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AU 15 - Human Phys > Edocrinology - Lecture 1 > Flashcards

Edocrinology - Lecture 1 Flashcards

1
Q

What are the two major communication systems in the body

A

Endocrine System

Nervous System

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2
Q

What are the two major differences between the endocrine and nervous systems?

A

The route of communication

The onset and duration of their effects

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3
Q

What is the route of communication of the endocrine system?

A

Chemical signals that go through the blood

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4
Q

What is the onset and duration of the effects of the endocrine system?

A

Duration is prolonged

Onset is delayed

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5
Q

Why is the onset of endocrine systems delayed?

A

Hormones have to be released from one gland, travel through the blood, and then communicate with something else

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6
Q

T/F - Endocrine glands have ducts.

A

False. They are ductless and have a broadcast nature

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7
Q

The specificity of hormone responses are due to what?

A

Receptors (not the source of the signal)

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8
Q

At what levels can hormones be regulated?

A 
Release organ (secretion)
Transport (make it more/less available in the blood)
Target receptor (add/remove receptors)
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9
Q

What are the three major classes of hormones and what are they based on?

A

Peptide, Steroid, Amine

They are based on chemical structure

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10
Q

What is the most common type of hormone?

A

Peptide

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11
Q

What is the size of peptide proteins?

A

Very variable…can be either 3 amino acids or very large proteins

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12
Q

What holds peptide proteins together?

A

Peptide bonds

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13
Q

What can cause variability in peptide hormones?

A

Glycosylations - adding sugars to the amino acids

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14
Q

What do glycosylations do to peptide hormones?

A

Effects the binding of the hormone to its receptors

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15
Q

T/F - Peptide hormones are the same between species.

A

False - Peptide hormones are very variable between species (species-specific) and sometimes even individuals.
This is because the amino acids are coded by the DNA

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16
Q

T/F - Peptides function as both hormones and neurotransmitters

A

True - It’s the same molecule, but it is released in the synapses and not the blood

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17
Q

Describe the process of peptide hormone synthesis

A

Prehormones are synthesized by ribosomes (they include extra amino acids and folding)
Prohormone is formed by cleaving those extra amino acids in the RER and is packaged into the Golgi
Hormone is formed by additional cleaving prior to packaging, or further cleavage can occur within the vesicle (so some get formed in the vesicle or are finished while in the vesicle)

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18
Q

What happens when prohormones get further cleaved in a vesicle?

A

Prohormone fragments get released along with the hormone

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19
Q

What’s an advantage of packaging and storing peptide hormones in vesicles?

A

Allows for quick release of a large number of hormones
Prevents the hormones from being degraded
Prevents negative feedback which prevents more hormones from being made

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20
Q

Steroid hormones

A

Relatively small lipid hormones derived from cholesterols

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21
Q

What are teh glandular sources of steroids?

A

Gonads
Adrenal cortex
Placenta

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22
Q

T/F - Steroids are the same between species.

A

True - they are products of enzymatic reactions within the cell and are not tied to the DNA

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23
Q

What are the 5 classifications of steroid hormones?

A 
Progesterones
Androgens
Estrogens
Glucocorticoids
Mineralcorticoids
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24
Q

Where does most of the cholesterol used to make steroids come from?

A

Low-density lipoproteins (LDL) from circulation

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25
Q

Describe the process of steroid synthesis

A

Peptide hormones from other glands activate GPCRs, which activates adenyl cyclase, which increases cAMP, which activates PKA, which stimulates the activity of cholesterol esterases, which releases free cholesterol into the cytoplasm.
StAR binds to free cholesterol and transports it to the mitochondria
P450 enzymes in the mitochondria either add -OH or cleave C-C to make cholesterol into a steroid
Steroid gets sent to the SER to be modified

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26
Q

Steroidogenic enzymes

A

Proteins that determines which steroid is produced

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27
Q

What is the steoidogenic pathway?

A

Cholesterol –> Progesterone –> Corticosteroids or Androgens –> Estrogens

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28
Q

Steroidogenic enzymes

A

Proteins that determines which steroid is produced

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29
Q

T/F - Steroidogenic reactions are unidirectional and have a predictable outcome

A

False (kind of) - Sterodogenic reactions are in fact unidirectional. However, there are 2 possible products that can happen, it just depends on which enzymes are present and how much of them there are

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30
Q

What hormone class likely has the largest population of receptors?

A

Amines

31
Q

What are the two thyroid hormones and how are they formed?

A

T3 and T4

Produced by the iodination of tyrosine at one or two carbons and combining iodine molecules

32
Q

Which hormone class do T3 and T4 best compare to and why?

A

Similar to Steroids
Solubility and receptors are similar to steroids (lipophilic/nonpolar)
Can fuse through a plasma membrane (cannot be strored)

33
Q

Where are catecholamines synthesized?

A

Adrenal medulla and hypothalamus

34
Q

What can catecholamines also function as?

A

Neurotransmitters, particularly in the autonomic nervous system

35
Q

Where are epinephrine and norepinephrine synthesized?

A

Adrenal medulla

36
Q

Where is dopamine synthesized?

