Nervous System Test Two Flashcards
Nucleus
Cluster of nerve cell bodies within the CNS
Ganglion
Cluster of nerve cell bodies outside the CNS
Tract
bundle of axons inside the CNS
Nerve
Bundle of axons outside the CNS
Grey Mater Spinal Cord?
Contains interneurons, cell bodies of motor neurons, and axons of entering sensory axons. Butterfly shaped central area.
Dorsal root ganglion function?
Has cell bodies of sensory/afferent neurons
Dorasal root?
Group of sensory fibers entering the spinal cord on dorsal side
Ventral root?
Group of motor fibers entering the spinal cord on the ventral side
Spinal nerve make up?
Dorsal and ventral roots-Mixed
What else does the spinal cord do besides carry fibers?
Contains neuronal circuits for walking and reflexes, high brain centers control and activate these circuits
What would happen if a spinal nerve was severed?
Loss of function and sensation to the area that nerve supplies
What makes up the forebrain?
Cerebrum and diencephalon
What makes up the brainstem?
Medulla Oblongatea, Midbrain, Pons
What makes up the hindbrain?
Cerebellum, Medulla, Pons
What runs through the brainstem and thalamus, also has a role in sleep wake cycles, concentration and various reflexes such as vomiting and swallowing?
Reticular Formation
What does the thalamus do?
Relay station for incoming sensory information to the cortex. Also important for muscular control.
What makes up the limbic system?
Cortex, Hypothalamus, Thalamus
What part of the brain is the most complex integrating area that brings together sensory information into meaningful perceptual images, as well as decide to consciously make movements, produce language, and having thoughts?
Cerebral cortex
Where does subconscious activity take place in the brain?
Subcortical areas-Lower brain
What does the cerebellum do?
Involved in coordinated smooth movements of muscles, maintains balance and posture
What is the corpus callosum?
White matter that connects the left and right hemispheres of the cerebral cortex allowing for them to communicate.
What is the single most important control area in the brain for regulating internal environment?
Hypothalamus
What is associated with the limbic system?
Pleasure, learning, emotions
How many spinal nerves are there?
31 pairs
Where are afferent neuron cell bodies located?
Outside the CNS in ganglia
What is the somatic nervous system?
Part of the efferent division of PNS. Entirely motor axons going from CNS to skeletal muscles
Where are somatinc cell bodies located?
In the brainstem or spinal cord
What transmitter does the somatic nervous system always release?
Acetylcholine, which always excites the muscle.
What do all preganglionic fibers in the autonomic nervous system release?
Acetylcholine
What do postganglionic fibers in the parasympathetic nervous system releas?
Acetylcholine, Cholinergic receptors
What do post ganglionic fibers in the sympathetic nervous system release?
NE or Epi, Adrenergic receptors
What is the autonomic nervous system made up of?
All axons of neurons going from the CNS to smooth muscle, cardiac, or glands
T or F: A cranial or spinal nerve can carry both sympathetic and parasympathetic fibers.
False they can carry one but not the other
Describe the preganglionic fibers and post ganglionic fibers of the sympathetic nervous system.
Pre ganglionic fibers are short in the symp. system and the post ganglionic fibers are long as they are coming from the sympathetic chain ganglia near the spinal cord
Describe the preganglionic fibers and post ganglionic fibers of the parasympathetic nervous system.
The pre ganglionic fibers are long as the post ganglionic fibers sit on or very close to the effector. So post ganglionic fibers are short.
T or F: The sympathetic nervous system is always excitatory while the parasympathetic nervous system is always inhibitory.
False. Both systems can inhibit and excite.
What is potential and how is it measured?
Potential to do work, measured in Volts or mV.
The attraction between opposite charges tends to make them flow this is called?
Current
What does the amount of current depend on?
The potential difference (V) and the amount of resistance
Material with high resistqance to current flowing is called?
Insulator
Material with low resistance to current flowing is called>
Conductor
What is Ohms law?
C=V/R
How do you achieve more current flow?
