The Tissue Level of Organization Ch. 4
Terms
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- Tissues
- combination of diggerent types of cells and cell products that perform limited fuctions
- Four Types of Tissue
-
1. Epithelial
2. Connective
3. Muscle
4. Neural - Composition of the Epithelial Tissue
- Eptihelial and Glands
- Epithelial
- Layers of cells that cover internal and external surfaces
- Glands
- Structures that produce fluid secretions (derived from epithelia)
- Characteristics of Epithelia
- Cellularity, Polarity, Attachment, Avascularity, Regenerations
- Ceullularity
- Cells bound by cell junctions (interconnections)
- Polarity
- one surface is exposed (apical) and one is attached (basal)
- Attachment
- Bound by Basal Lamina
- Avascularity
- Lack of blood Vessels
- Regeneration
- Cells damaged are replaced
- Functions of Epithelial Tissue
-
-Provides protection from abrasion, dehydrations, chemicals
-Controls Permeability- any substance entering or leaving must cross epithelium
-Provides sensation- have large nerve supply
-Produce specialized Secretions - Neuroepithelium
- specialized to perform sensory functions
- Glandular epithelium
- produce secretions discharged on surface or to interstitial fluid as chemical messengers
- Apical surface
- Part exposed to internal or external environment
- basolateral surface
- includes base and parts where cell touches neighbor
- Tight Junctions
-
lipid portions of 2 cell membranes
-impermeable
-for examble stomach lining
-intracellular connection - Gap Junctions
-
Cells held together by interlocking proteins (channels present)
-Allows for rapid communication
-messages pass from cell to cell to cell - Desmosomes
-
Cell adhesion molecules (CAM) and proteglycans link membranes
-strong and flexible
-like strong rubber cement - Attachment to Basal Lamina
- By Lamina Lucida and Lamina densa
- Lamina Lucida
- closest to epithelium, barrier that restricts movement of large molecules from underlying tissue into epithelium
- Lamina Densa
- bundles of corse protein fibers produced by connective tissue
- Classification of Epithelia
- Cell shape, number of layers
- Squamous
- thin and flat cells
- Cuboidal
- look like boxes cells
- Columnar
- tall, slender rectangle cells
- Simple
- one layer
- Stratified
- multiple layers
- Pseudostratisfied
-
looks like it's two layers but it's only one
-found in intstines - Simple Squamous epithelia
-
-Most delicate epithelium
-Occur where abosorption and diffusion take place or where slippery surfaces reduce friction (plerua, lining of hear and blood vessels) - Two types of Simple squamous epithelia
-
-Mesothelium-lines pleura, peritoneum
-Endotheilum- lines blood vessels and heart, stretchy and can stand some adjustment of shape - Stratified epithelia
-
occurs where mechanical stresses are sever
-Skin surface
-Lining of mouth
-Keratinized-apical layer contain protein filaments, resistant to water loss ex. bottom of foot
-Non-keratinized must be kept moist ex. mouth lining - Simple Cuboidal Epithelia
-
provide limited protection to areas where secretion and/or absorption occur
ex. parts of kidney - Stratified Cuboidal epithelia
- Fairly rare, are located along ducts of sweat glands and large ducts of mammary glands
- Transitional epithelial
-
tolerant of repeated cycles of stretching
-Found in urinary bladder, when full it resembles simple epithelium, when empty resembles multiple layers of cuboidal cells - Simple Columnar epithelia
-
found where secretion and absorption occur
-small intestine
-secretions protect against chmeical damage in large intestine and stomach - Pseudostratified columnar epithelia
-
contain cilia
occur in
-lining of nasal passages
-trachea
-bronchioles
-and parts of male reproductive tract - Stratified Columnar epithelia
- Fairly rare, occur in parts of pharynx, epiglottis, anus and urethra
- Glandular Epitheli
- Endocrine glands and Exocrine Glands
- Endocrine Glands
- releases secretions on the inside, such as hormones
- Exocrine Glands
- releases secretions on teh outside, such as tears and sweat
- Connective Tissue
-
Connects epithelium to the rest of the body (reticular layer)
-Bone-provides structure
-Fat-energy stores
-Blood-transport material throughout body - Three Basic Components of CT
-
1. Specialized Cells
2. Extracellular Protein Fibers
3. Fluid (ground substance) - Matrix
- Ground Fluid and extracellular fibers
- Does the epithelial tissue or connective tissue have more matrix?
