Transcript TISSUES
HONORS ANATOMY & PHYSIOLOGY 4 basic types of tissues in human body contribute to homeostasis by providing diverse functions including protection support communication among cells resistance to disease & many more a tissue is a group of similar cells that usually have a common embryonic origin & function together to carry out specialized activities their structure & properties are influenced by factors such as: ◦ nature of the extracellular material surrounding tissue cells ◦ type of connections between cells 1. ◦ ◦ 2. ◦ 3. ◦ 4. ◦ Epithelial covers body surfaces & lines hollow organs, cavities, & ducts forms glands Connective protects & supports Muscular movement Nervous detects changes in/out body & responds by generating action potentials tissues develop from 3 primary germ layers: 1. Ectoderm 2. Endoderm 3. Mesoderm 1. ◦ 2. ◦ 3. ◦ 4. ◦ Epithelial from all 3 layers Connective mesoderm Muscular mesoderm Nervous ectoderm are contact pts between plasma membranes of adjacent cells found between most epithelial cells & some muscle & nerve cells 1. Tight junctions 2. Adherens junctions some form adhesion “belts” around entire cell 3. 4. Hemidesmosomes: fibers on 1 side only 5. Gap Jnctions thin, extracellular layer commonly has 2 parts: 1. basal lamina 2. reticular lamina classified according to 2 characteristics: 1. # of layers single layer = simple multiple layers = stratified single layer that looks like multiple = psuedostratified 2. cell shape squamous cuboidal columnar 1 layer of cells, often in sheets functions: diffusion/osmosis filtration secretion: production & release of substances (sweat, mucus) absorption: intake of fluids or other substances appears to have multiple layers because: 1. nuclei @ different layers 2. not all cells reach apical surface 2 or more layers of cells ◦ named by shape of top layer function: protection where there is considerable wear & tear arranged like floor tiles very thin: allows for rapid passage of substance thru cell shaped like cubes or hexagons +/- microvilli on apical surface ◦ finger-like cytoplasmic projections ◦ function increase surface area function: secretion or absorption taller than they are wide +/- microvilli or cilia on apical surface ◦ cilia: tiny hair-like projections that beat in unison: moves substances across surface of cell function: protection absorption secretion single layer flat cells viewed from ◦ apical surface looks like tiled flooring ◦ cross-section: fried eggs cross section found: @ sites where filtration (kidneys) or diffusion (lungs, capillaries) occur lines blood vessels & chambers in heart (endothelium), forms lining for serous membranes (mesothelium) nuclei round & centrally located functions: ◦ secretion ◦ absorption found in: ◦ thyroid gland ◦ kidneys 2 forms: nonciliated/ciliated nonciliated simple Columnar Epithelium ◦ 2 types: 1. Columnar epith. w/microvilli on apical surfaces 2. Goblet cells produce & secrete mucus cilia on apical surface +/- Goblet cells functions: ◦ move mucus or any foreign objects away from lower respiratory tract or ova towards uterus found in: ◦ airways of upper respiratory system ◦ fallopian (uterine) tubes all cells attached to bm but not all reach apical surface Ciliated Pseudostratified Columnar Epith.: cells that do reach apical surface either are goblet cells or are ciliated Nonciliated Pseudostratified Columnar Epith: no cilia or goblet cells basal layer continually undergoing cell division ◦ as new cells grow, cells near base pushed upward ◦ as near apical border moving farther away from their blood supply (in underlying connective tissue) dehydrate, shrink, harden, die cell jcts break down cells sloughed off upper layers contain keratin: tough, fibrous protein that protects underlying tissues from heat, microbes, chemicals found: skin Keratinized found: lining mouth (buccal mucosa) & esophagus protect underlying tissues from wear & tear and from invasion by microbes Nonkeratinized gland: single cell or group of cells that secrete substances into: ◦ ducts ◦ onto a surface ◦ into blood classified: 1. endocrine ◦ 2. ◦ secretions intercellular fluid capillary exocrine secretions ducts surface of skin or lining of hollow organ most abundant & widely distributed tissue in body 2 basic elements: 1. extracellular matrix 2. cells greater % in CT than other tissues it’s the material located between cells (secreted by those cells) determines qualities of the CT not usually found on surfaces, usually rich blood supply (x cartilage & tendons) consists of: ◦ protein fibers ◦ ground substance immature form suffix “blast” ◦ large capacity to divide ◦ secrete matrix mature form suffix “cyte” ◦ less likely to divide ◦ maintain matrix large flat cells w/ branching processes found in most CT migrate thru CT secreting fibers & ground substance develop from monocytes phagocytes irregular shape 2 types: 1. wandering ◦ move to sites of infection or inflammation fixed 2. ◦ ◦ reside in a particular tissue ex: alveolar macrophages small cells that develop from B lymphocytes Important in immune response most reside in CT ◦ GI & respiratory tracts ◦ lymph nodes, spleen, red bone marrow found along side blood vessels that supply CT produce & secrete histamine: dilates small blood vessels as part of inflammatory response (reaction to injury or infection) can also bind, ingest, & kill bacteria aka