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Physiology > Cell Communication > Flashcards

Cell Communication Flashcards

1
Q

Function of gap junctions:

A
  • for adjacent cells

- direct cytoplasmic transfer of chemical and electrical signals

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2
Q

Gap junctions have two components:

A
  • connexons

- connexins

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3
Q

Connexons:

A
  • protein channel (open/close) formed by united connexins

- connects pre and post synaptic cells

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4
Q

Connexins:

A

membrane proteins

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5
Q

Contact dependent signals:

A
  • needs cell adhesion molecules (CAM) for cell-cell signaling
  • has to bind to receptor on post synaptic cell
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6
Q

Chemicals that diffuse into ISF:

A
  • histamine
  • cytokine
  • eicosanoids
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7
Q

Histamines are produced by…

A

basophils and mast cells

- help vasodilate things

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8
Q

Cytokines are produced by…

A

lymphocytes and helper T cells

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9
Q

Cytokines:

A

regulatory peptides for local and long distance communication

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10
Q

Examples of cytokines:

A
  • interleukins
  • CSF
  • GF
  • lymphokines
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11
Q

Eicosanoids are produced by…

A

oxidation of phospholipids

  • lipid derivative of arachidonic acid
  • uses phospholipase A2
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12
Q

2 major groups of eicosanoids:

A
  • leukotrienes: produced by lipoxygenase

- prostanoids: produced by cyclooxygenase (COX)

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13
Q

Function of leukotrienes:

A

helps with asthma and anaphylaxis

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14
Q

Examples of prostanoids:

A
  • prostaglandins: vasodilators

- thromboxanes: vasoconstrictors and platelet aggregation

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15
Q

Methods of cell communication:

A
  • local

- long distance

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16
Q

Local communication:

A
  • gap junctions
  • autocrine: acts on same cell that secreted it
  • paracrine: secreted by one cell and diffuses to adjacent cells
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17
Q

T/F: local communication is not contact dependent

A

F, is contact dependent

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18
Q

Long distance communication is used by…

A
  • hormones
  • neurocrines
  • neurotransmitters
  • uses neuromodulators
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19
Q

Examples of neuromodulators:

A
  • carbon monoxide
  • nitric oxide
  • H sulfide
  • all are vasodilators
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20
Q

Carbon monoxide and nitric oxide both diffuse into….

A

smooth muscle cells to activate guanylyl cyclase forming cGMP

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21
Q

Nitric oxide is catalyzed by…

A

NO synthase

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22
Q

A good source of H sulfide is…

A

garlic

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23
Q

Components of signal pathways:

A
  • ligand (primary messenger) that binds to receptors
  • receptors: proteins that are on membrane
  • membrane signaling pathway: starts at membrane
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24
Q

Transduction pathway tells target cells…

A

what to do and create response

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25
Q

Extracellular signal molecules are…

A

primary messenger that activates membrane receptor

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26
Q

How do intracellular signal molecules create response?

A

it’s a secondary messenger that gets altered to send signal

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27
Q

Endocrine system regulates:

A
  • metabolic rate
  • H2O and electrolyte balance
  • cell proliferation
  • reproductive organs
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28
Q

How does endocrine system help the body cope with stress?

A

controls adaptive change

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29
Q

Hormones:

A
  • secreted in very small amounts by specialized cells
  • responds to specific change in environment
  • act on receptors of target cells to alter function
30
Q

Endocrine hormones:

A
  • made by classical endocrine cells
  • travel via blood to target tissue
  • ex: LH and FSH, growth hormone, thyroid stimulating hormone
31
Q

Neurocrine hormones:

A
  • released by axonal ends of neurons into blood

- ex: oxytocin, antidiruetic hormone

32
Q

Paracrine hormones:

A
  • diffuses to different local cell types via ISF/gap junctions
  • activates neighboring cells
  • ex: hormones from ovaries/testes (ovaries/testosterone)
33
Q

Autocrine hormones:

A
  • acts back on itself / other identical cells via gap junctions
  • ex: cytokine interleukin-1
34
Q

Pituitary gland and target glands has ______ feedback

A

negative feedback

35
Q

Neural control:

A
  • ANS alters hormone secretion that responds to change detected by nervous receptors
36
Q

Example of input for neural control:

A
  • visual
  • auditory
  • olfactory
  • gustatory
  • tactile
  • pressure
  • limbic
37
Q

Chronotropic control of hormones:

A
  • released in distinct phases based on rhythms that are genetically encoded or acquired
38
Q

Examples of chronotropic control:

A
  • circadian: 24 hr
  • dirunal: day/night
  • ultradian: multiple times w/in a day
  • circadian clock in: suprachiasmatic nucleus
  • seasonal variation: dependent on light cycle
39
Q

Function of pineal gland:

A

regulates circadian rhythm via release of melatonin

40
Q

Steroids:

