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Gut, metabolism and hormones > Anterior and posterior pituitary 2 > Flashcards

Anterior and posterior pituitary 2 Flashcards

1
Q

2 Posterior Pituitary hormones:

A

Oxytocin and Vasopressin (Antidiuretic hormone, ADH)

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2
Q

6 Anterior Pituitary Hormones

A
  1. Growth hormone (GH)
  2. Thyroid stimulating hormone (TSH)
  3. Adreno-corticotropic hormone (ACTH)
  4. Lutenising hormone (LH)
  5. Follicle-stimulating hormone (FSH)
  6. Prolactin
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3
Q

Secretion of hormones from pituitary is controlled by the?

A

Hypothalamus

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4
Q

Secretion of hormones from pituitary is controlled by the?

A

Hypothalamus

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5
Q

7 Hypothalamus hormones:

A
  1. Thyrotropin-Releasing hormone (TRH)
  2. Corticotropin-Releasing hormone (CRH)
  3. Gonadotropin-releasing hormone (GnRH)
  4. Prolactin-releasing hormone (PRH)
  5. Prolactin-inhibiting hormone (PIH)
    (dopamine)
    6.Growth-hormone releasing hormone (GHRH)
  6. Growth-hormone inhibiting hormone (GHIH)
    (somatostatin) (SS)
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6
Q

6 overall functions of the endocrine system:

A

egulates organic metabolism and H2O and electrolyte balance
* 2. Induces adaptive changes to help cope with stressful situations
* 3. Promotes smooth, sequential growth and development
* 4. Controlling reproduction
* 5. Regulating red blood cell production
* 6. Along with the autonomic nervous system, controlling and integrating
activities of both the circulatory and digestive systems.

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7
Q

Endocrine system is very complex, what can a single endocrine gland make and give an example:

A

A single endocrine gland can produce multiple hormones,
eg Anterior pituitary secretes 6 different hormones, each with distinct functions

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8
Q

A single hormone may be secreted by more than one endocrine gland
What do the pancreas and hypothalamus both secrete?

A

Somatostatin

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9
Q

Frequently a single hormone may have more than one target cell and hence produce more than one type of response - give vasopressin example

A

eg vasopressin - promotes H2O reabsorption by binding V2 receptors and cause vasoconstriction of arterioles throughout the body by binding with V1
receptors on arteriolar smooth muscle.

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10
Q

What does the rate of secretion of some hormones vary with? Give an example:

A

Rate of secretion of some hormones varies considerably over time in a cyclic pattern eg the menstrual cycle.

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11
Q

A single target cell may be influenced by more than one hormone give eg, in liver cell:

A

nsulin promotes conversion of glucose into glycogen
by stimulating one particular hepatic enzyme, while glucagon, stimulates another hepatic enzyme to enhance the degradation of glycogen to glucose.

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12
Q

Can the same chemical messenger be a hormone or a neurotransmitter, if so give an example?

A

Yes - norepinephrine

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13
Q

Where is norepinephrine secreted as a hormone and then as a neurotransmitter?

A

This is secreted as a hormone by the adrenal medulla and as a neurotransmitter from sympathetic postganglionic nerve fibers.

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14
Q

Some organs are exclusively endocrine in function (specialise in hormone secretion alone, eg anterior pituitary) while others perform nonendocrine functions as well as hormone secretions give eg testes example:

A

Testes produce sperm and also secrete the male hormone testosterone.

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15
Q

What is the neuroendocrinology study mainly concerned with?

A

Neuroendocrinology primarily concerns the
way the brain regulates pituitary hormone
secretion - hypothalamus/pituitary

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16
Q

Where does pituitary lay in the brain?

A

Pituitary lies 1com at the base of the brain below the hypothalamus

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17
Q

The hypothalamus-pituitary is a major unit of endocrine system
1. What systems does it integrate?
2. Pituitary function depends on?
3. What is it connected by?

