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BMS 344 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What are animal signal forms?

A

Sounds, scents, and visual cues

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2
Q

what is within animal signal forms?

A

chemical and electrical

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3
Q

what are the most types of signals (aka systems)?

A

the nervous and endocrine system

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4
Q

What does the complexity of animal physiology and behavior require?

A

diversity of signaling mechanisms

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5
Q

What causes cell signaling?

A

environmental trigger- need a cue for the production

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6
Q

Cell signaling Steps (3):

A
  1. produciton of a signal in one cell
  2. transport of that signal (chemical messenger) to a target cell
  3. the messenger binds to a receptor to transduce signal into the target cell to cause a response
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7
Q

What are the different types of direct signaling?

A

gap junctions and connexins

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8
Q

what are the different types of indirect signaling?

A

autocrine, paracrine, endocrine, neural, exocrine

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9
Q

Direct Signaling’s local communicaiton is

A

contact-dependent

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10
Q

the chemical messengers pass through what in direct signaling

A

gap junctions or specialized membrane junctions or even directly

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11
Q

what type of messengers are in direct signaling

A

ions, small molecules, and water

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12
Q

is direct signaling an active diffusion?

A

no passive: opened and closed to regulate the communication of substances between cells

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13
Q

steps for indirect cell signaling (3):

A
  1. release of a chemical messenger from signaling cell into the environment
  2. transport of chemical messenger through environment to target cell
  3. communication of signal to target cell by receptor binding
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14
Q

Indirect signaling’s local communication is

A

contact independent and endocrine signaling

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15
Q

Autocrine Signaling

A

messenger affects the signaling cell

itself

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16
Q

Paracrine Signaling

A

messenger affects nearby cells

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17
Q

How does distance affect the diffusion of the messengers in indirect signaling?

A

limits the rate of diffusion
diffusion is insufficient to carry signals to distant target cells

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18
Q

is there a high chance of the messenger getting to a farther location regarding diffusion

A

the longer the distance= the lower chance the messenger gets to its target cell

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19
Q

what are the messengers for endocrine signaling

A

hormones

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20
Q

Glands

A

secretory cells of the exocrine and endocrine tissues are often grouped together into structures

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21
Q

What system carries the hormones from the signaling cell to the target cell?

A

circulatory system

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22
Q

What is the messenger for Neural signaling?

A

neurohormones

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23
Q

does a electrical signal travel long or short distances?

A

long

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24
Q

neurotransmitter

A

reaches terminus trigger release of a chemical messenger

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25
Q

Once reaching the target cells the neurohormone binds to what structure

A

receptor

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26
Q

Can all neurons secrete neurotransmitters directly into the circulatory system

A

no, some!

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27
Q

do neurohormones act like hormones

A

yes!

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28
Q

the most important distinction among the different indirect signaling systems is

A

distance messenger travels
speed of communication

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29
Q

speed of communication for autocrine and paracrine

A

milliseconds to seconds

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30
Q

speed of communication for nervous

A

milliseconds

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31
Q

speed of communication for endocrine

A

seconds to minutes

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32
Q

do endocrine signaling last longer

A

longer-lived

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33
Q

exocrine signaling

A

pheromone

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34
Q

What affects the way signaling is accomplished?

A

structure of the messenger

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35
Q

Hydrophobic Messengers

A

can diffuse freely across cell membrane

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36
Q

what holds hydrophobic messengers in a solution

A

protein carriers

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37
Q

hydrophilic messengers

A

cannot diffuse acorss the cell membrane

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38
Q

what process do they (hydrophilic messengers) do to exit cell

A

exocytosis

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39
Q

do hydrophilic messengers have carriers to travel to target cell?

A

no, they have to dissolve to transport to target cell

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40
Q

Ligands

A

a molecule that binds to another molecule called a receptor to send signals within or between cells.

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41
Q

What are the main classes of chemicals known to participate in cell signaling in animals?

A

Peptide messengers (hydrophilic)
Steriod Messengers (hydrophobic)
Biogenic Amine Messengers
Lipid Messengers (hydrophobic)
Purine Messengers
Gass messengers (ex: CO)

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42
Q

Peptide Messengers

A

Amino Acid residues
- hydrophilic or hydrophobic
- act as neurotransmitters

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43
Q

Peptides < 50 amino acids chains

A

Hydrophilic

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44
Q

Proteins > 50 amino acids chain

A

Hydrophilic

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45
Q

Where and how are peptide messengers synthesized?

