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SEM3: PATH30210 Endocrine Health/Disease > L2: Hypothalamus and Pituitary Gland Phys > Flashcards

L2: Hypothalamus and Pituitary Gland Phys Flashcards

1
Q

The interface between the nervous and endocrine systems?

A

Hypothalamus

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2
Q

Main endocrine function of the hypopthalamus? (7)

A
  • growth
  • fertility and reproduction
  • osmoregulation (water balance)
  • metabolism (thermoregulation)
  • energy balance
  • stress response
  • lactation
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3
Q

Connections between the hypothalamus and Pituitary Gland?
Morphology and Function of each?

A

Magnocellular Neruons (large, long)
–large cell bodies with long axons projecting down to (posterior) pituitary
–oxytocin and vasopressin (ADH) released into systemic circulation

Parvocellular Neurons (small, short)
–small cell bodies w/ shorter axons projecting to top of pituitary stalk (infundibulum)
–6 hormones (hypophysiotropic hormones) released into Portal Circulation

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4
Q

Hormones secreted by Parvocellular Neurons?

A
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5
Q

Posterior Pituitary is made of __________ tissue

A

Pituitary gland is made of NEURAL tissue

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6
Q

Collection of axonal projections from the hypothalamus that serve as a site for the secretion of neurohypophysial hormones directly into the blood?

A

Posterior Pituitary

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7
Q

_____________: Unmyelinated nerve axons of neurons cells whose cell bodies are located in hypothalamus

A

Neurohypohysis (aka. Posterior Pituitary): Unmyelinated nerve axons of neurons cells whose cell bodies are located in hypothalamus

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8
Q

Another name for glial cells?

A

Pituicytes

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9
Q

______________: Secretory granules containing oxytocin and vasopressin in terminal region of axon of Posterior Pituitary

A

Herring bodies: Secretory granules containing oxytocin and vasopressin in terminal region of axon

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10
Q

Vasopressin is released from the _____________

A

Vasopressin is released from the Posterior Pituitary

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11
Q

Vasopressin’s physiological effects? (V1 vs. V2)

A

V1 receptors:
□ abundant in vascular smooth muscle cells
□ activation of V1 receptors => VSMC contraction (‘vasopressin’)

V2 receptors:
□ abundant in renal tubule epithelial cells
□ activation of V2 receptors => increased renal H2O reabsorption

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12
Q

___________ plays essential role in maintaining water balance in kidney

A

Vasopressin

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13
Q

How does Vasopressin (ADH/AVP) Function to regulate water balance?

A

Plasma osmolality of > 280mOsm/kg => AVP release

AVP acts on renal epithelial cells to promote reabsorption of H2O

Plasma volume is increased and its osmolality decreased
Urine volume is decreased and its osmolality is increased

Independently, thirst centers in the hypothalamus are activated increasing the urge to consume H2O

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14
Q

What 3 stimuli control Vasopressin Release?

A
  • Blood Osmolality > 280mOsM (sensed by hypothalamus osmoreceptors)
  • Hypovolemia (decreased atrial stretch receptor activation)
  • Hypotension ( decreased carotid and aortic baroreceptor activation
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15
Q

ADH Action on Kidney Tubule Epithelia?

A

ADH acts on renal epithelial cells V2 receptors to promote reabsorption of H2O

Leads to water channels (Aquaporin II ) insertion on apical membrane => allows water to enter cell and be returned to vasculature=> Smaller volume of more concentrated urine secreted

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16
Q

Inability of kidney to reabsorb H2O =>excretion of large volumes of dilute urine (25l/day)?

A

DIabetes Insipidus (ADH Deficiency)

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17
Q

Types of Diabetes Insipidus?

A

NEURAL (cranial) DI (hypothalamus/pituitary lesion)

NEPHROGENIC DI (renal ‘resistance’ to ADH)

  • Inherited -mutations in V2 receptor (X-linked) or aquaporin 2 (autosomal)
  • acquired -drug-induced (amphotericin B)
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18
Q

Diagnosis of Diabetes Insipidus?

A

Water deprivation test (DI individual will not concentrate urine)

19
Q

Treatment of Diabetes Insipidus?

A

Desmopressin (Synthetic Vasopressin)
NOT Appropriate to treat nephrogenic DI - resistant to vasopressin!!

20
Q

Which drug can induce Diabetes Insipidus?

A

Amphotericin B

21
Q

Excess ADH usually caused by GI/Pulmonary tumors that secrete ADH in unregulated function?

