Epithelium/Connective Tissue Flashcards
cells
the basic living structural and functional unit of the body
tissues
a group of cells that have a common embryonic origin and a common function
organs
functional units of the body that consist of a group of different tissues
general structure of organs - stroma
supporting connective tissue
general structure of organs - parenchyma
tissue for specific organ function
general structure of organs - stroma/parenchyma example
liver → has a bunch of reticular fibers throughout it to hold together
functional unit: hepatocytes → the cells doing the job of liver
4 tissue types
epithelial; connective; muscle (skeletal, smooth, cardiac); nervous (neurons, glia)
epithelium
- forms membranes/sheets of tightly knit cells
- superficial part of cell (apical) surface faces the outside of the body or the inside of a tube
- deep part of cell is anchored to a basement membrane
- NO direct blood supply - avascular → oxygen etc. diffuses to/from connective tissue
- cells divide rapidly → always being replaced
- internally: lines cavities (ex: blood vessels)
- externally: forms the epidermis of your skin
epithelium function
in order of priority:
- protection (ex: skin)
- secretion (ex: glands → exocrine & endocrine)
- absorption (ex: GI tract → lined w epithelium)
- filtration (ex: kidneys)
epithelium classification: shape
- squamous (flat)
- cuboidal (cubes)
- columnar (columns)
epithelium classification: layers
- simple: one layer
- stratified: > one layer (2 layers and up)
- named for the shape of the surface layer
epithelium classification: pseudostratified
“false layers” = simple
- all cells attached to basement membrane but the cell nuclei appear at different levels
epithelium classification: transitional
- stratified, distensible (stretchy) cells
- surface layer appears domed
ex: bladder → epithelium expands and stretches - has to stretch so tight junctions don’t break and let urine in
connective tissues: general characteristics
- well vascularized (except cartilage, tendons, & ligaments)
- cells are loosely connected (if at all) → don’t have tight junctions
- cells suspended in “matrix” (like putting fruit into jello)
- matrix = fibers + ground substance
→ fibers = proteins; collagen (tensile strength), elastic (resiliency), reticular (support)
→ ground substance = fluid (ex: plasma of blood) –> solid (ex: calcium - bone matrix)
general cell types: fibroblast
cells that make fibers
connective tissues: elements
fibroblast, mast cell, macrophage, collagen fiber(s), elastic fibers, reticular fibers, ground substance
connective tissues: functions
- binding: tendons (bind muscle to bone), ligaments (bind bone to muscle)
- support: bones (skeleton made of connective tissue), cartilage
- protection: bones, cartilage, adipose (helps insulate us - keep warm and protects - barrier between skin & organs)
- insulation: adipose (beneath skin to keep warm, covering organs → like bubble wrap on organs)
- transportation: blood (vascular system - blood & lymphatics)
types of mature connective tissue (decreasing density)
- bone
- cartilage: hyaline, fibrocartilage, elastic cartilage
- dense: dense regular (fibers lined up), dense irregular (fibers going every which way), elastic (stretched/contracted)
- loose: areolar (fascia), adipose (“fat” - energy store, insulate/protect), reticular (liver/spleen - scaffold of tissues → support for cells within cells that do work)
- liquid: blood, lymph (carry substances to/from tissues)
