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4 Tissue Types
- Epithelial- covers the outer and inner surfaces of the body
- Connective- connects parts of the body and protects organs
- Nervous- nerve cells and supporting (glial)
- Muscle- skeletal, cardiac, smooth
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Epithelial Cells
- line inner and outer surfaces
- "gatekeeper" everything that enters the body must go through it
- 1 layer- simple, multiple layers- stratified, pseudostratified- false stratified. transitional- simple as tissue stretches
- polarity- sides are functionally and structurally different; top exposed to outer (apical), bottom exposed to inner (basal)
- tight junctions bind together so things can't get through that aren't supposed to
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Squamous Simple Ephithelial Cells
- found where materials cross a membrane
- flat, with disk shaped nucleus
- allow passage of materials by diffusion when protection isn't important
- ex: kidney, air sacs of lungs, capillaries
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Stramous Stratified Epithelial Cells
- found where mechanical abrasion occurs
- protects underlying tissues in areas subject to abrasion
- base layers are cuboidal or columnar
- keratinized
- ex: esophagus, mouth, epidermis
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Cuboidal Simple Epithelial Cells
- single layer of cublike cells
- secretion and absorption
- ex: kidney tubules, ovary
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Columnar Simple Epithelial Cells
- single layer of tall cells with oval nucleus
- absorption, secreation of mucous, enzymes, cilary action
- ex: non ciliated- digestive tract, gallbladder, ciliated- uterus
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Pseudostratified Epithelial Cells
- single layer of cells of differing heights with nuclei at differing levels
- for secretion of mucous, cilary action
- ex: male sperm ducts, respiratory tract, trachea
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Transitional Epithelial Cells
- looks like stratified squamous and cuboidal surface cells- dome shaped
- stretchy to permit distension of urina organ by urine
- ex: lines ureter, bladder and urethra
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Merocrine
cell pushes out the protein but stays intact
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Holocrine
cells explodes and dies, secreting the protein
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Apocrine
part of the cell breaks off, releasing material in the middle, then it regenerates itself
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Connective Proper
- six types for binding, resist mechanical stress/tension
- made of ground substance which contains the cells and fibers (collagen, elastic, reticular)
- Loose areolar, loose adipose, loose reticular, dense regular, dense irregular, dense elastic
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Loose Areolar Connective Proper
- allows for sliding
- matrix of fibroblast cells, macrophages,
- wraps and cushions organs, holds fluid
- ex: under skin, around organs, capillaries
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Loose adipose Connective Proper Tissue
- sparse matrix of closely packed fat cells
- reserves food fuel, insulation, supports and protects organs
- ex: under areolar, breasts, around kidneys and eyeballs
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Loose Reticular Connective Proper Tissue
- network of reticular fibers which holds cells together as an organ
- soft internal skeleton that supports other cell types such as white blood or macrophages
- ex: lymphnoid organs (spleem, thymus)
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Dense Regular Connective Proper Tissue
- parallel collagen fibers and fibroblasts
- attach muscle to bones or muscle to muscle
- withstands great stress in 1 direction bc fibers run in 1 direction
- ex: tendons, ligaments
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Dense Irregular Connective Proper Tissue
- irregularly arranged collagen fibers and fibroblast cells
- can withstand tension in any direction, structural strength
- ex: dermis, part of digestive tract, in dermis with loose areolar
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Dense Elastic Connective Proper Tissue
- allows recoil of tissue following stretching
- maintains flow pulse through arteries/lungs
- ex: walls of large arteries, bronchial tubes, lungs, ligaments
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Hyaline Cartilage
- firm like bone but flexible made of collagen fiber network
- supports, cushions, resists stree
- chondrocyte in lacuna produce chondroblasts
- ex: nose, ends of long bones, costal cartilages, trachea, larynx
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Elastic Cartilage
- more flexible than hyaline
- chondrocyte in lacuna
- ex: ear, epiglottis
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Fibrocartilage
- similar matrix but less firm than hyaline
- shock absorber, thick collagen fibers
- ex: vertebrae, knees
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Epidermal Layers
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Corneum
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Stratum Basale
- living, dividing epidermal cels
- Form layers and grow upwards as they divide
- Melanocyte cells which produce melanin surround the cells. This acts a sunscreen and produces skin color that gets picked up by dividing cells and carried to the surface
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Stratum Spinosum
- keratinized cells are still alive but not dividing
- epidermal dendritic cells patrol for immunization
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Stratum granulosum
3rd layer- dying cells
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Stratum Corneum
4th layer -dead and kerotinized outer cells
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Sudoriferous glands secret...
