Introduction to Veterinary Anatomy and Physiology- Nervous System- Membrane Channels and Potentials
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channels that allow ions to filter in on their own
gated channels which open in response to chemical, voltage, or mechanical changes presented to the cell membrane
the post-synaptic cell membrane has receptors for neurotransmitters allowing them to open or close and mostly used when the action potential has arrived at its destination.
chemically-gated channels/ neurotransmitter-gated channels
receptors that the messenger from one side of the membrane to the other using direct ion exchange, which is supposed to be much faster.
direct channel/ ionictropic channel
sends out a protein once the transmitter has docked, which in turn ignites functions in the cell
Indirect channel/ Metabotropic channels
receptor releases a protein (G protein) that in turn starts the production of energy
indirect channel/ metabotropic channel
what is normal resting potential?
__?__ open when the membrane potential (charge) reaches about -55 to +50 mV, becoming less negative and stimulate membranes that need to generate an action potential themselves.
Na, K, and Ca are the most common ions involved in the ion-gated channels. Positive ions start hanging around and push negative ions away and help perpetuate the action potential and stimulate skeletal and cardiac muscle.
toxins such as as the curare frog skin and the puffer fish work by blocking these ion-gated channels causing
a physical change that causes the distortion in the cells to open the gate, like tactile senses
__?__ receive transmitters such as GABA, glycine, and serotonin
the amount of change depends on the __?__ of the change and __?__ of the neurotransmitter.
If there is a lot of neurotransmitter, there is a strong response. Too much of a neurotransmitter inhibits the response all together.
An excitatory neurotransmitter is one that causes the membrane potential to head back to 0 mV, or other wise called depolarization because it makes it more positive.
- excitatory post synaptic potential
__?__ causes the channel to open so the Na may flow in kicking out K, depolarizing the cell. Dendrites and cell bodies work with voltage-gated channels. The action potential is instant.
Certain neurotransmitters causes the membrane potential to become more negative, other wise called hyperpolarized. This inhibits or "turns off" the response. the different ways of making the cell back away from the threshold.
- inhibitory post synaptic potential
Open K channels to let K leak in and make cell more negative. Open Cl channels and let Cl leak in and make cell more negative.
The 4 phases of the action potential
- 1. resting phase
- 2. depolarization phase
- 3. rising phase
- 4. falling phase
when the voltage-gate channels have close and theres passive ion movement across the membrane
when chemical or mechanically-gated channels are stimulated open and produce PSPs, summating
or adding up to a big charge.
Signals meet at the dendrite and are transfered to the axon hillock
when actual generation of the action potential is the third step and the threshold reaches the voltage-gated channels open and Na flows in.
when the Na channels are inactivated at the peak of the AP and no stimulus of any kind can initate a new AP
absolute refractory period
when only a large stimulus can initiate a new AP
relative refractory period
periods of the rising phase
- 1. absolute refractory period
- 2. relative refractory period
when the peak of the action potential inactivates the Na channel and activates the K channel, so now K may flow in, repolarizing the cell. As K keeps flowing, there is a point where the cell becomes hyperpolarized, referred to as the undershoot.
2 phases an AP can initiate.
- 1. resting phase
- 2. the relative refractory period of the rising phase (if stimulus is strong enough)
Correctly order the following:
C. Normal (-75 mV)
D. Action Potential
Action potential --> Spike--> Hyperpolar --> -75 mV
True or False:
The K in the cell during the rising phase is attracted to the normal negativity of the charged cell along the membrane, causing the depolarization that allows the K channels in the new area to open.
- The Na in the cell during the rising phase is attracted to the normal negativiry of the charged cell along the membrane, causing the depolarization that allows the Na channels in the new area to open.
True or False:
The wave can move backwards if it has a strong enough signal.
The wave can not move backward, only forward because when the next channel opens the one before it is still in its absolute refractory period.
Conduction velocity relies on
- 1. diameter of axon
- 2. Myelin that surrounds the axon.
fatty material that works as an insulator for the axons
small gaps between each section of myelin on the axon
Nodes of Ranvier
__?__ channels are concentrated on the nodes. The node allows the AP to skip across it at a fast rate.
Neurotransmitters only work for what __?__ exist to decipher them.
The frequency and speed of the stimulus mostly has to do with __?__.
The strength of the stimulus
regional divisions of the brain
- 1. forebrain
- 2. midbrain
- 3. hindbrain
subdivisions of the forebrain
- 1. hippocampus
- 2. limbic system
- 3. thalamus
- 4. hypothalamus
subdivisions of the midbrain
1. circadian rhythms
subdivisions of the hindbrain
division of brain that deals with memory, learning, and has some control of periodic things.
division of brain that deals with emotion
division of brain that deals with master sensory relay
division of brain that deals with the control of many things including the endocrine glands
division of brain that deals with integration of sensory information
division of brain that deals with our internal clock of 24/7 hour period
division of brain that deals with motor and autonomic functions
Circadian rhythms controls:
- 1. sleep/wake cycles
- 2. internal or core temperature varies throughout the day
- 3. feed forward
- 4. photoperiod
- (5. mating for insects)
__?__ have free running rhythms lasting more then 24/7.
anticipation of change instead of waiting to respond to some things external
- 1. cranial nerve I
- 2. cranial nerve V
- 3. cranial nerve VII
- 4. cranial nerve X
cranial nerve I
cranial nerve V
the longest nerve
vagus/ cranial nerve X
decrease in sensitivity in response of a stimulus presented repeatedly
prolonged enhancement of a reflex by introducing a second, often noxious stimulus to "ramp out" the response.
uses both habituation and sensitization to get a conditioned response
what experiment is this a representation of?
pavlov dog experiment on classical conditioning which uses both habituation and sensitization
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