Chapter 7 Flashcards

Prepare for Exam 2

1
Q

Review the anatomy and functions of neurons and glia in the 1st 8 to 9 pages of the chapter.

A

Note: when figure numbers are mentioned, the 10th ed. Is sited 1st and the 9th is in REVIEW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a “resting membrane potential”? i.e. , what does this mean?

A

The potential difference across a cell membrane when the cell is in a unstiumlated stated, the resting potential is always negatively charged on the inside of the membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an “excitable” tissue” Give examples.

A

Ability of the specialized cells to answer the stimulation by a change in membrane potential or generation on action potential. Examples include: nerve, muscle, and certain secretor cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Depolarization:

A

Appropriate stimulation causes positive charges to flow into the cell. Up flow.
Depolarzation of dentrite is excitatory.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

threshold level:

A

The minimum amount of stimulus required to start an action potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Overshoot:

A

Continuation of depolarization until the peak of action potential has been reached.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Repolarization:

A

A return to the resting membrane potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Hyperpolarization:

A

If the stimulation inside the cell causes the inside of the cell to become more negative, the line will reflect downward. Hypolarization of dentries is called inhibitory.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why are the Na and K ion channels often called gates? Why are they “voltage regulated”?

A

These are called voltage regulated gates because they open when stimulated by depolarization.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

“All or None Law”:

A

Either a action potential happens or it doesn’t. If depolarization is below the threshold value, the voltage-regulated gates are closed; vise verce.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

“Coding for Stimulus Intensity”:

A

A stronger stimulus cannot produce an action potential of greater amplitude. Nervous system is frequency modulated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

“Recruitment”

A

another mechanism by which the nervous system can code for stimulus strength. Stimulus activate axons low with low/high with high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

“Refractory Period”:

A

Refractory Period is a period of time which the never / axon is not responsive to a second stimulus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Absolute

A

Cannot respond to any subsequent stiumults, gates are either open or inactive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Relative:

A

Na cell “recover” from their inactive state, membrane is in the process of repolarizing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give a definition of “Cable Properties: What happens to “signal strength” with distance?

A

Cable properties is the ability of a neuron to transmit charges through its cytoplasm. The strength of the signal decreases with distance. Amps help along the way.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Explain “conduction” in both an “unmyelinated” and “myelinated” axon

A

Conduction really means that each action potential is a separate, complete event that is repeated or “regenerated” along the axon’s length. Similar to a wave.
Unmyelinated: Conduction rate is relatively slow, however, faster if the unmyelinated axon is thicker (axons are less resistant to the flow of charges)

Myelinated: Myelin has interruptions (node of Ravier which cannot be separated by more than 1 to 2 mm). AP only occurs at the Nodes and “leap” from Node to Node which is called salutatory conduction. (Saltario = Leap in latin). AP is conducted much faster because of voltage-gates channels at the Nodes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do “saltatory” and “propagation” mean?

A

Saltatory = Jump

Propagation: increase (as of a kind of organism) in numbers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the range of speed of conduction in various axons?

A

10,000 per square micrometer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a “synapse”? What are they called at a neuron/muscle junction?

A

A Synapse is the functional connection between a neuron and a second cell (“Excitable Cells”). In the CNS this other cell is call a neuron, and in the PNS it can be either a neuron or an effector cell in a muscle or gland. These are called myoneural or neuromuscalr junctions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

There are 3 types of neuron/neuron junctions. What are their names?

A

The three names are: axodentritic, Axosomatic, and Axoaxonic synapses. Almost all synapses, transmission is in one direcetion: presynatpic to postsynaptic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are “electrical” synapses?

A

Electrical Synapses: Gap Junctions: cells must be the approximate equal size and much be joined by areas of contact with low electrical resistance, so impulses can regenerate from one cell to the next w/o interruption. GJ’s are composed of 12 proteins known as connexins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are “Chemical” synapses?

