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208 Cards in this Set
- Front
- Back
Animal Anatomy and Physiology
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All organisms contain the simplest level of life, cells. Whether the organism is made up of many cells or just one, they all have cells.
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Surface to Volume Ratio
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An animal body must be arranged so that all of its cells are bathed in an aqueous medium. The more surface area a cell has, the more volume it can support.
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Exchange with the environment
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An animals body size and shape have a large effect on how they exchange energy and materials with the environment. Exchange with the environment occurs as dissolved substances diffuse and are transported across the plasma membranes between the cells and their aqueous surroundings.
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Internal exchange surfaces with complex animals
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The internal environment of vertebrates is called interstitial fluid. Most animals have specialized surfaces that exchange materials with the environment.
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Epithelial Tissue
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Covers the aoutside of the body and lines organs and cavities; cells are closely joined in sheets; allows the epithelium to function as a barrier protecting against injury, invasive microorganisms, and fluid loss.
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Connective Tissue
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Binds and supports other tissues; the cells aren't spaced as close together as in Epithelial; connective tissue is made of fibers: Collagenous (made of collagen), Elastic (Made of protein elastin), and Beticular (Thin and branched)
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Nervous Tissue
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Senses stimuli and transmits signals from one part of the animal to another; the main unit of the tissue is the neuron (nerve cell) which transmits signals called nerve impulses; Dendrites transmit impulses from their tips toward the rest of the neuron; axons transmit impulses toward another neuron.
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Bioenergetics of an animal:
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Animals derive chemical energy from the environment in the organic molecules in food. Hydrolytic enzymes break food into small nutrients -> Some energy goes to environment in feces -> Body cells absorb nutrients producing ATP which fuels the cell *All cellular work, including work performed in biosynthesis and by the digestive system in processing food, involves a loss of energy to the environment as heat.
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Interstitial Fluid
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The internal environment of vertebrates; fills the space between cells, exchanges nutrients and wastes with blood contained in microscopic vessels called capillaries.
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Basal Metabolic Rate
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The metabolic rate of an endotherm at rest, with an empty stomach, and experiencing no stress; the rate when humans are inactive, lying motionless.
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Homeostatic Mechanism
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All animals have this which helps regulate the fluid environment bathing its cells; conditions of the internal environment vary slightly; the mechanism maintains conditions within a range in which the animal's metabolic processes can occur.
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Negative Feedback
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A change in the variable being monitored triggers the control mechanism to counteract further change in the same direction
Ex) When a thermometer on a heater detects room temperature to be above the set point which makes the heater turn off. |
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Positive Feedback
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involves a change in some variable that triggers mechanisms that amplify rather than reverse the change.
Ex) the human body reacts to certain infections by raising the set point for temperature to a slightly higher level, and the resulting fever helps fight the infection |
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Thermoregulation
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the maintenance of body temperature within a range that enables cells to function. It occurs in four different ways: (1) adjusting the rate of heat exchange between the animal and its surroundings; (2) cooling by evaporative heat less; (3) behavioral responses such as seeking shade; (4) changing the rate of metabolic heat production.
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Endotherms
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A type of animal which derives most or all of its body heat from its own metabolism
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Ectotherms
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An animal which warms its body mainly by absorbing heat form its surroundings
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vasodilation
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an increase in the diameter of superficial blodod cells (near the body surface) which increase blood flow
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vasoconstriction
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decreasing hte diamter of superficial blood cells which decreases blood flow
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countercurrent heat exchange
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important in controlling heat loss in many endothermic animals. alters heat exchange in a special arrangement of arteries and veins.
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homeostatic mechanisms of the hypothalamus in human thermoregulation
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the hypothalamus contains a thermostat that responds to change in body temperature above and below a set point. it activates mechanisms that promote heat loss or gain.
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suspension feeders
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many aquatic animals are suspension feeders. they sift small food particles form the water.
