Nervous Syst + Action Potentials Flashcards
What are the 3 rostral regions of the CNS in development that enlarge?
Prosencephalon, Mesencephalon, Rhombencephalon
How many ventricles does the central canal divide into ?
4
What parallels development of the CNS?
Evolution
What is the last evolutionary step of the CNS?
Diencephalon and Telencephalon
What’s the simplest structure of the CNS development?
Spinal cord
List the 4 main areas of the CNS
Cerebrum
Brain stem
Cerebellum
Spinal cord
List the 4 main areas of the CNS
Cerebrum, Brain stem, Cerebellum, Spinal cord
Which main area of the CNS has the highest brain function?
Cerebrum
Motor sensory functions are attribute to which part of the CNS
Cerebellum
The basic functions of life are carried out by which main area of the CNS?
Brain stem
What area of the CNS is the reflex site and carrier of information to the brain?
Spinal Cord
The craneal and spinal nerves are part of which Nervous system?
Peripheral NS
What is the function of the PNS?
The communication link: provides sensory input and motor output
What are the 2 parts the PNS divides into?
Somatic and Autonomic
Which PNS division is responsible for communicating with sensory organs and voluntary muscles with sensory and motor neurons?
Somatic division
The autonomic division of the PNS is made up of what 2 parts?
Sympathetic and Parasympathetic
Which part of the Autonomic PNS is arousing (fight/flight)?
Sympathetic
The calming (rest/digest) part of the Autonomic PNS is called?
Parasympathetic
Define ganglion
Collection of neuronal cell bodies OUTSIDE cells
Give and describe and example of a simple neural circuit
The Knee Jerk test:
- Sensory turns on extensors
- Flexors are turned off - interneurons
Are interneurons usually inhibitory or excitatory?
Inhibitory
In a simple circuit reflex, what causes a change in feeling or affect ?
Afferent neurons
Which neuron has its axons towards the body (motor)
Efferent
What does “glia” mean ?
Glue; non-neuronal cells assoc with the NS
Oligodendrocytes, Schwann cells, astrocytes and microglia are what type of cell groups of the CNS?
Local Groups
Which two cells produce myelin sheaths, which speeds up the neuronal transmission?
Oligodendrocytes and Schwann cells
In which part of the NS are Oligodendrocytes found?
CNS
Which myelin producing cell is only found in the PNS?
Schwann cells
Which local cell group of the NS intersects with blood vessels and synapses?
Astrocytes
The primary source of CNS immune function and the keepers of brain surveillance for damage and infection are ?
Microglia
The basic functional unit of the nervous system is called a ___________
Neuron
What are the 3 main parts of a neuron?
Soma, Neurites and Axon hillock
The neurites are an axon, dendrite and dendritic spines. Describe their function
Axon - output (pre-synaptic)
Dendrite - input (post-synaptic)
Dendritic spines - excitatory synapses
Which part of the neuron conducts the impulse of an action potential?
Axon hillock
The dendrites receive or give information?
Receive information from stimulus
What part of the neuron decides if the stimulus will fire or not?
The soma or body
Define neurotransmitter
Substance releases synaptically by a neuron to produce a response on another through a localized effect
Action potentials were published by who and which year?
Alan Hodgkin and Andrew Huxley in 1939
List the 5 steps of an action potential
- A stimulus surpasses the threshold from the Resting Membrane Potential
- Depolarization occurs - cell becomes more positive
- Repolarization - cell becomes more negative
- Hyperpolarization - cell overpasses RMP
- Cell goes back to RMP
In which step of the action potential does the cell go through a refractory period?
Hyperpolarization
In an excitable cell membrane, what structural and functional things are present?
Proteins
What is present in the excitable cell membrane that helps transport macromolecules?
Channels and transporter proteins
What are the 3 rules of ion flow ?
- From high to low concentrations
- away from opposite charge
- Membrane permeability alters movement
How is a measurable voltage established in the cell membrane?
When charged ions separate
What is the specific voltage where the cell is steady called?
Resting membrane potential
In a neuron, which ion is found in greater quantity outside of the cell?
Sodium
Potassium is found where in higher concentrations?
Inside the cell
The equilibrium potential of potassium is (positive/negative)
Negative
The equilibrium potential of potassium is (positive/negative)
Negative
Which ion has a positive equilibrium potential?
Sodium
What is Nernst equation used for?
To calculate equilibrium potential for an ion
The resting membrane is impermeable to which ion?
Sodium
What channels make up most of the resting membrane?
Potassium leak channels
How many sodium’s are pumped outside the cell for every 2 potassium’s?
3 Na out for every 2 potassiums in
Why is the resting membrane potential controlled in a neuron?
So the voltage changes can be detected within the neuron and an action potential can occur for a stimulus
An ALL or NOTHING principle allows what to happen?
Once the membrane reaches a threshold, an action potential will proceed no matter what and Na channels will open
In the regenerative cycle, what depolarizes the membrane and what flows in continuously?
A stimulus makes Na flow in, which depolarizes the cell continuosly
What is it called when the cell can’t fire again?
Refractory period
What causes the refractory period of a neuron?
Inactivates Na channels
In voltage gated ion channels, which ion channel shows slow activation?
Potassium channels
In which step of the action potential does the Na channel opens/activates?
In depolarization
Which voltage-gated ion channel does NOT inactivate?
K+ channels
During an action potential, what is characteristic of the Na channel activation ?
Rapid activation and depolarization
What propagates the action potential bidirectionally?
A myelin sheath
