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Neuro Block 4 - KJ > Neuroendocrine/Pituitary > Flashcards

Neuroendocrine/Pituitary Flashcards

1
Q

What are the two main roles of the hypothalamus?

A
  1. Defense of homeostasis
  2. Integrates information for control of the endocrine system, the autonomic nervous system and neural systems concerned with motivation (i.e. limbic system)
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2
Q

What is homeostasis?

A
  • Protecting cells in body from extremes

- Tendency for stability in the body established by system of control mechanisms

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3
Q

What is an example of homeostasis in the hypothalamus?

A

Receptor [to pressure, volume, pH] peripheral (baroreceptors) or central (temperature receptors in skin & CNS) –(afferent)–> hypothalamus —(efferent)—> Effects hormones, autonomic nervous system

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4
Q

What does the fornix do?

A

It projects information from the maxillary bodies down to the thalamus.

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5
Q

Where does the pituitary gland sit in relation to the brain?

A

At the base of the brain in indentation of sphenoid bone (sella turcica)

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6
Q

What are the parts of the pituitary gland?

A
  • Anterior pituitary (adenohypophysis)
  • Posterior pituitary (neurohypophysis) [infundibular stalk, posterior lobe]
  • Median eminence (infundibulum)
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7
Q

What does the posterior pituitary secrete?

A

Vasopressin & Oxytocin

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8
Q

Where are Vasopressin or Oxytocin synthesized?

A

Magnocellular (very large) neurons in supraoptic (SON) and paraventricular nuclei (PVN) —> these neurons will secrete either vasopressin OR oxytocin

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9
Q

How are vasopressin or oxytocin stored and secreted?

A
  • Stored in vesicles until released by neural activity (limbic system, motivation, emotions, solitary nucleus (bp, GI tract info))
  • Transported via axons to nerve terminals in posterior pituitary
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10
Q

When the supraoptic nucleus and paraventricular nucleus is stimulated by limibic system or solitary nucleus. . .

A

. . .Magnocellular (large) hypothalamic neurons secrete peptides directly into systemic circulation

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11
Q

What three things does Vasopressin do?

A

In response to. . . .it does . . .

  1. Increased blood osmolality (inc. solute) –> Inc. water resorption by kidney
  2. Hypovolemia (dec. blood volume) –> Anti-diuretic (Inc. water resorption by kidney)
  3. Hypotension (dec. blood pressure) –> Inc. Vasoconstriction –> Inc. bp!
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12
Q

What does Oxytocin cause? (when released in blood)

A

In response to . . .it does. . .

  1. Suckling/Nursing –> Inc. Oxytocin –> “milk ejection reflex”/smooth muscle contraction in breast
  2. Uterine stimulation –> Inc. Oxytocin –> Uterine contraction (smoother muscle) –> delivery of newborn
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13
Q

What is another name for Vasopressin?

A

ADH (anti-dieretic hormone)

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14
Q

What does oxytocin cause when released in the brain?

A

Contributes to bonding between people!

-It is made in men and women but is more prevalent in women

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15
Q

The posterior pituitary secretes 2 hormones. What about the anterior pituitary?

A

It secretes “families” of hormones into systemic circulation

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16
Q

What are the somatomammotropins? What secretes them?

A

Growth hormone
Prolactin
-Secreted by Anterior Pituitary
[growth promoting, has to do with breast]

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17
Q

What stimulates growth hormone and what does this hormone effect?

A
  1. Exercise, stress, sleep (80% released during slow wave sleep)
  2. Growth (tissue) & Metabolism
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18
Q

What stimulates prolactin and what does this hormone effect?

A
  1. Sucking, stress

2. Development of mammary tissue –> lactation (milk production)

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19
Q

What are the three glycoproteins? What secretes them?

A
  1. Thyroid-stimulating hormone (TSH)
  2. Follicle-stimulating hormone (FSH)
  3. Luteinizing hormone (LH)
    - Anterior Pituitary
20
Q

What are the gonadotropins?

A
  1. Follicle-stimulatting hormone (FSH)

2. Luteinizing hormone (LH)

21
Q

What stimulates TSH (thyroid stimulating hormone)? What does it do?

A
  1. Exposure to cold temperature causes. . .

2. Increase TSH –> Inc. cellular metabolism –> Inc. heat production

22
Q

What regulates Follicle-stimulating hormone (FSH)? What does FSH cause?

A

Hypothalamic peptide
Men - Inc. spermatogenesis
Women - Development of ovarian follicle

23
Q

What regulates Luteinizing hormone (LH)? What does LH cause?

