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Terms in this set (58)
a single nerve cell
Large bundle of many different axons from different neurons.
What are axons made up of?
function of kinesin
atp dependent motor protein that moves secretory vesicals in nerve terminals; anterograde("+" end;movement from soma to axon terminus) on microtubules
Drive movement of vesicles and organelles along microtubules in axons
channels that are always open and allow specific ions to move along their gradient
(IE: K+ leaks allow K+ to leak through, but no other ions)
The cell membrane is virtually impermeable to sodium.
resting membrane potential
the electrical charge of a neuron when it is not active
What is an action potential?
the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell (depolarization of plasma membrane)
An electrochemical impulse
On average, what is the resting membrane potential?
What is the threshold potential?
Opens the sodium channels to enter cell and depolarize that section of the membrane to about +35mV before inactivating
If action potential starts at one end of an axon, can it run out of energy and not reach the other end?
No, action potential are continually renewed at each point in the axon as they travel. Assuming there are enough voltage-gated sodium channels, once an axon potential starts, it will not stop until it reaches a synapse
Depolarization of membrane
Means that the membrane is getting less negative and also known as the excitatory state because it is getting closer to the threshold potential which triggers the action potential (-50mV).
Nodes of Ranvier
Gaps in the myelin sheath to which voltage-gated sodium channels are confined.
A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
the jumping of action potentials from node to node
Equilibrium potential for Na+
equilibrium potential for K+
absolute refractory period
The minimum length of time after an action potential during which another action potential cannot begin.
relative refractory period
A period after firing when a neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual
electrical synapses (gap junctions)
Occur when the cytoplasms of 2 cells are joined by gap junctions
If 2 cells are joined by an electrical synapse, the action potential will spread directly from one cell to the other.
a type of synapse at which a chemical (a neurotransmitter) is released from the axon of a neuron into the synaptic cleft, where it binds to receptors on the next structure (either another neuron or an organ)
chemical synapse steps
1. An action potential reaches the end of an axon, the synaptic knob.
2.Depolarization of the presynaptic membrane opens voltage-gated calcium channels.
3.Calcium influx into the presynaptic cell causes exocytosis of neurotransmitter stored in secretory vesicles.
4. Neurotransmitter molecules fuse across the narrow synaptic cleft (space btwn cells)
5. Neurotransmitter binds to receptor proteins in the postsynaptic membrane. These receptors are ligand-gated ion channels
6. The openings of these ion channels in the postsynaptic cell alters the membrane polarization
7. If the membrane depolarization of the postsynaptic cell reaches the threshold of voltage-gated sodium channels, an action potential is initiated
8. Neurotransmitter in the synaptic cleft is degraded and/or removed to terminate the signal.
Determining action potential initiation by adding the effect of all the synapses impinging on a neuron, both excitatory and inhibitory.
A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession.
EPSP and IPSP from all of the synapses on the postsynaptic membrane are summed at a given moment in time.
If this causes the postsynaptic membrane to reach threshold voltage, an action potential will be fired.
efferent neurons (motor neurons)
take information from the brain to the rest of the body
afferent neurons (sensory neurons)
take information from the senses to the brain
Interneurons (association neurons)
found in neural pathways in the CNS, connect sensory and motor neurons
glial cells (glia)
Specialized, non-neuronal cells that typically provide structural and metabolic support to neurons.
Maintain resting membrane potential, but do not generate action potentials
Schwann cells (PNS)
Form myelin sheath in the peripheral nervous system
Type of glial cell in the CNS that wrap axons in a myelin sheath.
for blood brain barrier; control external environment of neurons
regulate synaptic communication via regulation of neurotransmitter levels
Remove cell debris, wastes, and pathogens by phagocytosis
CNS; Produce and circulate cerebrospinal fluid
What is included in the Hindbrain?
medulla, pons, cerebellum
function of medulla oblongata (hindbrain)
Part that connects to the spinal cord; Regulates vital autonomic functions (breathing, blood pressure, digestion (including vomiting), blood flow, respiratory rate, swallowing)
INVOLUNTARY (sneezing and coughing)
function of pons
Regulates respiration, swallowing, facial muscle movements, AND antigravity posture/balance
function of cerebellum
Balance and coordination
Relays visual and auditory information and contains much of the reticular activating system (RAS), which is responsible for arousal or wakefulness.
Brainstem consists of
midbrain, pons, medulla oblongata
In most people, which side o the brain considered dominant?
Left side (most concerned with speech)`
What is the right side of the brain most responsible for?
visual-spatial reasoning and music
relay station for sensory impulses, pain
emotions, autonomic functions, and major role in hormone production and release
homeostasis and behavior
Controls the pituitary gland
Thick band of axons that connect the left and right cerebral hemispheres
Area of the brain responsible for all voluntary activities of the body; largest part of the brain
Cerebral cortex consists of?
1.) frontal lobe
2.) parietal lobe
3.) temporal lobe
4.) occipital lobe
frontal lobe function
involved in motor function: problem solving, memory, judgment, impulse control (voluntary)
Parital lobe function
Involved in general sensations (touch, temperature, pressure, vibrations, etc.) and taste
temporal lobe function
hearing (auditory) and smell (olfactory sensation)
also involved in short-term memory, language comprehension, and emotion
basal ganglia (nuclei)
help initiate and terminate movements, suppress unwanted movements, and regulates muscle tone
thalamus and hypothalamus
What does the limbic system consist of?
hippocampus, amygdala, cingulate gyrus
What role does the limbic system play?
Emotion and memory
unmyelinated neuron cell bodies and short, unmyelinated axons
* Runs along carotids
* Motor to some sensory for other organs
types of sensory receptors
mechanoreceptors, chemoreceptors, electromagnetic receptors, thermoreceptors, nociceptors
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