A
  1. Integrates nervous and endocrine systems
  2. pituitary function depends on hypothalamus
  3. it is connected by nerve fibers and blood vessels
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18
Q

Hypothalamus and pituitary regulate the function of? 6

A
  1. Thyroid
  2. adrenal
  3. reproductive glands
  4. somatic growth
  5. lactation
  6. water metabolism
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19
Q

Where does hypothalamus lie?
The pituitary is connected to the base of the brain by what?

A

The hypothalamus lies at base of brain
The pituitary connects to base of brain by infundibular stalk

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20
Q

What structure does the anterior pituitary have and where does it develop from?

A

The anterior pituitary has a epithelial structure that develops from Rathke’s pouch

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21
Q

What structure does the posterior pituitary have and where does it develop from, what does it consist of?

A

The posterior pituitary has a neural structure that develops from floor of the midbrain, and consists of nerve fibers that run from hypothalamus to anterior pituitary

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22
Q

The posterior pituitary along with the hypothalamus forms the neuroendocrine system and is made up of neural tissue -
1. What does it store and where?
2. What does it release?

A
  1. Stores two peptide hormones in axonal ends
  2. Release Oxytocin and Vasopressin (Antidiuretic
    hormone, ADH)
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23
Q

How are vasopressin and oxytocin made? 3 main points

A

They are made as nerve cell bodies in the hypothalamus
Then peptides are packaged into vesicular granules
and the granules are transported down axons into posterior lobe
The peptide is then released from the terminal (similar to neurotransmitter release)

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24
Q

Another name for vasopressin?

A

ADH - Anti-Diuretic hormone

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25
Q

Vasopressin-controlled, variable water reabsorption occurs where?

A

Occurs in the final tubular segments of the kidney.

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26
Q

What % of H2O is obligatory in the proximal tubule, what about the distal tubule and collecting duct?

A

65 % of water reabsorption is obligatory in the proximal tubule.
In the distal tubule and collecting duct it is variable,
based on the secretion of ADH.

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27
Q

What does the secretion of vasopressin do to the permeability of the tubules cells to water?

A

The secretion of vasopressin increases the permeability of the tubule cells to water.

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28
Q

An osmotic gradient exists outside the tubules - what is this for?

A

The transport of water by osmosis.

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29
Q

What happens during a water deficit with ADH?

A

During a water deficit, the secretion of vasopressin increases. This increases water reabsorption.

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30
Q

What happens during an excess of H2O with ADH?

A

During an excess of water, the secretion of vasopressin decreases. Less water is reabsorbed. More is eliminated.

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31
Q

Give the 6 steps that explain the mechanism of action of vasopressin, how does it carry out the water reabsorption:

A
  1. Blood-borne ADH binds with its receptor sites on the basolateral membrane of a principal cell in the distal or collecting tubule.
  2. The binding activates the cAMP 2nd messenger system within the cell.
  3. cAMP increases the opposite luminal membrane’s permeability to H2O by promoting the insertion of ACP-2 water channels into the membrane. This membrane is impermeable to water in the absence of vasopressin.
  4. Water enters the tubular cell from the tubular lumen through the inserted water channels.
  5. Water exits the cell through a different water channel (either AQP-3/4), permanently positioned at the basolateral border, and then enters the blood in this way being reabsorbed
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32
Q

What is the main difference between anterior and posterior pituitary?

A

Does not make its own hormones it simply stores them and upon appropriate stimulation can release them: oxytocin and ADH

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33
Q

How is the production of ADH and oxytocin triggered?

A

Triggered by an action potential that originates in hypothalamic cell body and sweeps down the axon to the neuronal terminal in the posterior pituitary

34
Q
  1. What does ADH control?
  2. What does it act on to increase water absorption in the distal tubule?
A
  1. ADH controls blood volume
  2. Acts on kidney to increase water reabsorption in distal tubule
35
Q

How does ADH respond to increased blood volume - 3 points?

A
  1. Sensed by stretch receptors in heart atrium
  2. signal to hypothalamus
  3. Decreased vasopressin production
36
Q

How does ADH respond to decreased blood osmolarity - 2 points:

A
  1. Reduced activity of hypothalamic osmoreceptors
  2. Reduces vasospressin secretion
37
Q

What happens in diabetes in relation to ADH?