- Connective Tissue
- Functions of CT
-
-Structural framework of body
-Transportation of fluids and dissolved materials
-Protection of dlicate organs
-Supporting, surrounding, connecting other types of tissue
-storing energy reserves
-Defending body from microorganisms - What is the most delicate epithelial tissue
- Simple Squamous
- Classification of CT
-
Connetive Tissue Proper
Fluid Ct
Supporting CT - Connective Tissue Proper/ FibroCT
-
many cell types and extracellular proteins
-Loose CT (adipose-fat tissue)
-Dense CT (tendons) - Fluid CT
- Fluid matrix ground cells do not from insoluble fiber
- Supporting CT
- Low diversity cell population and dense fibers (bone, cartiledge)
- Fibroblasts
- most abundant cells, only cell always present in CT proper
- Functions of Fibroblasts
- secrete intracellular cement that locks epithelial cells together, secretes protein subunits that interact to form large extracellular fibers
- Macrophages
-
Engulf damaged cells or pahogens
CT cells - Adipocytes
-
Contain large lipid droplet (fat cells)
CT cells - Mesenchymal cells
-
stem celll
CT cells - melanocytes
-
synthesize and store melanin
CT cells - Mast cells
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common near blood vessels, contain histamine and heaprin
CT cells - lymphocytes
-
cells involved in imune system, travel to damaged areas may develop into plasma cells and produce antibodies
CT cells - Collagen fibers
-
long, straight and unbranched, most common in CT proper
-bundle of fibrous proteins wound together
-looks like they're braided - Reticular fibers
-
branched interwoven framework, tough and flexible
-resist forcesapplied in many directions
-stablixie positions of blood vessels in organs
-very stretchy and flexible
CT fiber - Elastic Fibers
-
contain elastin, branced and wavy
-once they stretch they retunrn back to original form
CT tissue - Loose Connective Tissue
-
packing material of the body
3 types
-Areolar
-Adipose
-Reticular - Areolar Tissue
-
least specialized, may contain fibers of all CT proper types
-resitant to distortion (elastic fibers)
-rich in capillaries
-between skin and muscle - Adipose tissue
-
account for most of volume
Functions: Padding, heat loss prevention, backing or filler (keeps organs from having too much space to wiggle around in) - White Fat
- most of fat in body
- Brown fat
-
infants and young children only,
-between shoulder blades and around neck
-mitochondria rich, highly vascularized lots of capillaries - Reticular Tissue
-
found in spleen and liver
-reticular fibers from stroma (a 3d matrix) supports parenchyma of organs
-also found in some bone marrow and lymph nodes - Dense Connective Tissue
-
fibers make up most volume
-collagen fibers are dominant - Two types of Dense CT
-
-Dense regular
-Dense irregular - Dense Regular CT
- -parallel to each other, tightly packed, align with forces applied to tissue
- Tendons, ligaments
- examples of Dense Regular CT
- Dense Irregular CT
-
interwoven meshwork with tno pattern
resists force in nearly every direction - Blood
-
ex. of fluid Ct
the plasma is water matrix - Lymph
-
froms as interstitial fluid and enters lymphatic vessels
-99% lymphocytes
-1% macro and microphages - Cartilage
- firm gel with chondroitin sulfates that combine with proteins to form protegoglycans
- Chondrocytes
-
only cell type in cartilage
-avascular- wastes/nutrients transferred via diffusion - What separates cartilage from tissue?
