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Whats special about epithelial tissue?
- high in cellular content
- unique contact points
- polarity
- supported by connective tissue
- can regenerate
- innervated
- avascular
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How is epithelial tissue classified?
- number of layers
- shape of cells
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What is simple epithelial tissue?
- single cell layer
- allows for diffusion
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What is pseudostratified columnar epithelium?
- may have cilia or goblet cells
- function: secretion
- ex: trachea
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What is stratified epithelial tissue?
- multiple cell layers
- regenerate from the bottom cells upward
- function: support, protection
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What is stratified squamous epithelium?
- basal cells are cubodial or columnar
- surface cells are flattened or squamous
- most dominant kind
- function: protects underlying tissue
- ex: esophagus, mouth
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What is keratinized stratified squamous epithelium?
- surface cells are full of keratin and are dead
- make up the epidermis
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What is stratified cubodial and columnar epithelium?
- less common and less sophisticated
- function: protection
- found in the digestive tract
- most have sweat glands
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What is transitional epithelium?
- resembles stratified squamous and stratified cubodial
- function: stretches and allows distention of urinary system
- ex: urinary system
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What are epithelial glands?
- function: secrete a specific product
- excretes: water-based, protein, lipid or steroid rich substance
- transported by: water, blood, sweat
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Endocrine glands:
- duct-less
- produce hormones
- released directly into extracellular space
- ex: pancreas
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Unicellular exocrine glands:
have goblet cells that secrete mucus
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multi-cellular exocrine glands:
- epithelium-covered duct
- secretory unit
- can have simple or compound duct structures
- can be tubular or alveolar/acinar secretory structures
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Connective Tissue:
- originates from: mesenchymal cells
- vascularity: differs
- extracellular matrix: ground substance, fibers, cells
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Major classes of Connective Tissue:
- CT proper
- cartilage
- osseous
- blood
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What is in the ground substance of CT?
- interstitial fluid
- cell adhesion molecules
- proteoglycans
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What does the ground substance do for CT?
- filler
- contains fibers of the specific CT
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What do fibers do for CT?
- provide support for CT
- works with the ground substance (rebar or scaffolding)
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What are the common types of fibers in CT?
- collagen fibers
- elastic fibers
- reticular fibers
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What are the properties of connective tissue?
- cell poor
- ECM rich
- limited or non-vascular
- dense, rigid structure
- serves to connect, protect and support
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What are the subclasses of CT Proper?
- loose CT: areolar,adipose,reticular
- dense CT: regular, irregular, elastic
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Areolar CT:
- gel-like matrix with all 3 types of fibers
- wraps and cushions organs
- found throughout the body
- fibroblasts, macrophages, mast cells, some white blood cells
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Reticular CT:
- loose ground substance w/ reticular fibers
- reticular cells lie in a fiber network
- forms soft, internal skeleton or stroma
- found in lymph nodes, bone marrow and the spleen
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Adipose CT:
- gel-like matrix with closely packed adipocytes
- reserve food stores, insulates against heat loss, supports and protects
- found under skin, around kidneys, within abdomen and in breasts
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Dense Regular CT:
- parallel collagen fibers w/ few elastic fibers
- major cell type: fibroblasts
- attaches muscle to bone or other muscles or bone to bone
- ex: ligaments, tendons and aponeuroses
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Dense Irregular CT:
- irregularly arranged collagen fibers w/ some elastic cells
- major cell type: fibroblasts
- withstand tension and provide structural strength
- found in dermis, digestive tract and fibrous organ capsules (joints)
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Dense Elastic CT:
- high proportion of elastic fibers
- allows for the recoil of tissue following stretching
- located in the walls of arteries, certain ligaments in the vertebral column, walls of bronchial tube
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Properties of Tendons:
- Type I collagen
- very little elastin
- sugar molecules including proteoglycans, aggrecan and glycoaminoglycans
- inorganic molecules (copper, calcium, magnesium)
- tenocytes
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structure of a tendon:
- collagen fibril
- collagen fiber
- primary fiber bundle
- secondary fiber bundle
- tertiary fiber bundle
- tendon
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Properties of Ligaments:
- similar to tendons
- parallel collagen fibrils
- fibrocytes in ECM
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Function of tendons:
- connects muscle to bone
- assists muscle groups in locomotion
- provide locomotive support
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Function of ligaments:
- connect bone to bone
- stabilizes/limits movement
- force resistance
- wraps around movable joints
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Cartilage
- avascular
- small amount of cells
- protect gliding surfaces
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sub-classes of cartilage:
- hyaline: most rigid
- fibrocartilage: (collagen/fibrocytes structure) intervertebral discs
- elastic cartilage: least rigid (ear)
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Bone (Osseous) Tissue
- compact or spongy
- used in body structure
- function: support, protection, attachment site for muscles
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What type of cells are found in osseous tissue?
- oesteoblasts
- osteocyte
- osteoclasts
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What does the periosteum do?
covers compact bone
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Why is blood a connective tissue?
- derived from mesenchymal cells
- has blood cells (vascular)
- surround by a fluid matrix (plasma)
- has "fibers"- clotting factors
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What is Wolf's Law?
- way to remodel bone by straining the bone in order to stimulate growth
- most effective when animal is young
- recovery and confinement cause the opposite effect
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How can cartilage adapt?
- calcified layer can increase
- adapts similar to bone
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What is osteochandrosis?
cartilage lesions found in young animals
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What is osteoarthritis?
- inflammation leading to cartilage loss
- irreversible
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What types of cells are found in nervous tissue?
- glial cells: regulate neurons
- neurons: connect to each other
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Dendrite:
receives signal
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Skeletal muscle:
- contracts during movement
- voluntary
- striated due to myosin and actin
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Cardiac muscle:
- allows heart to beat
- involuntary
- intercalated discs send messages for the heart to beat
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Smooth muscle:
- move fluids through the digestive system
- involuntary
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two types of membranes:
- synovial membrane
- serrous membrane
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