Chapter 5 Histology

1. Chapter 5Histology • HISTOLOGY-Study of tissues • Tissue- a group of similar cells that share a function • Molecules---cells---tissues---organs • Pathologist- examines pathology of tissue

2. The Body Has Only 4 Types of Tissues • EPITHELIAL (EPI = Around) • CONNECTIVE - Connects • MUSCLE • NERVE

3. Closely packed cells, arranged in sheets Two surfaces: top = apical, base =basal Avascular (without vessels)- No room for blood vessels depends on underlying connective tissue for oxygen Anatomy: (top to bottom) Apical surface, basement membrane, connective tissue. Epithelial Tissue

4. Epithelial Tissue Features • Has nerves, high mitotic rate so the tissue can renew itself often • Some functions: • protection • filtration • secretion • digestion / absorption • excretion

5. Epithelial Layers • Simple • single layer • Stratified • 2 or more layers • Pseudostratified • single layer that looks stratified, only long columnar cells

6. Epithelial Cell Shapes • Squamous, squashed flat • Cuboidal, cubes • Columnar, columns - tall and cylindrical • Transitional, can transform from cuboidal to flat, found in bladder

7. Naming Epithelium • First name is the number of layers in the tissue (simple, stratified, pseudostratified) • Middle name is the cell shape of the tissue (I.e. flat, cubed, column) • Last name is the tissue type which is epithelium • Sometimes we add a modifier in the beginning i.e. ciliated

8. Simple Squamous Epithelium • Single row of flat cells • Allows rapid diffusion of substances; secretes serous fluid • Found in alveoli, glomeruli, endothelium, & serosa

9. Simple Cuboidal Epithelium • Single row of cube-shaped cells • Liver, thyroid, mammary, salivary and other glands, bronchioles, and most kidney tubules

10. Simple Columnar Epithelium Goblet cell • Single row of tall, narrow cells • Secretion of mucus • Inner lining of GI tract, uterus, & uterine tubes Microvilli

11. Pseudostratified Epithelium Cilia • Single row of cells • nuclei give layer a stratified look • Found in respiratory system Goblet cell Basal cell

12. Special Features of Epithelium • Endothelium is simple squamous that lines vessels i.e.. Blood Vessels, lymphatic vessels • Simple columnar • ciliated (has hair) like respiratory tract • May have goblet cells= mucous production. • Microvilli- fingerlike projections • ? What mammals don’t have cilia?

13. Stratified Squamous

14. Stratified Cuboidal Epithelium • Secretes sweat; ovarian hormones & produces sperm

15. Transitional Epithelium • Multilayered epithelium with rounded surface cells that flatten when the tissue is stretched • Stretches to allow filling of urinary tract • Found in urinary tract -- bladder

16. Connective Tissue • 3 basic elements: Cells, ground substance, fibers • Matrix = ground substance and fibers • Fibers, 3 types: • CoLLagen- thick, found in bone, cartilage, ligaments, tendons • Elastic- thin, found in skin, blood vessel walls, lung • Reticular- medium sized, found in basement membrane, organs • Highly vascular usually • Exception: Cartilage is NOT vascular

17. Naming Connective Tissue • First part of word, last part of word • First part of word: type of cell: • Fibro-, a fiber cell • Osteo-, a bone cell • Erythro, a red blood cell • Chondro-, a cartilage cell • Last part of word: the age of the cell • Young = -blast • Old = -cyte • Examples: TYPE OF CELLYOUNG/OLD? • Fibrocyte _____ _____, Osteocyte ____ ____ • Erythroblast _____ ____, Erythrocyte _____ _____

18. Loose connective tissue contains gel-like ground substance between cells 3 types areolar reticular adipose Dense connective tissue fibers fill the spaces between cells 2 types varying in fiber orientation dense regular connective tissue dense irregular connective tissue Cartilage Hyaline, Elastic cartilage, Fibro cartilage Bone and Blood Types Connective Tissue

19. Areolar Tissue • Loose arrangement of collagenous and elastic fibers, scattered cell types & abundant ground substance • Underlying all epithelia forming passageway for nerves & blood vessels; fascia between muscles

20. Reticular Tissue • Loose network of reticular fibers and cells • Found in lymph nodes, spleen, thymus & bone marrow

21. Adipose Tissue • Large, empty-looking cells with thin margins; nucleus pressed against cell membrane • Energy storage, insulation, space filled as cushioning

22. Dense Regular Connective Tissue • Densely, packed, parallel collagen fibers • Tendons & ligaments hold bones together and attach muscles to bones

23. Dense Irregular Connective Tissue • Densely packed collagen fibers running randomly • Withstands stresses applied in different directions • Deeper portion of skin; capsules around organs

