Chapter 8 Flashcards
What is electrical signaling?
It is the transport of ions through neurons
What is chemical signaling?
It is the transport of a chemical signal that gets transported via binding a receptor to send a message to the cell.
What kind of signaling is only present in the endocrine system?
Chemical
What are hormones?
Hormones are chemical signals released by the endocrine system that are secreted into the blood and distributed throughout the body via circulation.
What are neurocrines?
It is a term to describe anything released from an neuron
What are the 3 different kinds of neurocrines?
Neurotransmitters, neuromodulators, and neurohormones
What are neuromodulators?
They are released from neurons and change synapses
What are neurotransmitters?
Chemical messengers that transmit signals between neurons from across the synapse
What are neurohormones?
They are hormones that are released by neurons and get transported through the bloodstream
What is a ligand?
Any molecule that irreversibly binds to a receiving protein molecule (aka receptors)
What are the two kinds of ligands?
hormones and neurocrines
What is specificity at receptors?
Only certain cells have receptors that bind to a particular ligand and only certain cells produce those ligands
What is competition at cell receptors?
It is when ligands of similar type compete to bind to their specific receptor
What are agonists?
They are ligands of a similar type to the initial ligand and they beat it to the receptor to produce a response
What are some examples of drugs that are agonists?
- Hormones of every kind ex birth control
- Morphine binds to opioid receptors
What are antagonists?
They are competing ligands that block an initial ligand but do not produce a signal
What is an example of an antagonistic drug?
Beta blockers because they block receptors in the heart and blood vessels from both types of adrenaline
What is distinct about intercellular ligands?
They are lipophilic and they are mostly hormones (ex estrogen and testosterone)
What is distinct about extracellular receptors?
That they are lipophobic and are mostly neurotransmitters
Are all hormones ligands?
Yes but not all ligands are hormones
What does the nervous system do?
It takes in sensory information, processes it, and sends out signals on what to do about it.
What is in the CNS?
The brain and spinal cord
What does the CNS do?
It is the intergrating center and decides what to do regarding the sensory information
What types of nerves make up the peripheral nervous system (PNS)?
Sensory or afferent neurons brings info in to the CNS and Motor or efferent neurons brings info out of the CNS
What does the somatic division of the nervous system control?
It controls the skeletal muscles
What does the autonomic division of the nervous system control?
It controls both the sympathetic and parasympathetic parts of the nervous system
What does the sympathetic nervous system control?
It controls our reflexive biological responses that are associated with fight or flight reactions
What does the parasympathetic nervous system control?
It controls our biological responses related to rest and digest behaviors
What is the part of the neuron that recieves information from other neurons?
The dendrites
Which part of the neuron integrates information?
The axon
What part of the neuron sends out information?
The axon terminal
Describe what an anaxonic axon looks like and how it relates to its function
anaxonic axons do not have an identifiable body and instead consist of a cell body that is surrounded by dendrites. this structure allows for it to be a connector or an interneuron between other neurons in the CNS
Describe what a bipolar neuron looks like and how it relates to its function
A bipolar neuron has dendrites that is connected by long dendrite to the cell body in the middle which connects to the axon and the axon terminal. Which allows for it to take in and interpret sensory information from the nose or the eye
Describe what a pseudounipolar neuron looks like and how it relates to its function
A pseudounipolar neuron has dendrites with an axon that connects to the cell body in the middle and has another axon that connects to the axon terminal. Which help them send information from the peripheral senses to the CNS
Describe what a multipolar neuron looks like and how its shape relates to its function
A multipolar neuron has dendrites that connect to the cell body and the axon extends out from the other side until it branches into the axon terminal. Its branches allows for it to an interneuron in the CNS and along with a efferent sensory neuron
What is a nerve?
It is a cluster of multiple neurons and can be of both kinds including afferent and efferent meaning that in a single nerve, it can both send and recieve information from the CNS
What is the role of afferent neurons?
To bring in sensory information to the CNS
What is the role of efferent neurons?
The efferent neurons are bringing the responses from the CNS out to the body
What kind of sensory information do afferent neurons carry into the CNS?
