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104 Cards in this Set
- Front
- Back
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resting membrane potential
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between -60 to -85 mV. Maintained be Na+/K+ pump but generated by unequal ion distribution. closer to K+ equilibrium potential
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Schwann Cells
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form myelin sheaths in PNS
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Oligodendrocytes
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responsible for the formation of myelin sheaths in CNS
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Microglia
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phagocytic cells that clean up debris from dying cells
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astrocytes
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cells that regulate transport of molecules from blood to brain
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Ependymal
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line the ventricles and help produce brain fluid
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Satellite cells
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support neuron cell bodies within the ganglia of the PNS
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How do Schwann cells participate in neural regeneration?
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They engulf the degenerated portion of the axon and line a regeneration tube. They then secrete chemicals which attracts the axon to its destination.
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Astrocyte Function
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- take up K+ ions released by neurons
- take up specific neurotransmitters released from exon ending - perivascular feet help form blood-brain barrier |
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Action Potential
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localized, rapid reversals of membrane potentials brought about by rapid changes in membrane permeability to Na and K ions
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Polarization
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plasma membrane has a resting membrane potential due to separation of opposite charges
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Depolarization
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when the membrane potential is decreased from the resting membrane potential (becomes more positive)
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Hyperpolarization
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when the membrane potential is increased or becomes more negative from resting membrane potential
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repolarization
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membrane potential returns to the resting potential after depolarization
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Ion channels (gates)
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proteins spanning the thickness of the membrane, open and close in response to changes in the membrane potential
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All or None
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action potentials occur or they don't because if threshold is not reached then no action potential will occur.
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Conduction of action potentials
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the action potential would be conducted to an adjacent area that will has a resting potential. the original area returns to its resting potential
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saltatory conduction
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leaping of action potential from one node to another
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Neuron-Neuron synapse
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between the axon terminal of one neuron and the dendrites of another
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Chemical Synapse
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synaptic vesicles that contain a neuron-specific neurotransmitter that is synthesized/packaged by presynaptic cell into the synaptic cleft
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Excitatory postsynaptic potential (EPSP)
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when sufficient depolarization occurs in the postsynaptic cell, the threshold potential might be brought down, thus triggering an action potential
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Inhibitory postsynaptic potentials (IPSP)
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Hyperpolarizations move the postsynaptic cell even further from the threshold potential, thus inhibiting the generation of an action potential
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ACh
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binds to nicotinic receptor which leads to an influx of Na+ and some efflux of K+. This produces a small EPSP
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Efflux of K+?
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causes a small hyperpolarization leading to an IPSP
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How is ACh removed?
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acetylcholinesterase (AChE), enzyme associated with outer side of plasma membrane of post synaptic neuron
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Curare
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competes for ACh receptros and decreases the end plate potential. Acts as a muscle relaxant
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Nerve gas
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blocks AChE which leads to inability to remove ACh from the synapse resulting in spastic paralysis
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Catecholamines
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epinephrine, adrenaline, dopamine, tyrosine (used as a second messenger or another pathway for neurotransmitters)
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How to terminate neurotransmitters
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- reuptake into the presynaptic neuron endings
- enzymatic degradation in presynaptic nerve terminals by MAO - enzymatic degradation of monoamines in the postsynaptic neurons by COMT |
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Amphetamines
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stimulate neural pathways by inhibiting the reuptake of catecholamines into the presynaptic cell (prolongs the effect of neurontransmitters)
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Glutamic acid and aspartic acid
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produce EPSPs
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Glycine and GABA
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produce IPSPs and control coordination of skeletal muscle movements, mood and emotion
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Endorphins
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block the release of substance P which is involved in the transmission of pain
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Spatial Summation
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summation from different synapses over distance
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Temporal Summation
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due to successive activity of a single presynaptic neuron over time
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Right and Left cerebral hemispheres mostly communicate through?