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substrate feeders
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they live in or on their food source, eating their way through the food
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fluid feeders
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live by sucking nutrient rich fluids from the host
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bulk feeders
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animals that eat large pieces of food. their adaptations include such diverse utensils as tentacles, pincers, claws, poisonous fangs, and jaws and teeth that kill their prey or tear off pieces of meat or vegetation
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herbivores
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animals that eat mainly autotrophs
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carnivores
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eat other animals
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ingestion
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the act of eating; taking in food; this is the first stage of food processing
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digestion
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the process of breaking food down into molecules small enough for the body to absorb; digestion cleaves macromolecules into their component monomers.
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enzymatic hydrolysis
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a process when bonds are broken with the enzymatic addition of water during digestion. hydrolytic enzymes catalyze the digestion of each of the classes of macromolecules found in food.
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absorption
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when the animal's cells absorb small molecules such as amino acids and simple sugars from the digestive compartment
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elimination
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when undigested materials passes out of the digestive compartment
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intracellular digestion
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the simplest digestive compartments are food vacuoles located in cells. the vacuoles fuse with lysosomes. this process mixes the food with the enzymes.
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extracellular digestion
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this is the breakdown of food found outside the cells. it occurs within digestive compartments which are continuous, via passages, with the outside of the animal's body
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gastrovascular cavity
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many animals with simple body plans have digestive sacs with single openings. these function in digestion and distribution of nutrients throughout the body.
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alimentary canal
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tubes in which food moves in one direction
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salivary amylase
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saliva contains this enzyme which hydrolyzes starch. the main product of the enzyme's action nare smaller polysaccharides and the dissacharide maltose.
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peristalsis
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rhythmic waves of contraction by smooth muscles in the wall of the canal, pushes food along the tract.
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stomach digestion
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the epithelium that lines the stomach secretes gastric juice which digests food. gastric juice has a high concentration of hydrochloric acid; the acid also kills bacteria stored in food.
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pepsin
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an enzyme that begins the hydrolysis of protein, it is one of the enzymes that works only in acidic environments.
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duodenum
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the first 25 cm of the small intestine; acid chyme squirting here in from the stomach and mixes with digestive juices from other organs
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acid chyme
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a result of mixing and enzyme action; it is the digest meal in a nutrient broth
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secretin
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a hormone which signals the pancreas to release bicarbonate which neutralizes the acid chyme
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bile
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produced in the liver; contains no digestive enzymes but it does aid in the digestion and absorption of fats
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emulsification
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a process when bile salts from the gall bladder secreted into the duodenum coat tiny fat droplets and keep them from coalescing.
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trypsin
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they are specific peptide bonds adjacent to certain amino acids; they break large polypeptides into shorter chains
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lipase
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enzyme the hydrolyzes fat molecules; macromolecules from food are completely hydrolyzed to their component monomers as peristalsis moves the mixture of chyme and digestive juices along the small intestine.
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villi
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the large circular folds in the small intestine lining; they look like small fingers. each of the epithelial cells of the villus has many microscopic appendages called microvilli.
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lacteals
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these penetrate the cure of each villus making a net of microscopic blood vessels and a small vessel of the lymphatic system.
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large intestine
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also known as the colon; a major function is to reabsorb water that has entered the alimentary canal as a solvent of the various digestive juices
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symbiotic microorganisms digesting cellulose for herbivores
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many herbivorous vertebrates have special fermentation chambers where symbiotic bacteria and protists live; these microorganisms have enzymes that can digest cellulose, which the animal can't digest.
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Open vs. closed circulatory systems
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in an open circulatory system arrangement blood bathes the internal organs directly; in this system there is no distinction between blood and interstitial fluid; in closed the blood is confined to vessels and is distinct from the interstitial fluid
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hemolymph
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general body fluid in a closed circulatory system where blood and interstitial fluid is mixed
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heart rate
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this is the speed and amount of heart beats; the heart pumps blood throughout the circulatory system
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stroke volume
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the amount of blood pumped by the left ventricle each time it contracts; this is one of the factors which determines cardiac output, the volume of blood per minute that the left ventricle pumps into the systemic circuit.
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atrioventricular (AV) valve
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located in the wall between the right atrium and right ventricle of the heart; prevents a back flow of blood when the ventricles contract; anchored by strong fibers;
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semilunar valve
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located at the two exists of the heart, where the aorta leaves the left ventricle and the pulmonary artery leaves the right ventricle; blood is pumped to arteries through these valves
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sinoatrial (SA) nodes
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also known as the pacemakers; maintain the heart's pumping rhythm by setting the rate at which all cardiac muscle cells contract; located in the wall of the right atrium
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atrioventricular (AV) node
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where impulses are delayed for a tenth of a second which ensures that the atria will contact first and empty completely before the ventricles contract.
