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Biology - Tissues

Chapters 5-7 Tissues
the study of tissues
Intercellular Junctions
the cell membranes of tightly packed cells are connected by these
Tight Junctions
1 of 3 types of Intercellular Junction ... fuse cell membranes of adjacent cells (belt) ... found in the lining walls of capillaries in the brain (blood-brain barrier)
structures forming "spot welds" between adjacent cell membranes ... found in the epidermis (top layer of skin)
Gap Junctions
funnels between cell membranes of adjacent cells ... found in cardiac muscle
epithelial cells
cells that make up the epithelial tissue ... lack blood vessels ... tightly packed together ... divide very fast ... classified by shape and number of cells
epithelial tissues
1 - lines body cavities, 2 - cover organs, 3 - protect, 4 - absorb substances, 5 - lacks blood cells ... always has a free surface and a basement membrane ... found: covers body surfaces and organs ... forms the inner lining of cavities ... it lines hollow organs (colon, small and large intestines, stomach) ... function: line body cavities, cover organs, protect, absorb substances
free surface
a side exposed to the outside or to an open space internally
basement membrane
the underside of epithelium tissue is anchored to CT by a thin, nonliving layer
simple epithelium
one single layer of epithelial tissue ... functions: absorb, secrete, filter
stratified epithelium
2 or more cell layers of epithelial tissue ... functions: protect, some secretion
squamous epithelium
thin, flat, irregular shaped cells
cuboidal epithelium
cube-like shaped cells
columnar epithelium
tall, elongated cells with nucleus generally near the bottom
simple squamous epithelium
1 layer ... flat cells ... substances pass easily through ... easily damaged (thin) ... found: lungs, kidneys, blood capillaries ... function: to allow easy filtration, secretion, absorption
simple cuboidal epithelium
1 layer ... cube-like cells ... found: kidneys, thyroid gland ... function: allow easy absorption, filtration, secretion
simple columnar epithelium
1 layer ... long cells ... sometimes have cilia ... found: linings of uterus, stomach, intestines, fallopian tubes ... function: some protection, secretion, absorption
hair-like extensions of a cell membrane ... moves
pseudostratified columnar epithelium
1 layer ... columnar cells ... appears to be stratified, but not all cells reach the surface ... usually have cilia ... found: trachea
stratified squamous epithelium
many layers ... top layer squamous ... deep layer cuboidal ... found: outer layer of skin, lining of oral cavity ... vagina ... anal canal ... function: protection
stratified cuboidal epithelium
2-3 layers ... top layer cuboidal ... found: surface of ovaries, salivary and mammary glands, lining of kidney tubules ... function: secretion of substances (saliva, milk, etc.)
stratified columnar epithelium
many layers ... top layer columnar ... function: protection ... found: urethra, pharynx (throat)
transitional epithelium
several layers ... cuboidal, then stretch in response to pressure (squamous) ... found: inner lining of urinary bladder, ureter, urethra ... function: allow stretching of the organ that has it ...
connective tissue (CT)
covers, supports, protects ... MOST abundant tissue in body ... function: BINDS organs to body cavities, provides SUPPORT and PROTECTION, fills spaces between organs and body parts, STORES energy in the form of lipids, PROTECTION from pathogens, DELIVERS gases (O2, CO2) STORES calcium ... cells far apart ... abundant extracellular matrix
extracellular matrix
liquid (plasma) ... molecule (calcium phosphate) ... protein fibers ... good blood supply
3 types of CELLS in CT
1 - fibroblast ... 2 - macrophages (histiocytes) ... 3 - mast cells
fixed cell ... common in CT ... star shaped ... function: make protein fibers and to release them into the extracellular matric ... produces CT fibers
wandering cell ... originate as monocytes (from bone) cells ... function: phagocytizes (engulfs) cells: bacteria, dead cells
mast cells
release histamine (dilate blood vessels) and release heparin (prevents blood clotting)
3 types of FIBERS in CT
1 - elastic, 2 - collagenous, 3 - reticular
elastic fibers
made from the protein elastin ... flexible, not too strong ... found: outer ear, tip of nose
collagenous fibers
very strong (great tensile) ... made of collagen ... thick ... not too flexible ... skin, sclera, tendons, ligaments
reticular fibers
made of thin collagen ... form network to support organs ... mesh-like
connective tissue proper
loose and dense CT (Areolar, Adipose, Dense Regular CT)
specialized connective tissue
cartilage, bone, blood
2 types of CT categories
CT proper ... specialized CT
Areolar CT
loose, thin membrane ... most COMMON type ... several collagenous and elastic fibers ... fibroblasts are MAINLY found here ... found: under skin, fills spaces between muscles, beneath most epithelial tissues
Adipose CT
(fat) ... cells are called adipocytes ... found: beneath skin, behind and around organs, between muscles ... function: protection, insulation of body temp, cushions organs, stores energy
nucleus is pushed to one side to allow for more space in cytoplasm to store fat
Dense Regular CT
mainly fibroblasts ... thick collagenous fibers and few elastic fibers ... poor blood flow ... function: binds body parts or organs ... found: tendons, ligaments
attaches muscle to bone (CT)
attaches bone to bone (CT)
contains mainly collagenous fibers and some elastic fibers ... chondrocytes ... found: between vertebrae (intervertebral discs), sternum, external ear, tip of nose
cartilage cells
Hyaline cartilage
most common type ... tip of nose, ends of bones, an embryo's skeleton
most rigid CT (stores minerals - calcium, phosphate - contains a lot of collagenous fibers) ... function: support body weight, protects organs, stores and releases minerals (calcium, phosphate)
bone cells that deposit bone matrix
mature bone cells
RBC, WBC ... found: heart, blood vessels ... function: transports substances (O2, nutrients, etc.) ... fights infection
extracellular matrix of blood
muscle tissue
function: moves body parts ... are contractible (shorten and thicken) ...
muscle cells
aka muscle fibers (elongated cells)
3 types of muscle tissues
1 - skeletal, 2 - cardiac, 3 - smooth
skeletal muscle tissue
muscle attached to bone ... striated, voluntary ... long, cylindrical in shape ... multi-nucleated cell ... have striations
more than one nucleus
cells joined end-to-end ... alternate dark and light bands found on skeletal and cardiac muscle
cardiac muscle tissue
only found in heart ... striated, involuntary ... long, but branched, one nucleus per cell, cells joined by intercalated discs ... function: heart movement (contraction)
intercalated discs
gap junctions
smooth muscle tissue
found at the walls of MOST hollow organs ... found: stomach, intestines, esophagus, etc. ... nonstriated, involuntary ... shorter than skeletal and cardiac muscle tissue cells, one nucleus, spindle-shaped cell
Nervous Tissue
coordinates body functions ... found: 1 - brain, 2 - spinal cord, 3 - peripheral nerves ... function: sensory reception (pain, touch, etc.), conduction of nerve impulses
2 nervous tissue cells
Neuron, Neuroglia
function: senses changes in body environment (internally and externally) and responds by firing nerve impulses
supports neurons, kills pathogens, supplies nutrients to neurons, cleans surrounding of neurons