adipose cells or fat cells store triglycerides functions: ◦ store fats for nrg ◦ insulate ◦ cushion organs acellular component of CT that supports cells, binds them together, stores water, provides medium thru which substances are exchanged between blood & cells may be: fluid semifluid gelatinous calcified 1. ◦ ◦ 2. ◦ ◦ ◦ 3. ◦ ◦ Collagen “colla” = glue a protein (25% of all protein in body!) very strong fibers that resist pulling Elastic smaller strong but stretchy fibers made of protein called elastin plentiful in skin, blood vessel walls, lung tissue Reticular made of collagen in fine tubes coated with glycoproteins forming branching networks & found in BM skin, adipose, reticular CT (spleen, lymph nodes) 1. Areolar CT 1 of most abundant types includes all types of CT cells & fibers found in: subcutaneous tissue 2. Adipose Tissue cells: adipocytes found ass’c with areolar CT 2 types: 1. white ◦ most of the adipose in adults brown 2. ◦ ◦ darker due to rich blood supply widespread in newborns: helps maintain body temperature contains more numerous fibers but fewer cells than in loose CT 3 types: 1. Dense Regular CT 2. Dense Irregular CT 3. Elastic CT collagen fibers lined up in parallel pattern allowing it to withstand pulling aling axxis of fibers: very strong tissue silvery white, tough ex: tendons & most ligaments collagen fibers irregularly arranged found where pulling forces exerted in various directions found: dermis, pericardium, periosteum predominate fiber: elastic fibers quite strong & able to return to original shape after being stretched found: elastic arteries, lungs are flat sheets of pliable tissue that cover or line a part of the body 2 types: 1. epithelial membrane: ◦ ◦ epithelial layer + underlying CT types: mucous membrane, serous membrane, cutaneous membrane (skin) synovial membrane: 2. ◦ ◦ + CT but - epithelium line joints line body cavities that open directly to exterior line: entire digestive, upper respiratory, & reproductive tracts cells connected by tight jcts Goblet cells secrete 1. mucus slippery so prevents cavities from drying out 2. enzymes from some 3. site of nutrient absorption line cavities that do not open directly to exterior & covers organs w/in those cavities made of: areolar CT covered by mesothelium (simple sq. epith.) which secretes serous fluid 2 layers: 1. parietal peritoneum ◦ covers cavity wall visceral peritoneum 2. ◦ ◦ ◦ covers organs in pericardial cavity = pericardium in abd. Cavity = peritoneum Cartilage Compact Bone Blood consists of a dense network of collagen (strength) & elastic (flexibility) fibers, no blood vessels or nerves (x perichondrium) so heals very slowly chondrocytes: mature cartilage cells ◦ occur singly or in small groups w/in space called lacunae perichondrium: membrane of dense CT ◦ covers surface of most cartilage 3 types: 1. Hyaline cartilage ◦ ◦ most abundant cartilage in body, also the weakest provides flexibility & support Fibrocartilage 2. ◦ ◦ no perichondrium provides strength & rigidity (strongest of the 3) Elastic cartilage 3. ◦ ◦ + elastic fibers provides strength & elasticity articular cartilage (@ joints) @ epiphyseal plates bluish-white & shiny found: pubic symphysis (anterior junction of hip bones) intervertebral discs, menisci in knees found: epiglottis, auricle of ear aka osseous tissue 2 types: 1. Compact bone 2. Spongy bone basic unit of compact bone is the osteon (haversian system) has 4 parts: 1. Lamellae ◦ ◦ 2. 3. 4. concentric rings of extracellular material & collagen make bone hard & strong Lacunae Canaliculi Central (haversian) canal) lacks osteons found only inside compact bone consists of columns of bone called trabeculae ◦ spaces between trabeculae filled with red bone marrow liquid CT made up of: Plasma ◦ liquid portion of blood (yellow) ◦ water, dissolved nutrients, wastes, plasma proteins, hormones, gases, ions RBCs: transport O2 WBCs: phagocytes, immune response, allergic reactions Platelets: cell particles involved in blood clotting consists of elongated cells called muscle fibers that can use ATP to generate force movement, maintain posture, generate heat 3 types: 1. Skeletal 2. Smooth 3. Cardiac most attached to a bone muscle fibers up to 12-16 in in longest muscles: ◦ multinucleated (on edges) ◦ striated ◦ voluntary in walls of hollow internal structures ◦ blood vessels ◦ urinary bladder ◦ intestines muscle fibers small, 1 centrally located nuclei, +/- gap jcts ◦ nonstriated ◦ involuntary forms wall of heart muscle fibers are branched with 1 centrally located nuclei ◦ striated ◦ involuntary ◦ *intercalated discs: attach individual fibers end-toend (desmosome + gap jct) allows for quicker conduction of action potentials coordinated contractions of heart chambers 2 cell types: 1. neurons ◦ nerve cells that can generate action potentials which are conducted to other neurons, muscles, or glands neuroglia (glia) 2. ◦ ◦ supportive cells to neurons cannot generate action potentials electrical excitability: ability to respond to certain stimuli by producing electrical signals (action potentials) in neurons: travel (propagate) along plasma membrane release of neurotransmitter in muscle fibers: action potentials cause the fiber to contract (shorten) atrophy: decrease in size of cells decrease in size of organ hypertrophy: increase in size of a tissue because its cells enlarge w/out undergoing cell division