Types/Functions of Epithelial Tissue

Transcription

1 A&P I Exam 3 Review Slides Fall 2014 Lectures 9-12 Ch. 4 and Ch. 5 Types/Functions of Epithelial Tissue Types of epithelium 1. Covering and Lining Epithelium External Surfaces, e.g., skin, Internal surfaces 2. Glandular Epithelium Functions of Epithelial Tissue Physical protection Control of permeability Secretion, Absorption, Filtration Provide sensation Provide specialized secretions (glands) 2 Characteristics of Epithelial Tissue Specialized contacts with other cells Polarity (different ends of cell do different things) Avascularity (no blood supply) Regeneration (can divide to make new cells) Cellularity (lots of cells in close contact) Remember: Epithelial tissues always have a free surface and a basement membrane 3 1

2 Basal Lamina Formerly called: Basement membrane Two components: Lamina Lucida - glycoproteins and fine protein filaments - Barrier for passage of substances from underlying tissue into epithelium Lamina = thin layer Lamina Densa - bundles of coarse protein fibers - gives basal lamina its strength Figure from: Martini, Fundamentals of Anatomy & Physiology, Benjamin Cummings, Classification of Epithelial Tissues Epithelial tissues are classified according to both their: Shape Squamous (Thin, flat, irregular in shape) Cuboidal (Square or cuboidal) Columnar (Rectangular, tall) Type of layering (stratification) Simple (one layer) Stratified (two or more layers) Note that classification of stratified epithelium is based on the shape of the superficial, not deep, layers 5 Characteristics of Epithelial Tissue Specialized Contacts Tight junction forces substances to go through cells, rather than being able to pass between them Gap junction allow rapid passage of small molecules/ions between cells Desmosome binds cells together firmly so they stay connected Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Hemidesmosome binds cells to basement membrane 6 2

3 Review NAME OF ET SIMPLE SQUAMOUS SIMPLE CUBOIDAL SIMPLE COLUMNAR PSEUDO- STRATIFIED COLUMNAR DESCRIPTION STRUCTURE a single layer of flattened cells a single layer of cubeshaped cells with large centrally located nuclei a single layer of tall cells with basally located nuclei, goblet cells, & mucrovilli a single layer of tall cells with scattered nuclei, cilia, & goblet cells LOCATION linings of air sacs, capillaries, lymph vessels, body cavities; covering ventral organs linings of kidney tubules, ducts of glands lining of intestine lining of trachea, lining of fallopian tube FUNCTION diffusion, reduction of friction absorption, secretion protection, absorption, secretion protection, secretion 7 Review NAME OF ET DESCRIPTION STRUCTURE LOCATION FUNCTION STRATIFIED SQUAMOUS many layers of flattened cells keratinized = epidermis; non-keratinized = lining of vagina, anus, throat, mouth protection TRANSITIONAL several layers of cells that change shape under pressure lining of urinary bladder and ureters Distensibility (able to stretch) GLANDULAR simple cuboidal lining the ducts of glands secretion 8 Review of Epithelial Tissues Glands are specialized epithelium Secrete on to a surface (exocrine) Secrete into a duct (exocrine) Secrete into the blood (endocrine) Exocrine glands have several different mechanisms of secretion Merocrine Release of product from vesicles by exocytosis none of cell is lost Holocrine Entire cell is lost: packed with secretion and then bursts Ex: Unicellular = mucous gland; multicelluar = sweat gland, sebaceous gland, mammary gland, etc. Glandular epithelium is classified by: 1. Shape of secretory portion of gland 2. Branching pattern of the duct 9 3

4 Membranes A membrane is a combination of epithelium and connective tissue that covers and protects other structures and tissues. Technically, then, a membrane is an organ. Serous line body cavities that lack openings to outside reduce friction inner lining of thorax and abdomen secrete serous fluid Cutaneous covers body skin Mucous line tubes and organs that open to outside world lining of mouth, nose, throat, digestive tract, etc. secrete mucus Synovial surround joint cavities 10 Review of Connective Tissues NAME OF CT DESCRIPTION LOCATION FUNCTION MESENCHYME Precursor (stem) tissue to other CTs Embryo gives rise to all other CT s AREOLAR ADIPOSE RETICULAR DENSE REGULAR gel-like matrix with fibroblasts, collagen and elastic fibers closely packed adipocytes with nuclei pushed to one side by fats network of reticular fibers in loose matrix dense matrix of collagen fibers beneath ET (serous membranes around organs & lining cavities) beneath skin, breasts, around kidneys & eyeballs basement membranes, lymphatic organs tendons, ligaments diffusion, cushioning organs insulation, energy store, protection Support; forms stroma of organs attachment (high tensile strength) DENSE IRREGULAR loose matrix of collagen fibers dermis of skin strength in several directions 11 Review of Connective Tissues NAME OF CT DESCRIPTION LOCATION FUNCTION ELASTIC CT matrix of elastic fibers lung tissue, wall of aorta durability with stretch HYALINE CARTILAGE FIBRO- CARTILAGE chondrocytes in lacunae in amorphous matrix less firm than above embryonic. skeleton, costal cart, tip of nose, trachea, larynx intervertebral discs, pubic symphysis support tensile strength, shock absorber ELASTIC CARTILAGE above plus elastic fibers external ear, epiglottis shape maintenance plus flexibility BONE BLOOD concentric circles of calcified matrix red cells, white cells and platelets in liquid plasma Bones in heart and blood vessels support, protection, movement, Ca ++ storage, hematopoiesis transport of nutrients, wastes & gases 12 4

