Post on 17-Dec-2015
What is a tissue?• Group of similar cells and cell products that work together to perform
a specific structural or physiological role
What is a tissue?
• Arise from three primary germ layers:
Germ Layer Contributions to BodyEctoderm Integumentary system – epidermis; Nervous
system; Skeletal – hyoid and auditory ossicles; Endocrine – pituitary gland and adrenal medulla; Respiratory and Digestive systems – mucous epithelium of nose, mouth, and anus
Mesoderm Skeletal, Muscular, Cardiovascular, Lymphatic systems; Integumentary system – dermis and hypodermis; Endocrine – adrenal cortex; Urinary – kidneys; Reproductive – gonads
Endoderm Respiratory system; Digestive – including liver and pancreas; Urinary – except kidneys; Reproductive – except gonads; Endocrine – thymus and thyroid
• Most abundant
• Widely separated cells
• Connect organs to each other
• Functions:
• binding of organs
• support
• physical and immune protection
• movement
• storage
• heat production
• transport
Connective Tissue
Connective TissueMarfan Syndrome
• Inherited – dominant gene• Defective gene that would normally enable the body to
produce fibrillin• Symptoms:
• Tall and thin with disproportionately long appendages• Severe near-sightedness
• CAN AFFECT ANY PART OF THE BODY!• Heart: aorta, heart valves• Eyes: dislocation of lens, glaucoma, cataracts, detachment
of retina• Lung: breathing difficulties
• Treatment: only of the complications
Components:
• Cells:
• Fibroblasts – fixed, produce the matrix of the tissue
• Macrophages – large phagocytic cells that move
• Leukocytes – wander around looking for pathogens
• Plasma cells – synthesize antibodies
• Mast cells – secrete heparin and histamine
• Adipocytes – energy storage, insulation, cushioning/protection
Fibrous Connective Tissue
Fibrous Connective Tissue
Components:
• Fibers:
• Collagenous – tough, flexible, made of collagen
• Reticular – thin, branching collagen fibers, framework for certain organs
• Elastic – made of elastin; stretch and resume original shape
Fibrous Connective Tissue
Components:
• Ground Substance:
• Glycosaminoglycan (GAG) – regulation of water and electrolyte balance
• Proteoglycan – important in holding tissues together
• Adhesive glycoproteins – bind components within a tissue together
Fibrous Connective Tissue
Types:
• Loose and Dense Connective Tissue
Loose Connective Tissue
• Areolar
• Reticular
• Adipose
Dense Connective Tissue
• Dense regular
• Dense irregular
• Chondroblasts
• Supportive with a flexible rubbery matrix
•No blood vessels
• Uses diffusion to bring in nutrients and remove wastes
• Types:
• Hyaline
• Elastic
• Fibrocartilage
Cartilage - Connective Tissue
• An organ made of multiple tissues including osseous tissue which makes up most of the mass of the bones
• Osteoblasts
• Matrix – Calcium and collagen
• Types:
• Compact bone
• Spongy bone
Bone - Connective Tissue
Central canal
Osteon
Compact bone LM x 375
Osteocytes occupy lacunae that lie between the lamellae.
• Exposed to the environment or an internal space in the body
• Flat sheet of closely adhering cells
• No room for blood vessels
• Basement membrane – extremely thin layer of connective tissue between an epithelium and underlying tissue
• Apical surface
• Lumen
Epithelial Tissue
•Contains all types of cells and fibers
•Passageways for nerves and blood vessels (packing material)
•Underlies all epithelia, between muscles
Loose Connective TissueAreolar
• Loose network of reticular fibers and blood cells• Forms supportive framework for lymphatic organs• Found in lymph nodes, spleen, and bone marrow
Loose Connective TissueReticular
• Large empty-looking cells with thin margins; nucleus pressed against cell membrane
• Energy storage, insulation, cushioning• Deep to the skin and around kidneys and eyes• Well suited for function because – a. b.
Loose Connective TissueAdipose
• Densely, packed, parallel collagen fibers
• Stretched in one predicable direction
• Tendons and ligaments
Dense Connective TissueDense Regular
Collagenfiber
Fibroblastnuclei
Dense regular connective tissue in a tendon from the triceps muscle
LM x 440
• Densely packed, randomly arranged, collagen fibers and few visible cells
• Stretched in multiple directions• Deeper layer of skin, capsules around organs
Dense Connective TissueDense Irregular
Dense irregular connective tissue from the dermis
Collagenfiber
bundles
LM x 111
• Rubbery proteoglycan matrix; dispersed collagen fibers; clustered chondrocytes in lacunae
• Stiff but flexible, reduces friction
• Ends of bones at movable joints; sternal ends of ribs; supportive material in larynx, trachea, tip of nose, and fetal skeleton
Cartilage - Connective TissueHyaline
Hyaline cartilage from shoulder joint
Chondrocytesin lacunae
Matrix
LM x 500
• Hyaline cartilage with elastic fibers• Provides flexible, elastic support• External ear and epiglottis
Cartilage - Connective TissueElastic
• Hyaline cartilage with extensive collagen fibers
• Resists compression and absorbs shock
• Pubic symphysis, meniscus and intervertebral discs
Cartilage - Connective TissueFibrocartilage
Collagenfibers inmatrix
Chondrocytesin lacunae
Fibrous cartilage from intervertebral discLM x 400
• Calcified matrix in lamellae around a central canal• Osteocytes in lacunae between lamellae • Osteon– functional unit; canaliculi for exchange of
nutrients• Skeletal support; leverage for muscles; mineral storage
Bone - Connective TissueCompact
•Variety of cells and cell fragments: Non-nucleated or nucleated
• Plasma = ground substance, NO fibers!
• Transport cells and dissolved matter
• Found in heart and blood vessels
Blood - Connective Tissue
• Diffusion• Ex.: inner lining of heart and blood vessels, lungs,
kidneys
Epithelial TissueSimple Squamous
Nucleus Cytoplasm
LM x 270
View from top
• Dead layers packed with keratin– epidermis
• Retards water loss, barrier to organisms, resists abrasion
Keratinized
Epithelial TissueStratified Squamous
General function – resistance against abrasion/frictionTwo types:
Epithelial TissueStratified Squamous
• Lacks surface layers of dead cells
• Forms a moist, slippery layer, resists abrasion
• Ex.: Oral cavity, pharynx, esophagus, anus, vagina
Nonkeratinized
• Absorption and secretion, mucus production
• Lines glands
• Liver, thyroid, mammary and salivary glands, and kidney tubules
Epithelial TissueSimple Cuboidal
• Nuclei line up at basal surface, microvilli on apical surface• Absorption and secretion; mucus secretion • Inner lining of stomach, uterus, and kidney, intestine
Epithelial TissueSimple Columnar