A

Chemical synapses: Release of chemical neurotransmitters from presynatpic axon endings. Requires that a syptice cleft stay narrow. Composed of Presynatpic endings (terminal boutons) and separated from the postsynaptic cell by a synaptic cleft. This is mechanism releases all neurotransmitters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are “neurotransmitters”? What was the 1st one discovered? What was it called initially?

A

Neurotransmitters stimulate action potential in postsynaptic cells. The first one that was discovered was ACh (acetylcholine), it was initially called Vagusstoff because Otto Loewi concluded that the nerve endings of the Vagus must have released a chemical.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Understand how “Gap Junctions’ work and where you might find them in our body.

A

Present in cardiac muscles, some smooth muscles (uterus during labor), neurons in the brain, found between neuroglial cells. GJ’s are composed of 12 proteins known as connexins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The axon may branch into many _________ axons and each of these ends in a _____________.

A

The axon is typically a long, slender process of the cell body that sends nerve impulses. It emerges from the cell body at the cone-shaped axon hillock. Nerve impulses arise in the trigger zone, generally located in the initial segment, an area just outside the axon hillock. The cytoplasm of the axon, the axoplasm, is surrounded by its plasma membrane, the axolemma. A few axons branch along their lengths to form axon collaterals, and these branches may return to merge with the main axon. At its end, each axon or axon collateral usually forms numerous branches ( telodendria), with most branches terminating in bulb-shaped structures called synaptic knobs (synaptic end bulbs, also called terminal boutons). The synaptic knobs contain neurotransmitters, chemicals that transmit nerve impulses to a muscle or another neuron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do “pre-synaptic”, “post-synaptic” and “synaptic cleft” refer to?

A

“pre-synaptic”:
“post-synaptic”:
“synaptic cleft”: UPDATE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are “CAMs”? What is their significance?

A

CAMs, Cell Adhesion Molecules, are proteins in the pre- & postsynaptic membranes that project from the membranes into the synaptic cleft, where they bond to each other. These ensure that the membranes stay in close proximity for rapid chemical transmission.

29
Q

Know the processes involved in ‘The release of a neurotransmitter” Fig. 7.23 (7.22)

A
  1. Action potential reach axon terminal
  2. Voltage-gated Ca2 channels open
  3. Ca2 in cytoplasm activates proteins leading to fusion of vesicles with plasma membrane.
  4. Pore forms in fused vesicle and exocytosis releases neurotransmitter.
30
Q

How do “Botulinum” and “Tetanus” toxins work?

A

These are bacterial products that cause paralysis by preventing neurotransmission. Proteases (protein digesting enzymes). Botulinum prevent the release of Ach; Tetanus blocks inhibitory synapses.

31
Q

What are “chemically regulated” gates? Some produce a partial depolarization called an_________

A

Chemically regulated gates open in response to the binding of postsynaptic receptor proteins to their neurotransmitter ligands.
EPSP – Excitatory postsynaptic potential (moving towards threshold – Depolarization
IPSP – Inside of the postsynaptic membrane becomes more negative (hyperpolarized), moves farther from the threshold

32
Q

Where do you find these chemically regulated gates?

A

Chemically regulated gates are typically found in postsynaptic membrane.

33
Q

For most neurons, where are the 1st “voltage regulated” gates located? What do they cause?

A

Voltage regulated gates are found primarily in axons, and open in response to the postsynaptic membrane.

34
Q

. A protein receptor that binds (responds to) Ach is often referred to as a ____________receptor.

A

Cholinergic

35
Q

There are 2 such types of Cholinergic receptors, their names are: ______________ & ______________

A
  1. Nicotinic - always generate EPSP (e.g. Stimulates muscle contractions) found in autonomic ganglia and skeletal musc
  2. Muscarinic - acts like a G Protiens, found in smooth musc cells, cardiac muscles, and particlar glands.
36
Q

Nicotinic and Muscarinic have these names because in addition to binding Ach they bind _________ & _______________

A

Ligand gates channels-neurotransmitter molecule is the ligand that binds to a specific receptor protein. Think EPSP (no threshold, graded in magnitude, no refractory period, capable of summation) Nicotinic receptors.
G-protein coupled channels- opened by the binding of a neurotransmitter to its receptor protein. Unlike Ligand, the receptors and ion channels are different, separate membrane proteins. Muscarinic receptors (do not contain ion channels, binding is causes it to activate a complex of proteins called G-Proteins.