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artery
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have thicker middle and outer layers than veins; have thick walls which provide strength and elasticity that accommodate the flow of blood pumped rapidly and at high pressure though the arteries by the heart.
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vein
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thin walled; transport blood back to the heart; they are on e way valves.
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capillary structure
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lack two outer layers; have very thin walls and consist only of endothelium and its basement membrane;
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capillary function
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facilitates the exchange of substances between the blood and the interstitial fluid that bathes the cells
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blood flow velocity
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blood travels 1,000 times faster in the aorta than in the capillaries; the volume of flow per second must be constant though the entire pipe;
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blood pressure
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the hydrostatic force that blood exerts against the wall of a vessel is called blood pressure; greater in arteries than in veins
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systolic
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a contraction phase of the cyle
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diastolic
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a relaxation phase
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lymph
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a fluid with a composition about hat of interstitial fluid.
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blood plasma
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all blood cells float in this liquid; about 90 % water; the kidney maintains blood plasma; also acts as a means of transport from one part of the body to another
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erythrocytes
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also known as red blood cells; the most numerous blood cells; lack mitochondria and generate their ATP only by anaerobic metabolism; transports oxygen;
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leukocytes
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AKA white blood cells; 5 types: monocytes, neutrophils, basophlis, eosinophils, and lymphocytes; they all fight infections; spend most of their time outside the circulatory system.
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thrombocyte (Platelet)
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no nuclei and originate as pinched off cytoplasmic fragments of large cells in bone marrow; main function is in the process of blood clotting
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fibrinogen
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the self sealing material in blood during the process of clotting; this is the inactive form
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fibrin
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plasma protein convert fibrinogen to its active fform whihc is this
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gas exchange
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the intake of oxygen from the environment and the discharge of carbon dioxide; to keep energy levels high animals must take in oxygen which fuels their cells; involves both the respiratory and circulatory systems
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respiratory medium
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the source of oxygen; provides air for terrestrial animals and water for aquatic animals
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respiratory surface
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the part of an animal where oxygen from the environment diffuses into living cells and carbon dioxide diffuses out
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direct gas exchange w/ the environment
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many small animals have moist skin and exchange gases by means of diffusion; larger animals have a region of the body extensively folded or branched which enlarges the respiratory surface for gas exchange.
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gills
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outfoldings of the body surface specialized for gas exchange; surface area of gills is larger than that of the rest of the body; some gills ventilated so that they can continuously have water which has low 02 concentration passing trhoguh.
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countercurrent exchange
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when blood flows through the capillary it gets more oxygen in it, and at the same time encounters water with a higher oxygen concentration since the water is passing over the gills.
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tracheal systems
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made up of air tubes that branch throughout the body; the largest tubes are called tracheae, they are mainly in insects and small animals
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lungs
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restricted to one location; not directly connected to the respiratory surface; must be bridge by the circulatory system; have a dense net of capillaries
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alveoli
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air sacs; located in the tips of the lungs' bronchioles which serves as the respiratory surface; oxygen diffuses across them into a web of capillaries; co2 comes from the capillaries into the alveoli.
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breathing control centers
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one is located inthe medulla oblangata and the other in the pons of the brain; the control center in the medulla helps maintain homeostasis and regulate the CO2 level of the blood.
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role of CO2 in breathing
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70 % of CO2 is transported inteh blood in the form of bicarbonate ions; they form into bicarbonate ions and diffuse into the plasma of blood; when CO2 diffuses out of the blood the chemical equilibrium within red cells shift in favor of the conversion of bicarbonate to CO2.
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diaphragm
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the volume of the lungs increases as a result of contraction of the ribs muscles and the diaphragm; it is a sheet of skeletal muscle that forms the bottom wall of the chest cavity; the chest cavity expands as the diaphragm contacts and descends.
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hemoglobin
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an oxygen carrying protein containing iron; it binds the gaseous molecule nitric oxide as well as O2.
