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4- The Tissue Level of Organization- anatomy and physiology


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What is a tissue?
a group of similar cells that usually have a common embryonic origin that function together to carry out specialized activities.
What are the 4 basic types of tissue?
Epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
Epithelial tissue purpose:
forms a barrier to protect exosed srfaces, lines insides of body cavities and organs, and forms glands.
Connective Tissue purpose:
all tissues that provide support (skeleton) and fill space (fat), tendons, cartilage.
muscle tissue purpose:
support, movement, heat generation
Nervous tissue purpose:
controls other organs, receives and transmits information
made up of epithelia; cells are polar (top[functional] and bottom [organelles])
basement membrane
holds epithelial tissues together and make them stronger
2 layers of basement membrane
basal lamina- closest to epithelial layer
reticular lamina- coarse fibers that provide strength
3 functions of epithelial tissue
1. protection
2. provides structure for sensory nerves
3. secretory
6 classes of epithelial tissue:
1. simple squamous (heart, alveoli)
2. simple cuboidal (pancreas, kidneys)
3. simple columnar (intestines, stomach)
4. stratified squamous (lining skin surface, mouth)
5. Stratified cuboidal (ducts of sweat glands)
6. stratified columnar (urethra, anus)
Pseudostratified columnar epithelia
looks like multiple layers but only one; some cells don't make it through to the top. (line airways and larger ducts of a lot of glands)
2 categories of glands:
endocrine and exocrine
endocrine glands
secrete hormones
exocrine glands
secretions excreted out ducts
merocrine secretion
product released by exocytosis in rough ER, packaged by Golgi Apparatus
apocrine secretion
top part of cell pinches off, rest of cell repairs itself and repeats the process
holocrine secretion
cell is packed with secretion and burst (acne)
Connective tissue:
connective and support structures of the body; defined by specialized cells within matrix of extracellular protein fibers and filler fluid
immature cell
secrete matrix that makes cartilage
secrete matrix that makes bones
not tissue; secrete glycoproteins
ground substance
contains many sugars
hyaluronic acid
main sugar in Ground substance
4 functions of connective tissue
1. structural framework
2. support, protection for organs
3. energy reserves (lipids)
4. defense (immune system)
not tissues; fat cells
not tissue; melanin cells
fibroblasts secrete:
collagen, reticular fibers, and elastin
very ropey and strong; main fibers of tendons and ligaments
reticular fibers
fibrous net of collagen fibers; forms stroma (matrix) of organs
able to stretch and retract; important in lungs; have collagen tissue to tell it when to stop stretching
mesenchymal cells
undifferentiated precursor cells to fibroblasts, macrophage and other connective tissue cells
fixed or free; 1st line of defense against a virus/bacterial
smaller phagocytic cells
bind invading cell and kill it
plasma cells
produce antibodies
loose connective tissue:
less fibers, more fluid; stroma composed of reticular tissue; areolar tissue (between skin and underlying tissue); adipose tissue
brown fat
generates heat in infants
regular dense connective tissue:
fibers arranged in parallel, strength in one direction
Irregular dense connective tissue:
interwoven net of fibers that give strength in all directions
connective tissue proper
those types of cells which live and function in extracellular fluid
fluid connective tissue
distinct cell populations in fluid matrix (blood)
normal hematocrit in men and women:
men: 42%
Women: 38%
lymphatic system (fluid connective tissue)
set of tubes next to blood vessels that carries WBC around
supporting conective tissue
bone and cartilage
cartilage cells (chondrocytes) in thick gel of proteoglycans
3 types of cartilage:
elastic, hyaline, fibrocartilage
elastic cartilage
lots of elastin fibers (nose, ears, epiglottis)
hyaline cartilage
strength and flexibility (ribs, knees, trachea)
strength (spine, knees, pelvis)
T/F: there are blood vessels in cartilage.
has minerals for strength and blood vessels; heals quickly; 50% water.

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