sweat- eccrine by merocrine
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Sebaceous glands secret...
oil by holocrine
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Role of Cartilage in Bones
- physical support and protection- form bone like structures
- hyaline important for child development of bone
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Flat Bones
- flat, compact surface and and spongy bone called diploe
- spongy bones resist compression- made of trabeculae (honey comb)
- provide strength but don't weigh a lot
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Long Bones
- spongy inside, compact outside called periosteum membrane where blood veins enter through
- medullary cavity on inside- holllow and lined with endosteum where bone marrow is which creates white blood cells
- proximal and distal epiphyses- end of bone covered in articular/hyaline cartilage
- Diaphysis- tube down long part of bone constructed of compact bone, surrounds medullary cavity
- Osteons- in compact bone, circular structure blood veings come through. Lined with lamellae (circumferential lamellae wrap osteon) supported by collagen fibers which run in opposite directions circular to provide strength- no breaks in twisting
- blood transported through bone by osteocytes which are connected by canals called canaliculi found in the lacunae b/w lamellae
- made of calcium- 39%, organics (collagen), phosphate
- Hydroxylapatite- chemical that crystalizes around collagen fibers
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Cell Types in Bones
- Osteogenic
- Osteoblast
- Osteocyte
- Osteoclast
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Osteogenic Cells
stem cells- differentiate into the other types
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Osteoblast
- bone forming
- in periosteurn and endosteurn
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Osteocyte Cell
- Maintains bone structure
- in lacunae of osteon
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Osteoclast Cell
- breaks down bone to release calcium in bloodstream
- in periosteurn and endostern
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Bone Development in Flat Cells
Intramembrane Ossification
- 1. Start as Fibrous connective tissue called mesenchymal cells which produce collagen fibers
- 2. osteoblasts secrete osteoid, calcifies to become bone. some blasts trapped in bone become osteocytes which complete spongy bone and trabeculae around nerve blood vessels
- 3. Mesenchymal cells form periosteum and compact bone in lamellae
- ex: skull, scapula, sternum
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Bone development- endrochondral ossification of long, short, and irregular
- 1) starts as hyaline cartilage, osteoblasts destroy hyaline to create bone
- 2) Secondary ossification occurs in epiphyses, a little hyaline stays in epiphyseal plate (growth plate)
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Remodeling of bone
Osteoclasts destroy while osteoblasts rebuild
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Appositional growth
due to osteoblasts in periosteum which lay new bone matrix which widens the bone
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Drop or Raise in Calcium levels
Parathyroid- PTH hormone
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Bone Repair- fractures
- area fills with blood to begin healing
- fibroblasts make new fibers, chondroblasts make new cartilage, and osteoblasts make new bone, 1st spongy then remodeling
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Fibrous Joints
- Sutures- Synarthrotic
- Syndesmoses- Synarthrotic/Amphiarthrotic
- Gomphoses- Synarthrotic
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Cartilages
- Synchondroses- synarthrotic- hyaline cartilage
- Symphyses- Amphiarthrotic- fibrocartilage
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Suture
- held by a very short collagen fibers, bones interlock- only in skull
- synarthrotic
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Syndesmosis
- joints held by ligament
- ankle
- synarthrotic/amphiarthrotic
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Gomphoses
- "peg in socket"
- ex: tooth, synarthrotic
- periodontal ligament holds in place
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Synorial
- Diarthrotic
- sealed sac of liquid to allow flexibility and minimize friction
- ligament and fibrous capsule encase synovial
- membrane and hyaline to keep in place
- secrets hyaluronan/hyaluronic acid
- ex: knee
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Tendon Sheath and Bursae
- Prevents friction and protects, has synovial fluid
- Sheath- wraps like hotdog bun around tendon
- Bursae- flat sac lined with synovial membrane, rolls when bones move
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