A

ribosomes on the rough ER;
synthesized as large inactive polypeptides

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46
Q

Preprohormones

A

large inactive polypeptides

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47
Q

What do peptide messengers possess that target the polypeptide for secretion?

A

signal sequence

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48
Q

Prohormone (inactive)

A

prior to being packaged into secretory vesicles, signal sequence is cleaved from the preprohormone

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49
Q

Biogenic Amine Messengers: aka….

A

Small Water Soluble Hormones

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50
Q

Why do biogenic amine messengers require specific receptors?

A
  • cannot cross plasma membrane
  • too large
  • carry a charge at physiological pH
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51
Q

Where are biogenic amine messengers to be stimulated?

A

vascular system

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52
Q

biogenic amine messengers are carried _____ to needed site

A

freely

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53
Q

examples of biogenic amine messengers:

A
  • Epinephrine (Adrenaline)
  • Norepinephrine (Noradrenaline)
  • Serotonin
  • Histamine
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54
Q

What receptors typically recognize hormones?

A

intracellular receptors (not cell surface receptors)

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55
Q

Where are hormones synthesized and secreted from?

A

Synthesized from cholesterols (hydrophobic); endocrine cells to act on distinct target sites in the human body

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56
Q

Examples of Steroid Hormones

A

estrogen, progesterone, testosterone

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57
Q

examples of thyriod hormones

A

thyroxin, retinoids (vitamin A), cortisol and vitamin D

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57
Q

What happens if there is no receptor for a signal?

A

cell will never be able to detect it

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57
Q

What is cell signaling?

A
  • Extracellular signaling molecule (1st Messenger)
    recognized by the receptor.
  • Leads to the production of small transient signaling
    inside the cell (2nd Messenger)
  • Leads to alter the activity of the next component of
    the transduction pathway.
  • Formation of chains of molecules (cascades), where
    each molecule passes the message to the next.
  • Until the final signal causes the desired cell event.
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57
Q

What are the four criteria that must be met by a functioning receptor?

A

1) Has to have specificity
2) Binding affinity must be high
enough to detect ligands in
concentration found in
vicinity of cell
3) Must be able to transmit
message into the cell.
4) Needs to be turned off once
the message is received and
acted on

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57
Q

Agonist:

A

A ligand that binds to a receptor and it activates
the receptor.

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58
Q

Roles of receptors: Signal Detection

A
  • The location of receptors can
    vary.
  • Receptor dysfunction
    can/will lead to disease.
  • Capacity of a cell to recognize
    a signal will not be constant;
    receptors change over time.
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59
Q

Antagonist:

A

A ligand that binds to a receptor and it does not
activate the receptor

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60
Q

If the ligand can bind to multiple receptors, the target’s cell receptor _____ response

A

Specificity

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61
Q

One ligand can have one or multiple receptors

A

multiple

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62
Q

Example of a ligand that can bind to multiple receptors

A

epinephrine (adrenaline) - sympathetic nervous system

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63
Q

breakdown of epinephrine receptors

A

α-Receptors on
intestinal blood
vessels will cause
vasoconstriction
* β2
-Receptors on some
skeletal muscle
vessels will cause
vasodilation

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64
Q

can receptors become saturated? Why?

A

yes
- the receptor activity reaches a maximum rate due to the limited number of receptors on cell membrane
- Allowing for flexibility to vary responses based on extracellular conditions and internal needs

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65
Q

Down-regulation (desensitization)

A

decrease receptor number to desensitize cell response

Sustained Agonist Activity -> Endocytosis -> Recycling or Degradation -> Synthesis of New Protein -> Incorporation into Membrane

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66
Q

Up-regulation:

A

increase receptor number to sensitive cell response

Receptor Downregulation -> Increase total number of receptors -> decrease down-regulation -> withdrawal of antagonist -> elevated number of receptors can produce exaggerated response

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67
Q

High-Affinity Ligand Binding

A

results from greater
intermolecular force between the ligand and its receptor

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68
Q

High-affinity binding involves a __ ___ ___ for the ligand at its receptor binding site

A

longer residence time

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69
Q

What type of energy can be used to cause a conformational change in a receptor regarding high-affinity ligand binding?

A

physiologically important binding energy

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70
Q

Low-affinity ligand binding

A

results from lesser
intermolecular force between the ligand and its receptor.

