Module 3: Lecture 8

Question 1

what is the adrenal gland composed of?

Answer 1

two areas
- inner adrenal medulla
- a surrounding adrenal cortex

Question 2

what does the inner adrenal medulla secrete?

Answer 2

epinephrine and norepinephrine

Question 3

what does the surrounding adrenal cortex secrete?

Answer 3

steroid hormones

Question 4

the adrenal glands are modified sympathetic ganglion whose cell bodies _________________________ –> ______________________.

Answer 4

do not have axons –> they release their secretions into the blood

Question 5

instead of the adrenal gland having a post-ganglionic neuron, what does it have/do instead?

Answer 5

from the pre-ganglionic neuron it goes straight into the adrenal gland like acts like the postganglionic neuron

Question 6

is the adrenal gland an adrenergic fibre?

Answer 6

yes, but it also secretes epinephrine

Question 7

how much of the adrenal medullas secretion is epinephrine and norepinephrine?

Answer 7

• 80% epinephrine
• 20% norepinephrine

Question 8

why does the adrenal medulla only secrete 20% norepinephrine?

Answer 8

because it contains high amounts of phenyl-N-methyltransferase (PNMT)

Question 9

what does phenyl-N-methyltransferase (PNMT) do?

Answer 9

converts norepinephrine into epinephrine

Question 10

which one has a more wide ranging effects within the body, epinephrine or norepinephrine?

Answer 10

epinephrine
- this is why the adrenal gland should release more of it because it can act more generally rather than locally

Question 11

are acetylcholine, epinephrine and norepinephrine neurotransmitters?

Answer 11

yes

Question 12

its not only the neurotransmitter that determines how the tissue is going to respond, its also depends on the?

Answer 12

receptor that, that neurotransmitter is binding to

Question 13

what are the two types of cholinergic receptors(Ach)?

Answer 13

1. nicotinic (ionotropic receptor) - ligand gated ion channel
2. muscarinic (metabotropic receptor) - act through a secondary messenger

Question 14

where is the nicotinic receptor found?

Answer 14

on the postganglionic cell bodies on all autonomic ganglia (because acetylcholine is released at that synapse between the pre and post ganglionic neurons)

Question 15

what happens when acetylcholine binds to a nicotinic receptor?

Answer 15

its just an ionotropic receptor
- just an ion channel that opens to allow sodium ions into the cell creating the excitatory postsynaptic potential (EPSP)
- depolarizing event

Question 16

what is responsible for generating an action potential in the postganglionic neuron?

Answer 16

the nicotinic receptor

Question 17

what are the receptors on your end effector organs?

Answer 17

the muscarinic cholinergic receptors

Question 18

which system utilizes acetylcholine?

Answer 18

parasympathetic in the post ganglion neurons

Question 19

depending on the receptor subtype that the tissue is expressing, it will change how ______________________.

Answer 19

that neurotransmitter effects it
- can have either an excitatory effect or an inhibitory effect

Question 20

stimulation of Beta1 usually leads to?

Answer 20

an excitatory effect (eg. heart stimulation)

Question 21

stimulation of Beta2 usually leads to?

Answer 21

an inhibitory effect (eg. salbutamol for asthma: smooth muscle cells relax causing bronchodilation without affecting heart rate)

Question 22

what are G-proteins?

Answer 22

second messengers for metabotropic receptors
- (i could be wrong about this)

Question 23

what G-protein is for beta receptors?

Answer 23

cyclic AMP (cAMP)

Question 24

what G-protein is for alpha receptors?

Answer 24

calcium ions

Question 25

what are cetacholamine receptors?

Answer 25

A catecholamine receptor is a type of G protein-coupled receptor that binds to and responds to neurotransmitters that include, norepinephrine, and epinephrine.

Question 26

what happens when there is a binding of an agonist to a receptor?

Answer 26

activates the receptor similar to the neurotransmitter's actions - essentially binds to that receptor and acting like the neurotransmitter - it activates that receptor

Question 27

what happens when there is a binding of an antagonist to a receptor?

Answer 27

- blocks the neurotransmitters response

Question 28

where are your nicotinic receptors?

