Chapter 6/ Neuronal Signaling and the Structure of the Nervous System Flashcards
CNS
Central Nervous System
PNS
Peripheral nervous system
BLANK are the basic cell type in both division
-Generate electrical signals
Neurons
Do not generate signals, play important
supportive functions for neurons
Glial cells
Dendrites
Structure of a Neuron
Cell Body
Structure of a Neuron
Axon (Nerve Fiber)
Structure of a Neuron
Receive incoming
information
Dendrites
-contains nucleus
-integrates incoming info
cell body
Carry outgoing signals to
target cell
Axon (Nerve Fiber)
In CNS – Oligodendrocytes
In PNS – Schwann cells
Myelin Sheaths
Many axons are myelinated
– 20-200 layers of modified plasma membrane
Myelin Sheaths
Oligodendrocytes
Central Nervous System
Schwann cells
Peripheral Nervous System
Speed up conduction of
electrical signals along
the axon.
Saltatory conduction
Myelin Sheaths
Afferent neurons
Efferent neurons
Interneurons
Functional Classes of Neurons
Carry information towards CNS
Afferent neurons
Carry information away from CNS
Efferent neurons
Connect neurons within the CNS
interneurons
Blank and blank neuron axons bundled together.
Afferent and efferent
Specialized junction between two neurons.
Synapses
Pre-synaptic neuron releases
Nuerotransmitter
Neurotransmitters diffuse across the synaptic cleft
and bind to receptors on BLANK
post-synaptic neuron
Synapses can be BLANK
(Depends on neurotransmitter released)
stimulatory or inhibitory
Found in CNS and PNS
Glial cells
Astrocytes
Microglia
Ependymal cells
Oligodendrocytes
in the CNS (Central nervous system)
Schwann cells
in the PNS(Peripheral nervous system)
regulate extracellular environment of neurons, form “blood-brain barrier”
Astrocytes
specialized “macrophage-like” cells, perform immune functions
Microglia
produce cerebrospinal fluid (CSF)
Ependymal cells
produce myelinate axons
Oligodendrocytes
produce myelinate axons
Schwann cells
separated electrical
charges have the
potential to do work
Electrical potential
Inside of the cell negatively charged, relative
to the outside
-40 to -90 mV
resting membrane potential
Result from excess negative ions inside the cell
resting membrane potential
Changes to membrane potential are due to movement of ions
Na+, K+, Cl-
(More Na outside, more K inside)
resting membrane potential
Na+/K+ ATPase pump establishes the concentration gradients for Na+ and K+
Establishing Resting
Membrane Potential
More open K+ channels than Na+ channels in a resting membrane
Greater efflux of positive charges,
negative membrane potential
develops
-Depolarization
-Overshoot
-Repolarization
-Hyperpolarezing
-Resting Potential
Changes in resting potential
Changes to membrane potential that are confined to a small region of the plasma membrane
Graded Potential
Na+/K+ ATPase pump maintains
concentration gradients
Magnitude of
the potential
change can
vary
Graded Potential
Change in membrane potential BLANK as distance BLANK from site of initial change
decreases
increases
-Large alterations in membrane potential
-“All or none” response
-Very rapid, 1-4 milliseconds
Action Potential
the ability to generate action
potentials
(Neurons and muscle cells)
Excitability
To cause an action potential a cell must utilize
several types of BLANKS
ion channels
Ligand-gated and mechanically gated serve as the BLANK for the action potential
initial stimulus
Voltage-gated channels give a membrane the
ability to undergo rapid blank and blank
depolarization and
repolarization
EK
potassium
equilibrium
potential
PK
permeability of
potassium
PNA
permeability of
sodium
Generation of action potentials can be prevented by BLANK
(Procaine and lidocaine)
local anesthetics
Animals can produce BLANK that interfere with
nerve conduction
Toxin
Tetrodoxin
-During the action potential
-No stimulus can produce a second AP during this
time
Absolute refractory period
-Following absolute RP
– Second AP can be produced if stimulus is strong
enough.
Relative refractory period
Action potentials
are BLANK
unidirectional
Velocity of AP propagation depends upon
BLANK and BLANK
(Larger the nerve fiber, faster AP propagation)
fiber diameter and myelination
Utilize neurotransmitters
Chemical synapse
Electrical activity of the presynaptic neuron affects the BLANK
postsynaptic neuron
-Electrical activity of the presynaptic neuron
affects the postsynaptic neuron
– Cells are connected by gap junctions
Electrical synapses
Cells are connected by BLANK
gap junction
1- Action potential reaches terminal
2- Voltage-gated Ca2+ channels open
3- Calcium enters axon terminals
4- Neurotransmitter is released and diffuse into the cleft
5- Neurotransmitter binds to postsynaptic receptor
6- Neurotransmitter removed from synpatic cleft
mechanism of neurotransmitter release
To terminate the signal in a chemical synapse
the BLANK must be removed
neurotransmitter
axon is stimulated a
second time before the first EPSP
Temporal summation
two axons are
stimulated simultaneously
Spatial summation
Axons of neurons that
end on another neuron’s
axon terminal
Axo-axonic synapse
1- increase leakage of neurotransmitter from vesicles to cytoplasm, exposing it to enzyme breakdown
2- increase transmitter release into cleft
3- block transmitter release
4- inhibit transmitter synthesis
5- block transmitter reuptake
6- block cleft or intracellular enzyme that metabolize transmitter
7- bind to receptors on postsynaptic membrane to block (antagonist) or mimic (agonist) transmitter action
8-
a drug might
Neurotransmitters affect BLANK
ion channels
can amplify or dampen
synapse strength
Neuromodulators
BLANK for neuromodulators can bring
about changes in metabolic processes
Receptors
Two general types of ACh receptors
( found in pns and cns)
-Muscarinic receptors (G protein coupled)
-Nicotinic receptors (ion channels)
Neurons associated with the ACh system degenerate in people with BLANK disease
Alzheimer’s
disease
Small charged neurotransmitters, made
from amino acids.
