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TISSUES. HONORS ANATOMY & PHYSIOLOGY. Tissues & Homeostasis. 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. Definition . - PowerPoint PPT Presentation
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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
Tissues & Homeostasis
• a tissue is a group of similar cells that usually have a common embryonic origin & function together to carry out specialized activities
Definition
• their structure & properties are influenced by factors such as: – nature of the extracellular material
surrounding tissue cells– type of connections between cells
Tissues
1. Epithelial – covers body surfaces & lines hollow organs,
cavities, & ducts– forms glands
2. Connective– protects & supports
3. Muscular– movement
4. Nervous – detects changes in/out body & responds by
generating action potentials
Classification of Tissues
1. Epithelial– from all 3 layers
2. Connective– mesoderm
3. Muscular– mesoderm
4. Nervous – ectoderm
Embryology of Tissues
• are contact pts between plasma membranes of adjacent cells
• found between most epithelial cells & some muscle & nerve cells
Cell Junctions
Surfaces of Cells
• thin, extracellular layer• commonly has 2 parts:1. basal lamina2. reticular lamina
Basement Membrane (bm)
• 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
Covering & Lining Epithelium
• 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
Simple Epithelium
• appears to have multiple layers because:
1. nuclei @ different layers2. not all cells reach apical surface
Pseudostratified Epithelium
• 2 or more layers of cells– named by shape of top layer
• function: protection where there is considerable wear & tear
Stratified Epithelium
• arranged like floor tiles• very thin: allows for rapid passage of
substance thru cell
Squamous Cells
• shaped like cubes or hexagons• +/- microvilli on apical surface– finger-like cytoplasmic projections– function increase surface area
• function: secretion or absorption
Cuboidal Cell
• 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
Columnar Cells
• single layer flat cells• viewed from– apical surface looks like tiled flooring– cross-section: fried eggs cross section
Simple Squamous Epithelium
• found:• @ sites where filtration (kidneys) or
diffusion (lungs, capillaries) occur• lines blood vessels & chambers in
heart (endothelium), forms lining for serous membranes (mesothelium)
Simple Squamous Epithelium
• nuclei round & centrally located• functions:– secretion– absorption
• found in:– thyroid gland – kidneys
Simple Cuboidal Epithelium
• 2 forms: nonciliated/ciliated• nonciliated simple Columnar
Epithelium– 2 types:1. Columnar epith. w/microvilli on apical
surfaces2. Goblet cells• produce & secrete mucus
Simple Columnar Epithelium
• 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
Ciliated Simple Columnar Epithelium
• 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
Pseudostratified Columnar Epithelium
• 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
Stratifed Squamous Epithelium
Stratified Squamous Epithelium
• Keratinized
• upper layers contain keratin: tough, fibrous protein that protects underlying tissues from heat, microbes, chemicals
• found: skin• Nonkeratinized
• found: lining mouth (buccal mucosa) & esophagus
• protect underlying tissues from wear & tear and from invasion by microbes
• gland: single cell or group of cells that secrete substances into:– ducts – onto a surface – into blood
• classified:1. endocrine– secretions intercellular fluid capillary
2. exocrine– secretions ducts surface of skin or lining of
hollow organ
Glandular Epithelium
Classification of Glands
• most abundant & widely distributed tissue in body
• 2 basic elements:1. extracellular matrix2. cells
Connective Tissue (CT)
• 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
Extracellular Matrix
• immature form suffix “blast”– large capacity to divide– secrete matrix
• mature form suffix “cyte”– less likely to divide–maintain matrix
CT Cells
• large flat cells w/ branching processes
• found in most CT• migrate thru CT secreting fibers &
ground substance
Fibroblasts
• develop from monocytes• phagocytes• irregular shape• 2 types:1. wandering– move to sites of infection or inflammation
2. fixed– reside in a particular tissue– ex: alveolar macrophages
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
Plasma Cells
• 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
Mast Cells
• aka adipose cells or fat cells• store triglycerides• functions:– store fats for nrg– insulate– cushion organs
Adipocytes
• 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
Ground Substances
1. Collagen– “colla” = glue a protein (25% of all protein in body!)– very strong fibers that resist pulling
2. Elastic– smaller strong but stretchy fibers– made of protein called elastin– plentiful in skin, blood vessel walls, lung tissue
3. Reticular– made of collagen in fine tubes coated with
glycoproteins forming branching networks & found in BM
– skin, adipose, reticular CT (spleen, lymph nodes)
CT Fibers: 3 Types
1. Areolar CT• 1 of most abundant types• includes all types of CT cells &
fibers• found in: subcutaneous tissue
Mature CT: Loose CT
2. Adipose Tissue• cells: adipocytes• found ass’c with areolar CT• 2 types:1. white– most of the adipose in adults
2. brown– darker due to rich blood supply– widespread in newborns: helps maintain body
temperature
Mature CT: Loose CT
• contains more numerous fibers but fewer cells than in loose CT
• 3 types:1. Dense Regular CT2. Dense Irregular CT3. Elastic CT
Mature CT: Dense 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
Dense Regular CT
• collagen fibers irregularly arranged• found where pulling forces exerted in
various directions• found: dermis, pericardium,
periosteum
Dense Irregular CT
• predominate fiber: elastic fibers• quite strong & able to return to
original shape after being stretched• found: elastic arteries, lungs
Elastic CT
Membranes • 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)2. synovial membrane:– + CT but - epithelium– line joints
Mucous Membranes (Mucosa)• 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 some3. site of nutrient absorption
Serous Membranes (Serosa)• 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
2. visceral peritoneum– covers organs– in pericardial cavity = pericardium– in abd. Cavity = peritoneum
• 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
CARTILAGE
• 3 types:1. Hyaline cartilage– most abundant cartilage in body, also the
weakest– provides flexibility & support
2. Fibrocartilage– no perichondrium– provides strength & rigidity (strongest of the 3)
3. Elastic cartilage– + elastic fibers– provides strength & elasticity
Cartilage
• aka osseous tissue• 2 types:1. Compact bone2. Spongy bone
Bone Tissue
• basic unit of compact bone is the osteon (haversian system)
• has 4 parts:1. Lamellae– concentric rings of extracellular material &
collagen– make bone hard & strong
2. Lacunae3. Canaliculi4. Central (haversian) canal)
Compact Bone
• lacks osteons• found only inside compact bone• consists of columns of bone called
trabeculae– spaces between trabeculae filled with
red bone marrow
Spongy Bone
• 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
Blood
• consists of elongated cells called muscle fibers that can use ATP to generate force movement, maintain posture, generate heat
• 3 types:1. Skeletal2. Smooth3. Cardiac
Muscular Tissue
• most attached to a bone
• muscle fibers up to 12-16 in in longest muscles:–multinucleated (on edges)– striated– voluntary
Skeletal Muscle Tissue
Smooth Muscle Tissue• 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-to-end (desmosome + gap jct) allows for quicker conduction of action potentials coordinated contractions of heart chambers
Cardiac Muscle Tissue
• 2 cell types:1. neurons– nerve cells that can generate action
potentials which are conducted to other neurons, muscles, or glands
2. neuroglia (glia)– supportive cells to neurons– cannot generate action potentials
Nervous Tissue
Neurons
• 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)
Action Potentials
• 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
Medical Terminology
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