Bio: The Nervous and Endocrine Systems, Neurotransmitters, Parts of Brain Flashcards
Dendrites Soma Myelin (what is it actually?) Schwann cells oligodendrocyte Axon hillock The impulse is send from what to what?
Dendrites send impulse to soma
Soma is basically where nucleus is and protein is made
Myelin = a CELL and insulator, so can increase speed of impulse transmission (Schwann cells serve as the myelinating cell of the PNS (they literally make the myelin) vs oligodendrocyte is name of myelin in CNS)
and “jumps” over nodes of ranvier -> saltatory conduction
Axon hillock connects soma to axon
impulse send from dendrites to axon terminus and all the way to the synaptic knobs
What is the difference b/w unipolar, multipolar, and bipolar neurons
Unipolar -> Looks like soma in middle with regular axon terminal and multiple dendrites (sensory neuron)
Multipolar -> neurons with many dendrites (one we’re used to) (motor neuron)
Bipolar -> neurons with one dendrite (interneuron)
What is resting membrane potential and what perspective is it always from? That is threshold when Na+ voltage gated channels and K+ voltage gated channels open? Describe the channels you see in membrane and how this allows for this specific resting membrane potential
What happens when threshold is reached to Na+ and K+ voltage gated channels?
RMP = - 70mV
Threshold is -50mV
NOKIA321
Na+/K+ ATPase pumps out one net positive ion out
Na+/K+ ATPase establishes Na+ and K+ concentration gradients
many pos ions are lost through K+ leak channels (K+ leaks out of cell) (like “K bye”)
end result is that cell is more neg inside than out (-70mV)
in addition to these channels, there is K+ voltage gated channel and Na+ voltage gated channel but these only open when threshold is reached (-50mV) -> **When hit threshold Na channel works right away but K channel delayed, feel effect of Na first and it rushes inside down gradient
Depolarization, hyperpolarization, repolarization
Equilibrium potential
What does the action potential look like, using the top 3 terms above?
Impulse is all or nothing
Depol -> move away from rest potential in the pos direction
Hyperpol -> move away from rest potential in neg direction
Repol -> return to rest potential
Equilibrium potential -> potential at which there is no driving force on an ion
Action potential:
Depolarization -> repolarization -> hyperpolarization -> repolarization
Why is the impulse unidirectional?
What is the absolute and relative refractory period/ what is open/closed/inactivated? when do they occur?
What happens if add electrode in middle of axon?
Absolute refractory period -> absolutely impossible to fire another action potential, Na+ channels are inactivated, cell is too positive, near Na+ equilibrium potential
Relative refractory period -> possible but difficult to fire a second action potential, Na+ channels are now closed, cell it too neg, further from threshold, near K+ equilibrium potential
The impulse is unidirectional bc of the refractory period which begins when Na channels are inactivated (when membrane potential is repolarizing) and a neuron CANNOT fire another action potential no matter how strong a membrane potential depolarization is bc the voltage gates Na+ channels are inactivated after depolarization. They will not be able to be opened again until the membrane potential reaches the resting potential and the Na+ channels have returned to their “closed” state.
During the relative refractory period (right after the absolute refractory period), a neuron can be induced to transmit an action potential, but the depol required is greater than normal bc the membrane is hyperpolarized
If added electrode to middle of axon, impulse can go in either direction -> neither side is in refractory period
Electrical synapses are ___junctions, always/sometimes excitatory, bidirectional, unregulated/regulated
common/rare in nervous system
very important to the organ system(s):
Electrical synapses are gap junctions, always excitatory, bidirectional (either cell can be pre/post synaptic, unregulated
Rare in nervous system, VERY IMPORTANT IN CARDIAC MUSCLE CELLS and smooth muscle
Chemical synapse Are excitatory/inhibitory, Synapsin bonds? Cytoskeleton filaments? How is Ca2+ involved?
Chemical synapse is opposite of electrical synapse
Can be excitatory or inhibitory, normal thing we find in nervous system
Synapsin bonds Keeps cytosketeton filaments and vesicles bound and these synapsin bonds can be broken by Ca2+
- There are Ca2+ voltage gated channel so that only when action potential arrives, can stimulate these voltage gated channels to open, so that Ca2+ (commonly found outside of cell) can go inside to break these bonds
What is SSRI (selective serotonin re-uptake inhibitory?
Given: K+, Na+, Cl-, Mg2+, PO4 3-, Ca2+ -> where can the greatest concentration of these be found, inside or outside of neuron?
SSRI -> serotonin can stay in synaptic cleft for longer
Inside: k+, Mg2+, PO43-
Outside: Na+, Cl-, Ca2+
and these ions flow from high to low concentrations once certain channels open
*If you want to know how post synaptic cell will respond, what do you need to look at?
What is the difference between an inhibitory and excitatory neurotransmitters?
If a neurotransmitter causes entry of chloride into the postsynaptic cell, is the neurotransmitter excitatory or inhibitory?
