Nervous Flashcards
What is the nervous system?
The master controlling and communicating system of the body
What reflects the nervous sytem’s activity?
Every thought, action, and emotion
What is the signaling device for body cells?
Elcectical impulses
Characteristics of responses
Rapid, specific, and almost immediate
What does the central nervous system consist of?
Brain and spinal cord
What do the brain and spinal cord occupy and do?
The dorsal body cavity and act as the integrating and ccommand centers of the nervous system
What does the central nervous system interpret?
Sensory information
What does the coentral nervous system issue?
Instructions based on past experience and current conditions
How are supporting cells lumped together?
As neuroglia or glia which means glue
WHat do supporting cells do for neurons?
They support, insulate, and protect delicate neueons
What can neuroglia cannot do?
Transmit nerve impulses because it is highly developed in neurons
What is nissl substance?
Rough ER
Where are neurofibrils found?
Inside the cell body
What is the funncion of neurofibrils?
To mantain cell shape
How big are neurofibrils?
The armlike processes or fibers vary in length from microscopic to 3 to 4 feet
Where are the longest neurofibrils?
Reach from the the lumbar region of the spine to tghe big toe
What are dendrites?
The neuron processes that convey invoming messages towards the cell body
What are axons?
Neuron processes that generate nerve impulses and consuct them away from the cell body
What are axonal terminals?
All axons branch at their teminal end, forming hundreds to thosands of them
What do axonal terminals contain?
Hundreds of tiny vesicles or membranous sacs that contain chenmicals called neurotransmitters
What is the synaptic cleft?
Each exonal termianal is separated by the next neuron by a tiny gap called it
What does syn mean?
To clasp or join
What is the synaptic cleft called?
A synapse
What are schwann cells?
Myeliate axons outside the CNS
What are schwann cells specialized in?
Supporting cells
What do schwann cells do and what is it called?
Wrap themselves tightly around the axon, myelin sheath
What are the three types of neurons?
Sensory, motor, and association
What dies afferent mean?
Towards
What does efferent me?
Away
How do motor neurons work?
Neurons carrying impulses from the CNS to the viscera and/or muscles and glands
Where are cell bodies of motor neurons located?
The CNS
How do association neurons work?
They connect the motor and sensory neurons in neutral pathways located in the CNS
What is another word for association?
Interneurons
What is structural classification for neurons based on?
The number of processes extending from the cell body
What kind of neurons are multipolar?
All motor and association
What makes a neuron multipo;ar?
If there are several processes
What kind of neuron is most common?
Multipoalr
What are bipolar neurons?
Neurons with two processes, an axon and a dendrite
What are bipolar neurons rare in?
Adults
Where are bipolar neurons found?
In some special sensory receptor cells of the eye and ear
What are unipolar neurons?
They have a single process emerging from the cell body
Where are unipolar neurons found?
In the PNS
What is the PNS?
Nerves extending from the broin and the Spinal cord, where unipolar neurons are found
What is the inside of the neuron and what does it have in it?
Negative, Potassium(K+)
What is the outside of the neuron and what does it have in it?
Positive, Sodium(NA+)
How does this phenomenon happen inside the neuron?
As long as the inside remains more negative as compared to the outside, the neuron will stay inactive.
What happens when a neuron is adequately stimulated?
The “sodium gates” in the membrane open
What happens when the sodium gates open?
Because of diffusion, sodium in higher concentration outside the cell will diffuse quickly into the neuron
What is depolarization?
The inward rush of NA+ changes the polarity of the neuron’s membrane, the inside is now positive and the outside is now negative
What happens if the stimulus is strong enough in depolarization?
It activates the neuron to initiate and transmit an action potential (essentially it keeps moving down the neuron), and it creates a nerve impulse in neurons
What is repolarization?
This outflow of positive ions from the cell restores the electrical conditions at the membrane to the polarized or resting state
What happens to a neuron until it is repolarized?
It cannot conduct another impulse
What happens after repolarization occurs?
The initial concentrations of the sodium and potassium ions inside and outside the neuron are restored by activation of the sodium/potassium pump
What does the sodium/potassium pump use?
Cell energy (ATP) to pump excess NA+ put of the cell aand to bring K+ back into the cell
What do cold and continuous pressure do?
Hinder impulse conduction
Why do cold and continuous pressure hinder impulse conduction?
They interrupt blood circulation and the delivery of oxygen and nutrients to the neurons
What is conductivity?
The travel of an impulse along one neuron to another neuron
What happens when action potential reaches the axonal endings?
The tiny vesicles containing the neurotransmitter chemical fuse with the axonal membrane, which ruptures and releases neurotransmitters
What is the transmission of an impulse?
An electrochemical event
When is the transmission down the neuron electrical?
Depolarization and repolarization
When is the transmission down the neuron chemical?
The release of the neurotransmitter into the synapse
What is was the body does every day programmed by?
Reflexes
What are three characteristics of reflexes?
Rapid, predictable, and involuntary responses to stimuli
What are reflexes like and why?
One way streets, once they begin they go in one direction
What is the reflex arc?
The neural pathways that a reflex travels
What do autonimic reflexes do?
Regulate the activity of smooth muscles like the heart and glands, examples are secretion of saliva- salivary reflex, and changes in the size of the pupil, papillary reflex
What do autonomic reflexes regulate?
Digestion, elimination, blood pressure, and sweating
What do somatic reflexes include?
All reflexes that stimulate the skeletal muscles
What is an example of somatic reflexes?
When you quickly pull your hand away from a hot object
What do all reflex arcs have a minimum of?
Five elements
