HIstology 2.pdf

Chapter 4 Lecture Slides Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Chapter 4-Tissues What is a tissue? group of cells with similar structure and function plus extracellular substance (matrix) Histology: study of tissues...

Chapter 4 Lecture Slides Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Chapter 4-Tissues What is a tissue? group of cells with similar structure and function plus extracellular substance (matrix) Histology: study of tissues 2 Types of Tissues 1. Epithelial 2. Connective 3. Muscular 4. Nervous 3  Epithelial Tissues Location: - cover body (internal and external) - Ex. Skin, kidney, trachea, glands, etc. 4  Characteristics: - cells close together (very little extracellular matrix) - form most glands - have free surface - Basal surface: attaches epithelial cells to underlying tissues 5 Functions of Epithelial Tissues 1. Protect: Ex. Skin 2. Act as a barrier: Ex. Skin keeps bacteria out 3. Diffusion and Filtration: Ex. Lungs and kidneys 4. Secretion: Ex. Sweat glands 5. Absorption: Ex. Small intestine 7 Classification of Epithelial Tissue Classified according to number of cell layers and cell shape Simple and stratified = number of cell layers Squamous, cuboidal, columnar, transitional= cell shape 8  Types of Epithelial Tissues Simple Epithelium Structure: 1 layer of cells Stratified Epithelium Structure: many layers of cells 10  Simple Squamous Structure: 1 layer of flat, tile-like cells Function: diffusion and filtration Location: blood vessels, lungs, heart, kidneys Simple Cuboidal Structure: 1 layer of square-shaped cells Function: secretion Location: glands, ovaries, kidneys 11 12 13  Simple Columnar Structure: 1 layer of tall, narrow cells Function: secrete mucus and absorption Location: stomach, intestines, resp. tract Pseudostratified Columnar Structure: 1 layer of tall, narrow cells appears stratified but isn’t Function: secrete mucus and propel debris out of resp. tract (cilia) Location: nasal cavity and trachea 14 15 16  Stratified Squamous Structure: many layers of flat, tile-like cells Function: protect and acts as a barrier Location: skin, mouth, throat, esophagus Transitional Structure: special type of stratified epi. changes shape (stretched squamous, not stretched cuboidal) Function: hold fluids Location: urinary bladder 17 18 19 20 21  Free Cell Surfaces Surface not in contact with other cells Smooth to reduce friction, Ex. Blood vessels Microvilli: - increase cell’s surface area - Ex. Small intestine 22  Cilia: - move materials across cell’s surface - Ex. Trachea Goblet cells: - produce mucus - Ex. Stomach 23  Cell Connections Tight junctions: - bind adjacent cells together - Ex. Intestines Desmosomes: mechanical links that bind cells 24  Hemidesmosomes: bind cells to basement membrane Gap junctions: - small channels that allow molecules to pass between cells - allow cells to communicate - most common 25 Figure 4.2  Glands What are they? structures that secrete substances onto a surface, into a cavity, or into blood Exocrine glands: - glands with ducts - Ex. Sweat or oil glands Endocrine glands: – no ducts (directly into bloodstream) – Ex. Thyroid, thymus, pituitary glands, etc. 27 Types of Exocrine Glands Simple: no branches Compound: many branches Tubular: end of duct Alveolus: sac-like structure 28 Figure 4.3  Connective Tissues Characteristics Cells far apart Contain large amounts of extracellular matrix Classified based on type of extracellular matrix and function Ex. Blast cells build, clast cells carve Extracellular matrix contains 3 components (in varying amounts): protein fibers, ground substance, fluid Ground substance: proteins and sugars 30  Types of Protein Fibers Collagen fibers: look like ropes and are flexible but resist stretching Reticular fibers: supporting network that fills spaces between organs and tissues Elastic fibers: recoil after being stretched 31 Functions of Connective Tissue 1. Enclose and separate: Ex. around organs and muscles 2. Connect tissues: Ex. Tendons: connect bone to muscle Ex. Ligaments: connect bone to bone 3. Support and Movement: Ex. bones 32 4. Storage: Ex. bones store calcium and adipose tissue stores fat 5. Cushion and insulate: Ex. adipose tissue protects organs and helps conserve heat 6. Transport: Ex. Blood 7. Protect: Ex. Immune cells 33 Types of Ordinary Connective Tissue Loose Location: between organs, muscles, glands, skin Structure: collagen fibers far apart Function: support and protect 35 36  Dense Location: tendons, ligaments, skin Structure: collagen fibers packed close together Function: connect and can withstand pulling forces Adipose Location: under skin and around organs Structure: collagen and elastic fibers, cells filled with lipids Function: storage, insulate, cushion 37 38 39  Cartilage Type of connective tissue Composed of chondrocytes Contains collagen Withstands compressions Provides support, flexibility, strength 40  Types of Cartilage Hyaline cartilage Location: covers ends of bones Structure: some collagen fibers Function: reduces friction (cushion) Fibrocartilage Location: between vertebra Structure: lots of collagen fibers Function: can withstand compression 41  Elastic cartilage Location: ear and tip of nose Structure: elastic fibers Function: can recoil 43 45  Bone Hard connective tissue 2 types: compact and spongy Composed of osteocytes 46 48  Blood Liquid connective tissue Erythrocytes, leukocytes, platelets Transport food, oxygen, waste, hormones 49 Table Art 4.10  Muscular Tissue Muscle type Nucleus/i Nucleus/i location Striated Skeletal many peripheral Y (most muscle) Cardiac 1 centrally Y (heart) Smooth 1 centrally N (organs) 51 52 Table Art 4.11a Table Art 4.11b Table Art 4.11c  Nervous Tissue Consist of neurons or nerve cells Found in brain, spinal cord, and peripheral nerves Controls and coordinates body movements Includes axons, dendrites, cell bodies 56 57  Tissue Repair What is it? substitution of dead cells for viable cells Regeneration: cells of same type develop (no scar) Replacement: cells of a different type develop (scar) 58  Inflammation Occurs when tissues are damaged Signals the body’s defenses (white blood cells) to destroy foreign materials and damaged cells so repair can occur. Chemical mediators: - released after injury - cause dilation of blood vessels 59 Symptoms of Inflammation 1. Redness: blood vessels dilate 2. Heat: due to increased blood flow 3. Swelling: from water and proteins 4. Pain: nerve endings are stimulated by damage and swelling 60