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Bohr shift
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Ex) A drop in pH lowers the affinity of hemoglobin for )2, called the Bohr shift; because CO2 reacts with water to form carbonic acid, an active tissue will lower the pH of its surroundings and induce hemoglobin to give up more of its oxygen, which can be used for cellular respiration;
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Phagocytosis
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the ingestion of invading organisms by certain types of white cells; this mechanism and others help limit the spread of microbes in advance of specific immune responses
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neutrophils
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constitute about 60 % to 70 % of all white blood cells; they enter the infected tissue, engulfing and destroying microbes there; they tend to self destruct as they destroy foreign invaders
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monocytes
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constitute only about 5 % of all leukocytes; they group together into large macrophages
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inflammatory response
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in teh injured area, pre-capillary arterioles dilate and post capillary venules constrict, increasing blood supply; the capillaries leak fluid into neighboring tissues, causing the edema (swelling) which is initiated by chemical signals
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B Lymphocyte
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antigen receptors on a B cell are trans membrane versions of antibody molecules and are often referred to as membrane antibodies.
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T Lymphocyte
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one cell bears about 100,000 receptors for antigen, all with exactly the same specificity
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antigen
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a foreign molecule that elicits a specific response by lymphocytes; include molecules belonging to viruses, bacteria, fungi, protozoa, and parasitic worms.
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antibodies
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proteins which are secreted by B cells; they help deal with certain antigens
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antigen receptor
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the means by which b cells and t cells recognize specific antigens are their plasma membrane bound antigen receptors
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effector cells
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short lived cells that combat the same antigen
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memory cells
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long lived cells bearing receptors specific for the same antigen
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clonal selection
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each antigen, by binding to specific receptors, selectively activates a tiny fraction of cells form the body's diverse pol of lymphocytes; this relatively small number of selected cells gives rise to clones of thousands of cells, all specific for and dedicated to eliminating that antigen.
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primary vs. secondary immune response
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in primary response, 10 to 17 days are required form the initial exposure to antigen for selected lymphocytes to generate the maximum effector cell response; if the person is exposed to the antigen again the response is much faster at a great magnitude which is known as the secondary response.
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humoral immune response
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involves b cell activation and results from the production of antibodies that circulate in the blood plasma and lymph; humoral immunity are antibodies form one organisms to another.
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cell mediated immune response
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immunity to some infections could be passed along only if cells, T lymphocytes, were transferred; this type of immunity is cell-mediated immunity;
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blood types
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a blood has a antigens on the surface of red blood cells; refereed to antigen since it may be referred to as foreign in someone else's body; b antigens in type b; a and b on type ab cells; o has neither antigens that is hwy o can go anywhere
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MHC molecules
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major histocompatibility complex; the protein fingerprint unique to each individual; responsible for stimulating the rejection of tissue gafts and organ transplants;
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active vs. passive immunity
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active immunity depnds on the response of the infecte4d person's own immune system; immunity is naturally acquired; can also be acquired by immunization also known as vaccination; passive immunity is achieved by transferring antibodies from one individual to another; only lasts as long as antibodies last
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allergy
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hypersensitive responses to certain environmental antigens, called allergens;
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HIV
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Human Immunodeficiency Virus; identified as the causative agent; the most lethal pathogen ever encountered
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osmoregulation
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how animals regulate solute balance and the gain and loss of water; all freshwater and many marine animals are osmoregulators which means they must adjust their water loss and gain
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excretion
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many waste materials pass through a transport epithelium which regulates solute movements; excretion is how an animal gets rid of nitrogen containing waste products of metabolism such as urea.
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osmoregualtion in saltwater fish
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many of the fish maintain internal salt concentrations less than that of the sea water; marine bony fishes are more similar to freshwater so they constantly lose water in osmolarity
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osmoregulation in freshwater fish
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they are constantly taking in water by osmosis because the osmolarity of their internal fluids is much higher than that of their surroundings;
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ammonia
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most aquatic animals excrete nitrogenous wastes as ammonia molecules; they are very soluble in water and easily pass through membranes
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urea
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ammonia excretion is unsuitable on land; about 100,000 times less toxic than ammonia; by excreting a concentrated solution of urea most animals conserve water;
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uric acid
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land snails, insects, birds, and many reptiles excrete this; can be excreted in a paste like form with very little loss of water;
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urine
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excretion through urethra; 98 % water
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filtration
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blood or other body fluids, depending on the type of excretory system, is exposed to a filtering device made of the selectively permeable membranes of transport epithelia.