5 Connective Tissue (CT) Summary Table Three main components of ALL types of CT: cell, fibers, ground substance Name of Different types of Main types of cells Main types of Consistency of CT this CT present fibers present matrix Examples of Locations 1) Areolar (Loose) 1) Fibroblasts 1) Collagen, Elastic 1) Skin, between muscles CT Proper 2) Dense regular 2) Fibroblasts 2) Collagen Semi-liquid 2) Tendons, ligaments 3) Dense irregular 3) Fibroblasts 3) Collagen 3) Dermis 4) Adipose 4) Adipocytes 4) Reticular 4) Body fat areas 5) Reticular 5) Fibroblasts 5) Reticular 5) Stroma of liver, spleen 6) Elastic 6) Fibroblasts 6) Elastic 6) Lungs, airways, arteries/heart Cartilage 1) Hyaline 1) Collagen (sparse) All types: Semi- 1) Ribs, ends of bones 2) Fibrocartilage (All) Chondrocytes 2) Collagen (dense) solid, gelatinous; 2) Intervertebral disks 3) Elastic 3) Elastic rubbery 3) Pinna of ear, epiglottis Bone 1) Dense (All) Osteocytes Collagen Solid 1) Outer portions of bone 2) Spongy (hydroxyapatite) 2) Inner portions of bone Blood 1) RBCs -- 2) WBCs Fibrinogen (soluble) Liquid Blood vessels, heart 3) Platelets (cell fragments) Lymph -- Lymphocytes Reticular (in stroma of lymphoid organs) Liquid Lymph vessels -cyte = fully differentiated; -blast = young, actively synthesizing cell 13 Connective Tissue - Major Cell Types Fibroblasts fixed cell most common cell; always in CT proper large, star-shaped produce fibers produce ground substance Macrophages wandering cell phagocytic important in defense derived from circulating monocytes Mast cells are mediators of inflammation see later 14 Connective Tissue Fibers Collagenous fibers thick composed of collagen great tensile strength hold structures together abundant in dense CT tendons, ligaments Reticular fibers very thin collagenous fibers highly branched form supportive networks Elastic fibers bundles of microfibrils embedded in elastin fibers branch elasticity vocal cords, air passages 15 5

6 The Ground Substance of CT glucosamine VERY hydrophilic! **Function: Very active in controlling passage of substances through this portion GAGs = glycosaminoglycans (negatively charged of the matrix and keeping CT polysaccharides); a major molecule in ground hydrated substance 16 Figures from: Alberts et al., Essential Cell Biology, Garland Press, 1998 Tendons and Ligaments Tendons: Connect muscle to bone Ligaments: Connect bone to bone Aponeuroses: Broad, fibrous sheets; usually attach muscle to muscle (or bone) 17 CT Framework of the Body Fascia: layers of fibrous connective tissue covering and separating muscle. It connects the organs of the dorsal and ventral cavities with the rest of the body Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Provide: - Strength - Stability - Organ position - Conduits 18 6

7 Muscle Overview General characteristics Elongated cells with special properties Muscle cells (myocytes) = muscle fibers Contractile (major property of all muscle) Use actin (thin) and myosin (thick) for contraction Three types of muscle tissue Cardiac (involuntary) Skeletal (voluntary) Smooth (involuntary) 19 Review of Muscle Types NAME OF MUSCLE TISSUE SKELETAL MUSCLE DESCRIPTION OF STRUCTURE long, thin fibers with many nuclei and striations TYPE OF CONTROL LOCATION FUNCTION Voluntary attached to bones to move bones SMOOTH MUSCLE CARDIAC MUSCLE spindle shaped cells with one centrally located nucleus, lacking striations a network of striated cells with one centrally located nucleus attached by intercalated discs - Intercalated disks consist of : 1)gap junctions and 2) desmosomes Involuntary walls of visceral hollow organs, irises of eyes, walls of blood vessels to move substances through passageways (i.e. food, urine, semen), constrict blood vessels, etc Involuntary heart pump blood to lungs and body 20 Nervous Tissue found in brain, spinal cord, and peripheral nerves conduction of nerve impulses - neurons sensory reception neuroglial cells are supporting cells 21 7

8 Introduction to Inflammation Histamine Heparin Histamine Restoration of tissue homeostasis after injury or infections involves two processes, in order: 1) inflammation and 2) repair Main signs of inflammation: Redness, heat, pain, swelling, and loss of function (Inflammation = -itis ) Figure from: Martini, Anatomy & Physiology, Prentice Hall, Functions of the Integumentary System Functions of the integument Protection (from mechanical/chemical/bacterial damage, UV radiation) Temperature regulation (extreme heat, extreme cold) and Fluid conservation Excretion Vitamin D production Sensation (touch, pressure) 23 Layers of the Epidermis - Overview Bare Skin Gets Lots of Cuts 24 8

