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- STRUCTURE:simple squamous
- LOCATION: found in some kidney tubules, in alveoli of the lung, lining blood vessel,
- and lining major body cavities
- FUNCTION:Diffusion of gases
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- STRUCTURE: simple cuboidal
- LOCATION: found covering the ovary, in some kidney tubules, forming thyroid follicles,
- and lining many glandular ducts
- FUNCTION:usually involved in secretion and resorption
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- STRUCTURE: simple columnar
- LOCATION: Found in some glandular ducts, the gall bladder, the ovarian tube, the stomach and the intestine
- FUNCTION:Movement of particles
- OTHER:some specializations found include goblet cell inclusions (in the gut) and ciliated surfaces(such as insome tubes of the genito-urinary system)
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- STRUCTURE: stratified squamous
- LOCATION: found on external surfaces (e.g. epidermis of the skin)
- FUNCTION:can resist abrasion and entry of bacteria and water
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- STRUCTURE:stratified cuboidal or columnar
- LOCATION:found lining many gland ducts
- FUNCTION: Secretory
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- STRUCTURE: transitional epithelium
- LOCATION: found in the ureter and urinary bladder
- FUNCTION: designed to accommodate stretching of the organ
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- STRUCTURE: Pseudostratified
- LOCATION:seminal vesicle, upper respiratory tract, olfactory regions, epididymis and ductus deferens
- FUNCTION: Absorption, movement of particles
- OTHER: Can have cilia and goblet cells (for secretion and removal of contaminants), microvillia (odor detection), stereocilia (re-absorption)
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zonula occludens (tight junction) - seals between adjacent epithelial cells
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macula adherens (desmosome) - spot-shaped; binds to intermediate filament cytoskeleton of adjacent cells to bind cells together
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gap junction (nexus) - allow for direct communication between cytoplasmic compartments of adjacent cells
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Simple tubular glands of the large intestine
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- Simple coiled tubular gland: sweat gland
- Duct region and secertory region
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- Myoepithelial cells
- - basket-shaped, smooth muscle-like cells
- - surround exocrine gland acini and contract in order to express acinar contents (e.g. mammary gland, sweat gland)
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- Serous - proteinaceous secretions - watery consistency (e.g. parotid gland)
Mucous - glycoproteinaceous secretions: complex polysaccharides named mucus - viscous, gel-like consistency (e.g. sublingual gland)
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- Loose irregular CT
- abundant ground substance, few fibres, and variable cell numbers
contains many capillaries
diffusion in ground substance facilitates waste and nutrient exchange with capillaries
contains many immune cells to fight bacteria
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- DENSE IRREGULAR CT
- •same as loose CT (Type I collagen & glycosaminoglycans), except that:
•fibres are much larger & more tightly packed
•irregular fibres are specialized for strength such that DICT resists mechanical stresses in all directions (so keeps its shape) - •there is less ground substance
•there are fewer cells (mostly fibroblasts) - •such tissue forms:
–capsules & septa for many glands and organs
–the periosteum (outer covering) of bone, perichondrium (outer covering) of cartilage, tendon & ligament sheaths, epimysium, epineurium, dura mater, submucosa of the GI and respiratory tracts, muscle fascia, and dermis of skin
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- DENSE REG CT
- •tendons are made of tissue very like dense irregular CT
–Type I collagen & glycosaminoglycans
–minimal ground substance
–mainly fibres & inactive fibrocytes, but fibres run in only one direction (along long axis of the tendon)
–fibrocytes are arranged in rows between the fibres
•ligaments are similar to tendons, but are more elastic
–elastic ligaments are almost all elastin
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•highly specialized cells with a little loose CT
- •fat cells are closely related to fibroblasts (same precursors)
- •fat cells can make their own collagenous basement membrane
•fat cells are metabolically very active
•fat tissue develops from the 30th week of gestation to shortly after birth
•mesenchymal stem cells replace adipocytes throughout life
•two types of fat - white and brown
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- HYALINE
- •cartilage is an avascular tissue
•maintenance of cells depends upon diffusion of nutrients and oxygen from the vascularized perichondrium (outside layer)
- •diffusion through the matrix (fibres and ground substance) provides nutrients and removal of waste metabolites
- •growth continues slowly throughout life
•pathology can occur when central cells die (e.g. due to lack of diffusion), and the matrix then will calcify
- •if mechanical damage occurs, complete repair of cartilage does not occur
- ELASTIC HAS ELASTIN FIBERS
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- BONE
- §functions to provide skeletal support for the body and act as a storehouse of calcium
§dynamic tissue, constantly changing in response to mechanical and other influences, and capable of repairing itself
§ground substance is packed with calcium phosphate crystals and contains compact bundles of Type I collagen fibres, stem cells, osteoblasts, osteocytes, osteoclasts
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- Skeletal Muscle
- •myoblast cells converge to make a muscle fibre = single, large (can be > 1 metre), multinucleated cell (a syncytium)
- •connective tissue forms a support structure for the muscle fibre: facilitates the transfer of force to bones and provides a conduit for the vascular and neural supply to the muscle
–endomysium – surrounds individual muscle fibres
–perimysium – surrounds muscle fascicles
(i.e. groups of muscle fibres having the same motor innervation so that they contract together)
–epimysium – surrounds a collection of fascicles; this is the fascia seen in the gross anatomy laboratory
•within each cell, myofibrils form the functional unit
–give the cells a striated appearance
–myofilaments within myofibrils are the contractile elements of muscle
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- Cardiac Muscle
- cardiac muscle fibres called cardiomyocytes:
– striated
–centrally located nucleus
–large quantity of mitochondria (aerobic muscle)
–t-tubule located at Z-line level
–SER less developed and diads instead of triads
–intercalated disk: complex intercellular cell junction comprising desmosome, fascia adherens and gap junction components
–atrial myocytes have contractile function and endocrine function: production and secretion of natural diuretic hormones atrial natriuretic factor (ANF) and brain natriuretic factor (BNF)
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- Smooth Muscle
- •originates from muscle mesenchyme
- • no cross striations
• has contractile myofilaments and intermediate filaments
• intermediate filaments form a complex architecture with dense bodies being the equivalent of Z disc in other muscles
• caveolae are permanent sarcolemmal invaginations (equivalent to the t-tubules of other muscles)
- • sarcolemmal junctions are mainly gap junctions
- •smooth muscle in some organs can regenerate by mitosis if injured
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- NEURON
- •consists of cell body (perikaryon or soma) and two types of branches: dendrites and an axon
•the soma contains much rough endoplasmic reticulum (called Nissl substance or Nissl bodies) as well as normal complement of other organelles
• dendrites tend to be relatively short and very branched and transmit information towards the soma
•a single axon, arising from the axon hillock, transmits information away from the soma
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- Erythrocytes and Reticulocytes
- -Erythrocytes are non-nucleated cells that use the molecule hemoglobin to carry oxygen from the lungs to peripheral cells and tissues
-an increase in the numbers of reticulocytes indicates an increased need for oxygen, often the result of hemorrhage
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