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The Endocrine System > Introduction to the Physiology and Pharmacology of the Endocrine System > Flashcards

Introduction to the Physiology and Pharmacology of the Endocrine System Flashcards

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1
Q

The endocrine system essentially consists of many ___________ glands

A

The endocrine system essentially consists of many ductless glands

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2
Q

How is the specificity of signalling achieved in the endocrine system?

A
  1. Chemically distinct hormones
  2. Specific receptors
  3. Distinct distribution of receptors across target cells
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3
Q

Why is specificity of signalling required in the endocrine system?

A

Hormones in the blood stream can reach any tissue

(and only “need” to act on certain tissues)

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4
Q

What are the 4 main secretion types from endocrine glands?

A
  1. Modified amino acids
  2. Steroids
  3. Peptides
  4. Proteins
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5
Q

Give an example of a modified amino acid secretion from an endocrine gland?

A
  1. Adrenaline
  2. Thyroxine (T4)
  3. Triiodothyronine (T3)
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6
Q

Give an example of a steroid hormone

A
  1. Cortisol
  2. Progesterone
  3. Testosterone
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7
Q

What do all steroid hormones originate from?

A

Cholesterol

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8
Q

Give an example of a peptide hormone

A
  1. Adrenocorticotropic hormone (ACTH)
  2. Anti-diuretic hormone (ADH)
  3. Oxytocin
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9
Q

Peptide hormines come from _________ ___________ proteins

A

Peptide hormines come from larger precursor proteins

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10
Q

Give an example of a protein hormone

A

Insulin

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11
Q

What are the 7 main endocrine organs?

A
  1. Pituitary gland
  2. Thyroid gland
  3. Parathyroid glands
  4. Adrenal glands
  5. Pancreas
  6. Ovary
  7. Testis
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12
Q

What is autocrine signalling?

A

When a cell is both the originator and recipient of the signal

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13
Q

What is paracrine signalling?

A

Signalling molecules travel short distances by diffusion and act on cells close by

(they do not enter systemic circulation)

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14
Q

What is endocrine signalling?

A

Hormone is released into the circulation and reaches the target organ this way

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15
Q

Hormones can only function in one of the following three ways, autocrine, paracrine or endocrine. True or false?

A

False

(hormones can function in more than 1 way)

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16
Q

Why do receptors for endocrine hormones have very high affinity for hormone?

A

Organ function is regulated at very low hormone concentrations

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17
Q

Endocrine hormones have high ________

A

Endocrine hormones have high potency

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18
Q

Due to the scarcity of the endocrine hormone signal, what does the target cell do to combat this?

A

Signal transduction pathways amplify the original signal

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19
Q

The onset and duration of hormone action is fairly consistent.

True or false?

A

False

It is highly variable froms seconds to days

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20
Q

The onset and duration of hormone action depends on deactivation of enzyme, but which two locations does this mainly occur at?

A
  1. Enzyme mediated deactivation in the liver
  2. Deactivation at the site of action
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21
Q

Which two categories of functions can hormones have?

A
  1. Complementary
  2. Antagonistic
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22
Q

Are amines either presynthesised or synthesised and secreted on demand?

A

Presynthesised

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23
Q

When would amines be released?

A

In response to stimuli by Ca2+ dependent exocytosis

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24
Q

What are the three key characteristics of amines?