37
Q

Be able to describe what happens at a “nicotinic” receptor and why it produces an EPSP. Fig. 7.26 (7.24)

A
  1. Channel closed until neurotransmitter binds to it
  2. Open channels permits diffusion of specific ions. Na and K diffuse simultaneously, in opposite directions. More Na comes in than K leaves which results in depolarization known as EPSP.
38
Q

What are the characteristics of an EPSP as shown in your textbook? Be able to explain these.

A

EPSPs: occur in thr dendrites and cell body, have no threshold (tiny depolarization of the postsynaptic), graded in magnitude (when more vesicles are stimulated to release their ACh, the depolarization is greater), no refactory period (because they are graded), and they are capable of summation (depolarization of several different EPSPs can be added together)

39
Q

What are G-proteins?

A

The binding of ACh to muscarinic receptors causes the activation of the G-proteins. There are three subunits: alpha, beta, and gamma. Alpha disassociates from the other two, the other two stick together to form the beta-gamma complex. Depending on specificity, either alpha or beta-gamma will diffuse through the membrane until it binds to an ion channel which will then either open or close.

40
Q

Be able to describe the processes shown in Fig. 7.27 (7.25) which shows a “muscarinic” receptor.

A

Pacemaker cells off the heart: ACh binds to receptor, Gprotein subunits dissociate, Gprotein binds to K Channel causing it to opens

41
Q

In what tissue is the example of Fig 7.27 found? When activated what happens?

A

Pacemaker, slowed the heart rate due to the outward diffusion of K.

42
Q

Do all muscarinic receptors work the same way?

A

No

43
Q

Both nicotinic and muscarinic receptors have 2 functions. What are they?

A

ESPS and IPSP

44
Q

Be able to explain what is happening in Fig 7.28 (7.26)

A

AChE (Acetylcholinesterase-an enzyme which inactivates ACh) this figure shows inactivating of ACh released into the synaptic cleft, which prevents continued stimulation.

45
Q

neuromuscular junction

A

Somatic motor neurons form synapses with skeletal muscles cells (muscle fibers). These are the synapses.

46
Q

motor end plate

A

Find this is the post-synaptic membrane of the muscle fiber.

47
Q

end-plate potentials mean

A

the graded depolarization produced by ACh at the neuromuscular junction. This is equivalent to the excitatory postsnyaptic potential produced at neruron-neruon synapses.

48
Q

Curare is a drug used by Indians in So. America. What does it do? How does it do it? Is it used today?

A

Resin from So Am tree, prevents interaction of ACh with its nicontinic receptor proteins. See Table 7.5

49
Q

What molecules are known as “monoamines”? “Catecholamines”? From what amino acids are they derived?

A
Pg 188
Monamines: contains one amino acid, a class of neurotransmitter molecues which includes serotonin (derived from the amino acid tryptophane), dopamine, and norepinephrine. 
Cateholamines: Sub-group of monoamine which are dervied from the amino acid tryosine, this is a family of molecules which includes Epinephrine (adrealine), norepinephrine, and dopamine.
50
Q

Know the steps in the metabolic pathway for the production of “Norepinephrine” (NE), Fig.7.30 (7.28)

A

Tryosine - Dopa - Dopamine = Norepinephrine

pg 188

51
Q

How is NE gotten rid of? i.e., what enzymes or other process is involved? How do MAOs work?

A

MAOs - (Monoamine Oxidase) inactivate neurotransmitters. They break down monoamines in the presynaptic neuron endings
COMT - (Catechol-O-methyltransferase) are enzymes that destroy catecholamine nerotransmitters

52
Q

What is Epinephrine known as in the rest of the world?

