1. Ch. 4 Tissues

2. Objectives Define tissue Describe the four main tissue types Identify the various tissues that fall under the four main tissues types, their functions and composition Know how tissue growth and repair occur

3. Tissues – Group of cells that are similar in structure and perform a common or related function – The study of tissues and their arrangement into organs Histology – Four main types Differ by type of cells and characteristics of matrix

4. Four Main Tissue Types Epithelial Connective Muscle Nervous lima.osu.edu sohoparenting.com clcpages.clcillinois.edu science.tjc.edu

5. Epithelial Tissue Sheet of cells that covers a body surface or lines a body cavity – Covering and lining epithelium Cells that compose glands of the body – Glandular epithelium Functions – Protection, absorption, filtration, secretion, excretion, sensory reception

6. Characteristics of Epithelium Cellularity – Almost entirely composed of closely-packed cells Minimal ECF Specialized connections – Continuous sheet of cells – Tight junctions and desmosomes Polarity – Apical surface and basal surface – Basal lamina Connective tissue support – All epithelium supported by connective tissue – Reticular lamina – Basal lamina + reticular lamina = basement membrane Avascular – No blood vessels within epithelium – Is innervated Regeneration – high regenerative capacity

7. Classification of Epithelium Based on number of cell layers and on cell shape Cell layers – Simple – refers to one layer of cells – Stratified – refers to two or more layers of cells Cell shape – Squamous – flat, scale-like cells – Cuboidal – cube shaped cells – Columnar – column shaped cells How is pseudostratified columnar classified?

8. Simple Squamous Epithelium Thin and permeable – Found where rapid filtration and diffusion is desired Kidneys, lungs unm.edu

9. Simple Cuboidal and Columnar Function in secretion and absorption Found in tubules of the kidneys and in ducts of glands Function in absorption and secretion Found in stomach, intestines, uterus, uterine tubes uoguelph.cafaculty.palomar.edu

10. Pseudostratified Columnar Epithelium Function in secretion, absorption, and motility of mucus Cells vary in height, but all cells touch the basement membrane Found in the respiratory tract and male urethra faculty.palomar.edu

11. Stratified Squamous Most abundant stratified epithelium Functions in protection against abrasion Found on outer layer of skin and extend a short way into every body opening that is continuous with the skin – Keratinized and non-keratinized dspace.udel.edu

12. Stratified Cuboidal and Columnar Functions in secretion and sperm production Found in sweat gland, ovaries, seminiferous tubules Function in protection and secretion Rare, found in ducts of large glands, male urethra

13. Transitional Epithelium Functions to allow distention of the urinary bladdery Found in the bladder Basal cells are typically cuboidal Apical cells vary in shape dspace.udel.edu

14. Glandular Epithelia Glands are cells or organs that secretes a substance for use or elimination – Originate from invagination of epithelial tissue Classified into two categories – Endocrine – Exocrine Unicellular glands – Composed of one cell that secretes its products into its surroundings

15. Exocrine Glands Typically enclosed by fibrous capsule – Septa – capsular extension that divide gland into lobes – Parenchyma – cells that synthesis and secrete Classified based on the duct – Simple – single unbranched duct – Compound – branching ducts

16. Exocrine Glands

17. Types of Secretions Serous glands – Thin watery fluids Mucus glands – Secrete mucin that is converted into mucus upon absorption of water Cytogenic glands – Secrete whole cells Testes and ovaries

18. Epithelial Surface Features Three ways: Adhesion proteins, interdigitating folds, and specialized junctions Specialized junctions – Desmosomes – Tight junctions – Gap junctions vivo.colostate.edu

19. Cell Adhesions Tight junctions Gap junctions bio.davidson.edu academic.brooklyn.cuny.edu

20. Epithelia Surface Features Basal Features – Basement membrane Basal lamina Reticular fibers Apical Features – Microvilli – Cilia micro.magnet.fsu.edu users.umassmed.edu journalofillustratedscience.blogspot.com

21. Connective Tissue Found everywhere in the body and most widely distributed Functions – Connects, supports, protection, insulation, and transportation Four main classes – Fibrous tissue and fat – Cartilage – Bone – Blood

22. Characteristics of Connective Tissue Common origin – All arise from mesenchyme Degree of vascularity – Some avascular, while others highly vascular Extracellular Matrix – Tissue made up mostly of matrix Ground substance

23. Structural Elements of CT Ground substance – Interstitial fluid between the cells allows for diffusion between blood vessels and cells – CAP, GAG, Proteoglycans Fibers – Provide support Collagen Elastic Reticular Cells – Fibroblasts, macrophages, leukocytes, plasma cells, mast cells, adipocytes

24. Fibrous Connective Tissue Loose connective tissue – Areolar Serves to support most epithelium Very loose fibers run in various directions – Reticular Framework of “soft organs” Dense connective tissue – Dense regular Composed of closely packed parallel collagen fibers Fibroblast only type of cell Tendons and ligaments – Dense Irregular Thick collagen fibers running in various direction Compose the dermis, and fibrous sheaths around various organs

25. dspace.udel.edu

27. Fibrous Connective Tissue Adipose tissue – Composed of adipocytes that store fat – Functions as insulation and support – Most fat is white fat – Children also produce brown fat Heat production carlalbert.edu

28. Cartilage Supportive connective tissue with flexible rubbery matrix Chondroblasts secrete matrix until they are trapped. – Chondrocytes Avascular – Dependent on diffusion – Slow metabolism, slow to heal

29. Cartilage Three types – Hyaline Clear glassy matrix with collagen fiber Found at the ends of bones, larynx, trachea, and chest Composes fetal skeleton – Elastic Matrix composed of elastic fibers Perichondrium sheath Ear, epiglottis – Fibrocartilage Matrix composed of thick parallel collagen bundles No perichondrium sheath Pubic symphysis, intervertebral discs, menisci Compression and shock absorption Sometimes transition between dense connective tissue and hyaline

30. dspace.udel.edu

32. biology.clc.uc.edu

33. Bone Osseous Tissue – Spongy – Compact Hard calcified matrix containing collagen fibers – Deposited in concentric lamellae around central canal Blood vessels and nerves – Osteoblasts, osteocytes, osteoclasts Support, protection, movement, mineral and fat storage, blood production technion.ac.il

34. Blood Fluid connective tissue – Formed elements in a fluid matrix (plasma) Transport nutrients, wastes, gases... Found within blood vessels altered-states.net

35. Muscle Tissue Highly cellular, well vascularized tissues responsible for movement Capable of contraction and producing tension Three types – Skeletal – Smooth – Cardiac

36. Nervous Tissue Main component of nervous system – Regulates and controls various functions Capable of transmitting electrical impulses Two cell types – Neurons Conduct impulse – Supporting cells Nonconducting, insulate and protect neurons

37. Read the section on inflammation and repair