Week 7: Endocrine Feedback Loops Flashcards

1
Q

Describe hypothalamic and metabolic homeostasis

A
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2
Q

ACTH AKA

A
  • Adrenocorticotropic hormone
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3
Q

GH AKA

A

growth hormone

or

STH (Somatotropic Hormone)

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4
Q

TSH AKA

A

Thyroid-stimulating hormone

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5
Q

Prl AKA

A

Prolactin

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6
Q

LH AKA

A

Luteinizing hormone

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7
Q

OT AKA

A

Oxytocin

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8
Q

AVP

A

Arginine Vasopressin

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9
Q

Posterior pituitary secretions and functions

A
  • OT (Parturition & Lactation)
  • AVP (Water balance)
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10
Q

Anterior pituitary secretions and functions

6 listed

A
  • ACTH (response to stress)
  • GH (Growth & development)
  • TSH (Metabolism)
  • Prl (Lactation)
  • LH (Reproducion)
  • FSH (Reproduction)
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11
Q

Describe all Anterior & Posterior Pituitary secretions and functions

A
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12
Q

Describe hypothalamic control of pituitary function

A
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13
Q

List of pituitary disorders

A
  • Hypopituitarism
  • Hormone-producing Pituitary adenomas
  • Growth Hormone Insensitivity
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14
Q

Case discussion question

A

B Pituitary adenoma

can cause secretory dysfunction of the pituitary gland

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15
Q

Hypopituitarism Pathophysiology/etiology

A

Ischemic damage to the pituitary gland or hypothalamic pituitary stalk during the peripartum period leads to Sheehan syndrome

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16
Q

What is Sheehan Syndrome?

A

Hypopituitarism

Ischemic damage to the pituitary gland or hypothalamic pituitary stalk during the peripartum period leads to Sheehan syndrome

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17
Q

Hypopituitarism Clinical Manifestations

5 listed

A
  • hypothyroidism
  • adrenal insufficiency
  • hypogonadism
  • GH deficiency
  • Hypoprolactinemia
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18
Q

Hormone-producing Pituitary adenomas epidemiology

5 listed

A
  • Prolactinomas are the most common pituitary tumors (40-45%)
  • Somatotroph adenoma (20%)
  • Corticotroph adenomas (10-12%)
  • Gonadotroph adenomas (15%)
  • Thyotroph adenomas (1-2%)
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19
Q

Etiology of GH Insensitivity

A

Growth failure can be the result of decreased GH release, decreased GH action or GH Insensitivity Syndrome

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20
Q

GH Insensitivity Syndrome AKA

A

Laron Syndrome

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21
Q

Laron Syndrome AKA

A

GH Insensitivity Syndrome

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22
Q

Describe the Hypothalamus-pituitary-thyroid axis

A
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23
Q

Describe the biosynthesis of thyroid hormones

A
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24
Q

Thyroid hormone structure

A

Thyroid hormones are basically 2 tyrosines linked together with the critical addition of iodine at three (T3) or four (T4) positions on the aromatic rings

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25
Q

Hypothalamus and metabolic regulation

A
  • decrease hepatic glucose production in the liver
  • increase glycogen synthesis and glucose uptake in muscle
  • Increase lipogenesis and decrease lipolysis in adipose tissue
  • Can regulate the appetite
  • MAYBE MORE STUFF NOT SURE
26
Q

Describe the mechanisms of how the hypothalamus controls pituitary function

A

2 mechanisms

  1. Neuronal hormone secretion to the circulation and to the pituitary gland
    • ACTH
    • STH (GH)
    • TSH
    • LH
    • FSH
    • Prl
  2. direct neural synapsis from hypothalamic preganglionic to pituitary neurons postganglionic
    • OT
    • AVP
27
Q

STH AKA

A

GH

28
Q

What is acromegaly?

