Anatomy & Physiology PDF

Anatomy & Physiology 4 Tissues: The Living Fabric Tissues Histology – The study of tissues Groups of cells similar in structure and function The four types of tissues: Epithelial Connective...

Anatomy & Physiology 4 Tissues: The Living Fabric Tissues Histology – The study of tissues Groups of cells similar in structure and function The four types of tissues: Epithelial Connective Muscle Nerve 1  Nervous tissue: Internal communication Brain, spinal cord, and nerves Muscle tissue: Contracts to cause movement Muscles attached to bones (skeletal) Muscles of heart (cardiac) Muscles of walls of hollow organs (smooth) Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters Skin surface (epidermis) Lining of GI tract organs and other hollow organs Connective tissue: Supports, protects, binds other tissues together Bones Tendons Fat and other soft padding tissue Developmental Aspects Primary germ layers ectoderm, mesoderm, and endoderm Formed early in embryonic development Specialize to form the four primary tissues Nerve tissue arises from ectoderm Muscle and connective tissues arise from mesoderm Epithelial tissues arise from all three germ layers 2 16-day-old embryo (dorsal surface view) Muscle and connective tissue (mostly from Ectoderm Mesoderm mesoderm) Endoderm Nervous tissue Epithelium (from ectoderm) Interpreting Tissue 3 Epithelial Tissue Occurs as: Covering or lining epithelium Glandular epithelium Functions: Forms boundaries Excretion Protection Secretion Absorption Sensory reception Filtration Epithelial Tissue – Special Characteristics Cellularity Special contacts 4 Special Contacts Epithelial Tissue – Special Characteristics Cellularity Special contacts Polarity 5 Polarity Apical Basal Basement Membrane Basal Lamina – glycoproteins Reticular Lamina – collagen of CT Epithelial Tissue – Special Characteristics Cellularity Special contacts Polarity Supported by connective tissue Avascular but innervated Regenerative (mitotic) 6 Classification of Epithelia Squamous Flattened and scale-like Cuboidal Boxlike Columnar Tall and column shaped Transitional Classification of Epithelia 7 Classification of Epithelia Cellular Specializations - Cilia 8 Cellular Specializations - Microvilli Cellular Specializations – Goblet Cells 9  Classification Simple Stratified Pseudostratified Squamous Squamous Columnar ciliated Cuboidal Cuboidal Columnar Columnar Only columnar epithelium contains goblet cells Only columnar epithelium may be ciliated or non-ciliated Epithelia: Simple Squamous Description: Single layer of flattened cells Central nuclei Function: Passage of materials by (diffusion & filtration) Location: Kidney, lungs, heart 10  Epithelia: Simple Squamous Description: Single layer of flattened cells Endothelium Central nuclei -friction-reducing lining Function: Endocardium Passage of materials by -lining of heart (diffusion & filtration) Location: Kidney, lungs, heart Mesothelium -serous membranes lining ventral body cavity Epithelia: Stratified Squamous Description: Thick membrane of several layers Basal cells- Cuboidal / Columnar Apical cells- Squamousal (Keratin) Function: Protects underlying tissues Location: Nonkeratinized- moist lining of esophagus, mouth, vagina Keratinized- epidermis of skin 11  Epithelia: Simple Cuboidal Description: Single layer of cube-like cells Large central nuclei Function: Secretion and absorption Location: Kidney tubules, ducts, ovaries Epithelia: Stratified Cuboidal Description: Several cell layers Basal cells- Cuboidal Apical cells- Cuboidal Function: Secretion & Protection Location: Ducts of larger glands (sweat glands, mammary glands) 12  Epithelia: Simple Columnar Description: Single layer of tall cells Round/Oval nuclei Function: Absorption & Secretion Location: Nonciliated most of digestive, some excretory ducts Ciliated lines small bronchi, uterine tubes Epithelia: Stratified Columnar Description: Several cell layers Function: Secretion & Protection Location: Pharynx, male urethra 13  Epithelia: Pseudostratified Columnar Description: Single layer w/ differing heights Nuclei at varying levels Function: Secretion (mainly mucus) Location: Nonciliated in sperm-carrying ducts & large glands Ciliated lines the trachea & upper respiratory Epithelia: Transitional Description: Several cell layers Basal cells- Cuboidal Apical cells- Squamousal-like Function: Stretches to permit distension Location: Urinary bladder, ureters, and part of the urethra 14 Epithelia: Glandular A gland is one or more cells that makes and secretes an aqueous fluid Classified by: Endocrine or exocrine Unicellular or multicellular Endocrine