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71
Q

Low-affinity binding involves a __ ___ __ for the
ligand at its receptor binding site

A

lesser residence time

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72
Q

What is the general sequence that ligand binding will initiate?

A

1) Binding causes a conformational change in the
outer domain of receptor.
2) Change is transmitted through membrane to
induce conformational change in the intracellular
domain of receptor.
3) Change will either activate or inhibit receptors
intrinsic activity to interact with intracellular
proteins

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73
Q

What are the five main classes of receptors?

A

1) G protein-coupled receptors
(GPCRs)
2)Ion channel linked receptors
3)Intrinsic enzymatic receptors
4) Tyrosine kinase-linked receptors
5)Intracellular receptors

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74
Q

Where are G protein-coupled receptors found?

A

only in eukaryotes, yeast, and animals (maybe in plants….)

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75
Q

Large diversity of receptors and intracellular effectors
involved in many diseases

A

GPCRs

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76
Q

Receptors are coupled to ____ G proteins and function as ___ exchange factors to transduce signal

A

trimeric; guanine

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77
Q

GPCRs target ___ of all modern medicinal drugs

A

40%

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78
Q

G PROTEIN-COUPLED RECEPTOR-LIGAND BINDING
Activation Cycle include:….

A
  • GEF- Guanine nucleotide exchange Factor
  • RGS- Regulator of G Protein
    Signaling
  • GAPs- GTPase accelerating
    Proteins.
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79
Q

Membrane-bound receptors

A

Ligand-gated channels

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80
Q

Transient event

A

The ion channels open for a short time,
after which the ligand dissociates from the receptor and
the receptor is available once again for a new ligand to
bind.

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81
Q

Ligand-gated channels are involved in the detection of _____ and __ ___ used in synaptic signaling on electrically excitable cells

A

neurotransmitters; peptide hormones

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82
Q

What does the conformational change affect in ligand-gated channels?

A

Alters the ion permeability and charge across the plasma
membrane.

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83
Q

What undergoes a conformational change when a ligand binds forming a “water tunnel” allowing passage of specific molecules, such as sodium (Na+) or potassium (K+)?

A

Ligand-gated channels

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84
Q

Ligand-gated ion channel : Clinical Relevance

A

Likely to be the major site at which anesthetic
agents and ethanol have their effects, GABA.
* Drugs such as barbiturates used to treat insomnia,
depression and anxiety have been linked to
receptors.
* Diseases include schizophrenia, Parkinson’s
disease, Alzheimer’s disease, epilepsy and autism
have been linked, in part, to receptor defects.

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85
Q

Snake venom ( - α
neurotoxins)- antagonists

A
  • Bind tightly and
    noncovalently to nAChRs of
    skeletal muscles
  • Block the action of ACh at
    the postsynaptic membrane,
    inhibiting ion flow
  • Leading to paralysis and
    death
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85
Q

nAChRs normal vs agonist binding

A

Normally: nAChRs may exist in different interconvertible
conformational states.
Agonist binding: Stabilizes the receptor in the open
* allowing positively charged ions to move across it
* It will remain open until the agonist diffuses away.
* Usually takes about 1 millisecond

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86
Q

Nicotinic Acetylcholine
Receptor (nAChRs)
* Function:

A

– When acetylcholine is
bound, alter the receptor’s
configuration and cause an
internal pore to open.
– Pore allows Na+
ions to flow
into the cell.
– Inward flow Na+
ions
depolarizes the
postsynaptic membrane
sufficiently to initiate an
action potential.

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87
Q

Commonalities of Intraceullar Receptors

A
  • small and hydrophobic
  • allows for free passage into the cell
  • insoluble in aqueous fluids
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87
Q

Intracellular receptors

A
  • Steroid hormones
    – Thyroid hormones
    – Retinoids
    – Fatty acids
    – Prostaglandins
    – Leukotrienes
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88
Q

Cytosolic and Nuclear Receptor are all

A

transcription factors

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89
Q

Depending upon the intracellular steroid hormone Cytosolic and Nuclear Receptor bind, having two modes of action

A

– Located in the cytosol and move to the cell nucleus upon
activation
– Located in the nucleus waiting for the steroid hormone
to enter and activate them
– Covered up by heat shock proteins (HSP) which binds
the receptor until the hormone is present

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90
Q

Cytosolic-

A

Hormone binding causes receptor
conformational change, freeing the receptor from
HSP and the receptor-hormone complex enter the
nucleus to act affect changes in transcription