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reabsorption
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selective transport of water and valuable solutes, such as glucose, salts, and amino acids, from the filtrate back into the body fluids is called reabsorption
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secretion
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solutes are removed from the animal's body fluids and added to the filtrate.
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excretory systme in annelids
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"Flame-bulb systems;" protonephridium is a network of closed tubules lacking internal openings; the samlest brances are capped by a cellular unit called a flame bulb
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excretory system of arthropods
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"Malphighian Tubules;" they remove nitrogenous wastes from the circulatory fluid and also function in osmoregualtion; they open into the digestive tract and dead end at tips that are immersed in hemolymph.
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kidney
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in mammals, the kidneys are a pair of bean shaped organs; blood enters through the renal artery and leaves through the renal vein; urine exits through ureter which drain into the urinary bladder
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structer of nephron
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the functional unit of the vertebrate kidney; has a single long tubule and a ball of capillaries called the glomerulus
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glomerulus
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sends blood to the bowman's capsule
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bowman's capsule
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functions as a filter which is permeable to water and small solutes but not blood cells or other large molecules; filtrate contains solutes such as glucose, salts, and vitamins, nitrogenous wastes and other small molecules
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substances in filtrate
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some substances include glucose, salts, vitamins, other nitrogenous wastes such as urea.
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what enters/doesn't enter the filtrate from the blood
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what enters is water and other small solutes; blood cells and plasma proteins including other large cells don't enter.
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antidiuretic Hormone (ADH)
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important in osmoregulation; produced in a part of the brain called hypothalamus and released by the pituitary gland; targets are distal tubules and collecting ducts of the kidney, where it helps increase the permeability of the epithelium to water.
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angiotensin
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increases blood pressure and blood volume; is a hormone
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aldosterone
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stimulates cells in the kidney to reabsorb sodium ions and water form the filtrate, raising blood pressure and volume.
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endocrine system
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collectively, all of an animal's hormone secreting cells
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hormone
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function in homeostasis; many are related to reproduction an development and those are the hormones most widely studied; a chemical signal that is secreted in body fluids and communicates regulatory messages within the body.
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target cell
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each chemical signal has a specific shape that can be recognized by that signal's target cells; receptor cells are built into the plasma membrane of the target cell
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neurosecretory cell
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many endocrine organs and tissues contain these specialized nerve cells; they secrete hormones
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endocrine feedback
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the generation of nerve signals (impulses) also involves positive feedback; negative feedback regulates many endocrine and nervous mechanisms, especially those involved in maintaining homeostasis.
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signal transduction pathway
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convert an extracellular signal to a specific intracellular response, thereby changing the behavior of the target cells; most neurotransmitters, growth factors, and hormones can't pass through the plasma membrane of their target cells;
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hypothalamus
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plays an important role in integrating the vertebrate endocrine and nervous sytems; receives information from nerves throughout the body, then initiates endocrine signals appropriate to environmental conditions
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pituitary gland
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a small organ with multiple endocrine functions; obeys hormonal orders created by the hypothalamus; releases hormones;
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oxytocin
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acts on muscles of the uterus; induces contraction of the uterine muscles during childbirth and causes the mammary glands to eject milk during nursing;
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prolactin (PRL)
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stimulates mammary gland growth and milk synthesis in mammals; regulates fat metabolism and reproduction
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(FSH) Follicle stimulating Hormone
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also called a ganadotropin since it stimulates the activities of the male and female gonads
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Luteinizing Hormone (LH)
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also a ganadotropin; is a glycoprotein since it has protein molecules with a carbohydrate attached to it.
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thyroxine
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responsible for metabolic regulation; hormone of the thyroid gland; (T4) contains four iodine atoms
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calcitonin
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lowers calcium levels in teh blod as part of calcium homeostasis
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parathyroid hormone (PTH)
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raises the blood level of calcium; stimulates calcium reabsorption in the kidneys and induces specialized bone cells to decompose the mineralized matrix of bone releasing calcium.