A

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

22
Q

Physiological Role of Oxytocin?

A

Weak antidiuretic action (similarity to AVP)

Parturition (Childbirth)- Stimulates uterine contractions, can induce labor

Lactation- Milk letdown reflex

Social/mating/emotional behaviour (Love Hormone)

23
Q

______________ triggers myoepithelial contractions to expel milk from mammary alveoli into ducts/collecting chamber. This is known as __________

A

Oxytocin triggers myoepithelial contractions to expel milk from mammary alveoli into ducts/collecting chambers. This is known as the milk letdown reflex

24
Q

One of the few areas of the brain where the blood-brain barrier is compromised?

A

Hypothalamus/pituitary is one of the few areas of the brain where the blood-brain barrier is compromised because of fenestrated capillaries

25
Q

All the hormones released by the anterior pituitary are ________

A

All are peptide hormones

26
Q

Hormones that have other endocrine glands as their target?

A

Trophic Hormone: Triggers release of other hormones

27
Q

Only major Anterior pituitary hormone that is NOT trophic

A

Prolactin

28
Q

Regulation of Prolactin

  • ________________ increases release ( ie. during pregnancy)
  • ________________ inhibits prolactin release (suckling reflex)
A

Regulation of Prolactin

  • Estrogen/progesterone increases release ( ie. during pregnancy)
  • Dopamine inhibits prolactin release (suckling reflex)
29
Q

Physiological roles of Prolactin

A

Lactation (Primary) - Breast Development/milk production in pregnancy

Immune tolerance: Prevents body from reacting to fetus

Behavioral: nurturing instinct/broodiness

30
Q

High levels of ________ inhibits fertility by lowering GNIH
=> reduction of FSH and LH

A

High levels of PROLACTIN inhibits fertility by lowering GNIH
=> reduction of FSH and LH

31
Q

What mediates the Anabolic (growth promoting) effects of Growth Hormone. Where is it produced?

A

Anabolic (growth promoting) effects mediated by IGF-1
Produced in the liver in response to GH

32
Q

______ is a contrainsulin hormone

A

Growth hormone is a contrainsulin hormone

Insulin lowers plasma glucose, GH increases plasma glucose

33
Q

_______ has insulin like metabolic actions

A

IGF-I has insulin-like metabolic actions despite being stimulated from the liver by Growth Hormone that is a contra insulin hormone

34
Q

Normal age-related decline in GH (and IGF-I) of ~ _____% between the ages of 20-60?

A

Somatopause => ~50% decline
Linked to signs of aging

35
Q

Growth Hormone Regulation?

A

Hypoglycemia/Grehlin => Increased GH

Exercise: vigorous exercise => Increased GH

Somatopause: age-related decline in GH (and IGF-I) ~ 50%

36
Q

_________________ of GH Secretion is essential for normal growth

A

Pulsatile and circadian pattern of GH Secretion

37
Q

When does the majority of GH secretion occur?

A

70% daily GH secretion coincides with the onset of deep sleep (REM4)

38
Q

What causes GH Deficiency in Children?

A

head trauma
infections (eg, encephalitis, meningitis),
cranial irradiation
systemic diseases (eg. leukemia)

39
Q

Symptoms of GH Deficiency in Children?

A

short stature

low growth velocity for age/pubertal stage

increased amount of fat around the waist

delayed tooth development

delayed onset of puberty

40
Q

Main Causes of Adult Onset GH Deficiency?

A
  • pituitary tumors that impair somatotroph function
  • head trauma
  • vascular abnormalities of hypophyseal circulation
41
Q

Symtoms of Adult Onset GH Deficiency?

A

metabolic abnormalities

DECREASE lean body mass, INCREASE adiposity

osteoporosis

psychological disorders

42
Q

________ is important in the maintenance of skeletal muscle and bone and in glucose homeostasis

A

Growth Hormone is important in maintenance of skeletal muscle and bone and in glucose homeostasis

43
Q

Consequences of GH Hypersecretion (Congenital vs Adult)

A

Congenital (GH excess prior to fusion of epiphyseal growth plate)=> Acromegalic Gigantism

Adult Acquired (Growth plates fused)=> Acromegaly

  • bone thickening (not lengthening)
  • metabolic abnormalities similar to type 2 diabetes
  • increased risk of cardiovascular disease, cancer

SEM3: PATH30210 Endocrine Health/Disease (25 decks)

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