Week 1 - Neurons & Glia, Synapses & Neurotransmitters; Action Potentials & Synaptic Transmission Flashcards
What structures make up the Central Nervous System?
Brain & spinal cord
What structures make up the Peripheral Nervous System?
Cranial nerves, spinal nerves, ganglia, sensory receptors, somatic nervous system, autonomic nervous system, enteric nervous system
The spinal cord connects to the brain via what opening in the skull?
Foramen magnum
Afferent neurons are involved in what nervous system function?
sensory function - send sensory signals to the brain
Efferent neurons are involved in what nervous system function?
Motor function - brain sends signal to these neurons to act
What are cells contacted by efferent neurons called?
Effectors
Interneurons are involved in what function?
integrative function - spinal cord and brain level - signal relay
How many cranial nerves are there?
12 pairs
How many spinal nerves are there?
31 pairs
Describe what happens when the sympathetic nervous system is active
increased heart rate, blood vessels of digestive system vasoconstrict, pupils dilate, blood vessels to muscles vasodilate
Which part of the PNS is involuntary?
autonomic nervous system - breathing, heart beat
The autonomic nervous system consists of what two subdivisions?
sympathetic and parasympathetic
What is the function of enteric motor neurons?
govern contraction of the GI tract
List the general functions of neurons
sensing, thinking, remembering, controlling muscular activity, regulating glandular secretions
What is the function of neuroglia?
nourish, support and protect neurons
What are dendrites of a neuron?
the receiving (input) portion of the neuron
What is the function of a neuronal axon?
propagate impulses toward another neuron, muscle fiber or gland cell
What is the function of synpatic end bulbs?
store and release neurotransmitter
Define synapse
site of communication between two neurons or between a neuron and an effector cell
Describe the structure of multipolar neurons
one axon, many dendrites
What is the function of astrocytes?
provide structural support for neurons in CNS
form the blood/brain barrier
regulate chemical environment for generation of nerve impulses
influence formation of neural synapses (memory/learning)
What is the function of oligodendroctyes?
form myelin sheath around axons in the CNS
What is the function of microglia?
Responsible for phagocytosis in the CNS - removing cellular debris, microbes, damaged nerve tissue
What is the function of ependymal cells?
Form cerebrospinal fluid, form blood-CSF barrier
What is the function of Schwann cells?
Form myelin sheath around axons in the PNS
Assist axon regeneration
What is the function of satellite cells?
Provide structural support
Repair peripheral neurons
regulate transport between neuronal cell bodies and interstitial fluid
What is the function of the myelin sheath on an axon?
Form segments of insulation to increase speed of nerve impulse conduction
What is the average resting membrane potential of a neuron?
-70mV
Name the 4 types of ion channels
Ligand-gated channel, leakage channel, voltage-gated channel, mechanically gated channel
Describe the electrochemical gradient
An electrical difference and a concentration difference across a membrane
What is the threshold for action potentials?
-55mV
What are ganglia?
small masses of nervous tissue, consisting primarily of neuron cell bodies, that are located outside the CNS
Two homeostasis-controlling systems are ________
nervous system
endocrine system
The Effector Organs/Targets of Somatic Nervous System are the following:
external & internal lining of the body wall
extremities
special senses - smell, taste, vision, hearing, equilibrium
Two Effector Organs/Targets of the Autonomic Nervous System but located within the soma are ___________
sweat glands
erector pilli muscles
The Effector Organs/Targets for the Autonomic Nervous system are __________
smooth muscle
cardiac muscle
secretory glands
There are ___ types of neurons, namely ________
3
motor/efferent
sensory/afferent
interneurons
The most ubiquitous neurons within the CNS and PNS are _________. Their major function is to maintain the ___________
interneurons
balance between excitatory and inhibitory impulses
The principal difference between the functions of neuron versus glia is ________
glia cells are unable to transmit potentials
The major common function of oligodendrocytes and Schwann cells is _______
they form myelin sheaths around axons
The major functional difference between oligodendrocytes and Schwann cells is ___________
Schwann cells assist regeneration of axons
Oligodendrocytes resist regeneration of axons
A neuron consists of the following parts _________
cell body / perikaryon / soma dendrite axon axon hillock axon terminal synaptic bulb Nissl's bodies Nodes of Ranvier
Describe the resting membrane potential
an electrical potential difference across a plasma membrane. The interior side of the membrane has a relative negative charge while Na+ ions on the exterior of the membrane form a relative positive charge
How do leakage channels operate?
randomly alternate between open and closed positions
facilitate passage of K+ and some Na+ ions across concentration gradient
How do voltage channels operate?
open in response to change in membrane potential
participate in generation and conduction of action potentials
How do ligand channels operate?
open and close in response to specific chemical stimulus
How do mechanical channels operate?
open and close in response to mechanical stimulation - vibtration, touch, pressure, tissue stretching
How do Light channels operate?
open and close in response to light stimuli
What is the major ion, which is guarding a resting membrane potential and why?
K+
The cell membrane is more permeable to K+ than any other ion at rest
What ion channels are open during depolarization phase of action potential?
voltage-gated Na+ channels
What ion channels are opening during re-polarization phase of action potential?
voltage-gated K+ channels
What are two types of synapses?
electrical synapse
chemical synapse
What type of synapse is the most abundant within the human organism?
chemical synapse
The intrinsic nervous system of the GI tract, which is called ________, is represented by the clusters of functionality related and interconnected neurons. The clusters are called _______ and they represent _________
enteric nervous system
ganglia
Meissner’s plexus - GI secretion
Auerbach’s plexus - peristalsis
The axon hillock is most effective site of ______________ because _______
action potential initiation
it is densely populated by Na+ channels
White matter is compose primarily of ___________
myelinated axons
Gray matter of the nervous system contains ________
neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia
Gray matter is gray because __________
Nissl bodies impart a gray color
The nodes of Ranvier have a high density of ____
Na+ channels
What ion is needed for the transmission of a signal in a chemical synapse?
Ca2+