Biogenic Amines
Dopamine
Norepinephrine
Epinephrine
Catecholamines
emotions, regulating sleep,
Serotonin
Excitatory
– Aspartate
– Glutamate
Inhibitory
– Glycine
– GABA
neurotransmitter
Aspartate
Glutamate
Excitatory
Glycine
GABA
Inhibitory
two or more amino acids bound together
Endogenous opioids
Neuropeptides
Beta endorphins
Endogenous opioids
Receptors for Blank opiates are site of
action for opiate drugs
endogenous
Not released through exocytosis, produced
by enzymes
-short lived
gases
vasodilator
Nitric oxide
Act as neuromodulators
Nucleic Acids
Purines
-Adenosine
-ATP
Nucleic Acid
Brain
Spinal cord
Central Nervous System
Afferent division
Efferent division
Peripheral Nervous System
-Somatic sensory
-Visceral sensory
-Special sensory
afferent division
-Somatic motor
-Automatic motor
efferent division
-sympathetic
-parasympathic
-enteric
efferent division
-Forebrain
-Midbrain
-Hindbrain
structure of the brain
cerebrum, diencephalon
forebrain
pons, medulla oblongata,
cerebellum
Hindbrain
Midbrain, pons, medulla oblongata
brainstem
4 Structure of the brain
frontal lobe
parietal lobe
occipital lobe
temporal lobe
R and L hemispheres
Basal nuclei
cortex
Cerebrum
-Outer shell of grey matter, contains cell bodies.
-Participates in perception, generation of skilled
movements, reasoning, learning, and memory
cerebral cortex
-Subcortical nuclei (grey matter)
-Basal nuclei, function in controlling movement, posture,
aspects of behavior
Basal nuclei
BLANK tracts in white matter bring
information into the cerebrum and connect
different areas within the hemisphere
Myelinated fiber
-Septal nuclei
-frontal lobe
-olfactory lobe
-thalamus
-hypothalamus
-hippocampus
limbic system
thalamus, hypothalamus, and epithalamus
Diencephalon
-Collection of large nuclei
-Synaptic relay stations and integrating centers for most inputs
to the cortex.
-Involved in focusing attention
thalamus
-Control area for homeostatic regulation.
-Connected by a stalk to pituitary gland, an important endocrine
structure
hypothalamus
-Small mass, contains the pineal gland
-Functions in regulation of biological rhythms
epithalamus
Important center for coordinating movements,
controlling posture and balance
cerebellum (hindbrain)
Receives information from the muscles, joints,
skin, eyes, ears, viscera, parts of the brain.
cerebellum (hindbrain)
Implicated in some forms of learning
cerebellum (hindbrain)
All nerve fibers between the forebrain and the
cerebellum, and spinal cord pass through the BLANK
brainstem
loosely arranged neuron cell bodies intermingles with bundles of axons.
(Absolutely essential for life)
Reticular formation
– Motor functions
– Cardiovascular and respiratory controls
– Mechanisms of sleep and wakefulness.
– Focus and attention
brainstem
Contains nuclei involved in processing 10 of 12
cranial nerves
brainstem
Central grey matter
surrounded by white
matter
spinal cord
Tracts in white matter
run longitudinal
transmit information to
and from the brain
spinal cord
Afferent fibers enter
the spinal cord on the
dorsal side
spinal cord
Efferent fibers leave the
spinal cord on the
ventral side.
spinal cord
Transmits signals between the CNS and the
receptors and effectors in all other parts of the
body
Peripheral nervous system
12 pairs of cranial nerves
31 pairs of spinal nerves
Peripheral nervous system
Efferent innervation of smooth and cardiac
muscle, glands, other tissues
autonomic nervous system
fight or flight
autonomic nervous system
Sympathetic
rest and digest
autonomic nervous system
Parasympathetic
Bone
Meninges
Cerebrospinal fluid
Blood-Brain Barrier
Protective Elements of the CNS
membranes that line brain and spinal cord
Meninges
– Dura mater
– Arachnoid mater
– Pia mater
Meninges
protects and cushions the
structures.
Cerebrospinal fluid
capillaries in the brain are
the least permeable in the body
Blood-Brain Barrier
