Jan - 13 Central Nervous System Flashcards
what are the 2 major parts of the nervous system?
- The central nervous system
- the peripheral nervous system
What are the parts of the central nervous system?
cerebrum (brain)
brainstem
cerebellum
spinal cord
What does the peripheral nervous system consist of?
It consists of all remaining nerves outside the CNS (outside the cerebrum, brain stem, spinal cord)
how many pairs of nerves are in the spinal cord vs. the cranial nerves?
31 pairs in the spinal
12 pairs in the cranial
What does the PNS do?
connects the brain to the outside world.
Would the cranial nerve v11, facial nerve, be apart of the CNS or PNS
PNS.
What is a neuron or cell nerve?
It is a fundamental unit of the nervous system. They are specialized cells that transmit information throughout the body in the form of electrical and chemical signals. They are critical for communication between different parts of the body and the brain.
What are 7 major parts of the nerve?
- dendrites
- soma/cellbody
- axon
- myelin sheath
- nodes of Ranvier
- axon terminal
- synapse
What are dendrites and their function?
Dendrites are tree-like extensions at the beginning of a neuron that helps in receiving signal from other neurons.
Function: They increase the surface area for receiving incoming signals and transmit the electrical stimulation received from other neural cells to the cell body.
What are cell bodies and their function?
The soma is the bulbous end of a neuron, containing the nucleus.
Function: It combines the electrical signals received from the dendrites to send them down the axon.
What are axons and their functions?
The axon is a long, slender projection that conducts electrical impulses away from the neurons cell body.
Function: It’s responsible for transmitting the neurons electrical signals to other cells, either neurons or muscles.
Do thicker or thinner axons transmit faster?
Thicker axons transmit impulses faster than thinner axons.
What is the myelin sheath and its function?
The myelin shelth is a protective fatty laayer that wraps around the axon
Function: It increases the speed at which electrical impulses propagate aling the axon and also helps in protecting the nerve fiber.
What are the nodes of Ranvier and their function?
These are small gaps in the myelin sheath along the axon.
Function: They facilitate the rapid conduction of nerve impulses along the axon by forcing the electrical impulse to jump from one node to the next. This is called “Sultatory conduction”
What is Sultatory conduction?
Sultatory conduction is when the nodes of Ranvier facilitate the rapid conduction of nerve impulses along the axon by forcing the electrical impule to jump from one node to the next.
What is the axon terminal and its functions
The axon terminal is the end portion of the axon which makes synaptic contacts with the other nerve cells or effector cells (like muscles cells)
Function: It’s involved in releasing neurotransmitters, which are chemicals that transmit signals to other neurons or effectors
what is the synapse and its function
a synapse is a junction between 2 neurons, where the axon terminal of one neuron meets the dendrite of another.
Function: It allows neurons to pass signals to other neurons, muscles, or glands.
What is a motor neuron and its function?
motor neurons transmit signals from the central nervous system to muscles, causing them to contract.
Function: They play a key role in movement, including voluntary and involuntary actions.
What is a sensory neuron and its function?
Sensory neurons transmit sensory information (like touch, sound, sight) from the sensory organs to the central nervous system.
Function: They are responsible for converting external stimuli into internal electrical impulses.
What is a interneuron and its function?
Interneurons, located within the central nervous system, communicate internally and intervene between the sensory inputs and motor outputs.
Function: They play a crucial role in reflexes, neuronal oscillations, and neurogenesis in the human brain.
what are the 3 types of neurons?
sensory, motor, interneuron.
What is gray matter composed of, where is it found, and its function?
- Comprises neuronal cell bodies, dendrites, glial cells, and capillaries.
- Involved in muscle control, sensory perception, memory, emotions, speech, decision making, etc.
- Predominantly found in the cerebral cortex.
What is white matter composed of, where is it found, and its function?
- Composed of axons coated with myelin sheaths, giving it a white appearance.
- Connects different brain regions and facilitates rapid transmission of nerve signals.
- Males up a larger volume of the brain compared to gray matter.
Which type of matter does the brain have more of?
The brain contains more white matter in terms of volume; however both types of matter are essential for its overall function and health.
What is neural impulse transmission? What is another name for this? what neural activities is it crucial for?
- Neural impulse transmission refers to the process by which neurons send and receive signals.
- Its also called the conduction of action potentials
- this process is crucial for the functioning of nervous system and is fundamental to all neural activities including: sensing, thinking, moving, regulating internal body processes, etc.
What are the 7 key steps of neural impulse transmission?
- Resting potential
- Depolarization
- Rising phase
- Repolarization
- Hyperpolarization
- Refractory period
- Restoration
Resting Potential:
What is the resting membrane potential of the neurons?
-70mV
Resting Potential:
How is the resting potential maintained?
by the sodium potassium pump.
Depolarization/Rising phase:
A stimulus strong enough to reach the threshold of what triggers what?
A stimulus strong enough to reach the threshold of excitiaion triggers the opening of voltage-gated sodium channels.
Depolarization/Rising phase:
what causes depolarization?
Sodium ions rush into the neuron, causing depolarization as the interior becomes more positive.
Depolarization/Rising phase:
The membrane potential rapidly rises reaching what mV? what does this cause?
+30 - +40mV. This rapid change in charge consitutes the rising phase of the action potential.
Repolarization:
What happens during repolarization?
- Voltage-gated sodium channels close, and voltage-gated potassium channels open.
- Potassium ions flow out, causing the membrane potential to become more negative, moving towards the resting potential.
Hyperpolarization:
What is hyperpolarization?
- Membrane potential may temporarily become more negative than the resting potential.
- This state makes the neuron less sensitive to new stimuli.
Refractory period:
What is the refractory period? What can’t happen during the refractory period?
- After an action potential (during the period of hyperpolarization), the neuron experiences a refractory period.
- During the absolute refractory period, no new action potential can be initiated.
What happens during the restoration of the resting potential?
The sodium-potassium pump restores the original ion distribution.
This action returns the neuron to its resting potential, readying it for the next stimulus.