24. Cartilage • Supportive connective tissue with rubbery matrix • Chondroblasts produce matrix, once surrounded are called chondrocytes • No blood vessels so diffusion must bring in nutrients & remove wastes • injured cartilage heals slowly • Major types of cartilage depend upon fiber types • hyaline, fibrocartilage and elastic cartilage

25. Hyaline Cartilage • Clear, glassy matrix; fine dispersed collagen fibers; chondrocytes in small clusters enclosed in lacunae • Eases joint movements • Over ends of bones at movable joints

26. Elastic Cartilage • Hyaline cartilage with weblike mesh of elastic fibers • Provides flexible, elastic support and bounce back • External ear and epiglottis

27. Fibrocartilage • Cartilage containing extensive parallel collagen fibers • Resists compression and absorbs shock in some joints • Pubic symphysis, meniscus & intervertebral discs

28. Bone • Spongy bone looks spongy in appearance • no complex arrangement for blood vessels • fills heads of long bones called marrow • always covered by compact bone • Compact is solid in appearance • more complex arrangement of blood vessels • cells and matrix surround blood vessels in long bones

29. Compact Bone • Calcified matrix in concentric lamellae around a central (haversian) canal containing blood vessels; canaliculi connect to the osteocytes in their lacunae

30. Blood • RBCs, WBCs, and platelets

31. Nerve Tissue • TWO CELLS IN NERVOUS SYSTEM • Neurons • Cell body with nucleus • Axon and dendrites • Neuroglia (glia = glue) • Sites of tumors i.e. astrocytoma

32. 3 Muscle Tissues • Skeletal • Striated (alternating light / dark bands), voluntary, found in skeletal muscles • Cardiac • Striated, Involuntary, intercalated discs (aid in electrical conduction), found in the heart • Smooth • Non-striated, involuntary, found in the intestines

33. Skeletal Muscle • Long, cylindrical, unbranched cells with striations and multiple peripheral nuclei • Movement, facial expression, posture, breathing, speech, swallowing and excretion • Skeletal muscles

34. Cardiac Muscle • Short branched cells with striations and intercalated discs; one central nuclei per cell • Pumping of blood • Found in the heart

35. Smooth Muscle • Short fusiform cells; nonstriated with only one central nucleus • Swallowing, GI tract functions, labor contractions, control of airflow, erection of hairs & control of pupil • Sheets of muscle in viscera; iris; hair follicles & sphincters

36. 4 Tissue Review • 1. EPITHELIAL • Simple (one layer) • Squamous, cuboidal, columnar • Stratified (More than one layer) • Squamous, cuboidal, columnar, TRANSITIONAL • Pseudostratified- always columnar • 2. CONNECTIVE • Embryonic • Matrure • Loose- areolar, adipose, reticular • Dense- regular, irregular, elastic • Cartilage- hyaline, fibrocartilage, elastic • Bone • Blood • 3. Muscle 4. Nerve

37. Endocrine & Exocrine Glands • Glands are highly specialized cells, usually epithelium. • Secrete substances into ducts, onto a surface, into blood • Two types • Endocrine (endo = within), secrete into the blood, doesn’t use ducts, products go right into the blood- adrenals, thyroid, pancreas • Exocrine (exo = exit, crine = secrete) - sweat glands, salivary glands, has ducts Duct of Exocrine gland

38. Tissue Terms • Hyperplasia is tissue growth through cell multiplication • Hypertrophy is enlargement of preexisting cells • muscle grow through exercise • Atrophy is shrinkage from loss of cell size/number • Neoplasia is a tumor (benign or malignant) • Necrosis is pathological death of tissue • gangrene is due to insufficient blood supply • gas gangrene is due to anaerobic bacterial infection

39. Tissue Repair- 2 Ways • 1. Regeneration • replacement of dead or damaged cells with original cells • 2. Fibrosis • replacement of damaged cells with scar tissue (collagen) • keloid is healing with excessive fibrosis (raised shiny scars)

40. Wound Healing I • Cut • Clot forms • Scab forms on surface • Macrophages start to clean up debris

41. Wound Healing II • Scab falls off • Remodeling phase may last 2 years

42. Tissue Repair –Important Vitamins • A, B, C, D, E, _, _, _, _, _, K • A = epithelial repair and anti-oxidant • B = Riboflavin, Niacin important in cellular respiration- ATP synthesis • C = Collagen matrix, strengthens blood vessels • D = Heals fractures, mobilizes Calcium • E = Anti-oxidant, increases oxygen to tissues • K = Clotting factor (Klotting)