生物英语词汇释义

1. a. Sensory Input-Sensory receptors gather information about the internal and external environments and convert it to a form which can be used by the animal. This information is then conveyed to integration centers.b. Integration-The input is interpreted and associated with the bodies appropriate response. Integration is carried out in the Central Nervous System (CNS).c. Motor Input-Conduction of signals from the integration centers (CNS) to effecter cells.2. -neuron: cells specialized for transmitting chemical and electrical signals from one location in body to anothera. large cell body; contains most of cytoplasm, nucleus, and other organelles-cell bodies of most neurons located in CNS-ome neurons have cell body located in ganglia outsidethe CNSb.dendrites, one type of fiberlike extension (process) that convey impulses TO the cell body-short, numerous, & extensively branched to increase surface area where cell most likely to be stimulatedc.axons, other type of extension (process), conduct signals AWAY from the cell body-long, simple processes-vertebrate axons in PNS wrapped in concentric layers of Schwann cells, which form insulating myelin sheath -in CNS, myelin sheath formed by oligodendrocytes-axons extend from axon hillock (where signals are generated) to many branches which are tipped withsynaptic terminals that release neurotransmitters -synapse is gap between synaptic terminal and target cell—dendrites of another neuron or an effector cell -neurotransmitters are chemicals that cross the synapse to relay the impulse3. Reflex Arc – A simple pathway involving neurons OUTSIDE the CNS. Signals do not go to the brain4. -Nerve cells areas are also known as neurons. Neurons are the basic unit of the nervous system. They carry information or impulses as electrical signals from one place to another in the body. There are 3 types of neurons:a. Sensory Neurons- Sensory neurons carry electrical signals (impulses) from receptors or sense organs to the CNS. Sensory neurons are also called afferent neurons. The cell body of sensory neurons is outside the CNS in ganglia.b. Motor Neurons- Motor neurons carry impulses from the CNS to effector organs Motor neurons are also called efferent neurons. The cell bodies of motor neurons are inside the CNS.c. Interneurons- These are also called intermediate, relay, or associative neurons. They carry information between sensory and motor neurons. They are found in the CNS.d. distinguish: In the central nervous system, a collection of neuron cell bodies is called a nucleus.-In the peripheral nervous system, a collection of neuron cell bodies is called a ganglion (plural: ganglia).5. a. Convergent- several presynaptic neurons to 1 postsynaptic neuron- integration of info from several sourcesb. Divergent- 1 presynaptic neuron to multiple postsynaptic neurons- distribution of info to different parts of brainc. Reverberating- circular - memory storage6. S- Glial cellssupporting cells (glia cells) structurally reinforce,protect, insulate, and generally assist neurons-do not conduct impulses-outnumber neurons 10 to 50 fold-several types of glia are present- Astrocytesastrocytes encircle capillaries in brain-contribute to blood-brain barrier (restricts passage of most substances into CNS-communicate with each other/other neurons via chemical signals- Oligodendrocytesoligodendrocytes form myelin sheaths that insulate CNS nerve processesb. PNS- Schwann cellsSchwann cells form insulating myelin sheath around axons in PNS-myelination provides electrical insulation & increases speed of nerve impulse propagation7. a. the ion's electrochemical gradient (driving force)b.the ion's permeability8. a.Membrane potential = voltage (difference in electrical charge) across plasma membraneb. Resting potential = membrane potential of a resting neuron.-Does not send signals.9. a. returns the membrane potential to resting levelb. inactivation gates close Na+ channels and K+ channels open.10. That's like between the falling stage and the undershoot. The short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation of voltage-gated sodium channels.11. based on the frequency of action potentials generated12. a. Speed of action potential incr. with axon diameter. Axons are insulated by myelin sheets (made by glial cell), which causes an action potential speed to incr.b.Action potential jumps from node to node as it travels along the axon, b/c when it jumps to the next node it depolarize the membrane and regenerate the action potential.13. b/c the inflow of K+ after action potentials deactivatethe NA+ ion channel.14. a. When excited, EPSPs move the membrane potential toward threshold.-Depolarizedb.When quiet, IPSPs move the membrane potential away from threshold.-Hyperpolarized15. -Summation is when synapses occur at the same time.a. Temporal summation happens on the same synapses but occurs at the same time.b. Spatial summation happens on two different synapses but occurs at the same time.16. The AXON HILLOCK: is the neurons integrating center, the region where the membrane potential at any instant represents the summed effect of all EPSPs and IPSPs.- Whenever the membrane potential at the axon hillock reaches the threshold, an action potential is generated and travels along the axon to its synaptic terminals.17. a. Acetylcholine is a common neurotransmitter in vertebrates and invertebrates-In vertebrates it is usually an excitatory transmitterb. Biogenic amines include epinephrine, norepinephrine, dopamine, and serotonin- They are active in the CNS and PNS18. a. Amino Acids-GABA (gamma aminobutyric acid): Inhibitory, CNS; invertebrate neuromuscular junction-GLYCINE: Inhibitory CNS-GLUTAMATE: Excitatory, CNS; invertebrate neuromuscular junction-ASPARTATE: Excitartory, CNSb. Neuropeptidies-Substance P: Excitatory CNS PNS (pain perceptions)- Met-enkephalin: Generally inhibitory CNS19. a. Cells synthesize them on demand.