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91
Q

Nuclear-

A

Hormone binding causes receptor
conformational change, freeing the receptor from
HSP and the receptor-hormone complex can act
upon transcription factor

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92
Q

Regulation of Cell Signaling

A
  • sensor (regulated variable)
  • integrating center
  • effector
  • negative and positive feedback
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93
Q

Feedback Regulation: local vs long distance

A

local level: paracrine and autocrine
long distance: nervous and endocrine

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94
Q

Step 1 in a Response Loop for Feedback Regulation

A

Stimulus: Change in a variable that sets the pathway in motion

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95
Q

Step 2 in a Response Loop for Feedback Regulation

A
  • Sensor or Receptor: Monitors environment for changes in variable; must reach
    Threshold: Minimum stimulus needed to start reflex response
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96
Q

Step 3 in a Response Loop for Feedback Regulation

A
  • Afferent Pathway: Sends input signal to Integrating Center
97
Q

Step 4 in a Response Loop for Feedback Regulation

A
  • Integrating Center: Compares variable with set point to determine if it is out of range. If so, initiates output signal
98
Q

Step 5 in a Response Loop for Feedback Regulation

A
  • Efferent Pathway: Electrical or chemical signal that travels to target
99
Q

Step 6 in a Response Loop for Feedback Regulation

A
  • Target or Effector: Cell or tissue that carries out the appropriate Response to bring variable back to homeostasis
100
Q

direct feedback loop

A
  • Endocrine system only: No
    CNS/PNS integrating center
  • Endocrine cell itself senses
    a change in the extracellular
    environment and releases a
    chemical messenger that
    acts on target cells
    elsewhere in the body.
  • The endocrine cell acts as
    the integrating center that
    interprets the change in the
    stimulus variable
101
Q

First-Order Feeback Loop

A

Direct feedback loop but nervous
system becomes involved
* A sensory organ perceives a
stimulus and sends a signal via the
nervous system to an integrating
center (brain) that interprets the
signal.
* Neurons then transmit the signal
(neurotransmitter or neurohormone) to a specific target organ,
causing a response.
* Only a single step links the
integrating center and the response

102
Q

Second-Order Feedback Loop

A

Second order feedback loops:
* There are 2 steps that link integrating
center and the response.
* Sense organ perceives a stimulus and
sends a signal to the integrating center
* Integrating center will then sends a
signal by a neuron telling the neuron to
secrete either a neurohormone or a
neurotransmitter
* Act on an endocrine glands will secrete
a hormone into the blood
* Travel to the target cell to cause a
response

103
Q
A
104
Q
A
105
Q

Third-Order Loop

A

3 steps link integrating center and response
* Every step in a response loop may act as a
control point over the pathway
* Provide the most sophisticated and tightly
regulated feedback
* Sense organ perceives a stimulus and sends a
signal to the integrating center
* Sends a signal by a neuron telling the neuron
to secrete either a neurohormone or a
neurotransmitter
* Act on an endocrine glands to secrete a
hormone into the blood
* Travel to the target cell of second endocrine
gland, which will then induce a response.

106
Q

Endocrine can refer to

A

a class of glands (exocrine & endocrine)
type of hormonal action (chemical signaling)

107
Q

exocrine glands

A

secrete products externally (ex: sweat, salivary, sebaceous, mucous glands)

108
Q

endocrine glands

A

secrete products internally (ex: pituitary, thyroid, pancreas, adrenal glands)

109
Q

Chemical signaling can be

A

autocrine, paracrine, or endocrine
ectocrine & intracrine signaling

110
Q

hormones are responsible for

A

long-term, on-going functions of body

111
Q

Hormone functions of the body are

A

growth and development
metabolism
regulation of the internal environment
reproduction

112
Q

what makes a chemical a hormone?

A
  1. Secreted by a discrete and identifiable cell or group of cells derived from epithelial cell lineage
  2. Secreted into the blood
  3. Transported to a distant target and bind to target receptor
  4. Exert their effect at very low concentrations (sometimes femtomolar)
112
Q

the root word of hormones

A

to excite

113
Q

3 Basic ways hormones act on target cells

A

By controlling rates of enzymatic reactions
By controlling the transport of ions or molecules across cell membranes
By controlling gene expression and synthesis of proteins

114
Q

Four main classes of hormones

A
  1. Peptide/Protein Hormones
  2. Steroid Hormones (cholesterol derived hormones)
  3. Amino Acid Derived
  4. Miscellaneous (immune hormones)
114
Q

