Exam 1 (CHAPTERS 1-4) Flashcards
How many Neurons are there?
200 Billion (some say 100)
What do interneurons do?
Bridge communication between sensory and motor in CNS
What are the 3 Neuron classes?
1) Sensory
2) Motor
3) Interneurons
Sensory (afferent neurons)
Ascending messages TO CNS from PNS
Motor (efferent)
Descending messages FROM CNS back TO PNS
Diffusion
Pressure to move from higher concentration to lower concentration
Electrostatic
Similarly charge ions repel each other
What are the resting potentials?
1) Diffusion
2) Electrostatic
What is the all or none law?
neuron fires at one level of intensity
What is the caveat to all or none law?
Number of neurons affected and frequency of firing can change with different intensities of stimuli
What affects the speed of neurons?
longer neurons and myelinated neurons make speed faster.
Saltatory (dancing) conduction
The way an electrical impulse skips from node to node down the full length of an axon
What is released when action potential reaches terminal button and what does it release?
Calcium is released and it triggers the release of NT.
Receptors
Proteins or amino acids located on the postsynaptic membrane (PSP)
What are receptors like?
A lock and key (each has a specific molecular configuration that allows substances to bind with it)
What are the two receptor types?
1) Ionotropic
2) Metabotropic
Which receptor type controls the ion channel directly?
Ionotropic
What does the binding of NT lead to in ionotropic receptors?
The opening of ion channels
Which receptor type quickly depolarize postsynaptic membrane?
Ionotropic
Which receptor type exerts its effects indirectly?
Metabotropic
Which receptor types requires a G protein to trigger the chain reaction that activates a second messenger?
Metabotropic
What is the chain reaction that a G protein triggers in a metabotropic receptor?
G protein triggers chain reaction that activates second messenger, cAMP, which then activates 3rd protein that controls ion channel
Which receptor is slower action and remains open or closed longer?
Metabotropic
What happens to remaining NT?
It is broken down by enzymes and then returns to terminal buttons OR returns intact (Reuptake)
What is the most important excitatory?
Glutamate
What is the most important inhibitory?
GABA
What Synapses depolarizes the membrane?
EPSP (Excitatory)
What Synapses hyperpolarizes the membrane?
IPSP (Inhibitory)
Where are autoreceptors located?
on the sending cell that regulate activity of that neuron
What does an autoreceptor do?
Modulates amount of NT released through a second messenger system
What receptor is more specific for certain NT and have more potential for drugs without side effects?
Autoreceptors
Neuron specific
Autoreceptors
Heteroreceptors
Not neuron specific
What is the imaginary line drawn through the spinal cord up to the front of the brain?
Neuraxis
What are anatomical directions understood relative to?
Neuraxis
What is toward the head (beak)
Anterior (rostral)
What is towards the tail?
Posterior (caudal)
What is toward the belly?
Ventral (inferior)
What is toward the back (top of head)
Dorsal (superior)
What is same side of brain?
Ipsilateral
What is opposite side of brain?
Contralateral
What are the planes of the brain?
1) Sagittal
2) Coronal (transverse)
3) Horizontal
What forms the outer surface of the cerebral hemispheres?
The cerebral cortex (bark)
How thick is the Cerebral Cortex?
3mm thick roughly
What is the cortex convoluted by?
grooves
What type of grooves are there on the Cortex?
1) Sulci (small grooves)
2) Fissures (large grooves)
What are Bulges in the cortex called?
gyri
What is the cortex primarily composed of?
Cells with give it its gray appearance (gray matter)
What is the Subcortical Region
1) It contains limbic system and basal ganglia
2) called white matter because of large concentrations of myelin around axons
Who first discovered the chemical agent for acetylcholine?
Otto Leowi in 1920s
What is acetylcholine made of?
1) Choline in dietary fat
2) Glucose metabolism
Muscarinic receptors
Metabotropic smooth and cardiac muscle
Nicotinic
ionotropic Skeletal muscle
What is acetylcholine terminated by?
acetylcholinterase (enzyme)
What is norepinephrine synthesized from?
From dietary tyrosine (Part of the catecholamines with dopamine)
What is norepinephrine terminated by?
1) Reuptake
2) Enzymatic deactivation by monoamine oxidase (MAO)
What receptor does norepinephrine go with?
Metabotropic receptors
Domaine
1) It is a Catecholamine
2) Metabotropic receptors
3) Synthesis and breakdown similar to NE
What are the Dopamine Pathways?
1) Nigro-striatal system
2) Mesolimbic system
3) Mesocortical system
4) Tuberoinfundibular system
Nigro-striatal system
Substantia nigra to caudate nucleus and putamen (parts of basal ganglia)
2) Disrupts results in Parkinson’s
Mesolimbic system
1) Reward system e.g. Remembering pleasure
2) Ventral tegmental area (VTA) to Nucleus accumbens
Mesocortial system
1) Reward system e.g. Seeking to repeat pleasure
2) VTA to prefrontal cortex (e.g. resourceful efforts to acquire drug)
Tuberoinfundibular system
Regulates prolactin in anterior pituitary
Serotonin
Monoamine - indolamine like histamine but NOT a catecholamine
What kind of receptors does Serotonin have?
Mostly metabotropic
What is Serotonin synthesized from?
Tryptophan
Examples of tryptophan…
Dairy products, soy products, meats, poultry, nuts, eggs, seeds, fruit, whole grains, chocolate and seafood
Does eating a lot of turkey at Thanksgiving increase SE and make you sleepy?
Not really, SE changes slightly but you do get a carb overload at Thanksgiving.
What is serotonin terminated by?
Reuptake and enzymatic deactivation
Does Glutamate allow positively charge ions or negatively charged ions in?
Positively charged (Na+ and Ca+)
Does Glutamate have long-term or short-term potentiation?
Long-term potentiation (LTP)
Long-term potentiation (LTP)
Post synaptic membrane is actually changed to depolarize more readily
What kind of receptors does Glutamate have?
Ionotropic and metabotropic
What does Glutamate come from?
protein or ingested directly (MSG)
What happens if you have too much glutamate? What is excessive exposure called?
Too much leads to dizziness an numbness or cell death. Excessive exposure is called excitotoxity
What terminates Glutamate?
Reuptake
GABA
Gamma-amino-butyric acid
What receptors does GABA have?
Ionotropic and metabotropic
How does GABA inhibit?
By allowing more negatively charge ions into cell
What is GABA synthesized from?
Glutamate
How is GABA terminated?
Reuptake
Endorphins
Endorphins are peptides (small proteins) that bind to opioid receptors in the central nervous system. An endorphin is a type of neurotransmitter.
What do endorphins do?
1) endogenous opiates
2) Inhibitory metabotropic receptors
What is muscarinic?
Smooth muslces
