Exam 2 Flashcards
What are the “rules” regarding neurotransmitters and receptors?
A given neuron only produces one neurotransmitter for release, but the same neuron can have receptors for many neurotransmitters?
What is the role of calcium in neurotransmission?
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What are Ionotropic receptors?
Chemically-gated ion channel which opens when bound by a NT:
- When open, it directly alters the membrane potential in a neuron
- The NT only remains bound to the receptor for a short time and then returns to the synapse
What are metabotropic receptors and what types of processes can they regulate?
Receptors that, when bound with a NT, activate other proteins within neurons (The “other proteins” are G Proteins or second messengers)
What are agonists (direct vs. indirect) and antagonists?
*look at fig.4.4
Agonists: Drugs that enhance NT effects at their receptors.
Direct agonist: directly stimulates receptors (ex. nicotine)
Indirect agonist: increases NT levels in synapse by inhibiting NT breakdown (ex. Aricept)
Antagonists: drugs that decrease NT effects at their receptor, typically by blocking a specific NT receptor.
Describe three ways to terminate neurotransmitter action.
- ) Metabolism: an enzyme breaks down the neurotransmitter
- ) Reuptake or transport: a protein on the terminal or glial cell removes the neurotransmitter from the synapse
- ) Autoreceptors: A Neurotransmitter receptor on the terminal shuts off neurotransmitter release or synthesis
Describe the effects of neurotransmitters in the peripheral nervous system.
Neurotransmitters in the peripheral nervous system are excitatory.
Acetylcholine excites skeletal muscle.
Norepinephrine excites smooth muscle
Provide the following information on Glutamate:
- Main effect on neurons (inhibitory or excitatory)
- How is it made? (what is its Precursor?, what enzyme is needed to make it?)
- Types of receptors that bind it
- Where it is found/made in the brain
- How we get rid of it (how it is removed from the synapse?)
- EXCITATORY: it is the principle excitatory NT in the mammalian brain
- It is made from the amino acid GLUTAMINE
- Binds to 3 receptors:
- NMDA (N-methyl-D-aspartate): gates Na+ and Ca2+
- AMPA: gate Na+
- Metabotropic glutamate receptors (mGluRs) - Released mainly by neurons in the CORTEX, LIMBIC SYSTEM, and THALAMUS
- Removed from synapse through reuptake into glial cells and terminal buttons
Provide the following information regarding GABA:
- Main effect on neurons (inhibitory or excitatory)
- How is it made? (what is its Precursor?, what enzyme is needed to make it?)
- Types of receptors that bind it
- Where it is found/made in the brain
- How we get rid of it (how it is removed from the synapse
- INHIBITORY
- Made from GLUTAMATE by an enzyme called GLUTAMIC ACID DECARBOXYLASE (GAD)
- Binds to 2 receptors:
- GABA-A gates a Cl- channel
- GABA-B is a metabotropic receptor - Released THROUGHOUT THE BRAIN by inhibitory interneurons
- Removed from synapse by reuptake
Provide the following information regarding Acetylcholine:
- Main effect on neurons (inhibitory or excitatory)
- How is it made? (what is its Precursor?, what enzyme is needed to make it?)
- Types of receptors that bind it
- Where it is found/made in the brain
- How we get rid of it (how it is removed from the synapse
- It depends
- Made from the synthesis of ACETATE and CHOLINE by an enzyme called CHOLINE ACETYLTRANSFERASE (ChAT)
- Binds to 2 receptors:
- Nicotinic receptor is ionotropic and tends to excite neurons
- Muscarinic receptor is metabotropic - Released by neurons in RETICULAR FORMATION and BASAL FOREBRAIN
- Broken down by the enzyme, acetylcholinesterase (AChE), in synapse
Provide the following information about norepinephrine:
Precursor-
MAO-
Brain regions-
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Provide the following information about Dopamine:
- Main effect on neurons (inhibitory or excitatory)
- How is it made? (what is its Precursor?, what enzyme is needed to make it?)
- Types of receptors that bind it
- Where it is found/made in the brain
- How we get rid of it (how it is removed from the synapse
- Made from an amino acid, TYROSINE, by an enzyme known as TYROSINE HYDROXYLASE (TH)
- Binds to two receptors (both are metabotropic):
- D1
- D2 - Released from neurons in the SUBSTANTIA NIGRA and VENTRAL TEGMENTAL AREA (into the caudate nucleus and nucleus accumbens respectively)
- Removed from the synapse via:
- reuptake
- “autoreceptors”
- enzymatic breakdown (Monoamine oxidase, “MAO”, is an enzyme that breaks down DA)
Provide the following information about serotonin:
- Main effect on neurons (inhibitory or excitatory)
- How is it made? (what is its Precursor?, what enzyme is needed to make it?)
