L25 Hormones & Intercellular Communication Flashcards

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1
Q

There are 4 main categories of intercellular communication, these are:

A
  • GAP junctions
  • Synaptic
  • Paracrine and autocrine
  • Endocrine
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2
Q

Under the classical definition, the endocrine system comprises of cell with endocrine glands which release hormones. However, it is now known that…

A

Many tissues can release hormones (not just endocrine glands)

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3
Q

Hormone

A

Chemical messenger synthesised by specialised cells secreted into the blood

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4
Q

Hormones have a high affinity. Thus they are effective…

A

At low concentrations!

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5
Q

Which of the following is not a property of hormones?

a) can be synergistic
b) can be permissive
c) can be polycistronic
d) can be antagonistic

A

c) can be polycistronic

Polycistronic described mRNA transcripts containing more than one gene (i.e. in prokaryotes)

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6
Q

If a hormone is permissive, the presence of one hormone is required…

A

For another to work

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7
Q

Competitive hormones compete for the same…

A

Receptors

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8
Q

There are 3 main classes of hormone…

A
  1. Steroids
  2. Peptides
  3. Amino Acids
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9
Q

Steroid hormones are synthesised by modification of…

A

Cholesterol

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10
Q

Steroid hormones are lipophilic, so they ( cannot / easily ) cross cell membranes

A

Easily

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11
Q

Because they are lipophilic, steroid hormones are ( easy / difficult ) to store

A

Difficult

This is why they are produced on demand and released immediately after synthesis

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12
Q

Because they are lipophilic, steroid hormones require:

a) Carrier protein in the blood
b) Secondary messenger systems
c) Storage molecules inside the cell
d) Synthesis in an inactive form (preprohormone)

A

a) Carrier protein in the blood💉

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13
Q

Steroid hormones characteristically have:

a) rapid but long lasting effects
b) slow but long lasting effects
c) rapid but transient effects
d) none of the above

A

b) Slow but long lasting effects

This is because they affect gene expression, which in turn must then influence protein production. This is a relatively slow process. 🐢

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14
Q

The most abundant class of hormones are…

A

Peptides

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15
Q

Peptide hormones are synthesised from…

A

Amino acids

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16
Q

Peptide hormones bind to cell surface receptors because they are…

A

Hydrophilic and so don’t cross cell surface membranes easily

17
Q

Peptide hormones are synthesised as an inactive form prior to release, known as…

A

Preprohormone

18
Q

Peptide hormones bind to cell surface receptors, which activate…

A

Secondary messenger systems to cause their effects

19
Q

Amino acid hormones are synthesised from:

a) Peptides
b) Tyrosine
c) Phenylalanine
d) Glutamine
e) Cholesterol

A

b) Tyrosine

20
Q

Amino acid hormones are:

a) Lipophilic
b) Hydrophilic
c) Can be either
d) None of the above

A

c) Can be either

If they are lipophilic they bind intracellular receptors, whereas the hydrophilic types bind cell surface receptors.

21
Q

Which hormone types can be hydrophilic?

a) Amino acid and steroid
b) Amino acid and peptide
c) Peptide and steroid
d) Only peptides

A

b) Amino acids and peptides

Peptide hormones are hydrophilic and so are some amino acids hormones!

22
Q

Amino acid hormones are:

a) Stored allowing instant release
b) Produced on demand and not stored
c) Synthesised from cholesterol
d) Stored but slow to release

A

a) Stored allowing instant release

23
Q

Hormone release can be (4)…

A
  • Continuous
  • Pulsatile
  • Circadian
  • From exocytosis on stimulus
24
Q

An example of a hormone with circadian release pattern is…

A

Melatonin

25
Q

An example of a hormone with pulsatile release is…

A

Growth hormone (somatotropin)

26
Q

Some hormones are activated by…

A

Post-release modification

27
Q

Hormone mediated effects CANNOT be terminated by which of the following:

a) Negative feedback
b) Modification of the hormone
c) Receptor down regulation
d) Pathway changes
e) Excretion of the hormone

A

d) Pathway changes

28
Q

Epinephrine/norepinephrine receptor type Beta-2 activates the ( IP 3 / cAMP ) pathway

A

cAMP

29
Q

When epinephrine binds to Beta-2 receptors the end result is the ( relaxation / contraction) of muscles

A

Relaxation (cAMP pathway leads to phosphorylation of contractile proteins)

30
Q

Hormone effects can be controlled via (5)….

A
  • Modification (modulates hormone activity)
  • Degradation (break down or excrete)
  • Receptor Down-Regulation
  • Termination of intracellular effects
  • Negative feedback