9 Thick and Thin Skin Thin ( mm) (epidermal thickness) Thick ( mm) (epidermal thickness) Thick skin - palms of hands, soles of feet; five epidermal layers Thin skin - everywhere else; four epidermal layers (no s. lucidum) Figure from: Martini, Anatomy & Physiology, Prentice Hall, Cells of the Epidermis Epidermis of the skin is classified as a keratinized stratified squamous epithelium Cells of the epidermis include Keratinocytes (90%) Keratin a tough, fibrous intracellular protein (protection) Lamellar granules (waterproofing, extracellular) Melanocytes (8%) Produce melanin (protection from UV radiation) Langerhans cells (1-2%) Migrate to skin from bone marrow Participate in skin s immune response (dendritic cells) Merkel cells (< 1%) Least numerous; specialized epithelial cells Function in sensation of touch 26 Skin Color 1. Genetic Factors varying amounts and type of melanin varying size/number of melanin granules albinos lack melanin (but not melanocytes!) 2. Environmental Factors sunlight UV light from sunlamps X rays 3. Physiological Factors dilation of dermal blood vessels (erythema) constriction of dermal blood vessels (less pink, pale = pallor) level of oxygenation of blood * normal = pink (fair-skinned) * low = bluish (cyanosis) carotene -> Vit A (yellow) jaundice (yellow) 27 9

10 Skin Color and Melanin Dark-skinned Fair-skinned Melanocytes produce melanin - tyrosine melanin - UV radiation up-regulates production of melanin - Dark-skinned individuals have * same number, higher activity of melanocytes * more pigmented layers of epidermis Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, Keratin and Vitamin D Keratin (tough, fibrous intracellular protein) Protection Water resistance Vitamin D 3 ( sunshine vitamin ) After UV irradiation epidermal cells in s. spinosum and s. basale convert a cholesterol-related steroid to Vit D 3 (cholecalciferol) Vit D 3 absorption of calcium and phosphorus by small intestine 29 Two Layers of the Dermis 1. Papillary layer (near epiderm.) - areolar connective tissue (CT) - capillaries and sensory neurons - dermal papillae - fingerprints (with epi. ridges) 2. Reticular layer - dense, irregular CT - collagen fiber bundles extend upward and downward - also contains elastic fibers and cells of CT proper - accessory organs of integumentary system (from epi.) Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall,

11 Subcutaneous Layer Basal lamina - Stabilization of dermis - Insulation (retains heat) - Reservoir of blood - Areolar and adipose tissue - Male/female hormones Also called hypodermis. This is the superficial fascia. 31 Hair (pilo-) epidermal cells tube-like depression extends into dermis hair root (in dermis) hair shaft (outer 1/3) hair papilla (growth area) hair follicle (surrounds hair root) melanin arrector pili muscle Basal lamina (from epidermis) 32 Hair Follicles Most hair color Three types of hair: 1. Lanugo long, blond, fine (fetal, anorexia nervosa) 2. Vellus short, blond (children) (Protection) 3. Terminal course, pigmented (adults) Some hair color Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall,

12 Sebaceous (Oil) Glands usually associated with hair follicles multicellular, holocrine glands secrete sebum, a waxy, oily material inhibits growth of bacteria lubricates and protects keratin of hair shaft, and conditions skin absent on palms and soles Sebaceous follicles not associated with hair. Discharge directly on to skin. On face, back, chest, nipples and male sex organs. 34 Sweat Glands (Multicelluar) also called sudoriferous glands apocrine (merocrine secr.) glands - associated with hair follicles - thick, odorous secretion eccrine (merocrine secr.) glands - most numerous - palms, soles, forehead, neck, back - directly on to surface - watery secretion - for thermoregulation Sweating with visible wetness = diaphoresis ceruminous glands mammary glands Specialized (apocrine secretion) 35 Nails (Perionychium) Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 Hyponychium Be able to identify these structures by labeling this diagram 36 12

13 Regulation of Body Temperature Hyperthermia Abnormally high body temperature May be caused by - environment (heat, humidity) - illness (fever [>= C], pyrexia) - anesthesia (malignant h.) Corrected by loss of heat mainly by radiation (dilation of blood vessels), evaporation (sweating) Heat exhaustion (prostration) - Fatigue - Dizziness - Headache - Muscle cramps - Nausea - May lead to heat stroke 37 Regulation of Body Temperature * * Hypothermia Abnormally low body temperature (at least 2 0 C below normal body temp) May be caused by: - exposure to cold (primary) - illness (secondary) - surgical induction (clinical) Cardiac arrest is likely if temperature falls below 28 o C (82 o F) Corrected by mechanisms to retain body heat (see * left) 38 Healing of Cuts Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9 th ed., Pearson 1. Bleeding/clotting 2. Scab formation 3. Epidermal cell migration and collagen production 4. Shedding of scab; covering of wound with epithelium Tissue repair can occur by either: 1) regeneration healing with tissue that was originally present 2) fibrosis healing with scar tissue 39 13