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ISB 204 Online Quiz Study Guide 2

ISB 204 Online Quiz Study Guide 2 - Accommodation A change...

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Accommodation A change in the shape of the lens of the eye brought about by contraction of the smooth muscle of the ciliary body that changes the degree to which light rays are bent so that an image can be focused on the retina. Acetylcholine A neurotransmitter found in both the central nervous system and the peripheral nervous system. It is the neurotransmitter released at neuromuscular junctions and causes muscle contraction. actin filament The thin filaments in muscle cells composed primarily of the protein actin and essential to muscle contraction. In addition to actin, thin filaments contain two proteins important in the regulation of muscle contraction: tropomyosin and troponin. action potential A nerve impulse. An electrochemical signal conducted along an axon. A wave of depolarization caused by the inward flow of sodium ions followed by repolarization caused by the outward flow of potassium ions. adaptation The process by which populations become better attuned to their particular environments as a result of natural selection. age structure Of a population, the number of males and females of each age in a population. The ages are often grouped into prereproductive, reproductive, and postreproductive categories. Generally, only individuals of reproductive age add to the size of the population. analogous structure A structure of one organism that is similar to that of another organism because of convergent evolution and not because the organisms arose from a common ancestry. Compare with homologous structures. anticodon A three-base sequence on transfer RNA (tRNA) that binds to the complementary base pairs of a codon on the mRNA. appendicular skeleton The part of the skeleton comprising the pectoral girdle (shoulders), the pelvic girdle (pelvis), and the limbs (arms and legs). aqueous humor The fluid within the anterior chamber of the eye. It supplies nutrients and oxygen to the cornea and lens and carries away their metabolic wastes. arthritis An inflammation of a joint. auditory tube Small tubes that join the upper region of the pharynx (throat) with the middle ear. They help to equalize the air pressure between the middle ear and the atmosphere. Also called eustachian tubes. autonomic nervous system
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The part of the peripheral nervous system that governs the involuntary, unconscious activities that maintain a relatively stable internal environment. The autonomic nervous system has two branches: the sympathetic and the parasympathetic. axial skeleton The part of the skeleton comprising the skull, the vertebral column, the breastbone (sternum), and the rib cage. axon A long extension from the cell body of a neuron that carries an electrochemical message away from the cell body toward another neuron or effector (muscle or gland). The tips of the axon release a chemical called a neurotransmitter that can affect the activity of the receiving cell. Typically, there is one long axon on a neuron.
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ISB 204 Online Quiz Study Guide 2 - Accommodation A change...

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