NEED TO LOOK AT RECEPTOR, NOT NEUROTRANSMITTER -> EX GABA -> has “inhib effects” bc it bind to chlorine receptors
If a neurotransmitter such as acetylcholine is released at neuromuscular junction (b/w neuron and muscle cell) binds to its receptor on post synapic membrane, the receptor opens its associated sodium channel, allowing sodium to flow down its gradient into the cell, depolarizing the postsynaptic cell membrane . If a neurotransmitter such as acetylcholine opens a channel that depolarizes the postsynaptic membrane, the neurotransmitter is termed excitatory
Other neurotransmitters however, have the opposite effect, making the post synaptic membrane potential more negative than the resting potential or hyperpolarized so these neurotransmitters are called inhibitory
Chloride ions are negatively charged so entry into the cell would make the postsynaptic potential more negative, or
What does Acetylcholinesterase do?
degrades acetylcholine
Neurons make one/more than one NT, and can respond to one/many
T/F: the amount of time neurotransmitter is in synaptic cleft adjusts response
T/F: takes more than one NT to have a significant effect on the postsynaptic cell
Neurons make one NT, and can respond to many
T
T
IPSP (inhibitory postsynaptic potentials) and EPSP (excitatory postsynaptic potential)
See printed out diagram
Get a mini depolarization from lil bit of neurotransmitter dumped to open ex. Na channel (green in diagram) = EPSP
But if dump more and more neurotransmitter to bind and open Na channel (green) then get past threshold and get large action potential peak
Get mini hyperpolarizaiton for chlorine receptor bc Cl-makes membrane potential more neg (red in diagram) =IPSP
But when bombarded with neurotransmitter to chlorine receptor get large hyperpolarization
What is idea of summation?
Spatial vs Temporal?
What influences the intensity of a action potential?
Action potential is an all or nothing event
A post-synaptic neuron has many different neurons with synapses leading to it, however, each of these synapses can release neutrotransmitter many times per second. The “decision” by a possynaptic neuron whether to fire an action potential is determined by adding the effect of all of the of the synapses impinging on a neuron, both excitatory and inhibitory. This addition of stimuli is termed summation.
Spatial summation -> add up EPSPs and IPSPs from all the synapses on the post synaptic membrane are summed at a moment in time and majority rules (will tell you if overall excitatory or inhibitory)
Temporal summation -> add up frequent impulses from a single source, so basically a presynaptic neuron fires action potentials so rapidly that EPSPs or IPSPs
Intensity is coded by frequency
What happens if an inhibitor of acetylcholinesterase is added to the neuromuscular junction, then the postsynaptic membrane will…
a) be depolarized by action potentials more frequently
b) be depolarized longer with each action potential
c) spontaneously depolarize
B
What does afferent/efferent neuron mean? Where do they come from/go and why? Afferent neuron? Ventral root? Dorsal root?
afferent neurons = approaching the CNS from PNS
Efferent neurons = exit CNS to PNS
Dorsal = “enter through doors” and enter CNS
Ventral root = “leave through vents” and leave CNS
- Sensory info coming into CNS from PNS and carried on sensory neurons = afferent neurons (dorsal)
- Integration in CNS -> decision making, interneurons (entirely contained within CNS)
- Motor output (PNS) -> commands sent out to the body and carried on motor neurons (efferent neurons) exiting the CNS
What are you able to feel/do if you cut dorsal root and get thumb injury?
If cut dorsal root, you can’t feel thumb but can move it
Reflex -> what part of nervous system does it include?
What type of neuron is sensory neuron?
Motor neuron = _____neuron
Sensory neuron =____neuron
rapid integration to avoid potential injury
connects muscle to spinal coral
Sensory neuron is unipolar (weird looking one with head in middle)
For kick flip reflex -> you sense pressure from sensory neuron (afferent neuron), signal sent to spinal cord, and directly to motor neuron (efferent neuron) which causes quad muscle to contract and at the same time sensory neuron also sends signal to inhibitory interneuron which then sends signal to efferent motor neuron to relax the hamstring muscle, both of these actions cause you to kick up
Reflex -> what part of nervous system does it include? What type of neuron is sensory neuron? Reciprocal inhibition (book) Motor neuron = \_\_\_\_\_neuron Sensory neuron =\_\_\_\_neuron
rapid integration to avoid potential injury
connects muscle to spinal coral
Sensory neuron is unipolar (weird looking one with head in middle)
For kick flip reflex -> you sense pressure from sensory neuron (afferent neuron), signal sent to spinal cord, and directly to motor neuron (efferent neuron) which causes quad muscle to contract and at the same time sensory neuron also sends signal to inhibitory interneuron which then sends signal to efferent motor neuron to relax the hamstring muscle, both of these actions cause you to kick up
This is called reciprocal inhibition
Motor neuron = efferent neuron
Sensory neuron = afferent neuron
Dicephalon Hypothalamus Pons Medulla Spinal cord Cerebellum Midbrain Limbic system Telencephalon Corpus callosum
continues on next card
These can be labeled counter clockwise on brain diagram starting from top left
Dicephalon -> forebrain and includes thalamus and hypothalamus
- thalamus contains relay and processing center for sensory info
- Hypothalamus interacts with various parts of brain -> Maintains body homeostasis, contains centers for controlling emotions and autonomic functions and hormone regulation, controls pituitary gland
Telencephalon -> consists of two separate cerebral hemispheres, the cerebral hemispheres are connected by a thick bundle of axons called the corpus callosum
The telencephalon consists of two separate cerebral hemispheres, generally speaking the areas of the left and right hemispheres have the same functions. But the the left hemisphere controls the motor functions of the right side of the body, and the right hemisphere controls those of the left side. The left side of the brain is said to be dom and is responsible for speech, right hemisphere more concerned with visual-spatial reasoning and music.
Pons -> facial movement, balance, posture
Medulla -> basic vital/involuntary functions -> controls autonomic processes such as blood pressure, blood flow, HR, respiratory rate, swallowing, vomiting, cough, hiccup
Spinal cord -> simple reflexes, controls primitive processes such as walking, urination, and sex organ function
Cerebellum -> coordination of complex movement, BALANCE
(damage here result in poor hand eye coordination and balance)
Midbrain -> visual and auditory info, wakefulness and consciousness, startle reflex
Limbic system -> psychological response to emotional stimuli, helps memory storage