Hormone release follows the basic pattern of a reflex

A
  • stimulus
  • sensor by receptor
  • signal input
  • signal integration
  • signal output
  • response
115
Q

The endocrine cell is a sensor

A

simplest reflex control pathway
cell directly senses stimulus and responds by secreting hormone
cell acts as both a sensor and an integrating center
the output signal is the hormone released
negative feedback turns off reflex

116
Q

Peptide Hormone Mechanism

A

acts through cAMP second messenger system of signaling cascade

117
Q

example of peptide hormone

A

insulin (pancreas)

118
Q

Cholesterol Dervied Hormones are ___ and can ___ diffuse through cell membranes

A

lipophilic; passively

119
Q

Cholesterol Derived Hormones aka

A

Steroid Hormones

120
Q

Cholesterol Derived Hormones are ___ soluble in plasma; bind to ___ protein (either ___ or ___)

A

not; carrier; globulin; albumin

121
Q

Bound steroid is protected from degradation; meaning

A

extends hormone half-life, but blocks cell entry (must be unbound to act)

122
Q

Low-Density Lipoprotein-

A

a wide array of sizes and densities; stays in circulation longer and more easily enter arterial walls

123
Q

which one is bad cholesterol ?

A

low density lipoprotein

124
Q

Why is lipoprotein considered bad cholesterol?

A

can create plaques, stay in the stream pretty long

125
Q

High-Density Lipoprotein

A

smaller than LDLs; transport cholesterol from peripheral tissues to the liver. The liver can convert to bile acids and secreted in the bile

126
Q

Why is high-density lipoprotein considered “good cholesterol”?

A

it removes excess cholesterol

127
Q

Cholesterol is translocated into the mitochondria via consecutive actions of __ __ ___ ___ and the __ __ __ ___

A

steroid acute regulatory protein (StAR); 18 kDa translocator protein (TSPO)

128
Q

cholesterol metabolized to pregnenolone by ____ and further metabolized in the __ ___

A

P450scc; smooth ER

129
Q

Classic (Transcription) Steroid Hormone Receptors

A
  • direct interaction with intracellular nuclear receptors
  • takes longer to produce biological effect (minutes to days)
129
Q

Steroid Hormone Receptors two general categories:

A

classical; non-traditional

130
Q

Non-traditional Steroid Hormone Receptors

A
  • Non-nuclear actions that alter nuclear receptor activation or cell signal transduction
  • Rapid production of biological effect (seconds to minutes)
131
Q

Examples of ligand: receptor complexes:

A

*Progesterone:Progestin Receptor

*Estradiol:Estrogen Receptor

*Testosterone:Androgen Receptor

*Cortisol:Glucocorticoid Receptor

132
Q

In the resting state, some ___ ____ ___ are tethered in the cytosol, some are always nuclear, and some shuttle back and forth

A

nuclear steroid receptors

133
Q

Biogenic Amines: Two Families from Tyrosine

A

Catecholamines and Thyroid Hormones

134
Q

Catecholamines

A

Epinephrine (Adrenaline)
Norepinephrine (Noradrenaline)
Dopamine

135
Q

Neurohormones: 3 major groups

A
  1. Catecholamines – tyrosine-derived neurohormones (Dopamine, Epinephrine, Norepinephrine)
  2. Hypothalamic neurohormones secreted from the posterior pituitary
  3. Hypothalamic neurohormones that control hormone release from the anterior pituitary
135
Q

Thyroid Hormones (T3,T4)

A

Behave like steroids and have intracellular receptors

136
Q

Anterior Pituitary Gland

A
  • true endocrine gland
  • hormones are adenohyophyseal secretions
  • second-order feedback loop system
137
Q

Median eminence

A

functional connection between the hypothalamus and the pituitary gland

138
Q

6 Anterior Pituitary Neurohormones (tropic hormone controls secretion of other hormones)

A
  1. Prolactin (PRL)- Milk production
  2. Thyrotropin (TSH)- Thyroid stimulating hormone
  3. Adrenocorticotropin (ACTH)- Adrenal cortex hormone synthesis and secretion
  4. Growth hormone (GH)- Somatotrophin- affects cellular metabolism
  5. Follicle-stimulating hormone (FSH)-Gonadotrophin; females and males
  6. Luteinizing hormone (LH)- Gonadotrophin hormone; females and males
139
Q

Posterior Pituitary Gland

A
  • false endocrine gland, extension of neural tissue in the brain
  • hormones made in the hypothalamus and neurphypophyseal secretions
  • Third-order feedback loop system
140
Q

Posterior Pituitary Neurohormones

A

Vasopressin (Antidiuretic Hormone-ADH) and Oxytocin

141
Q

Vasopressin acts on the ___ ___ in the kidney nephrons to ____ ____ in the body

A

collecting ducts; retain water

141
Q

why is vasopressin released?