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insulin
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glucose is a major fuel for cellular respiration and a key source of carbon skeletons for the synthesis of other organic compounds; insulin lowers glucose concentration in the blood when it is above the set point.
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glucagon
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increases blood glucose concentration
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Epinephrine
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member of the catecholamines class; gives the body a rapid bioenergetic boost, increasing the basal metabolic rate.
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testosterone
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stimulates the development and maintenance of the male reproductive system; when produced early in fetus development determines that a person is male
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estrogen
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development of female reproductive system and the development of female secondary sex characteristics.
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progesterone
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involved in preparing and maintaining the uterus, which supports the growth and development of an embryo.
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melatonin
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modified amino acid; regulates the functions related to light and to seasons marked by changes in day length; affects skin pigmentation; only secreted at night
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sexual reproduction
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the creation of offspring by the fusion of haploid gametes to form a zygote (fertilized egg), which is diploid
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asexual reproduction
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the creation of new individuals whose genes all come from one parent without the fusion of haploid gametes to form a zygote.
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binary fission
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asexual reproduction; the separation of a parent into two or more individuals of relatively equal size
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budding
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asexual reproduction; new individuals splitting off from existing ones
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parthenogensis
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a process in which the egg develops without being fertilized; adults produced by this are often haploid and their cells do not undergo meiosis in forming new eggs
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hermaphroditism
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when some animals can change their sex; usually depending on age and size
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external fertilization
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when eggs are shed by teh female and fertilized by teh male in the environment; occurs exclusively in moist habitats; many eggs are usually she since they are not as well protected as in an internal environment.
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internal fertilization
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when sperm are deposited in or near the female reproductive tract; fertilization occurs within the tract
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pheromones
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chemical signals released by one organism that influence the behavior of other individuals of the same species; many function as male attractants.
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gonad
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the organs that produce gametes; not contained in simple organisms
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ovary
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the female gonads which lie in the abdominal cavity; develop the eggs;
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testes
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the male gonads; highly coiled tubes surrounded by several layers of connective tissue; produce sperm
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follicle
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consists of one egg cell surrounded by one or more layers of follicle cells, which nourish, and protect the developing egg cell; all of the 400,000 follicles a woman will ever have are formed before her birth;
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corpus luteum
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secretes additional estrogens and progesterone, the hormone that maintains the uterine lining during pregnancy; if the egg cell does not fertilize the corpus luteum disintegrates, and a new follicle matures during the next cycle
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spermatogenesis
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the production of mature sperm cells; continuous and prolific process in the adult male;
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oogenesis
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the development of the ova (mature, unfertilized egg cells); between birth and puberty egg cells enlarge, and the follicles around them grow.
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menstrual cycle
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ovulation cocurs at a time in this cycle after the endotrium has started to thicken and develop a rich blood supply, which prepares the uterus for the possible implantation of an embryo;
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follicular phase
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when several follicles in the ovary begin to grow; the egg cell enlarges, and the coat of follicle cells becomes multilayered; only one follicle usually continues to enlarge and mature while the others disintegrate;
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ovulation
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when the follicle and adjacent wall fo the ovary rupture, releasing the oocyte; the follicular tissue that remains in the ovary after ovulation develops into the corpus luteum;
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luteal phase
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a phase in which the corpus luteum releases female hormones
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fertilization
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when the male and female gametes, the sperma dn the egg, unite and form a zygote; the main function is to combine haploid sets of chromosomes from two individuals into a single diploid cell, the zygote.
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cleavage
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a succession of rapid cell divisions that follow fertilization; cells undergo DNA synthesis and mitosis phases; the embryo doesn't enlarge during htis period of development.
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morula
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continued cleavage produces a solid balls of cells known as the morula.
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blastula
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a fluid filled cavity called the blastocoel forms within the morula, creating a hollow ball stage of development called the blastula
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gastrulation
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a dramatic rearrangement of the cells of the blastula; result is that some of the cells at or near the surface of the blastula move to a new, more interior location.
