Chapter 2 - Synapses Flashcards
Neurons communicate at specialized junctions called ____.
Synapses
In the late 1800’s, ____ _ ____ anatomically demonstrated a narrow gap separating one neuron from another.
Ramon y Cajal
In 1906, _____ ___ _____ physiologically demonstrated that communication between one neuron and the next differs from communicating along a single axon (not an AP).
Charles Scott Sherrington
___ and ___ are considered the great pioneers of modern neuroscience.
Cajal, Sherrington
Sherrington had used ____ properties to infer the major properties of the synapse half a century before researchers had the technology to measure those properties directly.
Behavioural
- Sherrington studied ____, automatic muscular responses to stimuli.
- In a leg flexion reflex, a sensory neuron excites a ___ neuron, which in turn excites a ____ neuron.
- The circuit from a sensory neuron to a motor neuron is called a ____ arc.
- When Sherrington pinched a dog’s leg, the leg ___, and the pother legs ___.
- After a dog’s spinal cord was severed from his brain, the same reflexive movement ___.
- The spinal cord therefore controls the ___ and ___ reflexes.
- Reflexes
- Second, motor
- reflex
- Flexed, extended
- Remained
- Flexion and extension.
In an intact animal (brain and spinal cord connected), messages descending from the brain ____ the reflexes, making them stronger at some times and weaker at others.
Modify
In conclusion: Sherrington observed several properties of reflexes that suggest special processes at the junctions between neurons:
1) Reflexes are slower than conduction along an ___.
2) Several weak stimuli presented at nearby places or times produce a stronger reflex than ___ stimulus alone dories.
3) When one set of muscles becomes excited, a different set becomes ____.
1) axon
2) one
3) relaxed, inhibited
Previous research had concluded that APs have a speed of about __m/s, while the speed of a reflex arc was about __m/s
40m/s, 15m/s
Sherrington found that repeated stimuli within a brief time had a cumulative effect. he referred to this phenomenon as as ____ ____.
Temporal Summation
Elliot (1905)
Adrenaline applied to surface of heart,stomach, and pupils mimics ___ ___ ___.
Sympathetic nervous system
Calcium enters the Neuron body, triggering the release of NT, this is called ____
Exocytosis (exp = out, cytosine = transport) 1-2 ms
Difference between a Ionotropic and Metabotropic effects (difference between Hormone and NT)
Ionotropic = NT, quick, quickly open potassium (+) ion channels, uses the NT glutamate (the most abundant NT) - depolarizes membrane Metabotropic = hormone, slow acting, released in to region, open chloride gates (-) channels. Hyperpolarizes membrane. Uses NT GABA
Glycine is an ____ NT and is found mostly in the Spinal cord.
Inhibitory
Acetylcholine is an ____ NT, and is found at Ionotropic synapses
Excitatory
ACTIVATION AND REUPTAKE
1) After acetylcholine activates a receptor, the enzyme acetylcholine_____ breaks it into two fragments: ___ and ___.
2) The choline diffuses back in the ____ neuron, which takes it and reconnects with ____ to form ______.
3) It does not reabsorb all the ____ it releases, and it takes time, thus a sufficiently rapid series of action potentials ____ the NT, faster than the presynaptic cell replenishes it, thus slowing or interrupting ___.
1) acetylcholonesterase, acetate and choline
2) presynaptic, acetate, acetylcholine
3) molecules, deplete, transmission
- Serotonin and catecholamines ( ___, ___, and ___), do not break down into active fragments at the postsynaptic membrane. They simply ____ from the receptor.
- At that point, the next steps varies, the presynaptic neuron takes up much or most of the released intact and ____ them.
- This process is called ___
- This process is done through special membranes called ____.
- Norepinephrine, epinephrin, dopamine. Detach
- Reuses
- Reuptake
- Transporters
Amino Acids which contain an ___ group.