A

released in response to low blood volume

142
Q

Vasopressin ___ blood vessels

A

constrict

142
Q

What does the decreased release or decreased sensitivity of vasopressin lead to?

A

diabetes insipidus, hypernatremia (increased blood sodium concentration), polyuria (excess urine production), and polydipsia(thirst)

143
Q

High levels of vasopressin might lead to

A

hyponatremia (low sodium levels) and hypervolemia (high fluid volume)

143
Q

what does oxytocin play an important role in?

A

neuroanatomy of social trust, intimacy/sexual reproduction

144
Q

what does oxytocin do during childbirth?

A

by it being released in large amounts, it causes the distension of the cervix and uterus

145
Q

does oxytocin use positive or negative feedback mechanisms

A

positve feedback mechansims

145
Q

after childbirth, what does oxytocin do?

A

facilitates maternal bonding, and lactation and milk ejection

146
Q

oxytocin greek

A

“quick birth” to to refer to agents from Claviceps purpurea (“rye ergot fungus”)- Ergometrine

147
Q

Oxyoticin is the first ____ ____ to be sequenced and synthesized (du Vigneaud et al. in 1953)

A

polyphenol peptide

148
Q

what is the slowest negative feedback loop?

A

long feedback loop; taking days

148
Q

Negative feedback loop types

A

short, fast, long

149
Q

the release of what promotes the anterior pituitary release of ACTH

A

CRH

149
Q

what activates hypothalamic secretion of CRH

A

stress

150
Q

what activates adrenal cortisol production

A

release of ACTH

150
Q

Cortisol acts back on the hypothalamus to ___ ___ release and its own production

A

terminate CRH

151
Q

What is also stimulated by stress other than hypothalamic secretion of CRH?

A

gonadal steriod production

152
Q

Similar to ____ steroids, gonadal steroids act back on the brain at the level of the pituitary to ___ ___/____ release, which stops their own production

A

adrenal; terminate LH/FSH

153
Q

Clinical Estrogen/Progestogen Drug Targets:

A

Ant. Pit.: Inhibition of negative feedback for oral contraception

Ovary: Inhibition of ovarian function for oral contraception

Aromatase: Inhibition of estradiol formation for cancer

Receptor: Antagonism of ER in ER+ cancers; Agonism for HRT

154
Q

sex hormone-binding globin (SHBG)

A

vacuums testosterone that is circulating

155
Q

Clinical Androgen Drug Targets

A

Hypothalamus: Inhibition of GnRH feedback for prostate cancer; agonism for HRT

Testis: Inhibition of testicular function for Cushing’s or refractory prostate cancer

5α-reductase: Inhibition of DHT formation for benign prostatic hyperplasia

Receptor: Antagonism for prostate cancer; agonism for HRT

156
Q

Cell types of CNS

A

neurons and neuroglia

157
Q

support cells of the neuroglia

A

oligodendrocytes, microglia, astrocytes

158
Q

parts of neuronal signaling

A

Neuronal Zones
* Dendritic Signaling
* Synapse

159
Q

Neurons

A

functional unit of the nervous system
communicates and transports signals

160
Q

neuroglia

A

highly vasculature, tons of energy used; maintains privileged environment; blood-brain barrier

161
Q

oligodendrocytes

A

forms myelin sheaths around neurons
(important for regulating action potential)

162
Q

Microglia

A

immune cells of the brain; least abundant; inactive/active phenotypes; macrophage-like (engulfing the bad things)

163
Q

Myelin

A

lipoprotein that surrounds thicker axons

164
Q

astrocytes

A

most abundant; major support cell of the brain; essential for brain homeostasis

165
Q

Oligodendrocytes function

A

an insulating layer that prevents leakage of electrical current; increases speed of impulse conduction along axon; energy efficient; enhances electrical impulse jumping (leaping down the axon )

166
Q

What are the three phenotypes of microglia?

