Nervous System Flashcards
What is the nervous system composed of
Nerve cells called neurons
What do a bunch of neurons form
A nerve
What is the central nervous system
System that includes the spinal cord and brain
What is the peripheral nervous system
The system that contains the rest of the body besides the brain and spine
What is the somatic nervous system
The nerves under conscious control (voluntary)
What is the Autonomic nervous system
Nervous system thats not under conscious control
(Involuntary)
What is sensory input
The conduction of electrical signals from sensory receptors
What is integration
When information is interpreted and a response is generated by the central nervous system
What is motor output
When signals from the CNS are conducted to effector cells like muscle, gland, organ which carry out the response
What are the two main types of nerves in the nervous system
Neurons and neuroglia
What does a neuron do
Transmits messages in the form of nerve impulses
Where are neurons found
All throughout the bodies nervous system (PNS and CNS)
What do neuroglia do
They are supporting cells, provides structure, protection, insulation, and nourishment to neurons
What is a dendrite/function
A part of a neuron that receives signals and conducts an impulse towards the cell body
Is usually the branches
What is the cell body/function
A part of a neuron that contains a nucleus and organelles
It maintains the cell
What is the axon/function
A part of the neuron that conducts impulses away from the cell body
What are dendrites and axons also called
Fibers
What are longer fibers covered by
A myelin sheath
What are the spaces within myelin sheaths called
Nodes of ranvier
What is the myelin sheath in the PNS composed of
Schwann cells (a neuroglia cell)
What is the myelin sheath produced by in the CNS
Cells called oligodendrocytes
What are the myelin sheaths functions
To insulate the neurons from each other as they pass through the nerve
Helps to speed up the impulse
Also plays an important role in nerve regeneration
And if a nerve is severed it may remain as a passageway for new nerve growth
Where does nerve regeneration not occur
The CNS
What are nodes of ranvier
The points between schwann cells/ gaps where there is no myelin sheath
What does the node of ranvier do
Speeds the impulse as it jumps from node to node
What are the three types of neurons
Sensory neuron
Motor neuron
Interneuron
What does the sensory neuron do
Takes a message from a sense organ to the brain
What is the sensory neuron made of and where is it found
A long dendrite and a short axon (CNS)
What does a motor neuron do
Takes a message away from CNS to a muscle fiber or gland
What us a motor neuron made of
Short dendrites and a long axon
What does an interneuron do
Conveys messages between the parts of the system
Conducts impulses from sensory to motor neuron and will sum up all messages before communicating with motor neurons
What is the interneuron made of and where is it
Its completely in the CNS and is made of dendrites and axons that are both long and short
What are nerve bundles
A bundle if long fibers from neurons in the PNS
When does an action potential occur
When a nerve is stimulated by an electric shock, pH change, or mechanical stimulation
What does an action potential do
Generates a nerve impulse
What are nerve impulses
They are electrical chemical changes
Changes in voltage and changes in an ion that make a membrane potential difference
What are nerve impulses measured in
Millivolts (mV)
What are the three phases in the generation of a nerve impulse
Resting phase
Action phase: depolarization and repolarization
Recovery phase
What is the concentration of ions in resting potential
Na+ ions are more concentrated on the outside and K+ more concentrated on the inside
How is the uneven distribution of ions maintained
Through active transport across Na+/K+ pumps
What are the charges of the inside/outside of neurons at rest
The outside is slightly more positive compared to the inside of the neuron
What voltage is resting potential
-70mV (voltage inside is -70mV compared to outside)
What is the negative polarity at resting potential caused by
The presence of large organic negative ions inside the axoplasm
What is axoplasm
The cytoplasm inside an axon
Where are there more Na+/K+ ions at rest
More Na+ outside of the axon
More K+ inside of the axon
What is action potential
It is when a nerve is stimulated, a nerve impulse is generated and the rapid change in voltage can be detected
This nerve impulse is action potential
Why is action potential all or nothing
Because an action potential only occurs if a stimulus causes the axonal membrane to depolarize to a certain level
(Has to hit a threshold to happen and wont stop once it does)
What happens to action potential if an intense stimulus is given
The axon will fire more often instead of stronger firing since the strength of action potential does not change
What are the two parts to action potential
Depolarization and repolarization
What happens when the membrane depolarizes
Na+ ions move from the outside to the inside of an axon
The sodium gates open first when an action potential occurs hence Na+ flows into the axon
What happens when the membrane repolarizes
K+ moves from outside to inside of axon
Potassium gates open second so K+ flows outside the axon
What is the recovery phase
When K+ ions are returned to the inside of axon and Na+ to the outside actively by the Na+/K+ pump
With the use of ATP
Done slowly
What color are nerves
They have a white appearance
Along a myelin sheath why can action potential only occur at nodes of ranvier
Because the myelin sheath insulates against ion loss
What is a synapse
The region between end of an axon and the cell body or dendrite to which it is attached
What are synaptic endings
The knobs on the ends of an axon
What is a presynaptic membrane
The membrane if the axon synaptic ending (before the synapse)
What is a postsynaptic membrane
The membrane of the next neuron after the synapse
What is the synaptic cleft
The space between the presynaptic and the postsynaptic membranes
What are neurotransmitters
The chemicals that transmit the nerve impulses across a synaptic cleft
What are synaptic vesicles
Objects that contain the neurotransmitters
What are the 4 important neurotransmitters
Acetylcholine, noradrenalin, serotonin, and adrenalin