- Types of receptors that bind it
- Where it is found/made in the brain
- How we get rid of it (how it is removed from the synapse
- Made from the amino acid, Tryptophan
- Binds to seven different subtypes (5HT1-5HT7) and various iterations of each subtype (ex. 5HT1A, 5HT1B, 5HT1C)
- Released by neurons in the dorsal and median raphe (region of the midbrain).
- Removed from the synapse via:
- reuptake
- “autoreceptors”
- enzymatic breakdown (Monoamine oxidase, “MAO”, is an enzyme that breaks down DA)
Provide the following information about Cannabinoids:
Where they come from-
CB1 receptors-
How they inhibit neurotransmitter release
They are lipids produced in dendrites during depolarization?
CB1-found in high levels in the cortex, hippocampus, basal ganglia, and parabrachial nucleus (feeding)
How they inhibit neurons:
-calcium entry into dendrites causes ananamide to be produced–>ananamide travels from dendrite to terminal in order to activate the CB1 receptor–>CB1 receptor activation blocks calcium entry into terminal during action potentials and stops NT release
What are the dimensions of light?
Hue or color: depends on the wavelength
Brightness or intensity: depends on how tall the waves are
List the steps from light hitting receptive fields to activation of retinal ganglion cells.
- Light breaks the bond between opsin and retinal proteins in photoreceptor.
- Sodium channels in the photoreceptor close.
- Photoreceptor is inhibited (it becomes less active/hyperpolarized and stops releasing inhibitory NT’s onto the bipolar cell).
- Bipolar cell is excited (it is disinhibited and becomes more active/depolarized.)
- Retinal ganglion cell increases firing rate.
List the theories of color vision.
- Trichromatic theory
2. Opponent-process theory
Lines and colors in primary visual cortex.
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What are the pathways from retina to visual cortex?
Axons from the right side of each eye
Role of V4 and V5 in vision
V4: contains neurons that are sensitive to color contrast; process information about contrasting colors detected in the visual field
V5: Contains neurons sensitive to motion; process information about movement in the visual field
List the three different brain regions in the inferior temporal cortex that house neurons that recognize specific types of objects by sight or name. What object(s) are associated
- Parahippocampal Place Area (PPA): places
- Medial Fusiform: tools
- Lateral Fusiform & Fusiform Face Area (FFA): faces and animals
What area is involved in detection of human motion?
The right superior temporal sulcus (STS) is a brain region activated by perception of human motion; it is Located at junction of dorsal and ventral streams.
Describe the anatomy of spatial location and object identification.
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What are the steps involved in converting sounds to biological signals?p. 158-161
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How do we detect differences in tones or pitches? P. 162-4
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*What are the functions of the olivary complex and inferior colliculus?
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What are the different types of touch?
Cutaneous: pressure, vibration, hot, cold, pain
Kinesthetic: stretch in muscles and tendons
Organic: stretch in gut
What are the different nerve endings for pain and pressure/vibration? (What are the two main types of somatosensory neurons?)
- sensory neurons that detect TOUCH (pressure, vibration) have corpuscle-like coverings on their endings
- sensory neurons that detect PAIN have free nerve endings or no covering. The are called nociceptors
How does touch create action potentials in sensory neurons?
- mechanical force pulls an ion channel open on nerve ending of sensory neuron –> 2. Cations enter and depolarize the nerve ending –> 3. If enough nerve endings are depolarized, firing rate of the sensory neuron increases –> 4. sensory neuron releases glutamate into the spinal cord and stimulates ascending neurons
Are there different receptors for pain and temperature? How about hot and cold? How about warm and hot?
-Heat is detected by sensory neurons dedicated to detecting painful stimuli.
-There are receptors on free nerve endings that selectively detect hot, warm, and cold
Hot: TRPV2
Warm: TRPV1
Cold: TRPV8 (also sensitive to menthol)
What are causes of inflammatory and neuropathic pain?
Inflammatory Pain: Due to non-nervous tissue damage at the site of injury
Neuropathic Pain: Due to damage of sensory nerves
How does inflammatory pain work?
Tissue Damage–>synthesis of prostaglandin (PG)–>PG sensitizes nerve endings to histamine or bradykinin (BK), which are released by injured tissue or immune system cells–>pain ends when tissue damage resolves
What are symptoms of neuropathic pain?
Two Main Symptoms
- Allodynia: painful responses to stimuli that should not cause pain
- Hyperalgesia: greater and more prolonged responses to a painful stimulus
What are Enkephalins and dynorphins?
Enkephalins and dynorphins are the two main types of endogenous opioids.
Both types play a primary role in analgesia (aka pain relief). Enkephalins work through the brain and dynorphins work through the spinal cord.