1) G___
2) g__
Amine
1) GABA
2) Glutamate
1) Long chains of amino acids:____
Including poly____ and proteins
2) En____, ____ P, ____ Y
1) Peptides, peptides
2) Endorphins, Substance, substance
- Acetylcholine: similar to ____ acids, but structurally different
- Comprised of ____ coenzyme A and ____.
- When broken down forms into ____ and ___.
- Enzyme called acetylchole_____ breaks down acetylcholine
- Amino
- Acetyl, choline
- Acetate and choline
- Acetylcholinesterase
- Nonacidic neurotransmitter containing an amine group (“bioamines”): ____
- These have a catechol ring and two Hydroxl [OH] groups attached the them.
- They also form what 3 NT?
- This has a complex double organic ring called an indoor ring.
- It is an ____
- Monoamines
- Catecholamines
- Epinephrine, Norepinephrine, and Dopamine
- Serotonin
- Indolamine
ATP, Adenosine and it’s derivatives are called these NTs
Purines.
This is the only known gas to act as a NT
what does it do?
Nitric oxide [NO]
Dilate blood vessels
Action potential causes what to enter which releases NT?
Calcium
Neurons synthesize NT from substances in the ___
Diet
Peptide NT synthesized from ___ ___ provided by diet
Acetylcholine is synthesized from ___ which is abundant in ___ and milk
Amino acids
Choline, cauliflower
This precursor to serotonin is important in the brain and increases after a meal rich in protein
Tryptophan
Small NT are synthesized in ____ terminals, close to release point
Terminals
Larger NY, like peptides, are synthesized in the ___ body and transported slowly down the axon.
They are not reabsorbed and ____ like many smaller NT, thus they are exhausted ___
cell
Recycled, quickly
The release of NT through the membrane is called:
Exocytosis
Usually 2 or 3 transmitters are released from each neuron; always the same ____
Dale’s Law: a mature neuron makes use of the same NT at all of its synapses. This was proved ___
Daly’s law was proved false, and many mature neurons contain more than one NT, this is referred to as ____, and usually contains a low-molecular weight NT and a ____ peptide
Combination
False
Coexistence, neuroactive
Dale’s Law has been reformulated to: a neuron makes use of the same _____ of chemical messengers at all of its synapses, but neurons may receive and respond to many more.
Combination
Activations at receptors
Ionotropic
1. Quick start (___ms) and a short duration (__ms)
2. Localized effect on ____
3. Immediately opens gates for ions; eg ____
4. Most abundant: ____ (excitatory)
5. Most abundant inhibitory: ___
6. Ionotropic synapses for ____ events like visual stimulation, muscle movements etc.
- 10, 30
- Membrane
- Acetylcholine
- Glutamate
- GABA
- Quick
Metabotropic effects
- Late start (__ms)
- Activates _-protein
- G-protein ___/___ ion channels, changes protein ______, or activates ____ in cell
- 30ms
- G
3 opens/closes, production, chromosomes
These NTs are mainly peptides, they are chemicals released in small quantities that diffuse to nearby cells, and act at metabolic receptors; and are long lasting.
Chemicals released in larger quantities in blood stream and act like Metabotropic NT
Epinephrine, Norepinephrine, Insulin, oxytocin and others act as both ____, and ____
Neuromodulators
Hormones
NTs and hormones
These act as NT and hormones (INOE)
Insulin, Norepinephrine, oxytocin, epinephrine,
- A drug that mimics or increases the effect of a NT
2. A drug that blocks or takes away the effects of the NT
- Agonist
2. Antagonist
Ability of a drug to bind to a receptor.
(How long it says on the receptor)
The degree to which the drug activates the receptor once bound
Affinity
Efficacy
D_ receptor related to alcohol consumption, rec. drugs use, overeating and habitual gambling
D_ related to being impulsive, exploratory and quick-tempered, schizophrenia, no link to personality
D2 receptor
D4 receptor
Acetylcholine has at least _ types of nicotine and _ types of muscarinic receptors
Dopamine has _ typos of receptors
Seratonin has __ types of receptors
4, 5
5
15