A

Hypothalamus

37
Q

What can catecholamines also function as?

A

Neurotransmitters, particularly in the autonomic nervous system

38
Q

What class of hormones are catecholamines comparable to, and why?

A

Peptides
Hydrophilic/polar (water soluble)
Bine to surface receptors

39
Q

T/F - Most hormones are secreted in short bursts

A

True

40
Q

What controls the timing of hormone release?

A

An upstream signal

41
Q

What happens between the bursts of hormone secretion?

A

No other hormones are released.

It is still in circulation, it is just not being secreted

42
Q

What three things can control the patterns of hormone secretion

A 
Plasma concentrations of a nutrient (eg. GH and glucose)
Neural control (eg stress responses)
Hormonal control (eg feedback)
43
Q

How are hydrophilic hormones transported in the blood?

A

They are dissolved in the blood…

but they are subject to degradation because of the proteases in the blood

44
Q

How are lipophilic hormones transported in the blood?

A

They are bound to a carrier protein…

the carrier protein also protects the hormone from being degraded

45
Q

Where are most hormones degraded?

A

In the liver or kidney

46
Q

How do cells respond to steroid and thyroid hormones?

A

Receptor and the ligand forms a DNA-binding protein, which regulates transcription to make a protein
These responses are delayed because it takes time to make a protein

47
Q

What are the two types of receptor responses and what happens with peptide hormones?

A

Ionotropic responses: open ion channels and create a rapid response
Metabolic responses: alter cell activity by phosphorylating secondary messengers (slower response)

48
Q

How do steroid and thyroid hormones enter the cells?

A

They just diffuse through the membrane and bind to intracellular receptors

49
Q

How do cells respond to steroid and thyroid hormones?

A

Receptor and the ligand forms a DNA-binding protein, which regulates transcription to make a protein
These responses are delayed because it takes time to make a protein

50
Q

What parts of the brain are most responsible for hormone control?

A

Hypothalamus and pituitary gland

51
Q

Where is the hypothalamus?

A

Floor of the diencephalon and surrounds the 3rd ventricle

52
Q

Where is the pituitary gland?

A

Just below the hypothalamus in the sella turcica

53
Q

What is the infundibulum and what is in it?

A

The stalk of tissue that connects the pituitary gland to the hypothalamus.
It contains axons and blood vessels

54
Q

Median eminence

A

Where the infundibulum attaches to the hypothalamus

55
Q

What are the two parts of the pituitary gland?

A

Anterior
Posteiror
They’re actually two different glands that fused during development

56
Q

What two hormones are released from the posterior pituitary?

A

Oxytocin

Vasopressin

57
Q

T/F - hormones are made in the pituitary

A

False - they’re synthesized in the hypothalamus, then sent to the pituitary through the infundibulum for release

58
Q

What does Oxytocin do?

A

Stimulates smooth muscle contraction

59
Q

What does Vasopressin do?

A

Has actions in the kidney and blood vessels to regulate blood volume and pressure, respectively

60
Q

What are the Hypophysiotropic hormones

A 
Thryrotropin releasing hormone (TRH)
Growth hormone releasing hormone (GHRH)
Somatostatin (SS)
Gonadotropin releasing hormone (GnRH)
Dopamine
Corticotropic releasing hormone
61
Q

What are Hypophysiotropic hormones?

A

Hormones released from the hypothalamus that get sent to the anterior pituitary to trigger the release of another hormone

62
Q

What does Thyrotropin releasing hormone (TRH) do?

A

Stimulates the release of TSH

63
Q

What does Growth hormone releasing hormone (GHRH) do?

A

Stimulates the secretion of GH

64
Q

What does Somatostatin (SS) do?

A

Inhibits the secretion of GH

65
Q

What does Corticotropin-releasing hormone (CRH) do?

A

Stimulates the secretion of ACTH

66
Q

What does Gonadotropin-releasing hormone (GnRH) do?

A

Stimulates the secretion of LH and FSH

67
Q

What does dopamine (DA) do?

A

Inhibits the secretion of prolactin

68
Q

T/F - Hypophysiotropic hormones are only found in the infundibulum

A

False - they are found elsewhere in the body

69
Q

What is the hypothalamo-pituitary portion of the endocrine system called?

A

Neuroendocrine system

70
Q

What hormones are released from the anterior pituitary?

A 
Follicle stimulating hormone (FSH)
Leutinizing hormone (LH)
Growth hormone (GH)
Thyroid stimulating hormone (TSH)
Prolactin (PRL)
Adrenocorticotropic hormone (ACTH)
Atleast 2 others
71
Q

What are the two types of feedbacks associated with hypothalamic and pituitary hormone secretion

A

Long-loop negative feedback

Short-loop negative feedback

72
Q

Long-loop negative feedback

A

Self-regulation by the product/hormone of the ultimate target tissue
(eg. ACTH and CRH)

73
Q

Short-loop negative feedback

A

Hormone from the second gland in the axis effects the action of the first gland
(eg. LH and GnRH)

AU 15 - Human Phys (7 decks)

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