-These substances diffuse into neighboring target cells and produce a change and are broken down.-Ex. NO in erectile tissue. Smooth muscle cells in the blood vessel walls relax and blood vessels dilate and fill the spongy tissue with blood.-CO in the brain regulates the release of hypothalamic hormones. In the PNS it acts as in inhibitory neurotransmitter that hyperpolarizes intestinal smooth muscle cells.20. a. Hydra have a nerve netb. Sea star have a nerve ringc. Planarian and insect and squid have brain and ganglia (or nerve cord)d. Vertebrate have a CNS (the brain and the spinal cord), and a PNS (ganglia and spinal nerves and cranial nerves)21. a. CNS (brain and spinal cord) - spinal cord sends info to brain, and sometimes acts independently to brain and causes reflexes.b. PNS (ganglia and spinal nerves and cranial nerves) - brain sometimes transmits info to the PNS.22. a. Sensory neurons of the somatic nervous system receive input from the special senses, general somatic senses, and proprioceptors; sensory neurons of the ANS receive input from the special senses, general visceral senses, and general somatic senses.b. The somatic nervous system operates under conscious control; the ANS operates without conscious control.c. The axons of the motor neurons of the somatic nervous system extend from the CNS synapse directly to an effector and release acetylcholine, whereas autonomic pathways consist of two sets of motor (efferent) neurons.-The axon of the first (preganglionic) motor neuron of the ANS extends from the CNS and synapses in a ganglion with the second neuron.- The second (postganglionic) motor neuron synapses on an effector. Preganglionic fibers release the neurotransmitter acetylcholine and postganglionic fibers release acetylcholine or norepinephrine.d. Somatic nervous system effectors are skeletal muscles, and ANS effectors include cardiac and smooth muscle, and glands.e. The somatic nervous system responds to neurotransmitters as excitation while the ANS response to neurotransmitters is excitation or inhibition.f. A summary of the similarities of and differences between the somatic and autonomic nervous systems is presented.g. The output (efferent) part of the ANS is dividedinto two principal parts: the sympathetic and the parasympathetic. Organs that receive impulses from both sympathetic and parasympathetic fibers are said to have dual innervation.23. a. Forebrain- telencephalon -> cerebrum- diencephaion -> diencephaionb. Midbrain- mesencephaion -> midbrainc. Hindbrain- metencephaion -> pons, cerebellum- myelencephaion -> medulla oblongata24. a. medulla: center for respiratory, cardiac function; vomiting, sweating, gastric secretion, heartbeat.b. pons: bridge between two halves of the cerebellum; carries fibers that coordinate activity of muscles on two sides of the bodyc. midbrain: relay center; visual and auditory reflexesd. cerebellum: regulate and controls bodily muscular contractions; coordination, balance, equilibriume. thalamus: relay center for sensory impulses going to cerebrum control center for external manifestations of emotionf. epithalamus: in the middle of the brain which has the function of the connection between the limbic systemto other parts of the braing. hypothalamus: regulates hunger, thirst, body temp, CHO and fat metabolism, blood pressure, sleep; regulates the pituitaryh. cerebrum: controls learned behavior and memory; makes up about 80% of brain mass25. Reticular system does function in arousal/sleep. main location is the brainstem.26. a. frontal(speech, motor cortex)b.parietal (taste, reading)c. temporal (smell, hearing)d. occipital (vision)27. a. left: cerebral cortex: plays a key role in memory, attention, perceptual awareness, though, language and consciousness.corpus callosum: junction between two hemispheresb. right: basal nuclei: is responsible for body movement and coordination28. a. frontal lobe: involve the ability to recognize future consequences resulting from current actions, to choose between good and bad actions (or better and best), override and suppress unacceptable social responses, and determine similarities and differences between things or events.b. parietal lobe: plays important roles in integrating sensory information from various parts of the body, knowledge of numbers and their relations, and in the manipulation of objects. Portions of the parietal lobe are involved with visuospatial processing.c. temporal lobe: is involved in auditory perception and is home to the primary auditory cortex. It is also important for the processing of semantics in both speechand vision. The temporal lobe contains the hippocampus and plays a key role in the formation of long-term memory.d. occipital lobe: it contains the primary visual cortex and is the part of the brain where dreams come from.29. a. Long-term depression (LTD): LTD in the hippocampus and cerebellum have been the best characterized, but there are other brain areas in which mechanisms of LTD are understood.- LTD is one of several processes that serves to selectively weaken specific synapses in order to make constructive use of synaptic strengthening caused by LTP. This is necessary because, if allowed to continue increasing in strength, synapses would ultimately reach a ceiling level of efficiency, which would inhibit the encoding of new informationb. long-term potentiation (LTP) is a long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously.- LTP is widely considered one of the major cellular mechanisms that underlies learning and memory.30.31.。