A
  1. Small
  2. Water soluble
  3. Released on demand
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25
Are peptides and proteins either presynthesised or synthesised and secreted on demand?
Presynthesised
26
When would peptides and proteins be released?
In response to Ca2+ dependent mechanisms
27
In terms of peptides and protein hormones, what is the general term given to enzymes which alter the precursor to the mature hormone?
Convertases
28
Cholesterol is converted to steroid hormones via which intermediate?
Pregnenolone
29
Are steroids either presynthesised or synthesised and secreted on demand?
Synthesised and secreted on demand
30
How do steroid hormones travel in the plasma and why?
Via steroid binding proteins They are very sparingly soluble in water (mostly hydrophobic)
31
What three things do carrier proteins (for steroid hormones) allow?
1. More hormone to be transported in blood 2. Provides a reservoir of hormone 3. Extends hormone half life
32
Why do carrier proteins increase the half life of steroid hormones?
The protein prevents kidney filtration into the urine
33
Which carrier protein will bind cortisol and some aldosterone?
Cortisol-binding globulin
34
Which carrier protein will bind thyroxine and triiodothyronine?
Thyroxine-binding globulin
35
Which carrier protein will bind testosterone and some oestradiol?
Sex steroid-binding globulin
36
Which general carrier binding protein is associated with steroids and thyroxine?
Albumin
37
Which general carrier protein is associated with thyroxine and some steroids?
Transthyretin
38
In surges of steroid hormone production, why do hormone levels not immediately skyrocket?
Carrier proteins act as a buffer They mop up excess proteins and maintain an equilibrium between free and bound hormone
39
The rate of hormone secretion is ultimately dependent on what?
Plasma concentration of hormone
40
Hormones function in a negative/postive feedback loop?
Negative
41
Using cortisol as an example, what are the steps which ensure cortisol is secreted from the adrenal cortex?
1. Low cortisol levels (or stress requiring cortisol) 2. Hypothalamus releases corticotropin-releasing hormone 3. Corticotropin-releasing hormone acts on the anterior pituitary 4. Anterior potuitary secretes adrenocorticotropic hormone (ACTH) 5. ACTH acts on the adrenal cortex 6. Adrenal cortex secretes cortisol
42
In the control of cortisol secretion pathway, what is the short range inhibition loop?
High cortisol levels act on the anterior pituitary preventing ACTH hormone production This prevents further cortisol production
43
In the control of cortisol secretion pathway, what is the long range inhibition loop?
High cortisol levels act on the hypothalamus preventing corticotropin-releasing hormone from being secreted This prevents cortisol production further down the pathway
44
The secretion rate of certain hormones fluctuates with certain times in the day (ambient light level), what is the term given to this rhythm?
Diurnal (Circardian) rhythm
45
The plasma concentration of a hormone is dependent on which two things?
1. Rate of secretion/production 2. Rate of elimination
46
What are the 3 classes of hormone receptors?
1. G-protein coupled receptors 2. Receptor kinases 3. Nuclear receptors
47
Which types of hormones will generally utilise G-protein coupled receptors?
Amines Some proteins and peptides
48
What are the three classes of nuclear receptors?
1. Those activated by steroid hormones 2. Those activated by lipids 3. Those with hybrid activation
49
Nuclear receptors which are activated by steroid hormones are always in the nucleus. True or false?
False They are mainly located in the cytoplasm and move to the nucleus when activated
50
Nuclear receptors which are activated by lipids are always found in the nucleus. True or false?
True
51
What is the receptor for insulin?
A receptor kinase
52
What is the receptor kinase for insulin comprised of?
Alpha and beta subunits | (2 of each)
53
What happens when insulin binds to its receptor kinase?
1. Conformational change 2. Autophosphorylation occurs at the beta subunits 3. Insulin receptor protein subunits are subsequently phosphorylated 4. These carry out cell actions
54
What is a G-protein and what is it comprised of?
Guanine nucleotide binding protein 3 subunits (alpha, beta and gamma)
55
How do steroid molecules enter cells?
Diffusion | (they are lipophilic)
56
How can steroid hormones influence the transcription of certain proteins?
1. They diffuse into cells 2. Bind to intracellular receptors, displacing inhibitory heat shock proteins (HSPs) 3. The receptor/steroid complex forms a dimer and enters the nucleus 4. It binds to hormone response elements in DNA 5. Transcription of certain genes is influenced 6. Mediator protein levels are influenced
57
Name a hormone which can act on a G-protein coupled receptor
1. Angiotensin II 2. Gonadotrophin releasing hormone 3. Thyrotropin releasing hormone
58
When a G-protein coupled receptor and Gq is activated, what does the Gq act on and what is the effect?
Acts on **phospholipase C** Starts the conversion of phosphatidylinositol (4,5) bisphosphate (**PIP2**) to the soluble messenger molecule inositol (1,4,5) trisphosphate (**IP3**).
59
Once IP3 is produced, what occurs within a cell?
1. IP3 binds to IP3 receptors of the endoplasmic reticulum 2. This causes calcium release 3. This initiates a cellular response e.g. muscle contraction
60
What is DAG, how is it produced and what is its function?
**Diacylglycerol** 1. It is also produced by phospholipase C when it is activated 2. It stays in the membrane and recruits protein kinase C from the cytosol 3. The action of protein kinase C leads to phosphorylation of serine/threonine residues in target proteins 4. This results in different cellular effects

The Endocrine System (35 decks)

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