Glands Ductless glands that produce hormones Hormones secreted by exocytosis into blood Secretions include amino acids, proteins, glycoproteins, and steroids 15 Exocrine Glands More numerous than endocrine glands Secrete their products onto body surfaces or into body cavities Ex) mucous, sweat, oil, salivary glands, pancreas and liver Unicellular and Multicellular Unicellular Exocrine Glands Goblet cell Description: Shaped like a goblet Function: In humans, produce mucin, which eventually forms mucus Location: Epithelial linings of intestinal and respiratory tracts 16 Structural Classification of Multicellular Exocrine Glands – Simple Glands Structural Classification of Multicellular Exocrine Glands – Compound Glands 17  Modes of Secretion Merocrine – exocytosis (e.g., pancreas, sweat, and salivary glands) Holocrine – rupturing of gland cells (e.g., sebaceous glands) Apocrine –pinching off of the tip of the cell (controversial for humans) Epithelium Summary Which tissue type are responsible for: Protection Lubrication Secretion Filtration Absorption Movement 18 Connective Tissue Characteristics Common origin All arise from mesenchyme Degrees of vascularity From avascular, to poorly vascularized, to rich blood supply Extracellular matrix Nonliving extracellular matrix, consisting of ground substance and fibers Connective Tissue Functions Found throughout the body; most abundant and widely distributed in primary tissues Functions: Binding and support Protection Storage Insulation Transportation 19 Connective Tissue Structural Elements Three main elements: Ground substance (matrix) Fibers Cells Ground Substance Unstructured material that fills the space between cells Composed of: Interstitial (tissue) fluid Cell adhesion proteins Proteoglycans (glycosaminoglycans –GAGs) Functions as a molecular sieve through which nutrients diffuse between blood capillaries and cells 20 Proteoglycans Fibers Collagen fibers Composed of the protein collagen Tough; provides high tensile strength Elastic fibers Composed of the protein elastin Long, thin fibers that allow for stretch Reticular fibers Branched collagenous fibers that form delicate networks 21 Fibers (model) Cells Fibroblasts – produce fibers & ground substance Macrophages – phagocytic cells Leukocytes – white blood cells Plasma cells – synthesize antibodies Mast cells – secrete heparin Adipocytes – fat cells Hematopoietic stem cells – blood 22  Connective Tissue: Embryonic Mesenchyme Description: Gel-like ground substance with fibers and star-shaped mesenchymal cells Function: Basis for all connective tissue Location: Primarily in Embryo Connective Tissue: Wharton’s Jelly Description: Jelly-like tissue Matrix composed of: hyaluronic acid (binds cells / lubricates) chondroitin sulfate (support / adhesive) Function: Stem Cell Production Location: Umbilical Cord 23  Connective Tissue Proper: Loose (areolar) Description: Gel-like matrix w/ all 3 fiber types Macrophages, mast cells, WBC Function: Wraps & cushions organs Phagocytize bacteria Location: Widely distributed under epithelia (forms lamina propria) Connective Tissue Proper: Loose (adipose) Description: Matrix like areolar (sparse) Closely packed adipocytes(fat cell) Function: Reserve food fuel Insulates and protects Location: Under skin, around kidneys & eyes Abdomen and breasts 24  Connective Tissue Proper: Loose (reticular) Description: Loose ground substance w/ reticular fibers Reticular cells lie in a fiber network Function: Forms soft internal skeleton that supports other cells Location: Lymph nodes, bone marrow, spleen Connective Tissue Proper: Dense Regular Description: Parallel collagen fibers Major cell type is fibroblast Function: Attaches muscle to bone Attaches bone to bone Location: Tendons and most ligaments 25  Connective Tissue Proper: Dense Irregular Description: Irregular collagen fibers Major cell type is fibroblast Function: Withstand tension in many directions Location: Dermis of skin Submucosa of digestive tract Fibrous capsules of organs / joints (f) Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Elastic fibers Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Aorta Photomicrograph: Elastic connective tissue in Heart the wall of the aorta (250x). 