Chapter 4 - Nervous System Flashcards
Parts of the neuron
7
Cell body / soma
Dendrites
Axon hillock
Axon
-myelin sheath
-oligodendrocytes / Schwann cells
Nodes of Ranvier
Nerve terminal
SynapseWhat is a nerve?
What are 3 types of nerves based on the info they carry?
Nerve = many neurons bundled together
Sensory
Motor
Mixed
What is a ganglia?
Cell bodies of the same type clustered together.
What are tracts? Where are they found (general)?
Tracts are when axons are bundled together in the CNS
They only carry one type of information (unlike nerves)
Cell bodies of neurons IN THE SAME TRACT are grouped into nuclei.
What is an astrocyte?
Cell that nourishes the neuron and forms the BLODD-BRAIN BARRIER (which controls transmission of dilutes from he bloodstream to the nervous tissue)
What are ependymal cells?
These cells line the ventricles of the brain and produce cerebrospinal fluid (physical support for the brain, and shock absorber)
What are microglia ?
Phagocytic cells that break down waste products and pathogens in the CNS
What are oligodendrocytes and Schwann cells?
Oligo - CNS
Schwann - PNS
Produce myelin around axons
What is the threshold value of an action potential?
-55 mV to -40 mV
What is temporal summation?
What is spatial summation?
Summation is the additive effect of multiple inhibitory/excitatory signals.
Temporal: multiple signals are within a short period of time
Spatial: additive effects are based on the number and location of the signals.
What are the main functions of the nervous system?
Govern involuntary behavior
Govern voluntary behavior
Maintain homeostasis
What is a sensory neuron?
What does it do?
–> AFFERENT neuron
Transmit sensory info rom receptors to the spinal cord and brain
What is a motor neuron?
What does it do?
–> EFFERENT neuron
Transmits motor info from the brain and spinal cord to muscles and glands.
What is an interneuron?
Between other neurons
Located mostly in brain and spinal cord
Most numerous
Often linked to REFLEXIVE behavior
What is a supraspinal circuit?
When the sensory info is processed at the level of the brain / brainstem.
Differs from reflexes, which only require processing at the level of the spinal cord.
White matter & grey matter
In the brain vs in spinal cord
White - axons in myelin sheaths
Grey - cell bodies a and dendrites
White matter lies DEEPER in the brain.
White matter lies on the OUTSIDE in the spinal cord.
4 divisions of the spinal cord:
Cervical
Thoracic
Lumbar
Sacral
What is the dorsal root ganglia?
Sensory neurons bring in info from the periphery and enter the BACK of the spine - the cell bodies are found on the DORSAL ROOT GANGLIA.
Where do motor neurons exit the spine?
Ventral part of the spinal cord
The PNS (peripheral) has how many cranial and spinal nerves?
12 pairs of cranial nerves
31 pairs of spinal nerves
Two subdivisions of the PNS:
Somatic nervous system
Autonomic nervous system
(Voluntary/involuntary)
What does the somatic nervous system consist of?
Sensory and motor neurons
Distributes throughout skin, joints, and muscles.
What does the autonomic nervous system consist of?
Regulates Heartbeat Respiration Digestion Temperature control Glandular secretions
Manages involuntary muscles (ie internal organs and glands)
Regulates body temp via SWEATING or PILOERECTION.
Diff between somatic and autonomic:
In peripheral component:
Somatic: motor neuron goes directly from spinal cord to muscle
Autonomic: two neurons work in series - preganglionic and postganglionic. Preganglionic soma is in CNS (spine), axon goes to a ganglion in the PNS where it synapses on the cell body of the postganglionic neuron, which then affects the muscle.
What is a neuron?
A cell capable of transmitting electrical impulses and translating electrical impulses into chemical signals.
Two subdivisions of the Autonomic nervous system:
Sympathetic
Parasympathetic
(These are antagonistic)
Parasympathetic NS - what it does:
7
Constricts pupils Stimulates saliva Constricts bronchi* Slows heartbeat* Stimulates peristalsis & secretion* Stimulates bile release* Contracts bladder*
*innervated by cranial nerve X (vagus)
What does the sympathetic NS do?
9
Dilates pupils Inhibits salivation Dilates bronchi Accelerates heartbeat Stimulates sweating/piloerection Stimulates glucose prod + release Secretion of adrenaline + noradrenaline Inhibits bladder contraction Stimulates orgasm
Neurotransmitters in sympathetic versus parasympathetic responses:
Parasympathetic:
Acetylcholine (in both pre and post ganglionic neurons)
Sympathetic:
Acetylcholine in preganglionic
NOREPINEPHRINE in postganglionic
Monosynaptic reflex arc:
One example
Has a single synapse
(Between sensory neuron, and motor neuron)
Example: knee-jerk reflex
Polysynaptic reflex arc:
One example
AT LEAST one inter neuron between sensory neuron and motor neuron.
Ie withdrawal reflex (stepping on a nail, withdrawing the foot - requires balance from the other foot, inter neurons provide connection from sensory info to the motor neuron in the other leg)
What system controls all of the GLANDS in the body (except sweat glands)?
The parasympathetic nervous system