A
  • derived from cholesterol

- lipid soluble: diffuse from cell when formed

41
Q

1/2 life of hormone:

A
  • time required for [ ] to drop 1/2 of initial [ ]

- transportation form affects 1/2 life

42
Q

Free hormones:

A
  • fast acting
  • short 1/2 life
  • susceptible to enzymatic degradation
43
Q

Prohormone:

A
  • circulates as inactive precursor of H2O soluble hormones until cleaved
  • prolongs 1/2 life
44
Q

Hormone bound to carrier:

A
  • longest 1/2 life time
  • slowest response time
  • bind to specific globulins synthesized by liver
  • carriers protect enzyme degradation b/c hormone is inactive when bound
45
Q

What form of hormone removal from plasma is irreversible?

A
  • target cell uptake
  • metabolic degradation
  • urinary and biliary excretion
46
Q

Metabolic clearance rate (MCR):

A
  • sum of removal processes

- volume of plasma cleared per unit of time (mL/min)

47
Q

What are the two major sites of hormone extraction/degradation?

A
  • kidney and liver

- renal clearance is reduced by carriers

48
Q

Radioimmunoassay (RIA):

A
  • helps measure [hormone] in blood
49
Q

Enzyme linked immunosorbent assay (ELISA):

A
  • helps measure [hormone] in blood

- enzyme converts product into different color

50
Q

Mechanism of hormone action:

A
  1. hormone must be recognized and bound by specific cell receptor
  2. hormone receptor complex gets coupled to signal-generating mechanism/act on itself
  3. generated signal changes intracellular processes
51
Q

How does generated signal change intracellular processes?

A
  • enzyme activity/ [ ]
  • functional proteins
  • structural proteins
52
Q

What are the two receptor systems based on solubility?

A
  • membrane

- intracellular

53
Q

Plasma membrane receptors (Rm):

A
  • response is sec/min and target proteins are activated/inactivated
  • are large glycoproteins w/ specific extracellular binding sites
  • is within plasma membrane of target cell
54
Q

Plasma membrane is activated by…

A

non-lipid soluble (NLS) hormones

55
Q

T/F: hormone occupancy changes receptor conformation

A

T

56
Q

Receptor capacity:

A
  • increased binding affinity leads to more binding of hormone, which leads to decrease of [free hormone]
  • occupancy of 5-10% of total available Rm means max biological action
57
Q

Up-regulation:

A
  • increase # of Rm
  • results from intermittent exposure to submaximal [hormone]
  • hormones can recruit own receptor and enhance sensitivity of cell
58
Q

Down-regulation:

A
  • decrease # of Rm
  • results when excess hormones is sustained for awhile
  • lessens effect of chronic exposure to excessive hormones
59
Q

Phosphorylation and dephosphorylation of Rm:

A
  • alters K: affinity of receptor for hormone

- can also be affected by: pH, osmolarity, [ion], substrate levels

60
Q

Non-G protein signaling mechanism:

A

Rm with single transmembrane portion

61
Q

Mitogen-activated protein kinases (MAPK):

A

promotes growth

62
Q

Tyrosin kinases:

A
  • binding of hormone to receptor induces autophosphorylation of intracellular portion of receptor
  • strong modulators of gene transcription
63
Q

Intracellular receptor system:

A
  • used by lipid soluble hormones
  • Rc: cortisol
  • Rn: reproductive hormones
  • hormones diffuse through membrane and enters cell to attach to receptor, which is usually in the nucleus
64
Q

Receptor hormone complex in intracellular receptor system:

A

interacts w/ DNA in nucleus

65
Q

How does [hormone] affect responsiveness of target cells to hormones?

A
  • impacts # of receptors on cell

- target cell upregulate # of receptors if [ ] decreases

66
Q

How does # of receptors affect responsiveness of target cells to hormones?

A

can cause upregulation or downregulation

67
Q

How does chronotropic factor affect responsiveness of target cells to hormones?

A

affects how quickly receptors and hormones bind

68
Q

How do intracellular conditions affect responsiveness of target cells to hormones?

A

w/ rate limiting enzymes, co-factors, and substrates

69
Q

How do other hormones affect responsiveness of target cells to hormones?

A
  • concurrent effects of antagonistic/synergistic hormones

- permissive action: one hormone increases the responsiveness of a target tissue to another hormone

70
Q

How do the number of target cells affect responsiveness of target cells to hormones?

A
  • decreased # of target cells = lower response
  • # of receptors can be increased by hormone that stimulates movement through key points in mitotic cycle or by inhibiting apoptosis
71
Q

Receptor saturation, specificity, and competition on single receptor is impacted by:

A
  • agonists: promote binding/activation of signaling pathway

- antagonists: blocks receptors

72
Q

Termination of signal pathways occur with…

A

degradative enzymes

Physiology (33 decks)

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