Tissues Flashcards
4 primary tissue types
- Epithelial
- Connective
- Muscle
- Nervous
Epithelial vs connective tissue
- Epithelial has many cells closely packed with litteral extracellular matrix.
- Connective tissue has scattered cells with lots of material between cells. They are not densely packed and are small in number.
Epithelium
- Protective covering of surfaces inside and outside the body.
- Covers body surfaces and forms glands
- Categeoried as free (aprical), basal, and lateral surfaces
- Contains a basement membrane which is attached to the basal surface, holding the resting of the cells together.
- Avascular…gets nutrients via other neighbouring tissues.
- Capable of regenetaton
Functions of epithelia
- Protecting underlying structure
- Actings as barriers
- Permitting the passage of substances, filters toxins
- Secreting substances
- Absorbing substances
Microvilli
- Increases surface area for absorption or secretion
- Finger-like projections on apical side
Cilia
- Move material across cell surface
- Wave-like actions for moving those materials along the surface
Simple
- One layer of cells
- All in contact with the basement membrane
Stratified
- More than one layer
- Only the bottom cells are attached to the basement layer, whereas the rest of the cells are stacked on top of one another
Pseudostratified
- Tissue appears to be stratified but all cells contact basement membrane
- Cells are at different heights…some reach free surface, while others dont.
Squamous
- Flat, scale-like
Cuboidal
- About equal in heigh and width
Columnar
- Taller than wide
Simple squamous
Structure: Single layer of flat cells
Location: Lining the blood vessels, alveoli of the lungs, bowman’s capsule of kidney, lining ous serous membrane
Function: Diffusion, filtration, secretion
Simple cuboidal
Structure: Single layer of cube-shaped cells
Location: Kidney tubules, glands and their ducts, and surface of the overies
Function: Secretion and absorption
Simple columnar
Structure: Single layer of tall, narrow cells. Some have cilia and or microvilli (ciliated/ nonciliated)…all cells reach surface
Location: Glands, bronchioles, uterus, uterine tubes, stomach, intestines, gallbladder, vestricles of the brain
Function: Movement of particles, secretion by glands of the stomach
Pseudostratified columnar
Structure: All cells reach basement membrane. Almost always ciliated and associated with goblets (mucus-producing cells)…notice that nuleus is at varying heights…not all cells reach surface
Location: Lining of most of the upper repiratory tract; male urethra and epididymis
Function: Synthesize and secrete mucus, moves mucus (or fluid) that contains foregin particles, absorption and protection
Stratified squamous
Structure: Multiple layers of cells that are cuboidal in the basal layer and progressively flatten towards the surface
Location: Nonkeratinized (alive surface cells) are located in the mouth and throat, keratinzed (dead surface cells) is found on skin
Function: protection against abrasion, UV, water loss, infection
Transitional
Structure: Stratified, cells change shape depending upon amoung of distension of the organ
Location: lining of urinary system
Function: Accomodates fluctuations in volumes of fluid in the organ; protect against the caustic effects of urine.
Glands
- A single cell or mass of epithelial cell adapted for secretion of two kinds:
1. Endocrine: no open contact with exterior, no ducts, produces hormones which is released in extracellular space and travels through blood cells sending signals to other parts of the body
- Exocrine: open contact maintained with exterior; ducts…sweat, oil, mammary
Connective Tissues
- Abundant, found in every organ
- Consists of cells and extracullular matrix
- Require a direct supply of blood expect in cartilage and tendons.
Functions of connective tissues
- Enclose organs as a capsule
- Connect tissues to one another (ligaments, or tendons)
- Support and movement (bone)
- Storage of fat
- Cushion and insulate
- Transports blood
- Protection
Blasts
- Creates the matrix
- Immature cells, build the tissue up
- Once the blast finish their job, they turn into cyte cells, maka mature version of cell.
Cytes
- Maintain the matrix
Clasts
- Break the matrix down for remodeling
- Break previous matrix so that new blast cells can come in and rebuild
Extracellular matrix
- Protein fibers
- Collagen: Most common protein in body; strong; flexible; inelastic, bundled together.
- Reticular: Fill spaces between tissues and organs. Fine collagousous, form branching network
- Elastic: Returns to its original shape after distension or compression. Contain molecules of proteinelastin that resemble coiled springs; molecules are cross-linked. - Ground substance
- Hyaluronic acid, proteoglycan, glycosaminoglycans (GAGs), adhesion proteins
- May be fluid, semifluid, gelatinous or calcified
Mature connective tissue
- Connective tissue proper: Loose (areolar, adipose, reticular) vs dense (regular/ irregular collagenous/elastic)
- Supporting connective tissue
- Fluid connective tissue
Loose areolar
- Looses packing material of most organs and tissue
- Attaches skin to underlying tissue
- Contains collagen, reticular, elastic fibers
Adipose Tissue
- Specialized for storage of trigycerides
- Found inbetween the areolar CT
- Energy store, supports and protects organs
Dense Regular Collagenous
- Has abundant collagen fibers that resist stretching
- i.e tendons and ligaments
Dense Irregular Collagenous
- Protein fibers arragned in a randomly ortiented network
- Forms most of the dermis of the skin, scars, capsules of kidney and spleen
Dense regular elastic
- Ligament in vocal folds; nuchal ligament
- Collagen fibers give strength (for when your shout), but elastic fibers are more prevalent
Dense irregular elastic
- Bundles of sheets of collagenous and elastic fibers ortiented in multiple directions; contains mostly elastic fibers
- In walls of elastic arteries
- Strong, yet elastic
