Final Flashcards
Action potential
Electrical impulses in nervous system
Afferent nerve
Information from tissues to CNS No dendrites (only sensory receptor), unipolar neuron
Interneurons
Between sensory (afferent) and motor (efferent)
Within the spinal cord
Usually multipolar neuron
Efferent neuron
Nerve impulse from CNS to peripheral tissue
Multipolar neuron
Somatic nervous system is under ___________ control of __________ muscle
Voluntary; skeletal
Exteroceptors
Information about external environment in form of touch, temp, sight, smell, taste
Proprioceptors
Monitor the position and movement of skeletal muscle and joints
Interceptors
Monitor digestive, respiratory, cardiovascular, urinary, and reproduction
What two properties must a neuron have?
Excitability- ability to respond to a stimulus
Conductivity- ability to transmit a signal
What is the function of a neurotubule?
Intracellular transport of proteins and other substances in both directions between cell body and end the cell processes
What is a neurofilament?
Skeletal framework for the axon
Dendrite
Threadlike cytoplasmic projections which are actually extensions of the cell body
Conduct nerve impulses toward the cell body
A neuron axons originates from the____________
Axon hillock
What is the site called where the nerve impulse is initiated and lies immediately after axon hillock
Initial segment
The fine extensions at the end of an axon are _____________ which end in tiny swellings called ___________________________
Telodendron
Terminal buttons/boutons
The junction between end bulb and the axon/cell body/dendrite
Synapse
The lipid sheath surrounding a neuron is __________? Made up of ______________ cells in PNS and ____________ cells in CNS.
What is the purpose of this lipid sheath?
Myelin
Schwaan cells
Oligodendrocytes
Increase speed of nerve impulses
What are the functional segments of a neuron
Receptive segment
Initial segment -trigger zone for action potential
Conductive segment
Transmission segment
What facilitates slow axonal transport and what is being transported?
Peristaltic waves of axon membrane
Requires ATP
Transport of materials necessary to maintain axon and dendrites
What facilitates fast axonal transport and what is carried?
Convey neurotransmitter vesicles down neurotubles, requires ATP
Anterograde or retrograde
Anterograde transport
Material transported form cell body along axon to axon terminal
Kinesin
Retrograde Transport
Material returned to cell body where it is degraded or recycled.
Dyenin
Neural reflex
Sensory fibers deliver info to CNS and motor fibers carry motor commands to peripheral effectors
Endocrine reflex
Stimulus trigger production of a hormone which leads to a reduction in magnitude of a stimulus
Spinal reflex
Spinal cord is integrating center
eg. Contracting muscle pulls hand away form a painful stimulus
Negative control mechanism: corrective mechanism that opposes variation from normal limits
Cranial reflex
Sense stimulus and control output
Eg. Cranial nerve II (optic) detects light changes -> brainstem and cranial nerve III adjusts pupil diameter
Monosynaptic reflex
Most simple reflex
Sensory neuron directly synapse on motor neuron
Stretch reflex
Sensory nerve ->spinal cord -> motor neuron -> effector organ
Large myelinated type A fibers
Eg. Oppose sudden changes in muscle fibe length (maintain normal skeletal muscle)
Polysynaptic reflex
One or more interneurons synapse with sensory and motor neurons
Produce more complicated responses because the interneurons can control several different groups
Ligand gated channels
Opened by ligand (drug)
eg norepinephrine
Voltage gated ion channels
Change in voltage across the membrane causes opening of ion channels
What maintains the resting ion potential
Na+ K+ pump
Primary active transport (uses ATP)
Describe ion flow during an action potential
- Na channels open allowing Na into cell
- K channels open and K leaves cell
- Na channels close and no more Na enters the cell
- K continues to leave cell (cell membrane returns to resting potential)
- K channels close and Na channels reset
- Extra K outside diffuses away
Polarization
Membrane has potential/ separation of opposite charges
Depolarization
Membrane potential becomes less negative
Repolarization
Return of the membrane to resting potential after having being depolarized
Hyperpolarization
Membrane potential becomes more negative
Threshold potential
Membrane potential at which occurrence of the AP is inevitable
Saltatory conduction
nerves are exposed at nodes of Ranvier in myelin sheath
Sodium channels are concentrated here and AP travels from node to node
Refractory period
Period in which action potential cannot be generated (cause unidirectional propagation of AP)
Absolute/ Relative
Graded (local) potential
Change in resting membrane potential
Confined to a small region of the plasma membrane -> conducted with decreasing intensity
Describe the process of neurotransmitter release
Voltage gated Ca2+ channels open
Ca2+ enters cell and signals vesicle release
Vesicles exocytose
Neurotransmitter diffuses across the membrane
How can neurotransmitter be removed from the synaptic cleft
Diffuse away
Inactivated by specific enzymes within postsynaptic membrane
Actively reabsorbed into pre-synaptic membrane
How is norepinephrine removed from the synaptic cleft
Diffuses away or recaptured in ATP dependent uptake system (monoamine oxidase or catecho-o-methyltransferase)
How is acetylcholine removed from the synaptic cleft
ACh is split into acetic acid and choline by acetylcholinesterase
Describe an electrical synapse
In cardiac muscle through gap junctions at intercalated discs
Fast conduction of AP
Excitatory post synaptic potential
Response to neurotransmitter binding is opening of Na channels on postsynaptic membrane (depolarization)
Norepi , Epi, Glutamate, and ACh
Inhibitory post synaptic potential
Response to neurotransmitter binding is opening of Cl- channels in postsynaptic membrane -> hyperpolarization
Glycine and ACh
What is summation?
Combination of postsynaptic signals (temporal or spacial )
Temporal Summation
Excitatory post synaptic potential occurring in close succession
Excessive firing of single presynaptic neurons
Spacial summation
Excitatory postsynaptic potential originating simultaneously from several presynaptic inputs
Cancellation summation
Inhibitory and Excitatory post synaptic potentials offset each other
Neurotransmitter
Chemical compound released by one neuron to affect the membrane potential of postsynaptic cell
Neuromodulator
Chemical that adjusts the sensitivities of another cell to specific neurotransmitters
Presynaptic inhibition
Decreased amount of neurotransmitter released form presynaptic terminal
Presynaptic facilitation
Increase amount of neurotransmitter released form presynaptic terminal