A

Resting
M1 (pro-inflammatory)
M 2 (anti-inflammatory)

167
Q

Function of Microglia

A
  • cellular debris clearance
  • phagocytic of living/dying/dead cells
  • release diffusible factors (pro/anti- inflammatory cytokines)
168
Q

Astrocytes are major support cell of brain ___ ___ ____

A

especially for neurons

169
Q

Astrocytes maintains

A

pH, brain homeostasis, and elicits signals

170
Q

Astrocytes are the ____ between the neurons and environment (signals within the blood)

A

communicator

171
Q

Astrocytes prove ____ _____ and sweep up extra ______

A

necessary materials (parents); neurotransmitters

171
Q

Astrocytes modulate _____ ______ and _____ uptake/conversion

A

synapse formation; glutamate

172
Q

Unipolar neuron

A

the cell body is on one end (no dendrites) -> myelin-> axon terminal

172
Q

What are the commonalities between the multiple types of neurons?

A

cell body
axon
dendrite

173
Q

Multiple types of neurons

A

unipolar
bipolar
pseudounipolar
multipolar

174
Q

bipolar neuron

A

cell body is between sensory receptor (bottom) and axon terminal (end)

175
Q

pseudounipolar neuron

A

no myelin and is more common
sensory receptors at end
cell body is hanging off?

176
Q

Multipolar neuron

A

dendrite (multiple sources) on cell body -> myelinated axon -> axon terminal

177
Q

The cell body of a neuron

A

enlarged part of cell
that contains the nucleus and
organelles

178
Q

Axon Transport Types

A

slow and fast

179
Q

the axon of a neuron

A

long cytoplasmic extension;
specialized for signal transduction

179
Q

the dendrites of a neuron

A

cytoplasmic extensions from the cell body; receive incoming signals

180
Q

Slow axonal transport

A

cell components are transferred from the cell body to axon
terminal
* *used for materials not consumed rapidly by the cell; e.g., enzymes and cytoskeleton proteins)

181
Q

Fast axonal transport

A

transported vesicles “walk” with the aid of attached foot-like
motor proteins with the use of stationary molecules (microtubules) as tracks
* mitochondria, lipids, synaptic vesicles, proteins, and other organelles
* Neuroinvasive Viruses (i.e., Rabies and West Nile Viruse) uses retrograde fast axonal transport to
infect the CNS

182
Q

Types of fast axonal transport

A

anterograde and retrograde

183
Q

Anterograde

A

“forward” cell body to axon terminal

184
Q

Retrograde

A

“backward” axon terminal to cell body

185
Q

Signal reception zone

A

dendrites and the cell body: receiving incoming signals

186
Q

Singal integration zone

A

axon hillock: where the cell body meets the axon; if there is a large enough
stimulus, the stimuli is converted to an electrical signal (change in
membrane potential) that is sent down the axon

187
Q

Signal Conduction Zone

A

axon: nerve fiber that conducts electrical signals

188
Q

signal transmission zone

A

collaterals (axon terminals): swelling at axon terminus where comes in close contact with the
target cell; does not touch
* electrical signal is converted to a chemical signal
(neurotransmitter)

189
Q

what is the importance of surface area for synapses within the dendrites?

A

wide range of communication between a microenvironment

189
Q

Boutons (Pre) and Spines (Post)

A

convert chemical signal to electrical signal
ion channels opening or closing
alter membrane potential

190
Q

In the signal reception zone:
* Terminal _____ and ______
* Synaptic _____-_____ ____ between cells where chemical
communication/transmission occurs
* Changes in ______ ______ elicit chemical release from the presynaptic cell

A

boutons and synapse

cleft-small gap

membrane potential

191
Q

function of the axon

A

transmit outgoing electrical signals from the integrating center to the target cells at the end of the axon

191
Q

axon hillock is where the summation of signals are from the

A

boutons

191
Q

physiology of the axon

A

axon extends from the axon hillock
length (2uM -1m)

192
Q

What does the electrical signals from the integrating center cause?

A

neurotransmitters

192
Q

Resting Membrane potential

A

the separation of intracellular potassium ions from anions across the cell membrane of the cell; concentration gradient of potassium ions must be set up

193
Q

What pump is used in the resting membrane potential?

