Module 2 Flashcards
What is the threshold of excitation that sets the action potential in motion
-40 mV or higher (-35, -30, -20 etc)
what is the name of the potential that causes the charge to meet the threshold of excitation
post-synaptic potential
what are the Sodium (Na+) channels called, and why
voltage-gated Na+ channels, they are called that because they only open when the threshold of excitation is met
when do the voltage-gated Na+ channels open
when the threshold of excitation is met
where does the action potential start and end?
It starts at the axon hillock, travels down the axon, and ends at the axon terminals
Once the voltage-gated Na+ ion channels open what happens next?
sodium ions rush through the first channels and cause depolarization which sets off a chain reaction down the entire length of the axon.
what happens once the action potential reaches the end of the axon
it hits the axon terminals and causes them to release neurotransmitters into the synapse
once neurotransmitters are released into the synaptic cleft what happens to them?
They immediately search for receptor sites in the next neuron and may cause that neuron to fire as well.
Describe the lock and key analogy of neurotransmitters and receptor sites
Receptor sites are the locks and neurotransmitters are the keys. Each receptor site will only open if the correct key or neurotransmitter connects.
How does the domino analogy help to explain the action potential and active conduction?
It is all or nothing. Just like when a row of dominoes is set up in a line, once you push the first domino all the other dominoes fall. Once an action potential starts it creates a chain reaction that continues down the entire length of the axon.
What is the term that explains the all-or-nothing action potential?
This is called active conduction because it actively pushes the charge down the axon.
What happens to the negative charge when the sodium ions rush in.
It changes to a positive charge
What is the term that refers to the charge moving from negative closer to positive and once it reaches zero it has completely done what?
depolarization. Zero-point is depolarized meaning there is no charge.
Once depolarization happens and the negative charge changes to positive because of all the sodium ions rushing in, what happens to the potassium inside the axon?
Potassium (K+) is positively charged so it doesn’t what to be inside anymore so it rushes out of the axon.
In reference to potassium, are diffusion and electrostatic pressure working together or against each other during the action potential?
They join forces. Now electrostatic pressure joins forces with diffusion and tells potassium to get out of the axon.
What are the two terms for when the ions rush in and rush out of the axon?
efflux - going out
influx - going in
What happens when potassium rushes out of the ion following the sodium rushing in.
hyperpolarization
Are sodium/potassium pumps at play during the action potential?
no
Does hyperpolarization end at zero like depolarization?
no hyperpolarization can keep going either way.
Moving away from zero is called what?
hyperpolarization
Moving towards zero is called what?
depolarization
How does Lidocaine affect the action potential?
It blocks the sodium ion gates from opening or puts a cork in it so no sodium gets through and therefore no action potential happens.
Does the post-synaptic potential still happen when you receive Lidocaine, is there still pain being registered?
Yes, the body knows there is pain and the post-synaptic potential still happens but since there is a cork in the sodium ion channels nothing happens to start the action potential, and the message never reaches the axon terminal or the brain.
The glial cells outnumber neurons 10 to l because they are the helper cells, what is their main job?
to create myelin sheaths
What is the name of the sausage-shaped lengths that are created around the axon called?
myelin sheaths (singular) Myelin (plural)
In between each myelin sheath is a gap where the axon is exposed. What are these gaps called?
Nodes of Ranvier
This protects the axon and makes the action potential faster (not stronger).
Myelin
The Na+ and K+ channels are clustered together in this area.
Nodes of Ranvier
What is the purpose of the Nodes of Ranvier?
They help to speed up the action potential. (like a bus making fewer stops) because the ion channels are all clustered at the nodes the action potential can jump or skip down the axon.
what is the term for the skipping or jumping action that the action potential takes down the nodes of Ranvier?
saltatory conduction
Does the myelin sheaths or the nodes of Ranvier make the action potential stronger?
No, there is no stronger it is all or none, it just makes it faster.
What is the name of the lining that protects the brain?
Meninges
what is the bacterial infection in the lining of the brain?
meningitis (swelling of the lining of the brain)
what are the three subsets of the meninges?
Dura Mater
Subarachnoid space
Pia Mater
Otherwise known as the tough mother, what is the name of the durable tough outermost layer of the meninges?
Dura Mater (tough and durable)
which layer of the meninges contains vascularization and cerebral spinal fluid and looks like spiders under a microscope?
Subarachnoid space
What is the function of the subarachnoid space?
protection by providing a cushion
Otherwise known as the pious mother, what is the name of the soft, innermost layer of the meninges that actually touches the brain?
pia mater (soft and smooth)
What is it called when a blood vessel breaks in the brain (blood where it doesn’t belong)?
subdural hematoma
Why do people not know when they have a subdural hematoma?
there are no pain receptors in the brain so their head just feels funny or weird
This is a large fold of concentrated dura mater found at the caudal end of the brain, that functions to protect the crevice between the occipital lobe and the cerebellum.
Tentorium
This is a large fold of concentrated dura mater that is a bit tougher and stiffer than Tentorium, and functions to protect the longitudinal fissure and separates the cerebral hemispheres.
Falx Cerebri
(Latin: Turkish Saddle or “jockstrap of the brain”) This is a major subset of the ventral meninges that functions to hold up a subset of structures to the rest of the brain.
Sella Turcicas
What are the two subsets of the Sella Turcicas?
Pituitary Gland
Capillary Beds
This subset of the Sella Turcica is sometimes referred to as the “Testicles of the brain”.
Pituitary Gland
This is the main part in the middle of the Sella Turcica and dangles below the brain a little bit.
Pituitary Gland
These are immediately lateral to the pituitary gland. A bed of small blood vessels clustered together.
Capillary beds
These structures receive the hormones and transports them through the blood to the body.
Capillary beds
This structure is a neuro-endocrine structure that releases hormones to the body.
Pituitary Gland
What are the names of the two lobes of the pituitary gland?
Posterior and Anterior
This structure is also a neuro-endocrine structure that releases hormones for very important basic motivations, the primal drives, aka the 4 F’s.
Hypothalamus
This structure connects the hypothalamus to the pituitary and is full of long axons.
Infundibulum
This lobe of the pituitary is directly connected to the hypothalamus through the Infundibulum and is an outgrowth of the hypothalamus. (Why is it considered an outgrowth?)
Posterior Pituitary
It is directly connected to the hypothalamus because its cell bodies are in the hypothalamus, its axons run through the infundibulum and the axon terminals are in the posterior pituitary.
This lobe of the pituitary is its own self-contained structure. (Why is it considered self-contained)
Anterior Pituitary.
It has its own cell bodies, axons, and axon terminals all inside of it.
What are the two main hormones that the posterior pituitary releases?
Vasopressin (AVP)
Oxytocin
This hormone that the posterior pituitary releases plays a role in family relationships.
Vasopressin
This hormone that the posterior pituitary releases lowers anxiety and makes it easier to love somebody, and plays an important role in attachment.
Oxytocin
The anterior pituitary releases 6 hormones. What are the two important ones for this class? (ACTH & B)
adrenocorticotropic hormone (ACTH) Beta-endorphin
I am a stress hormone. I target the adrenal gland and cause it to produce cortisol.
Adrenocorticotropic hormone (ACTH)
I am a naturally produced type of opioid. I am great at reducing pain.
Beta-endorphin
Since the anterior pituitary is not directly receiving messages from the hypothalamus like the posterior is how does the hypothalamus communicate with it?
By producing hormones which then causes it to produce hormones.
I am a spongy tissue around the infundibulum stock that releases histamines in the brain to make you alert.
Tuber Cinereum