They carry information about temperature, pressure, and light
What shape of neurons are found in sensory neurons?
Bipolar (special senses only)
and psedounipolar ( that are myelinated and are general senses)
Where specifically, are bipolar neurons only found?
the retina of the eye
the inner ear
and the nasal cavity
What are the general senses?
touch, pressure, pain, and temperature (anything from the skin)
What shape of neurons are motor neurons?
Literally all of them are multipolar
What shape of neurons are found in interneurons?
The kinds that are found include anaoxic, and multipolar
What happens in anterograde transport?
This when vesicles that are made in the cell body of the axon get moved to axon terminal
What is an oligodendrocyte?
It is a CNS Glial cell that consists of branches that cover multiple axons at once in a myelin sheath which helps increase transmission speed
What are the roles of an astrocyte?
The roles of an astrocyte include:
-maintaining the blood, brain barrier
- provides structure for the neurons
- stabilizes damaged tissues
- direct neurons where to go in embryonic growth
- regulate the interstitial fluid around the neurons
What is the blood brain barrier (bbb)?
It is a barrier in the brain that selectively allows some substances into the blood and some out into the interstitial fluid to protect the neurons in the brain
What is the shape of the astrocytes?
they have a lot of branches coming off of them
What are the roles of the ependymal cells?
- they produce and regulate the cerebrospinal fluid (CSF)
- circulate the CSF
- may contain neural stem cells
- lines ventricles/central canal
What is unique about the structure of the ependymal cells?
That they create a layer of selectively permeable epithelial layer
What is distinct about the structure of the microglial cells?
They are NOT neurons they are immune cells that are permanently located in the CNS
What is the role of microglial cells?
-perform phagocytosis in the CNS
What is the role of schwan cells?
-to wrap around one axon with myelin in the PNS (it take 500 schwan cells to around 1 axon)
What is role of satellite cells?
- to surround the cell body of neurons in the PNS
How do ion channels affect selective permeability?
They affect permeability because they will open or close their channels to their corresponding ions such as na, or k based on the charges intercellularly or extracellularly.
What causes voltage-gated ion channels to open?
They respond based on changed to the cell’s membrane potential
What causes chemically gated ion channels to open?
Chemically gated ion channels open in response to ligands weather they are neurotransmitters or intercellular signal molecules
What is a graded potential?
A graded potential is the result of a stimulus entering the neuron via a signal. It can vary in length and it travels in short distances and loses strength as it does so. But if it is strong enough when it reaches the trigger zone it will cause an action potential to occur.
What is the trigger zone?
It is a point along the neuron (that can vary based on type) where if the graded potential reaches it and gets to -55mV than an action potential will go off but ONLY if it reaches that charger or more
What is an action potential?
It is a signal that goes off it the cell reaches the proper amount of depolarization. The signal will carry off info/ neurotransmitter portions form the cell body to the axon terminals to send off a signal of its own.
What does threshold mean?
It means the amount of mV an graded potential must be at in order to set of a action potential
What does the rising phase mean?
It is the phase when the Na+ (fast channels) are open which is depolarizing the charge of the cell
What does the falling phase mean?
The falling phase happens after the rising phase and it due to the K+ channels opening and letting K+ out of the cell which is making the charge more negative
What causes the cell to go into hyperpolarization after the falling phase?
It is caused by the K+ or slow channels taking longer to close meaning that the cell is still getting more negative and and more so than at resting potential
What is the absolute refractory period?
it is a period following an action potential where where a second one cannot be started for 1-2 seconds after the first because the inactivation gates na+ are up
What is the relative refractory period?
It is following an absolute refractory period because technically another action potential can be started because na+ is open again but so is k+ so the cell is hyperpolarized meaning only a strong stimulus can open it
What does the refractory period ensure?
That an action potential cannot travel backwards and that there is a maximum rate that a single axon can produce action potentials
What is local flow?
This is the movement of positive and negative charges being moved along the axon which goes in both directions
What how does local flow impact the opening of na+ channels?
but it means that parts of the axon deopolarize for na+ channels to open up not the whole thing at once
How does the large diameter of an axon affect the velocity of an action potential in an unmyelinated axon?
