Chapter 2 Flashcards
What are the two nervous systems/what do they consist of?
central (brain and spinal cord) and peripheral (nerves connecting spinal cord to the rest of the body)
The psychoactive books we discuss in this class exert their primary action on what? What do they exert their side effects on?
Most exert their primary action on the brain.
Side effects can be produced by actions on the brain, but many are also produced by actions on the peripheral nervous system
The brain is divided into which 3 subsections?
- hindbrain
- midbrain
- forbrain
The hindbrain is divided into?
- Myelencephalon
2. Metenchephalon
The midbrain is also known as
the Mesencephalon
The forebrain is divded into
- Diencephalon
2. Telenchepalon
The cerebellum is located in?
Metencephalon
the thalamus is located in?
Diencephalon
The cortex is located in?
Telencephalon
The basal ganglia is located in?
Telencephalon
The hypothalamus is located in?
Diencephalon
The Medulla is located in?
Myelencephalon
The Pons is located in?
Metencephalon
The limbic systm is located in?
Telencephalon
The cortex is also known as
cerebrum (not to be confused with cerebellum)
What does the brain stem consist of?
- Pons
- Medulla
- Midbrain
What is the large bulbous structure located behind the brain stem?
the cerebellum
What is ataxia? What does it result from?
Ataxia is loss of coordination and balance. It results from a depression of the cerebellum (which controls movement and posture)
the midbrain consists of which 2 parts?
- tectum
2. tegmentum
what are the 2 nuclei located in the tegmentum? what is their purpose?
- substantia nigra: responsible for coodination of movement, integration of motor control
- ventral tegmental area: part of the reward circuit (which also includes the limbic system)
What is the diencephalon composed of?
- hypothalamus
2. thalamus
What is the function of the hypothalamus?
- It modulates the functioning of the pituitary gland
- it is responsible for the intergration of the autonomic nervous sustem (e.g., eating, body temperature)
what are releasing factors?
a substance produced by the hypothalamus that signal the production of hormones by the pituitary gland
What is the puprose of the thalamus?
it is a type of way station that all sensory systems pass through and are directed to the appropriate cortical area (except the olfactory system)
what are the 2 subdivisions of the telencephalon?
- basal ganglia
2. limbic system
What are the major structures of the basal ganglia?
- caudet nucleus
- putamen
(together = striatum) - globus pallidus (lateral and medial)
What diseases result from impairment of the basal ganglia? Why?
Parkinsons - because a major function of the basal ganlia is the inetgration of momevent, so damage to it can result in the loss of the ability to initiate movement
Huntingtons - because damage can also result in an inability to prevent unintentional movement
What are the 2 major components of the limbic system? What are 5 other components?
- Amygdala
- Hippocampus
- Right cingulate cortex
- Left cingulate cortex
- Fornix
- Mammillary body
- Septum
What is the function of the hippocampus
memory
what is the function of the amygdala?
emotion
What does the cingulate cortex do?
It is involved in integrating sensory, motor, visceral, motivational, and emotional information
what is the anterior cingulate cortex do?
What about the posterior cingulate cortex?
Anterior: is involved in decisions related to empathy, fairness/unfairness, and the social context of behavior
Posterior: required for monitoring performance and keeping motivated during learning, particularly when problems are challenging.
What is the largest part of the brain?
cerebrum
What are the 4 divisions of the cerebral cortex?
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
What are the divisions of the frontal lobe?
- frontal cortex
- prefrontal cortex
- orbital prefrontal cortex
- dorsal-lateral prefrontal cortex
- ventral lateral prefrontal
- insular cortex (insula)
what is the special type of cell that exists in the insula?
Von Economo neurons
what 2 types of cells make up the central nervous system?
- Neurons
2. Glia
what is the ratio of neurons to glia in humans
1:1 (was previous thought to be 10:1)
What are the 4main types of glial cells?
- oligodendrocytes
- astrocytes
- ependymal and microglial cells
what is the function of oligodendrocytes
form the myelin sheath
what is the function of astrocytes
provide neurons with nutrients and structural support
what is the function of microglia
cleaning up damaged cells and debris and pruning neurons
what are the parts of the synapse?
- presynaptic membrane (typically the axon terminal) of one neuron
- the postsynaptic membrane of the receiving neuron (which might be a dendrite, the soma, or the axon terminal of another neuron)
- a tiny space (the synaptic cle ) between them
what 2 functions do synaptic vesicles serve?
- store and protect neurotransmitter
2. release NT
What is exocytosis.
When vesicles fuse with the presynaptic membrane and release the transmitter,
describe the 2 mechanisms through which neurotransmitters are removed from the synaptic cleft?
- an enzyme present in the synaptic cle breaks down any neurotransmitter remaining in the synapse. The metabolites are then taken back up into the presynaptic neuron to be resynthesized and repackaged for release.
