelium Transitional: urinary tract; accommodates stretching and toxicity of urine; surface cells larger, pale-staining, scalloped surface outline; luminal surface appears thickened; may be binucleate; large, round, prominent nucleoli. Function: distension- supplying elasticity/tension to urinary bladder 6

7 Transitional Epithelium (cont d) Stratified epithelium = more than 1 layer Function: protection 7

8 Stratified Squamous nonkeratinized (SSNK) Stratified squamous non-keratinizing (mucous membrane): resists abrasion; moistened by glandular secretions. Present in oral cavity, pharynx, esophagus, anal canal, uterine cervix, and vagina. Function: protection Stratified Squamous keratinized (SSK) Stratified squamous keratinizing: Upper cell layer composed of squamous cells. Present in surface of skin Function: protection 8

9 Concept Check The type of epithelium indicated by the arrow lines the: a) skin b) mucosa of the esophagus c) respiratory tract d) urinary tract f) mesentery The type of epithelium shown in this image is: a) Simple cuboidal b) Simple columnar c) Stratified columnar d) Pseudostratified columnar (respiratory) e) Transitional 9

10 GLANDULAR EDPITHELIUM Glandular Epithelium Two Main Types of Glandular Tissues: Exocrine release secretions through ducts Endocrine - release secretions directly to the blood (covered in subsequent lectures) 10

11 Glandular Epithelium structure Glands are classified structurally based on the duct and the secretory portions. Ducts considered compound when they are branched and are simple when they are not branched. shapes of the secretory portions of glands: tubular, acinar (rounded), or tubulo-acinar (rounded with tubular end) branched tubular or coiled tubular (long and not branched) Nature of secretions Serous secretion: secret watery fluid rich in protein (parotid glands) Mucous secretion: secret mucus; poor in protein (goblet cells) Muco-serus secretion: as in mixed salivary glands Milky secretion: mammary gland Wax secretion: glands in external ear Fatty secretion: sebaceous glands Watery secretion: sweat glands Cellular secretion: ovary and testis. 11

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13 Modes of Secretions Apocrine glands: a small portion of the apical cytoplasm discharged with the secretory products. e.g.. Mammary glands and some sweat glands. Holocrine glands: discharge whole cell; sebaceous glands (sebum). Merocrine glands: in which secretion occurs by exocytosis; i.e. no cellular changes as parotid glands. Simple Tubular Gland 13

14 Simple Branched Tubular Gland Simple Coiled Tubular Gland 14

15 Compound Acinar Gland Compound Tubuloacinar Gland 15

16 Mucous cells produce mucus, which doesn't stain very darkly, so the mucous cells look almost clear on these images and on slides. Serous cells produce a watery secretion that contains a lot of proteins and enzymes. Serous cells stain fairly dark. Endocrine Gland 16

17 Epithelium Summary Tables 17

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19 Connective Tissue 19

20 Connective Tissue s Functions Binding and Support Protection Mineral storage Insulation Energy Storage Transportation (blood) Immunity connective tissues (CT) consist of material between or outside of cells, largely fibers and a gel-like ground substance. C.T. Structure Cells are widely separated among the masses of fibers and ground substances. Fibers and ground substance are termed the extracellular matrix (ECM). Fibers, composed of collagen or elastin, are responsible for the tensile strength and elasticity of the tissue. Ground substance, composed of hydrated proteoglycans, provides the medium through which dissolved substances pass from capillaries to cells and back. 20

21 Connective Tissue is composed of: Cells Extracellular Matrix (material outside of cells) Extracellular matrix, ECM, is composed of fibers of protein and ground substance 21

22 Ground substance consists of glycosaminoglycans and glycoproteins Cells of the CT Mitotically active = blasts Mature cells = cytes Fibroblasts = cell that synthesizes the extracellular matrix and collagen Mast Cells = histamine release Plasma Cells = antibody release Adipocytes Leukocytes 22

23 Different Cell Types found in C.T. Connective Tissue Types 1) Loose Connective Tissue = loose arrangement of cells; not very organized Areolar Adipose Reticular 2) Dense Connective Tissue = Tightly packed cells; more organized Dense Regular Dense Irregular Elastic 23

24 Areolar Loose Connective Tissue Loose Connective Tissue 24

25 Loose Areolar C.T. Found in the lamina propria; in between muscles, in lungs. Acts as space filler Loose arrangement of Reticular fibers: Makes the framework for lymphatic organs i.e. (tonsils, thymus, spleen, lymph nodes) Loose Reticular C.T. 25

26 Adipose Tissue Dense Elastic CT Found in arteries, e.g. (aorta) 26

27 Dense Irregular Connective Tissue Found in Dermis, pericardium of heart, synovial joint capsule Dense Regular Connective Tissue Found in Tendons & Ligaments Tendons: attach bone to muscle, Ligaments: attach bone to bone 27

28 Dense Regular Connective Tissue(cont d) Dense Regular Connective Tissue(cont d) 28

29 Quiz # 2 next week 09/17 on this lecture & Assignment #1 due to be handed in at the BEGINNING of class Assignment #1 29

30 1. Identify the basic tissue indicated by the arrow 2. Identify the type of epithelium indicated by the arrow 30

31 3. Identify the type of epithelium & the cell type indicated by the arrow 4. Identify the type of epithelium indicated by the arrows 31

32 5.Identify the type of epithelium & name the apical structure (i.e. cilia or microvilli) 6. Identify the 2 different cell types in this submandibular gland:- Indicated by the wide and thin arrows 32

33 7. Identify the type of epithelium and where it is found 8. Identify the type of Epithelium and where it is found 33

34 9. Identify the type of Epithelium & where it is found 10. Classify the type of connective tissue 34

35 11. Classify the type of connective tissue & identify the cell types indicated by the arrow 12. Classify the type of connective tissue and the type of fiber stained black 35

36 13. Classify the type of connective tissue and the type of fiber stained black 14. Classify the type of connective tissue 36

37 15. Classify the type of connective tissue 16. Classify the type of connective tissue 37

38 17. Classify the type of connective tissue 18. Classify the type of glandular epithelium 38

39 19. Classify the type of glandular epithelium 20. Classify the type of glandular epithelium 39