Answer 28

the connection point between the pre and post ganglionic neurons of the parasympathetic and sympathetic systems

Question 29

what is the system that we have voluntary and conscious control over?

Answer 29

the somatic nervous system

Question 30

what is the system that innervates our skeletal muscles?

Answer 30

the somatic nervous system

Question 31

does the somatic nervous system utilize two neurons?

Answer 31

no, only one that travels from the central nervous system towards the actual skeletal muscle fiber itself

Question 32

what is the only way you can control your skeletal muscle?

Answer 32

through the motor axon

Question 33

the cell bodies of the motor neurons are located?

Answer 33

in the ventral horn of the spinal cord or brain stem for the head muscles

Question 34

what is the neurotransmitter that is released at the output of the motor neuron?

Answer 34

acetylcholine (ACh)

Question 35

why are motor neurons considered the "final common pathway"?

Answer 35

any time your muscle is activated, it is because your motor neuron was activated - all the output from your CNS towards your muscle fibers has to come through that motor neuron

Question 36

can the cell body of the motor neuron receive BOTH inhibitory and excitatory input?

Answer 36

yes

Question 37

what determines the level of activity of the motor neuron and its output to skeletal muscle fibres?

Answer 37

the relative balance of EPSP and IPSP

Question 38

is there involuntary input to the somatic nervous system?

Answer 38

yes - like breathing because if we think about it, we are controlling it. but if we do not think about it, we still do it

Question 39

what is the neuromuscular junction?

Answer 39

the link between each axon terminal of a motor neuron and skeletal muscle fibres - link of nerve to muscle

Question 40

when the axon becomes enlarged in the neuromuscular junction, what is it called?

Answer 40

terminal button - its just the axon terminal - bulbous swelling at the end of the axon terminal that holds all of your synaptic vesicles with that neurotransmitter

Question 41

when the neuromuscular junction comes in contact with a specialized portion of the skeletal muscle fibre what is it called?

Answer 41

the motor end plate

Question 42

what neurotransmitter is released from the neuromuscular junction?

Answer 42

acetylcholine

Question 43

what is on the motor end plate?

Answer 43

a whole bunch of ion channels that acetylcholine will bind to

Question 44

when sodium enters the muscle fiber, a graded potential/EPSP is generated. however, because it is in the muscle, what is it called?

Answer 44

end plate potential (EPP)

Question 45

what is the type of receptors that Ach is going to bind to on the motor end plate?

Answer 45

a nicotinic receptor - a cholinergic receptor that is an ion channel that opens in response to acetylcholine binding to it

Question 46

where on the muscle fiber does the motor neuron innervate it at the neuromuscular junction?

Answer 46

the motor neuron tends to innervate it in about the middle of the muscle fiber

Question 47

because the motor neuron innervates the muscle fiber in the middle of the fiber, what happens when it generates the action potential?

Answer 47

the axon potential will spread in both directions along the fiber, away from the neuromuscular junction

Question 48

one end plate potential, will always generated an?

Answer 48

action potential in the muscle fiber itself - unlike a synapse which needs many inputs on the postsynaptic neuron to generate an action potential

Question 49

if a motor neuron generates an action potential, it will generate _______________________________________________________.

Answer 49

an action potential in the skeletal muscle fiber

Question 50

is the action potential of a neuromuscular junction always excitatory?

Answer 50

yes - input zone can receive inhibitory or excitatory, BUT the output zone, when it actually fires the action potential, will always be excitatory at the level of the muscle fiber

Question 51

what does the venom from a black widow spider result in?

Answer 51

all of your synaptic vesicles to suddenly being released at once

Question 52

what does botilium toxin do?

Answer 52

its botox - blocks the release of ACh from the terminal button

Question 53

what does curare do?

Answer 53

block ACh receptors on the motor end plate (antagonist) - respiratory paralysis = inability to contract muscles

Question 54

what does sarin do?

Answer 54

- inhibits the acetylcholinesterase (degrades the acetylcholine to reset to synaptic cleft) - this blocks/prevents further depolarization of the cell from subsequent action potentials