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Tissues
groups of cells with a common structure and function
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Four main catagories of tissue:
- 1. epithelial tissue
- 2. connective tissue
- 3. nervous tissue
- 4. muscle tissue
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Epithelia are classified by:
- number of cell layers
- shape of the cells
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Simple epithelium:
single layer of cells
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Stratified epithelium:
multiple layers of cells
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Cuboidal:
cube shape (like dice)
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columnar:
like bricks on end
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squamous:
flat like floor tiles
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Epithelial tissue funtion:
a barrier protecting against mechanical injury, invasive microorganisms, and fluid loss.
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Basement membrane:
A dense mat of extracellular matrix that is attached to cells at the base of epithelium.
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Connective tissue Structure:
connective tissues have a sparse population of cells scattered through an extracellular matrix.
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Connective Tissue Function:
To bind and support other tissues.
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Three kinds of connective tissue fibers:
- Collagenous fibers
- Elastic fibers
- Reticular fibers
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Collagenous fibers:
made of collagen. Are non-elastic and do not tear easily when pulled lengthwise.
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Elastic fibers:
are long threads of elastin. Provide a rubbery quality.
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Reticular fibers:
are very thin and branched. Composed of collagen and continuous with collagenous fibers, they form tightly woven fabric that joins connective tissue to adjacent tissues.
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Loose Connective tissue:
binds epithelia to underlying tissues and functions as packing material, holding organs in place. Has all 3 fiber types
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Fibroblasts:
secrete the protein ingredients of the extracellular fibers
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Macrophages:
ameoboid cells that roam through fibers engulfing bacteria and debri of dead cells
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Adipose tissue:
a specialized form of loose connective that stores fat
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Adipose tissue funciton:
pads and insulates the body and stores fuel as fat molecules
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Fibrous connective tissue:
dense, due to its large number of collagenous fibers.
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Fibrous connective tissue that attces muscle to bone:
Tendons
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Fibrous connective tissue that attches bone to bone
ligaments
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Cartilage:
many collagenous fibers embedded in a rubbery matrix made of chondroitin sulfate.
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Chondrocytes:
secrete collagen and chondroitin sulfate.
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Blood plasma:
extracellular matrix consisting of water, salts, and dissolved proteins
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red blood cell function:
carry oxygen
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white blood cell function:
defense against invaders
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platelet function:
aid in blood clotting
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Nervous tissue:
senses stimuli and transmits signals
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Three types of muscle tissue:
- skeletal muscle
- smooth muscle
- cardiac muscle
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Homeostasis:
the ability to maintain physiologically favorable internal environments.
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Three ways in which an organism maintains homeostasis:
- thermoregulation
- osmoregulation
- excretion
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thermoregulation:
maintaining body temperature within a tolerable range
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Osmoregulation:
regulating solute balance and the gain and loss of water.
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Excretion:
the removal of nitrogen-containing waste products of metabolism.
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Regulator:
uses mechanisms of homeostasis to moderate internal change in the face of external fluctuations.
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Conformer:
allows its own internal conditions to alter with the environment.
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Four physical processes of heat exchange
- Convection
- Conduction
- Radiation
- Evaporation
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Conduction:
the direct transfer of thermal motion between molecules in direct contact with each other.
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Convection:
the transfer of heat by the movement of iar or liquid past a surface.
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Radiation:
the emission of electromagnetic waves by all objects warmer than absolute zero.
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Evaporation:
the removal of heat from the surface of a liquid that is losing some of its molecules as gas.
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Adaptations that help animals thermoregulate:
- insulation/sweating
- vasodilation (warm the skin = heat loss)
- vasoconstriction (keep warm blood inside)
- Countercurrent heat exchange ( lose heat to environment)
- cooling by evaporative heat loss
- behavioral repsonses ( move to cooler/ warmer area)
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Nonshivering thermogenisis:
increase metabolic activity within mitochondria, resulting in heat production.
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Leptin:
hormone produced by adipose cells, regulates fat storage and use.
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A high leptin level causes:
causes the brain to depress appetite and to increase muscular activity and body-heat production
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Pepsinogen is secreted by:
Cheif cells
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Hydrochloric acid is secreted by:
parietal cells
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Pepsinogen is converted to pepsin by:
Hydrochloric acid
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what is the longest section of the alimentary canal?
the small intestine
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most breakdown of food and absorption of nutrients to blood occurs in:
the small intestine
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function of bile salts:
act as detergents and aid in the digestion and absorption of fats.
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Aminopeptidase:
protein-disgesting enzyme secreted by the intestinal epithelium.
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Trypsin, chymotrypsin, and carboxypeptidase are secreted in inactive form by:
pancreas
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Lipase:
an enzyme that hydrolyzes fat molecules into glycerol, fatty acids, and glycerides.
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Most digestion occurs in:
duodenum.
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main funtions of jejunum and ileum:
absorption of nutrients and water.
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what has first access on absorbed sugars and and amino acids?
the liver
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Hepatic portal vessel:
conveys nutrients from capillaries and veins to liver
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3 types of transport systems:
- Gastrovascular cavity
- Open circulatory system
- Closed circulatory system
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Gastrovascular system:
material exchange through diffusion. ( Jellyfish)
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Open circulatory system:
no distinction between blood and interstitial fluid (hemolymph). Hemolymph is pumped into sinuses surrounding organs. (insects, arthrppods)
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Closed circulatory system:
blood is confined to vessels, distinct from interstitial fluid. large vessels branch into smaller ones cursing through organs. (eartworms, vertebrates)
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Atria:
chambers that recieve blood returning to heart.
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Ventricles:
chambers that pump blood out of heart.
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Arteries
carry blood away from heart. only oxygenated when leaving the left ventricle.
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