- perichondrion
- Hyaline Cartilage
-
most common
-connections between ribs, nasal, repiratory passagesways - Elastic Cartilage
-
contain elastic fibers
-external flap of outer ear, epiglottis, small cartilage of larynx - Fibrocartilage
-
dominated by densely woven collagen fibers
-pads between vertebrae, pubic bones and a few joints and tendons
-resists compression, absorbs shock, prevents bone to bone damage - What does the bone matrix consist of?
- 2/3 calcium salts and 1/3 collagen fibers
- Osteocytes
- main bone cells
- Canaliculi
- allow exchange between blood vessels and osteocytes
- Peristeum
- is the outer layer, it sheaths the surface of the bone and assits in attachment to tendons and ligaments
- Three types of Muscle Tissue
-
Skeletal
Cardiac
Smooth - Skeletal Muscle
-
-Responsible for gross movement
-Large multinucleated cells
-reproduce via satellite cells
-Striated voluntary muscle - Cardiac Muscle
-
-circulates blood
-1 to 5 nuclei
-Connected by intercalated discs
-Limited ability to repair damage
-STriated involuntary muscle - Smooth
-
-provides elasticity, contractility and support
-Cells can dived
-spindle shaped cell
-nonstriated involuntary muscle - cardiocytes
- cardiac muscle cells
- Where are smooth muscles located?
-
-walls of blood vessels
-hollow organs (urinary bladder)
-layers around repiratory, circulatory, digestive, reprodutive tracts - Neural Tissue
-
Specialixed for conduction of electrical impulses
-98% in brain and spinal chord - Neurons
-
Larges cells in body
-consist of cell body, nucleus, nucleolus, dendrites, axon
-One of the cells of neural tissue - Neurogila
- Supporting cells in neural tissue
- Fasciae- Connective Tissue layers (3 sections)
-
-Superfical fascia
-Deep Fascia
_Subserous Fascia - Superficial Fascia
-
subcutaneous layer or hypodermis
-Areolar tissues and fat that separates skin from tissure
-isulates
-lets skin and underlying structures move independently - Deep Fascia
-
Irregular CT
-resists froces from many directions
-Capsules surrounding organs bound to deep fascia - Subserous Fascia
-
Areolar Tissue
Between deep fascia and serous membrane - Merocrine Secretion
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Released from secretory vesicles by exocytosis
-saliva, mucus, sweat - Apocrine Secretion
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Loss of cytoplasm as well as secretory product
-cell repairs itself
-ex. milk production ois both merocrine and apocrine
the top of the cell comes off - Holocrine Secretion
-
Cell becomes packed with product and bursts, the cell is destroyed
-ex. oily hair coating - Serous Gland
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Secrete water soulution containing enzymes (i.e. paraotoid salivary glands)
exocrine gland - Mucous gland
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Secrete mucins that hydrate and form mucus (i.e. sublingual salivary glands)
exocrine gland - Mixed Exocrine Gland
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More than one type of gland cell May produce 2 different secretions 1 serous, 1 mucus
(i.e. submandibular salivary glands)
exocrine gland - Unicelluar Glands
-
Scattered throughout epithelium
-goblet cells
-secrete mucins - Multicellular exocrine glands
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-Secretory sheet
-Gland cells release secretions into inner compartment
-Secretions travel through ducts to surface - Characteristics of Muliticellular glands
-
-Structure of duct: simple or compound
-Shape of secretory portion of gland: tublular(cells form tubes), alveolar(cells form blind pockets), tubuloavleolar (form both tubes and pockets)
-relationship between ducts and glandular areas - What happens during inflammation of tissue?
-
-Damaged cells release prostaglandins, proteins, K ions
-Necrosis
-Mast cells release chmeicals (histamines, prostaglandins)
-->surrounding tissue releases, blood flow increases - Necrosis
-
lysosomal enzymes attack ijured cells
-Dead cells, necrotice tissue form pus - What happens with regeneration of tissue?
-
-Fibroblasts move into necrotic area and lay down collagen fibers (produce scar tissue)
-The scar tissue is "remodeled" and you get brand new tissue - What provides sturctural framework of body, protection of organs, and storage of energy?
- Connective Tissue