By raising the voltage or lowering resistance
Describe the RMP?
Difference in charged particles across the membrane so that the inside of a cell is more negative than the outside of the cell. The outside has more Na and Cl and the inside has more K.
How would you describe the bulk of ECF?
Neutral
What determines the magnitude of the RMP?
Differences in the numbers of ions in the ICF and ECF and the permeability of the plasma membrane to ions.
Is RMP more permeable to sodium or potassium?
RMP is more permeable to K
When a neuron goes from at rest to depolarizing which ion is more permeable in that moment?
Sodium, potassiums permeability does not change
What is the Nernst equation?
61x log (ion concentration out/ion concentration in)/Z
Why is Vm so close to Ek?
Because the membrane is much more permeable to potassium than sodium at rest.
When does the Na K pump work and how>
When a neuron is at rest, 3 sodium are pumped out and 2 potassium ions are pumped in to compensate for their diffusion in the opposite directions. This makes the outside more positive.
General definition of depolarization?
Change in the membrane potential where it becomes less negative closer to zero or even positive than the RMP
General definition of hyperpolarization?
Change in the membrane potential in which the potential becomes more negative than the RMP
What is repolarization?
When the membrane potential comes back down to the normal RMP
What are graded potentials?
Changes in membrane potential in the depolarizing or hyperpolarizing direction that die out as they travel along the membrane. Size relates to the size of stimulus.
What causes a GP?
specific change in the cells environment acting on a specialized region of the membrane.
What are the three types of GP?
- Receptor potential: produced at the end of a sensory neuron in response to an external stimulus
- Postsynaptic potential: Produced in a post synaptic cell in response to transmitter release by a pre synaptic neruon
- Pacemaker potential: spontenous production produced by ion leakage
How do graded potentials effect the the membrane potential?
They decrease the amount of charge separation of the adjacent membrane sites.
What is the function of a depolarizing GP?
To make the neuron more likely to produce an action potential. (EPSP)
What is the function of a hyperpolarizing GP?
To make the neuron less likely to produce an AP. (IPSP)
What is the difference between GP and AP?
The GP allows the neuron to listen to a pre synaptic cell or sensory receptor while an AP allows the neuron to talk by releasing a NT onto another cell. AP are larger and more rapid than GP.
What is the difference between GP and AP?
The GP allows the neuron to listen to a pre synaptic cell or sensory receptor while an AP allows the neuron to talk by releasing a NT onto another cell. AP are larger and more rapid than GP. AP is all or none, does not die out.
What occurs during an AP to the membrane potential?
During AP the membrane becomes permeable to sodium ions. The voltage gated sodium channel activation gate is opened quickly by depolarization, and the inactivation gate is closed slowly by depolarization.
What occurs during the rising depolarization stage of an AP?
The permeability to Na is increased by opening of the sodium voltage gated activation channels. THis changes the potential from -90 to +35. The inactivation gates close slowly and are finally closed once the cell reaches +35.
What occurs during the falling re -polarization phase of an AP?
As the sodium voltage gated channels close a “special” potassium channel opens allowing K ions to flow out of the cell bringing the potential back to negative.
Describe the positive feedback of the sodium voltage gated channels?
The sodium channels are voltage gated so as the charge spreads down the axon each channel will open up leading to more depolarization.
How can a GP cause an AP?
If the GP is in the depolarizing direction and large enough to reach threshold for the AP.
What is threshold?
The potential in which the positive feedback cycle starts and can’t be stopped. Usually occurs around -65mV
How is stimulus strength encoded in an AP?
In the frequency of the production of action potentials.
Summation?
Post synaptic signals can be added on a neuron, or subtracting IPSPs from EPSPs.
Called integration by neuroscientists.
Temporal summation?
When one axon fires on the same point at different times. Post synaptic neuron adds the EPSPs and subtracts IPSPs produced in rapid succession from the same pre synaptic cell.
Spatial summation?
Same time different space. Post synaptic neuron adds EPSPs and subtracts IPSPs produced simultaneously on different parts of a neuron by different axons.