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Corpus callosum
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Left Hemisphere
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logical, analytical, sequential, and verbal tasks
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Right Hemisphere
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non-language skills, spatial perception and artistic/musical activities
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Broca's Area
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located on the frontal lob, responsible for speaking ability
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Wernicke's area
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located at junction of parietal, temporal, and occipital lobes. responsible for speech comprehension
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Consolidation of short and long term memory
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accomplished by hippocampus and other nuclei
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diencephalon
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contains thalamus and hypothalamus
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hypothalamus
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integrates homeostatic functions, link between nervous and endocrine systems
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Superior Colliculi
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upper two elevations on the midbrain involved in visual reflexes
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Inferior colliculli
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lower two elevations on the midbrain, relay center for auditory information
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hindbrain
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contains three parts: Pons, cerebellum, and medulla oblongata
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Pons
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connects fibers from the medulla to the midbrain and cerebellum
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cerebellum
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- modification of the output of major motor system
- maintenance of balance - muscle tone - coordinates skilled voluntary movements |
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medulla oblongata vital centers
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cardioinhibitory center, vasomotor center, respiratory center
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reticular formation
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complex network of nuclei and fibers connecting various parts of the brain stem, thalamus and hypothalamus. sleep center
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dorsal root
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contains sensory fibers and the cell bodies for these nerves
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ventral root
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contains motor fibers
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A sensory receptor
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detects signals and generates an action potential in the afferent pathways
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Afferent Pathways
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relay information to the integrating center
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Integrating center
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processes the information and makes a decision/ transmits via the efferent pathway
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Efferent pathways
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relay information to the effector
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Effector
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affects a change
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Somatic Motor Nervous System
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one neuron from brain to effector, cell body in CNS, effector: skeletal muscle, neurotransmitter: acetylcholine, always excitory, voluntary, denervation results in Flaccid paralysis
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Autonomic motor nervous system
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two neurons from brain to effector, effector: cardiac/smooth muscle and glands, neurotransmitters: acetylcholine/norepinephrine, involuntary, denervations results in muscle tone, hypersensitivity
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Sympathetic system
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distributed throughout the body, fight or flight situations body prepares for physical activity
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Parasympathetic System
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distributed in head, viscera of thorax, abdomen, and pelvis area. promotes "housekeeping" like digestion
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Endocrine gland
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modified sympathetic ganglion. Secretes epinephrine in response to sympathetic stimulation (similar to norepinephrine)
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Organs without dual innervation
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adrenal medulla, arrector pili muscles in skin, sweat glands, most blood vessels
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Sensory receptors
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transduce forms of energy into nerve impulses that are delivered to the CNS
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Adequate stimulus
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the one type of stimulus that each receptor is specialized to respond to
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receptor potential
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leads to the production of local graded membrane potential change. how sensory receptors transduce signals into sensory nerves
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cutaneous receptors
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touch/pressure, warm/cold, pain
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vestibular apparatus
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sense of equilibrium that provides orientation with respect to gravity. consists of otolith organs and semicircular canals
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Hair Cells
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generate neural signals when they are mechanically deformed due to fluid movement
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Result of Hair Cell Deformation
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When the hair cells are pushed towards the kinocilium, it results in depolarization with in the hair cells, they then activate afferent nerves which carries information in the form of action potentials to the brain
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tympanic membrane
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vibrates when struck by sound waves
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Three bones in ear
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malleus, incus, stapes
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Malleus
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middle ear bone, attached to the tympanic membrane and sends vibrations to the incus
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Incus
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middle bone that transmits vibration to the stapes
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Stapes
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attached to the oval window of inner ear of the cochlea
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stapedius muscle
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attached to the stapes and pulls on it in response to loud sound waves
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Eustachian tube
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connects the middle ear to the pharynx, can be opened to equalize pressure on both sides of the tympanic membrane
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Three cavities in Inner ear
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scala vestibuli, scala media, scala tympani
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Conductive deafness
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caused by excessive fluid accumulation or immobilization of the stapes (middle ear)
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sensory deafness
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caused by damaged nerve endings
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Anterior chamber
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between cornea and iris, contains clear watery aqueous humor
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posterior chamber
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between iris and lens, filled with aqueous humor
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vitreous humor
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jellylike fluid between lens and retina
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Accommodation
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contraction of ciliary muscles. When relaxed, suspensory ligaments have tension and the lens is pulled flat. as an object moves closer, ciliary muscles contract
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Presbyopia
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a person can't focus on near objects
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myopia
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due to a long eyeball. can be corrected with a concave lens
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Hyperopia
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eyeball is too short. can be corrected with a convex lens
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Astigmatism
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cuvature of cornea is uneven. corrected by placing a cylindrical lens that evens out cornea
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Rods
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provide vision in shades of gray, responsible for sensitivity to low light
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cones
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three types that absorb different colors, responsible for day vision and visual acuity (sharpness)
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Sliding muscle model
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the muscle fibers shorten as a result of the sliding of thin filaments inward towards the center of the bands
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Cross bridge formation
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causes the heads of myosin to move inward pulling actin along (power stroke).
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Where does the energy for the power stroke come from?
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release of ADP and phosphate from the myosin head after the hydrolysis of ATP
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Where is Ca++ stored
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sarcoplasmic reticulum
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Muscle contraction
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muscle stimulated to contract, Ca++ released, Ca++ binds to troponin and sliding of filaments occurs. When stimulation stops, Ca++ pumpted back to SR, tropomyosin returns to blacking position, muscle relaxes.
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motor unit
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functional unit that ocnsists of the motor nerve with all the muscle fibers that the neuron innervates
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Smaller motor units
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present in muscles that produce precise/delicate movements (hands, eyes)
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Larger motor units
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present in muscles where strong tension is needed (arms, legs)
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Muscle Spindles
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specialized muscle cells located in center of muscle, responsible for detecting the length of muscles/how rapidly they are being stretched
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Alpha motor neurons
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innervate normal muscle fibers, activation causes muscle contraction
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Gamma motor neurons
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innervate intrafusal/spindle fibers, activation causes tightening of muscle spindles. Maintain or increase sensitivity of spindle
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Monosynaptic reflex
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present in all muscles to help mantain ideal muscle length for producing max contraction
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Golgi tendon organ
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monitor tension in the tendons produced by muslce contraction or passive stretch
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Dysynaptic reflexes
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alpha motor neuron inhibited via inhibitory interneurons to prevent harming the muscle due to excessive force
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