26 Connective Tissue: Cartilage Stands up to compression and tension Intermediate between dense connective tissue and bone Lacks nerve fibers and is avascular Nutrients come by diffusion Connective Tissue: Cartilage Ground substance: collagen and elastic Predominant cell type: Chondroblasts Contained in lacunae Three varieties: Hyaline, Elastic, Fibrocartilage 27  Connective Tissue: Hyaline Cartilage Description: Network lacking shape but held together w/ collagen fibers Function: Supports and reinforces Location: Ends of long bones, ribs, nose Most of embryonic skeleton Connective Tissue: Elastic Cartilage Description: Similar to hyaline but more elastic fibers Function: Maintains shape w/ flexibility Location: Supports external ear, epiglottis 28  Connective Tissue: Fibrocartilage Cartilage Description: Similar to hyaline but less firm Thick collagen fibers predominate Function: Tensile strength w/ ability to absorb shock Location: Intervertebral discs Discs of knee joint Connective Tissue: Bone Osseous Tissue Spongy Compact (dense) Very vascular Nutrient Storage Cell types: Osteoblast  Osteocyte Osteoclast 29  Connective Tissue: Bone (Osseous Tissue) Description: Hard, calcified matrix w/ collagen Very well vascularized Function: Bone supports and protects Levers for muscle contraction Stores calcium & minerals Marrow is blood formation Location: Bones Blood - Components Formed Elements Red Blood Cells (RBC) - Erythrocytes White Blood Cells (WBC) - Leukoctyes Platelets - Thrombocytes Liquid Portion Plasma 90% - Water 8% - Proteins 2% - Other solutes 30  Connective Tissue: Blood Description: Red & White Blood cells in fluid matrix Function: Transport of respiratory gases, nutrients, waste & substances Location: Within blood vessels Cells 31  Nervous Tissue Description: Branching cells May be quite long Function: Transmit electrical signals Location: Brain, spinal cord & nerves Muscle Tissue Well-vascularized Responsible for body movement Possess myofilaments Bring about movement or contraction 32 Muscle Tissue: Skeletal (striated) (a) Skeletal muscle Description: Long, cylindrical, multinucleate cells; obvious striations. Function: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control. Location: In skeletal muscles attached to bones or occasionally to skin. Photomicrograph: Skeletal muscle (approx. 460x). Notice the obvious banding pattern and the fact that these large cells are multinucleate. Muscle Tissue: Cardiac (b) Cardiac muscle Description: Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs). Intercalated discs Function: As it contracts, it propels blood into the circulation; involuntary control. Location: The walls of the heart. Photomicrograph: Cardiac muscle (500X); notice the striations, branching of cells, and the intercalated discs. 33 Muscle Tissue: Smooth (visceral) (c) Smooth muscle Description: Spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets. Function: Propels substances or objects (foodstuffs, urine, a baby) along internal passage- ways; involuntary control. Location: Mostly in the walls of hollow organs. Photomicrograph: Sheet of smooth muscle (200x). Membranes that Cover & Line Consist of epithelial + connective tissues 3 types Cutaneous Mucous Serous 34 Cutaneous Membrane Cutaneous = skin Covers surface of body Keratinized, stratified squamous epithelium Areolar & dense irregular CT Waterproof & dry Mucous Membranes Line body cavities open to the exterior Moist epithelia Stratified squamous Columnar CT = areolar Lamina propria Absorption, secretion & protection 35 Serous Membranes Closed ventral body cavities Simple squamous Thin areolar CT Produce watery secretion Double membranes: Parietal lines cavity Visceral covers organs Serous Membranes - Examples Pleural membrane Pericardium Peritoneum 36 Tissue Trauma & Repair Inflammation Nonspecific Quick Occurs at site of injury Immune response Specific Takes longer to occur Tissue Trauma & Repair Repair requires cells to divide & migrate Caused by growth factors Regeneration Replace with same tissue Fibrosis Replace with CT called scar tissue 37 Tissue Trauma & Repair Inflammatory chemicals: Histamine Kinins Prostaglandins Cytokines Leukotrienes Tissue Trauma & Repair Effects of inflammatory chemicals: Vasodilation Increased capillary permeability Chemotaxis Diapedesis Phagocytosis Pyogenesis 38 Tissue Repair - Inflammation Trauma causes release of histamine Capillaries dilate & become very permeable WBCs, antibodies, clotting proteins Blood clot forms Stop blood loss Hold edges together Isolate injured area Exposed part = scab Tissue Repair - Organization Blood clot replaced with granulation tissue Pink tissue with lots of new capillaries Fibroblasts make new collagen Macrophages phagocytize blood clot 39 Tissue Repair Regeneration Surface epithelium regenerates Grows under scab until scab falls off Gets thicker until resembles adjacent skin Fibrosis Fibrous tissue matures Never quite matches original Tissue Repair - Results Fully regenerated epithelium Underlying scar tissue 40