A

in Diabetes - failure of ADH secretion or reduced sensitivity of kidney to ADH (antidiuretic hormone) may occur

38
Q

What is an analogue?

A

It is a compound with a molecular structure closely similar to that of another.

39
Q

What is enuresis - urinary incontinence?

A

Medical term for bed wetting. Incontinence is accidental or intentional urination in children who are at an age where they should be able to have control of their bladders.

40
Q

Analogues for clinical use:
For Enuresis? For control of bleeding? For adjunct to local anaesthetic?

A

Vasopressin; desmopressin (enuresis); terlipressin
(control of bleeding); felypressin (adjunct to local
anaesthetic)

41
Q

Can oxytocin regulate brain function?

A

Yes it may be able to

42
Q

Where is oxytocin made and secreted?

A

Made by hypothalamus secreted by posterior pituitary

43
Q

During birth, estrogen rises, what does the uterus make and what happens?

A

The uterus produces oxytocin receptors, oxytocin contracts uterus and synthetic oxytocin induces
labour

44
Q

Oxytocin also helps in smooth muscle contractions which causes release of?

A

Milk

45
Q

What behaviours does oxytocin influence or faciliate?

A

Influence maternal behaviour, facilitates bonding or
attachment

46
Q

Explain 4 step cycle of oxytocin to releasing milk:

A
  1. Nursing stimulates nerve receptors in nipple
  2. Sensory nerves carry impulses to the neuroendocrine cells of the hypothalamus
  3. Neuroendocrine cells release oxytocin when stimulated
  4. Oxytocin is transported by blood to mammary glands where milk is ejected.
47
Q

Posterior Lobe is the site of production for what 2 hormones?

A

ADH and oxytocin

48
Q

ADH function and Oxytocin function:

A

Promotes water retention
Oxytocin Stimulates milk ejection

49
Q

What hormones are made by the anterior lobe? 6

A

Growth Hormone (GH), Adrenocorticotropic hormone (ACTH), Thyroid stimulating hormone (TSH), Prolactin (Prl), Luteinising hormone (LH) and Follicle stimulating hormone (FSH)

50
Q

Function of:
1. GH
2. ACTH
3. TSH
4. Prl
5. LH
6. FSH

A
  1. stimulates growth
  2. stimulates adrenal cortex
  3. stimulates thyroid gland
  4. stimulates lactation
  5. stimulates gonads
  6. stimulates gonads
51
Q

What are gonads?

A

Gonads are glands that produce hormones that are involved in reproduction and other functions of the body

52
Q

SEE box on slide 17 of lecture notes

A
53
Q

What does anterior pituitary secrete?

A

Tropic and direct hormones

54
Q

Anterior pituitary hormones are regulated by?

A

Hypothalamic hormones

55
Q

Anterior pituitary- what is the rathke’s patch?

A

Epithelia derived upgrowth from roof of oral cavity called the rathke’s patch

56
Q

Difference of posterior and anterior pituitary in relation to hormones?

A

Unlike the posterior pituitary the anterior pituitary itself synthesises the hormones it releases into the blood.

57
Q

Generally each cell type produces mainly one hormone what are cells named according to ?

A

The hormone they make

58
Q

Anterior pituitary cell type - how many cell population and how many peptide hormones are secreted?

A

Five different cell populations secrete 6 major peptide hormones

59
Q

Somatotrophs make, what do these hormones do?

A

Somatotrophs make growth hormone (somatotrophin) – primary hormone that regulates overall body growth.

60
Q

Thyrotropes make? What do these hormones do?

A

Thyrotropes secrete thyroid stimulating hormone (TSH, tyrotropin)
– stimulate secretion of thyroid hormone and growth of the thyroid gland.

61
Q

Corticopes make? What does this do?

A

Corticotropes, produce and release adrenocorticotropic hormone (ACTH)
– stimulates cortisol secretion by the adrenal gland and promotes growth of the adrenal gland

62
Q

Gonadotropes secrete?