It speeds it up because there will be a smaller percentage of ions traveling along the membrane which slows it down
What is saltatory conduction?
It is the passage of an action potential through a myelinated axon which due the myelin will speed up because that means only the nodes of ranvier will have na+ channels go through
What does it mean for a neurotransmitter to have multiple receptor isoforms?
that it allows for one neurotransmitter to have different effects in different tissues.
What happens in electrical synapses?
The current flows directly between gap junctions in the synapse which is quicker than chemical and it allows for the signal to go both ways
What happens in chemical synapses?
the presynaptic neuron releases neurocrines that travel across the synapse and bind to a receptor on the postsynaptic neuron
What are two different isoforms for receptors
Ligand gated ion channels and g protein coupled receptors (gpcr’s)
What happens in ligand gated ion channels?
The ligand will bind to the receptor which produces a rapid response (opens an ion channel(s)) in the postsynaptic cell
What happens in G- Protein coupled receptors?
-they take longer to produce a response (that is literally anything other than opening an ion channel) and can cause any other form of cellular activity
-it consists of a slow second messenger response
Using acetylcholine (ACh) describe how a neurotransmitter is released beginning with the action potential and ending with the postsynaptic cell producing a response
- the action potential arrives at the synaptic terminal
- the voltage gated ion channels open allowing for Ca 2+ to enter
- Cat 2+ causes exocytosis of the neurotransmitter
- the neurotransmitter binds to receptor
- a response is produced by the postsynaptic cell
What are the 3 main methods of terminating a signal?
- Reuptake of the neurotransmitter
- degrading of the neurotransmitter
- diffusion moves the neurotransmitter
What does reuptake of the neurotransmitter do?
there are 2 methods it either gets recycled from the axon terminal back to the cell body or extracelluarly it will be recycled by glial cells in the synapse
What does it mean to degrade the neurotransmitter?
It is when enzyme that specifically correlates to the neurotransmitter will inactivate the neurotransmitter while it is attached to it’s receptor ex acetylcholinesterase for acetylcholine
What does it mean that a neurotransmitter will diffuse out of the receptor?
That over time, the neurotransmitter will diffuse away from the synapse
What does divergence mean regarding presynaptic neurons?
It describes when a presynaptic neuron sends out multiple signals at once
What does divergence mean regarding postsynaptic neurons?
It is when a group of presynaptic neurons each send a smaller signal to one postsynaptic neuron
What does an excitatory postsynaptic potential (EPSP) mean?
It describes when a postsynaptic cell depolarizes after an action potential
ex na+ channels open
What does a inhibitory postsynaptic potential (IPSP) mean?
It describes when a post synaptic cell becomes hyperpolarized
ex cl- channels open
What happens to the graded potential at the axon hillock?
This is last part of the neuron where a graded potential can be summed.
(can it produce an AP? this is it’s chance)
Where on the axon does the action potential begin?
It begins at the initial segment of the axon
Where on an axon are voltage gated ion channels found?
They are found on at the:
axon hillock
axon (Na+ in and K+ out)
synaptic terminals (ca2+)
Where are the chemically gated ion channels found on an axon?
they are found in the dendrites
Where are electrical synapses found, in the CNS, PNS or both?
Electrical synapses are found in the CNS
Where are chemical synapses found, in the CNS, PNS or both?
they are found in both the CNS and the PNS
Does the term repolarization, hyperpolarization, or depolarization best describe the following?
Membrane potential changes from +10mV to -70 mV
Repolarization
Does the term repolarization, hyperpolarization, or depolarization best describe the following?
Membrane potential changes from -70mV to -90mV
hyperpolarization
Does the term repolarization, hyperpolarization, or depolarization best describe the following?
membrane potential changes from -70mV to -50mV
depolarization
Which part of the axon is enriched in voltage-gated ion channels and is where an action potential begins?
At the axon initial segment
Which of the following is not a part of the CNS?
A) somatic division
B) autonomic division
C) visceral sensory receptors
D) enteric nervous system
E) all of the above
E
Do bipolar neurons carry information about general or specialized senses?
Special senses
Do pseudounipolar neurons carry information about general or specialized senses?
General senses only
