Lecture 4 Flashcards
What are one to one synapses used for?
To convey information
What are one to many synapses used for?
To amplify a signal
-motor neurons in spinal cord
What are many to one synapses used for?
REALLY COMMON
-allows for integration of many signals and decides the proper response
What effect to excitatory post synaptic potentials have on the cell? What NT do this?
- depolarize the cell
- opening of sodium channels
- glutamate and acetylcholine
What effect to inhibitory post-synaptic potentials have on the cell?
Hyperpolarize the cell
- opening of chloride channels
- gaba and glycine
What is temporal summation?
Time in between impulses
-can be from one or more pre-synaptic cells
What happens when impulses overlap?
The membrane does not completely re polarize in between impulses
-effects are additive
What is spatial summation?
Multiple inputs at the same time
- multiple pre-synaptic cells provide input at the same time to the same post-synaptic
- impulses add together
What is short term depression?
Repeated stimulation can expend the stored NT and you will run out and the signal will stop
How do NT differ from hormones?
NT are just dumped on the cell and hormones travel by blood to reach their target organ
What must a neurotransmitter be?
- synthesized in a presynaptic cell
- released from pre-synaptic upon stimulation
- elicit a response similar to the normal response
Where is acetylcholine stored?
In vesicles
When is acetylcholine released?
In response to increased calcium influx into nerve terminal
How is acetylcholine broken down?
By acetylcholine esterase
What are biogenic amines derived from?
Derived from amino acids
What are the two things that break down biogenic amines
- monoamine oxidase
- catechol-o-methyltransferase
What are examples of biogenic amine
- tryptophan (serotonin and melatonin)
- histidine (histamine)
What are some examples of amino acids that act as neurotransmitters?
GABA, glutamate and glycine
What are gaseous transmitters?
Cell permeant gasses that act on post synaptic cells (NO)
What are neuromodulators?
Act on presynaptc cell to affect amount of NT release
-can also be co-secreted with NT to modulate post synaptic response
What are neruohormones?
Made by neurons and released into blood stream to have effects
-ADH
What are purines?
- released along with NT to augment effect
- ATP and norepinephrine increases VSMC contraction
What are ionotropic receptors?
-receptor is an ion channel
Nicotine receptors are primarily what kind of channels?
Sodium channels
GABA are usually what kind of channels?
Chloride channels
Ionotropic receptors opening and closing depends on what?
Binding of a ligand
What are metabotropic receptors?
Receptors coupled to an intracellular protein
-binding of ligand activates intracellular protein to generate second messenger molecules
What do the second messengers do?
- can interact with and alter ionic ion channels
- can activate kinases to eventually alter transcription
What are receptor tyrosine kinases?
- metabotropic receptors
- growth factor signaling
- starts kinase cascade to change transcription
- INSULIN
What are receptor tyrosine phosphatases?
- growth factor signaling
- dephosphorylates something
What are the secondary messengers that G-protein coupled receptors generate?
cAMP or IP3
Gs and Gi alter the activity of what secondary messenger?
CAMP
What does Gs do?
Stimulates adenylate Cyclase which means increases cAMP
What does Gi do?
Inhibits adenylate cyclase which decreases cAMP
What is cAMP degraded by?
Phosphodiesterase
What does Gq do?
-activates phospholipase C to make IP3 and DAG
What does IP3 do?
Can open calcium channels on intracellular stores
What does DAG do?
Can activate a kinase cascade through PKC
Where are Beta 1s located?
Predominantly in the heart
-cAMP in heart contracts
Where are Beta 2s located?
In smooth muscle
-cAMP in smooth muscle relaxes
What do muscarinic receptors respond to?
Acetylcholine
What do Beta adrenergic respond to?
Epi and norepinephrine
What does guanalyl cyclase do?
Makes cGMP