A

2 Hormones that act on gonads

63
Q

What does FSH do?
Females and males?

A

Helps regulate gamete production in both sexes.
In females stimulates growth of ovarian follicles, within which ova develop and also promotes secretion of oestrogen by the ovaries. In males required for sperm production

64
Q

LH what does it do? and in males and females?

A

Luteinising hormone (LH) – helps control sex hormone secretion in both sexes.
In females LH responsible for ovulation, and controls secretion of oestrogen and progesterone.
In males LH causes secretion of testesterone from the testes.

65
Q

Lactotrophs secrete? what does this do? function in males?

A

Lactotrophs secrete prolactin. Enhances breast development and milk production in females. Function in males is less certain

66
Q

See boxes on slide 23+24 of lecture

A
67
Q

How are hypothalamic releasing and inhibiting hormones secreted? What do they act on? How do they transduce signals?

A

Secretion in pulses
Act on specific membrane receptors
Transduce signals through second messengers

68
Q

What do hypothalamic releasing and inhibiting hormones stimulate and regulate? What do they make? Are they secreted at a constant rate?

A

Stimulate and regulate release of stored pituitary
hormones
Stimulate synthesis of pituitary hormones.
None of these hormones are secreted at a
constant rate.

69
Q

ACTH releases?

A

Cortisol deals with fight/flight

70
Q

The 2 most important factors that regulate anterior pituitary hormone secretion are:

A

hypothalamic hormones and feedback by target gland hormones

71
Q

There are 7 hypophysiotropic hormones:

A
  1. Tyrotropin releasing hormone (TRH).
  2. Corticotropin releasing hormone (CRH)
  3. Gonadotropin releasing hormone (GnRH)
  4. Growth hormone releasing hormone (GHRH)
  5. Somatostatin (Growth hormone inhibiting hormone; GHIH)
  6. Prolactin releasing hormone (PRH)
  7. Dopamine (Prolactin-Inhibiting hormone; PIH)
72
Q

TRH effect on anterior pituitary?

A

Stimulates release of TSH, thyrotropin and prolactin

73
Q

CRH Effect on anterior pituitary?

A

Stimulates release of ACTH (Corticotropin)

74
Q
  1. Hypothalamus hormones referred to as?
  2. Anterior pituitary hormones referred to as?
A
  1. Releasing hormones
  2. Stimulating hormones
75
Q

Effect of GnRH on anterior pituitary?

A

Stimulates release of FSH and LH: gonatropins

76
Q

GHRH effect on anterior pituitary?

A

Stimulates release of GH

77
Q

Somatostatin effect on anterior pituitary?

A

Inhibits release of growth hormone and TSH

78
Q

PRH effect on anterior pituitary?

A

Stimulates release of prolactin

79
Q

Dopamine - prolactin inhibiting hormone effect on anterior pituitary?

A

Inhibits release of prolactin

80
Q

Explain 6 steps of the vascular link between the hypothalamus and anterior pituitary?

A
  1. Hypophysiotropic hormones (releasing hormones and inhibiting hormones) produced by neurosecretory neurons in the hypothalamus enter the hypothalamic capillaries.
  2. These hypothalamic capillaries rejoin to form the hypothalamic-hypophyseal portal system, a vascular link to the anterior pituitary
  3. The portal system branches into the capillaries of the anterior pituitary
  4. The hypophysiotropic hormones which leave the blood across the anterior pituitary capillaries, control the release of anterior pituitary hormones.
  5. When stimulated by the appropriate hypothalamic releasing hormone, the anterior pituitary secretes a given hormone into these capillaries.
  6. The anterior pituitary capillaries rejoin to form a vein, through which the anterior pituitary hormones leave for ultimate distribution throughout the body for the systemic circulation
81
Q

Feedback in endocrine control?

A

Negative

82
Q

SEE 31 SUMMARY SLIDE from lecture notes

A

Gut, metabolism and hormones (22 decks)

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