A

Sodium-Potassium Pump (Na+/K+-ATPase)

194
Q

is Na+ mostly found in the intraceullar or extracellular

A

extracellular

195
Q

is K+ found mostly in the intracellular or extracellular

A

intracellular

196
Q

A resting (unstimulated) cell and membrane has
the potential to conduct

A

electrical signal or action
potential

197
Q

Sodium Potassium Pump

A
  • 3 sodium ions pumped out of the cell
  • 2 potassium ions pumped into the cell
  • Creates a deficit of positive ions on the inside
    of the cell
  • So inside is more negative than the outside
198
Q

The resting membrane potential is not an ____ potential, meaning it requires ATP

A

equilibirum

199
Q

3 important factors to establish a membrane potential

A
  1. The distribution of ions across the
    plasma membrane (at rest)
  2. The permeability of the membrane
    to these ions (highly permeable to
    a certain ion)
  3. Charge on the ions that are moving
200
Q

Goldman Equation -

A

describe the effects these factors have on the
membrane potential; predicts the equilibrium potential for certain ions

201
Q

If the membrane is ______ _______ to an ion, the ion _______ ______ ______to the membrane potential

A

not permeable; does not contribute

202
Q

If the membrane is _____ _____ to an ion, that ion ______ ___ _____ ________ to the membrane potential

A

highly permeable; makes a large contribution

203
Q

Excitable cells selectively alter the permeability of their membranes to ions

A
  • By opening and closing gated ion channels in the membrane.
  • Changing ion permeability alters the membrane potential and generates
    electrical signals
204
Q

Potassium has the highest permeability since

A

they have leak charges that allow for the movement of potassium across the membrane to achieve equilibrium potential

204
Q

Goldman Equation: Sodium and Potassium

A

sodium: +60 mV
potassium: -90 mV

205
Q

Most membrane potentials are around this range

A

Vm= -70 mV

206
Q

If you increase the extracellular sodium,

A

it would make the membrane potential less negative and more positive.

207
Q

Inside of the cell membrane is more ____ charged than outside

A

negatively

208
Q

Defined as a relativly stable, groud value of ____ ____ in animal and plant cells regarding resting membrane potential

A

transmembrane voltage

209
Q

Stimulus of resting membrane potential

A

positive ions influx

210
Q

Steps of Action Potentials:

A

threshold, depolarization, depolarization, hyper-polarization

210
Q

What voltage does threshold potential need to reach to be excitatory potentials?

A

-55 mV

210
Q

What are some possible inhibitors?

A

too sub-threshold potentials
too supra-threshold potentials

211
Q

Threshold Potential

A

are graded potentials need to be reached for action potential to “fire”

212
Q

so what happens at -55 mV?

A

voltage-gated Na+ channels on the membrane open allowing an influx of Na+ cations

213
Q

Depolarization

A

membrane potential becomes less negative either through more positive charged ions entering cell or more negative charged ions leave the cell

214
Q

Depolarzaiotn what type of channels ?

A

sodium/potassium leaky channels; very leaky to potassium not so leaky to sodium (potassium leaks out of the cell)

215
Q

what does the sodium/potassium leaky channels do?

A

stop the cell from reaching threshold potential

216
Q

Repolarization

A

cell returns to the normal resting membrane potential though negative charged ions entering or postive charged ions leave the cell

217
Q

what reestablishes the resting membrane potential (repolarization)

A

Na+/K+ ATPase pump

218
Q

Hyperpolarizartion

A

cell becomes more negative either through negative charged ions entering the cell or positive charged cells leaving (this reestablished resting membrane potential)

219
Q

which of the discussed mechanisms restores resting potential?

A

leaky channels

220
Q

Integration of Graded Signals: Two types

A

spatial and temporal summation

221
Q

spatial summation

A

Interaction
of graded potentials from
different receptors will “meet” at
the axon hillock
* add together to fire an AP
* different sites

222
Q

Temporal Summation

A

Interaction of graded potentials
that occur at slightly different
times at the axon hillock
* add together to fire an AP
* different times

223
Q

Regulating excitability types

A

Excitatory Post-Synaptic Potentials and
Inhibitory Post-Synaptic Potentials

224
Q

EPSPs (Excitatory Post-Synaptic Potentials)

A

change in membrane
potential following influx of
positively charged ions (e.g. Na+).

225
Q

IPSPs (Inhibitory Post-Synaptic Potentials)

A

-change in membrane
potential following influx of
negatively charged ions (e.g. Cl-)

226
Q

More narrow the dendrite, the _____ the propagation

A

faster

226
Q

Farther away, ___ the signal to AIS

A

weaker

BMS 344 (2 decks)

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