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ectoderm
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the ectoderm forms the outer layer of the gastrula
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mesoderm
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partly fills the space between the ectoderm and the endoderm
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endoderm
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lines the embryonic digestive tract
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organogenesis
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when the organs develop; folds, splits, and dense clustering of cells occur;
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differentiation
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when all the cells become specialized and are only suitable for one organ or area of the body
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central nervous system
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the brain and the spinal cord; integration occurs here which is the process by which information form the environmental stimulation of sensory receptors
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peripheral nervous system
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the nerves that communicate motor and sensory signals between the central nervous system and the rest of the body
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somatic vs. autonomic
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somatic carries nerve signals to skeletal muscles mainly in response to external stimuli; somatic is often considered voluntary because it is subject to conscious control; autonomic conveys signals that regulate the internal environment by controlling smooth and cardiac muscles and the organs of the gastrointestinal, cardiovascular, excretory, and endocrine systems.
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symphathetic vs. parasymphathetic
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signals carried by the parasympathetic division enhance activities that gain and conserve energy, such as digestion and slowing the heart rate. signals converyed by the symphathetic division generally increase energy consumption and prepare an individual for action by accelerating the heart rate, increasing metabolic rate, and performing related functions.
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sensory input
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sensory neurons communicate information about the external and internal environments from sensory receptors to the central nervous system.
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motor output
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convery impulses from the central nervous system to effector cells
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neuron
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the function unit of the nervous system and is specialized for transmitting signals from one location in the body to another; relatively large cell body
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dendrite
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convey signals from their tips to the rest of the neuron; structural adaptions that increase the surface area of the neuron where it receives inputs from other neurons or sensory receptors
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axons
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conduct messages toward their tips; many neurons only have one axon;
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myelin sheath
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many axons in the vertebrate nervous system are enclosed by an insulating layer called this
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synaptic terminal
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relay signals to other cells by releasing chemical messengers called neurotransmitters; the site of contact between a synaptic terminal and a target cell is called a synapse.
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neurotransmitter
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the substance that is released as an intracellular messenger into the synaptic cleft
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nerve impulse
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the message that is sent from one neuron or another mainly by a neurotransmitter
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resting potential
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the membrane potential of an excitable cell in the unexcited state; a change in states may result in an active electrical impulse.
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action potential
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a nerve impulse; the magnitude of it is independent of the strength of the depolarizing stimulus that produced it; once it is triggered the membrane potential goes through a series of a sequence of changes
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depolarization
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a reduction in the electrical gradient across the membrane.
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repolarization
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when the membrane returns to the resting level
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sodium potassium pump
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the inside of a cell is negative; two forces drive the diffusion of ions across a membrane; three sodium ions get pumped out of the cell for every two potassium; help store energy;
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medulla oblangata
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contains centers that control several autonomic, and homeostatic functions (visceral), including breathing, heart and blood vessel activity, swallowing, vomiting, and digestion;
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cerebrum
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most complex part of the brain; occupies about 80 & of the total brain mass;
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cerebellum
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primary function is the coordination of movements; receives sensory information about the position of the joints and the length of the muscles as well as information from the auditory and visual systems.
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endoskeleton
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consists of hard supporting elements such as bones, buried within soft tissues of an animal; the human skeleton is built from more than 200 bones;
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smooth muscle function
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lack the striations of skeletal and cardiac muscle because the actin and myosin filaments are not all regularly arrayed along the length of the cell; can't generate as much tension as striated muscles
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skeletal muscle functions
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(striated muscle); attached to the bones and is responsible for movemnts;
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sacromere structure
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the basic functional unit of a muscle; borders are lined in adjacent myofils; thick filaments are centered in the sacromere.
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sacromere function
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with all the crossing z, i , and a bonds the sacromere helps the filaments slide past each other and lets the muscle contract and release.
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myosin actin interactions underlying muscle fiber contraction
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when a muscle contracts, the length of each sacromere is reduced; myosin and actin make up the thin and thick filaments; myosin long fibrous "tail" region with a globular "head" sticking to one side; myosin binds to actin forming a cross bridge; when there is tension on the myosin it bends itself inward pulling the thin filament toward the center of the sacromere; this attachment occurs about 5 times per second with 350 heads forming and reforming.
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