- The transmitter itself is taken back into the presynaptic neuron and repackaged.
what are the major neurotransmitter families? (7)
- Amines
- Amino acids
- Neuropeptides
- Peptides
- Purines
- Lipids
- Gases
What is the function of Acetylcholine?
plays an important role in memory functioning
How is Acetylcholine produced?
synthesized in a one-step reaction from two precursors (choline and acetyl coenzyme A)
What are the 2 major cholinergic systems in the brain?
- The basal forebrain cholinergic complex
2. The pontomesencephalotegmental cholinergic complex
Describe the The basal forebrain cholinergic complex
neurons in
- nucleus basalis
- medial septal nucleus
projects to the telencephalon
Describe the pontomesencephalotegmental cholinergic complex
An acetylcholine circuit
cholinergic cell bodies in in the pedunculopontine and laterodorsal tegmental nuclei
Ascend to:
Diencephalon (including thalamus)
Descend to:
- pons
- medulla
- cerebellum
- cranial nerve nuclei
What does Biosynthesis of the catecholamines begin with?
the amino acid tyrosine
What type of enzymes break down catecholamines?
monoamine oxidase
Dopamine is involved in?
motor control, motivation, reward, and reinforcement
What is the precurser of dopamine?
DOPA
How is Dopamine’s action terminated?
reuptake by DAT
Neurons and glia contain Mononamine Oxidase (MAO) and Catechol-O-Methy Transferase (COMT) to catabolize dopamine
All dopamine receptors are?
metabotropic
What are two disorders that dopamine is important in?
psychosis and Parkinson’s
Norepinephrine is involved in?
sleep and wakefulness, attention, and feeding behaviour
What is a neurotransmitter?
A chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.
What are the two broad categories of neurotransmitters?
- Small molecule (includes biogenic amines)
2. Neuropeptide - > 3 amino acids
What are neurotransmitter Receptors
Neurotransmitter receptors are proteins embedded in the plasma membrane
What are the 2 types of neurotransmitter Receptors?
- Ionotropic receptors or ligand-gated
2. Metabotropic receptors
What is a Ligand?
a chemical messenger that binds to protein receptors
What are ligand gated ion receptors?
when a ligand binds to the receptor it causes structural changes that selectively allow ions to move in or out of the cell through an ion channel
What are 4 characteristics to be a neurotransmitter?
- Must be present in the presynaptic neuron
- Must be released in response to presynaptic
depolarization - Specific receptors for the substance must be
present of the postsynaptic cell - Must have a method for signal termination
Glutamate is excitatory or inhibitory?
excitatory
GABA is excitatory or inhibitory?
inhibitory
Where are synaptic vesicles formed?
from the endocytotic folds of the presynaptic membrane
What are secretory vesicles filled with?
neuropeptides
what is the docking complex?
a specialized site on the synaptic bouton
-> a way of directing the synaptic vesicles to where they need to go
what is the synaptic cleft filled with?
small filaments
List the 7 steps of chemical transmission
- Release of Neurotransmitter
- Receptor binding
- Ion channels open or close
- Conductance change causes current flow (the charge)
- postsynamptic potential changes
- Post synaptic cells excited or inhibited
- Summation of this determines whether or not an action potential occurs
What is Saltatory Conduction?
when an action opential jumps from node to node
Hyperpolarization means
membrane potential becomes more negative
Depolarization means
membrane potential becomes more positive
The Threshold potential is
the voltage at which an action potential is initiated
what is the resting membrane potential
The voltage (potential difference in charge) across the membrane
what is the Sodium-Potassium Pump?
Moves three Na+ out for each two K+ it brings in
It acts to transport sodium and potassium ions across the cell membrane in a ratio of 3 sodium ions out for every 2 potassium ions brought in.
What tells us the strength of the signal from a neuron?
the number of action potentials in a period of time (rate at which they occur)
Describe the process of an action potential?
- Depolarization of the neuron (past the threshold) activates sodium ion channels which makes it more depolarized (positive feedback)
- Sodium ion channel inactivates, this means sodium stops flowing in, and instead Potassium starts following out through the potassium channel
- The potassium leaving restores the resting membrane potentian
- The sodium potasium pump works to correct the distribution of sodium and potassium
What is Na+
Sodium ion
What happens once the action potential reaches the end of the axon? (4 steps)
- The action potential enters the terminal buttons of the presynaptic neuron
- The change membrane potential causes calcium channels to open
- Calcium enters the neuron and causes neurotransmitter filled vesicles to fuse with the plasma membrane
- Neurotransmitter is released in the synapse
What are the Presynaptic sturctures?
- synaptic bouton (terminal button?)
- synaptic vesivles
- secretory vesicles
- docking complex
What are the Postsynaptic structures?
- synaptic cleft
2. postsynaptic density
