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Nervous system
Biology 12
| Term | Definition |
|---|---|
| acetylocholine | neurotransmitter released by exocytosis into synaptic cleft at the end of specific neurons |
| acetylcholinesterase | chemical found in vertebrate neurons that carries information across the synaptic cleft, the space between two nerve cells |
| action potential | measurable aspect of a nerve impulse - caused by the sudden movement of Na into a nervel cell with the movement of K to the outside |
| adrenal medulla | adjacent to the tops of the kidneys in mammals. have a outer cortical region seperate from inner medullary region. |
| adrenalin | produces epinephrine |
| "all-or-none" response | effect on neuron by a stimulus that surpasses threshold. it either causes an impulse or doesn't |
| autonomic nervous system | effector system consisting of two motor neurons joined by synapses leading to specific effectors. subdivided into sympathetic and parasympathetic neurons |
| axomembrane | dendrites and axons of a neuron are basically tubes constructed of cell membrane |
| axon | part of the nerve cell that carries impulses away from the cell body -ends at a synaptic cleft |
| axoplasm | cytoplasm of a neuron. |
| calcium ion | co-factor in the body - role it plays in conversion of prothrombin to thrombin during formation of a blood clot, hardening of bone tissue, triggering exocytosis of neurotransmitters during synaptic transmission |
| cell body | part of neuron where the nucleus is located. cell bodies of interneurons and neurons are located within the CNS producing gray matter |
| central nervous system | composed of the brain and spinal cord; sensory information is conducted from periphery to the spinal cord for reflexive actions and to the brain for interpretation |
| cerebellum | large dorsal lobe of the brain located at the top of the spinal cord. coordinates body movements and balance |
| cerebrum | large anterior part of brain ("thinking part") central fissure divides cerebrum into right and left hemisphere(each has four lobes) |
| contractile protein | cytoskeletal feature made of proteins. exist in the end of a axon where they attach secretory vesicles to the presynaptic membrane |
| corpus callosum | band of nerve fibers that divides the cerebrum into left and right hemispheres. |
| dendrite | extension of a neuron that conducts impulses to cell body |
| depoloarization | loss of polarity. nerve cell membranes are polarized by NA/K pumps which accumulate NA on the outside and K in the axoplasm |
| effector | muscle or a gland. transmission of an impulse along a motor acon causes an action by an effector |
| excitatory neurotransmitter | chemical substance released by a motor axon, causes an increase in activity of the effector |
| hypothalamus | lower portion of the midbrain |
| impulse | electrical charge that moves across neuron |
| inhibitory neurotransmitter | chemical substance that is released an enzymatic an enzymatic reaction |
| interneuron | local circuit neuron of the central nervous system that relays impulses between sensory neuron and motor neuron. |
| medualla oblongata | portion of the CNS at the base of the brain. controls several reflexive, homeostatic actions involving non-skeletal muscle coordination such as heart rate etc |
| meninges | set of 3 membranous that surround and protect the CNS. dura mater (outer-layer) is the thickest and the toughest. inner layer is the pia mater. between is arachnoid layer |
| motor neuron | nerve cell with a long axon and short dendrite, cell body is located in the CNS |
| myelin sheath | fatty covering of motor axons and sensory dendrites outside CNS. covering is made out of schwann cells |
| myelinated nerve fibre | Nerve fiber enveloped by a sheath of myelin believed to be associated with saltatory conduction, which is a physiological mechanism for faster conduction of action potential along the nerve fiber. |
| neuroendocrine control center | combo of hypothalamus, pituitary glands. |
| neuron | nerve cell. motor neurone, sensory neurons, interneurons ( dendrite, cell body, axon) |
| neurotransmitters | chemical substance that is released by an axon for affecting cells on the other side of a synaptic gap. receptor sites on the postsynaptic membranes recieve the neurotransmitters |
| node of Ranvier | exposed spots along neurons between schwann cells making up the myelin sheath. |
| norepinephrine | neurotransmitter of the sympathetic nervous system |
| parasympathetic division | consists of motor neurons that release acetylcholine to affect the effector. acetylcholine slows the heart down, reduce breathing rate and increases digestive activity. |
| peripheral nervous system | axons of motor neurons and cell body and dendrite of sensory neurons are genrally considered to in the PNS. PNS is the link from receptors to the CNS and from the CNS to the effectors |
| pituitary gland | endocrine gland attached to the hypothalamus. anterior lobe and posterior lobe of the pituitary gland. |
| polarity | having either a positive or negative dipole |
| postsynaptic membrane | in synaptic transmission, its the membrane equipped with proteins to receive neurotransmitters |
| potassium gate | protein in membrane of neurons that change shape to allow K out of neurons once axoplasm gains positive charge from Na coming in |
| presynaptic membrane | membrane on the end of an axon at a synapse. during synaptic transmission, neurotransmitters are released from vesicles produced behind pre-synaptic membrane at an axon terminus |
| receptor | protein in cell membrane that has bonding site for substance that can be in its environment. |
| reflex arc | neural pathway- involves sensory neuron, interneuron and motor neuron. stimili are receives, impulsed are transmitted to CNS and motor neuron for a reaction |
| refractory period | period of time following an erection where the penis remains flaccid |
| repolarization | neurons membrane to regain polarized condition during resting potential.opening of the K gates, result from influx of Na ions giving it a positive charge.opening of gates alows K ions out, reducing positive nature and regaining resting potential |
| resting potential | difference in electrical nature between inner and outer surface of a neuromembrane when its at rest. resting potential is -65 mV inside relative to out. inside neuron are K ions and negative ions. outside is Na ions. |
| saltatory transmission | described as this because of the positioning of schwann cells. ion movements involved with the impulse occur at exposed parts of neurone-nodes of ranvier. |
| Schwann cell | fatty cell. specialized type of glial cell that support nerve cells and nerve cell function - make up the myelin sheath and result in saltatory transmission |
| sensory neuron | nerve cell that conducts an impulse from receptor to the CNS-long dendrites and short axons - located along dorsal root at ganglia |
| sodium-potassium pump | responsible for establishing and maintaining unequal ion distribution of resting potential |
| somatic nervous system | portion of the nervous system that conducts impulses to the skeletal muscles |
| sympathetic division | subset of the ANS. consist of motor neurons that release noradrenaline to affect the effector. noradrenaline increase the heart and breathing rate but decrease the digestive activity. |
| synapse | junction of neuron and the next cell |
| synaptic cleft | space between axon and next cell, space that must be bridged by neurotransmitters for continuation of the impulse |
| synaptic ending | ending of an axon at a synaptic gap |
| synaptic vesicle | secretory vesicle that delivers neurotransmitters to the presynaptic membrane |
| thalamus | region of middle brain that is named the sorting center. impulses traveling to cerebral cortex pass through the thalamus directing them to the right area |
| threshold value | amount of a substance thats required to cause an effect.ex- stimulus must pass a minimum threshold before it can open Na gates and cause an impulse |
Created by:
alubbe
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