A

Adrenaline

53
Q

Protein receptors that bind catecholamines are also known as_________ receptors. There are 2 types of these called _______ & __________

A

Epinephrine and Nor-epi are 2 catechoamines also known as Adrenaline and Nor- ad. Thus, their receptors are “adrenergic receptors”. There are 2 types, alpha and beta.

54
Q

The receptor shown in Figure 7.31 (7.29) is one of these 2 types. Which?

A

Find

55
Q

Know all of the processes illustrated in that Fig. 7.31

A
  1. Requires a G-Protein. NE binds to its receptor causes
  2. The dissociation of G-Proteins.
  3. Binding of the Alpha G-Protein to the enzyme adenylate cyclase activates this enzyme, whichs leads to the production of the 2nd messengar cyclic AMP (cAMP)
  4. cAMP, activates a protein kinase, whihc can open ion channels and produce other effects (e.g beta-receptors).
56
Q

Serotonin (S) is also known as ______________. Physiological functions attributed to S are:

A

Serotonin, 5-HT, otherwise known as tryptophan, is a reuptake inhibitor. The physiological functions attributed to Serotonin include a role in the regulation of mood and behavior, appetite, and cerebral circulation.

57
Q

What is the relationship of LSD to S?

A

The relationship is that is mimics the structure and function of Serotonin.

58
Q

How do the “antidepressant drugs” work?

A

Blocks Serotonin

59
Q

Neurons that release “Dopamine” are called:

A

Antidepressants work by blocking the reuptake of serotonin into the presynaptic endings, and thereby increasing the effectiveness of serotonin transmission at synapses.

60
Q

How is “Parkinson’s Disease” related to dopamine?

A

Neurons that release dopamine are called dopaminergic neurons. These are highly concentrated in the midbrain and their axons project to different parts into the brain and are divided into two systems. Nigrostrial dopamine system, involved in motor control. Mesolimbic dopamine system, involved in emotional reward.

61
Q

What is the significance of D2 receptors?

A

Parkinson’s Disease, is caused by the degeneration of the dopaminergic neruors located in the substantia nigra, which is a part of the nigrostriatal dopamine system the motor control system.

62
Q

What is the significance of D2 receptors?

A

D2 receptors, involved in the mesolimbic dopamine system the behavior/reward system, is strongly associated with addictive drugs and alcoholism. These drugs/booze promote the activity of dopamanergic neuros that arise in the midbrain and terminate in the nucleus accumbens of the forebrain.

63
Q

What kind of receptors are glycine and GABA? What do these 2 cause to happen ? What ion channels do they open?

A

Glycine and GABA (Gama-aminobutryric Acid) are inhibatory receports that cause a hyperpolization in the postsynaptic membrand and produces IPSPs. These both cause the opening of Cl(-) channels in the postynaptic membrane.

64
Q

What is substance P?

A

Substance P is a polypeptide that functions as a neurotranmitter in pathyways of the brain that meditate senstations of pain.
.

65
Q

What role does Nitric Oxide (NO) play in our body?

A

Nitric Oxide, cause the relaxation of smooth muscles (think Viagra) so that the blood vessels can dilate.

66
Q

What do the terms “spatial” and “temporal” summation mean?

A

Spatial - Place/Space

Temporal - Time

67
Q

What did I tell you “integration” (in the nervous system) means?

A

Integration in the nervous system means will the Axon Hillock be deporlazed to threshold and generate an action potential.

68
Q

Glutamic acid and aspartic acid are what kind of transmitters?

A

Glutamic acid and Aspartic acid function as excitartory neurotransmitters in the CNS and produce EPSPs.
Receptors for Glutamic acid are:
1. NMDA receptors (memory storage, receptor channels for Ca and Na. Permits the entry of Ca and Na and exit of K into the dendrites of the postsynaptic neurons)
2. AMPA receptors (another Glut. A receptor)
3. Kainate receptors (–)

69
Q

What are “Endogenous Opioids”?

A

Endogenous Opiods, such as opinum and morphine, can produce euphoria. This system is inactive under normal condutions, but when activiated by stressors it can block the transmission of pain. Polypeptides associated with this system are Beta-Endorphin, enkephalins, and dynorphin