A

Hypothalamic peptide
Men - Required for spermatogenesis, Stimulates testosterone (tropic effect - relating to cell growth?)
Women - Initiates ovulation (“trigger”), Stimulates progesterone

24
Q

What are the two Opiomelanocortin peptides? What secretes them? What is their common precursor?

A
  1. Adrenocorticotropic hormone (ACTH)
  2. Beta-endorphin
    - Anterior Pituitary
    - Pro-opiomelanocortin (POMC) - you can cleave the end into ACTH and Beta-EP
25
Q

What stimulates ACTH? What does ACTH cause?

A
  1. Stress

2. Secretion of cortisol from adrenal cortex

26
Q

What stimulates beta-endorphin? What does beat-EP cause?

A
  1. Stress

2. Opiate-like analgesia

27
Q

What test can be used clinically to assess pituitary function?

A

Stress test - give small injection of insulin –> drops blood sugar –> causes insulin induced hypoglycemia –>

  1. Inc. ACTH
  2. Inc. Cortisol
  3. Inc. Growth Hormone
  4. Inc. Beta-EP
  5. Inc. Prolactin
    - -> then these hormones can be measured
28
Q

How are hypothalamic releasing hormones released into the blood stream?

A
  1. No direct arterial supply to anterior pituitary cells (true portal system)
  2. Hypothalamic “releasing hormones” secreted into primary plexus
  3. Carried to pituitary cells via portal vein
  4. Delivered to pituitary cells at secondary plexus
  5. Anterior pituitary hormones secreted into systemic circulation
29
Q

What hormonal change(s) occur after pituitary stalk section?

A

-Big Inc. Prolactin (under inhibitory control), All others Dec.

30
Q

How are hypothalamic releasing hormones causing the release of anterior pituitary hormones?

A
  1. Hypothalamic releasing hormones are synthesized in parvocellular neurons
  2. Transported via axons to median eminence
  3. Released from nerve terminals into hypophyseal portal vein
  4. Parvocellular (small) hypothalamic neurons secrete to produce “local” effects
31
Q

What are the four excitatory hypothalamic releasing hormones?

A
  1. Thyrotropin-releasing hormone (TRH)
  2. Gonadotropin-releaseing hormone (GnRH)
  3. Corticotropin-releasing hormone (CRH)
  4. Growth Hormone-releasing hormone (GHRH)
32
Q

What are the two inhibitory hypothalamic releasing hormones?

A
  1. Somatostatin

2. Dopamine

33
Q

What does thyrotropin-releasing hormone cause?

A

Inc. TSH

34
Q

What does gonadotropin-releasing hormone (GnRH) cause?

A

Inc. FSH & Inc. LH (both gonadotropins)

35
Q

What does corticotropin-releasing hormone (CRH) cause?

A

Inc. ACTH, Inc. Beta-endorphin

36
Q

What does growth hormone-releasing hormone (GHRH) cause?

A

Inc. GH (growth hormone)

37
Q

What does somatostatin cause?

A

Dec. in GH <— influenced by both inhibitory and excitatory hormones = NET excitation by GHRH

38
Q

What does dopamine cause?

A

Dec. prolactin (in median eminence)

39
Q

What are two disorders associated with abnormal hypothalamic-pituitary function?

A
  1. Diabetes Insipidus

2. Galactorrhea-amenorrhea

40
Q

What causes diabetes insipidus?

A

“bitter urine”

-Due to loss of vasopressin secretion

41
Q

What is the etiology (clinical presentation) for diabetes insipidus?

A
  1. Head trauma —> severing of pituitary stalk
  2. Autoimmune –> destruction of magnocellular neurons
  3. Idiopathic
42
Q

What are the symptoms for diabetes insipidus?

A
  1. Polyuria (freq./excessive urination)

2. Polydipsia –> excessive drinking

43
Q

What is the treatment for diabetes insipidus?

A

Give desamino Vasopressin (VP)

-This causes you to retain H2O in kidney without increasing blood pressure!

44
Q

What is Galactorrhea - Amenorrhea?

A

Hyperprolactinemia (inappropriate lactation) with cessation of menstruation
-Hyperprolactinemia = Inc. in blood prolactin

45
Q

What causes cessation of menstruation in Galactorrhea-Amenorrhea?

A

Inc. pituitary prolactin due to the tumor causes Dec. FSH and Dec. LH.

46
Q

What is the etiology of galactorrhea-amenorrhea?

A

Microadenoma (tumor that releases prolactin) in pituitary gland

47
Q

What is the treatment of galactorrhea-amenorrhea?

A
  1. Surgery –> remove microadenoma

2. Pharmacology –> Give a DA (dopamine) receptor agonist to block prolactin!!

Neuro Block 4 - KJ (12 decks)

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