Nervous System Flashcards
What are two major subdivisions of the nervous system ?
Central nervous system (CNS) and peripheral nervous system (PNS)
What encompasses the CNS ?
Brain and spinal cord
What encompasses the PNS ?
All nervous tissue outside the CNS.
What are the brain and spinal cord contained in ?
The brain is contained in the cranial cavity of the skull. The spinal cord is within the vertebral cavity of the vertebral column.
What two basic cells are nervous tissue of both the CNS and the PNS comprised of ?
Neurons and glial cells.
What is another word for the cell body of neurons ?
Soma
What are processes ?
The extensions of the cell.
What is an axon ?
Process that all neurons. A fiber that connects neuron with its target.
Dendrite
Process that branches from the soma. Responsible for receiving most of the input from other neurons.
What is gray matter ?
Regions with many cell bodies and dendrites.
What is white matter.
Region of the brains with many axons.
Why is white matter white?
The axons are insulated by lipid rich axon substance, myelin.
What is a localized collection of neuron cell bodies in the CNS called ?
Nucleus
What is a cluster of cell bodies in the PNS called ?
Ganglion
What is a bundle of axons or fibers called in the CNS ?
Tract
What is a bundle of axons or fibers called in the PNS?
Nerve
What is sensation ?
Nervous system receives information about the environment around a person.
What is motor response ?
The response generated based on sensation.
Sensory functions
Regions of the brain which are responsible for sensation.
Motor functions
Regions of the brain responsible for response.
Integration
Region of the brain which is responsible for integration process; combining sensory perceptions and higher cognitive functions (memories, learning and emotion) to produce a response. The stimuli is compared to other stimuli (memory).
What does sensation involve ?
Stimulus - taste, smell, touch, sight and hearing.
What type of stimuli are the 5 senses ?
Taste and smell - chemical
Sight - light
Hearing - perception of sound which is physical
Touch - physical or mechanical
Are there more than the 5 senses in regards to stimuli ?
Yes, more sense can be found in the internal environment - stretching of organ wall or concentration of certain ions in the blood.
What does response entail in the nervous system ?
- based of stimuli
- nervous system can cause contraction of all three muscle types
- neurol control of the glands in the body (production and secretion)
How are responses divided in the body?
Voluntary (contraction of skeletal muscle) and involuntary (contraction of smooth muscle, regulation of cardiac muscle and activation of glands).
What governs involuntary responses in the nervous system ?
The automatic system.
What governs voluntary responses ?
The somatic nervous system.
What is the somatic nervous system ?
Responsible for conscious perception and voluntary motor response. Reflexes - skeletal muscle contractions.
What is autonomic nervous system ?
Responsible for involuntary control of the body - usually for homeostasis. Smooth and cardiac muscles, but also glandular. Role is to regulate the organ system.
What is the enteric nervous system ?
Responsible for controlling the smooth muscle and glandular tissue in your digestive system. Large part of the PNS not dependent on CNS.
What is the PNS divided into ?
- Somatic nervous system (SNS)
- Autonmic nervous system
What is the basis of communication in the nervous system ?
Action potential
What allows charged particles to move through the plasma membrane ?
Transmembrane proteins, specifically channel proteins
Does the Na+/K+ pump use energy ?
Yes, it uses ATP, so active transport as the Na+ and K+ move against their concentration gradient.
Why can channels interact with ions?
They have amino acids inside regions of the protein channel.
What will channels for cations (positive ions) have ?
The amino acids will have negatively charged amino acids.
What will channels for anions (negatively charged ions) have ?
They have positively charged side chains.
What is electrochemical exclusion?
The channel ision specific.
Size exclusion
Channels which are selective for size.
What is resting membrane potential ?
Steady state of the cell.
How is the dynamic process of the action potential maintained ?
Ion leakage and ion pumping.
What has to occur for a electrical signal to start ?
The membrane potential has to change.
What is depolarization ?
- channel opens for Na+ in the membrane
- Na+ moves into the cell due to the concentration gradient
- the voltage becomes less negative as the Na+ which are positively charged
- membrane potential moves towards zero
- the membrane potential will reach +30mV
Why does the voltage around the pores become positive during depolarization ?
The Na+ keeps moving into the cell even after the membrane potential reaches zero.
Repolarization
- as membrane potential reaches +30mV, the other potassium voltage gated channels open in the membrane
- K+ starts to leave the cell, taking a positive charge with it
- the membrane moves back towards -70mV
Hyperpolarization
- ## Occurs as the repolarization overshoots the -70mV resulting in it going below this number as potassium ions reach equilibrium with the membrane below -70mV (delay in K + channels closing)
What is the voltage change which occurs during depolarization ?
100mV, as -70mV to 30 mV
What type of Na+ channels are important for depolarization ?
-*some stimulus is needed
- ligand gated Na+ channel; opens when a neurotransmitter binds to it
- mechanically gated Na+ channel; opens when a physical stimulus affects a sensory receptor
- voltage gated Na+ channel
When does the voltage gated Na+ channel open ?
- help depolarization
- occurs due to a stimulus
What happens if depolarization does not reach -55mV or higher ?
If the threshold is not met then the action potential does not occur.
Do all action potentials peak at +30mV?
Yes, no action potential is bigger or smaller - all are the same.
What does a stronger stimuli do to action potentials?
Initiates multiple action potentials. NOT bigger action potentials.
What type of channels are depolarization and repolarization dependent on ?
Voltage gated Na+ channels and voltage gated K+ channel.