A

Acromegaly is a hormonal disorder that develops when your pituitary gland produces too much growth hormone during adulthood. When this happens, your bones increase in size, including those of your hands, feet and face. Acromegaly usually affects middle-aged adults

29
Q

Describe the Hypothalamus-pituitary-thyroid axis

A

hypothalamus activation -TRH-> pituitary -TSH-> Thyroid -T3 & T4-> negative feedback (hypothalamus and the anterior pituitary gland) & increased (metabolism, growth & development and increased catecholamine effects)

30
Q

Describe the biosynthesis of thyroid hormones

A

Thyroglobulin + Tyrosine -Thyroid peroxidase-> Diodotyrosine -Thyroid peroxidase-> thyroxine

Triiodothyronine loses an iodine and can be an active or inactive form stereoisomer

TSH drives biosynthesis of thyroid hormones

31
Q

What stimulates thyroid hormone synthesis

A

TSH drives biosynthesis of thyroid hormones

gPCR receptor heterotrimeric 7 transmembrane g-protein-coupled receptor -> adenylate cyclase -> cAMP -> PKA -> transcription in nucleus of thyroglobulin

32
Q

Where are thyroid hormones synthesized

A

Follicular cells of the thyroid

33
Q

Thyroid hormone precursors

A

Thyroglobulin & 2x Tyrosine

34
Q

Describe the hypothalamus-pituitary-thyroid axis endocrine feedback loops

A
  • Cold, acute psychosis, circadian rhythm stimulate the hypothalamic release of TRH
  • Severe stress or T3 inhibits the hypothalamic release of TRH
  • TRH stimulates the anterior pituitary to secrete TSH
  • Corticosteroids and dopamine inhibit the anterior pituitary from secreting TSH
  • TSH stimulates the thyroid to synthesize T3 & T4 and secrete them
  • Low iodide stimulates the thyroid to secrete T3 & T4
  • High iodide inhibits the thyroid from secreting T3 & T4
35
Q

Wolff-Chaikoff effect

A

High iodide levels inhibit the thyroid from synthesizing and secreting T3 & T4

The Wolff–Chaikoff effect is known as an autoregulatory phenomenon that inhibits organification in the thyroid gland, the formation of thyroid hormones inside the thyroid follicle, and the release of thyroid hormones into the bloodstream. This becomes evident secondary to elevated levels of circulating iodide

36
Q

Describe the action of thyroid hormone

A

Tyrosine is hydrophilic so it cannot passively diffuse

T3 and T4 have to bind to its transporter (thyroid hormone transporter) to enter the cell where it binds to TR (Thyroid hormone receptor) and RXR and a coactivator in the nucleus where it is able to affect gene transcription

37
Q

Thyroid hormone nuclear receptors

A

Different types regulating different gene sequences that are Cell type-specific

38
Q

Thyroid hormone functions

9 listed

A
  • Breathing
  • Heart Rate
  • Central and peripheral nervous system
  • body weight
  • menstruation
  • muscle strength
  • body temperature
  • Cholesterol levels
  • Body growth & metabolism
39
Q

Thyroid hormone effects on breathing

A
40
Q

Thyroid hormone effects on heart rate

A
41
Q

Thyroid hormone effects on the CNS and PNS

A
42
Q

Thyroid hormone effects on body weight

A
43
Q

Thyroid hormone effects on menstruation

A
44
Q

Thyroid hormone effects on muscle strength

A
45
Q

Thyroid hormone effects on body temperature

A
46
Q

Thyroid hormone effects on cholesterol levels

A
47
Q

Thyroid hormone effects on growth & metabolism

A
48
Q

Describe the biochemistry of thyroid hormone and metabolism

A
49
Q

WAT VS BAT

A
  • White adipose tissue (storage)
  • Brown adipose tissue (burn and release heat)
50
Q

BAT & Thyroid hormones

A
51
Q

Hypothalamic effects of thyroid hormones

5 listed

A

T3 & T4 can activate neurons in different nuclei of the hypothalamus

52
Q

Case discussion question

A

A. Graves disease

hyperthyroidism is a typical feature of graves disease

53
Q

Describe the hypothalamus-pituitary-adrenal axis

A

Hypothalamus -CRH-> anterior pituitary gland -ACTH-> adrenal gland -glucocorticoids & catecholeamines-> tissues

54
Q

Hypothalamus-pituitary-adrenal axis organs targeted

A

immune system

Muscle

Liver

Fat cells

Heart rate

55
Q

hypothalamus-pituitary-adrenal axis activation organs effects on the immune system

A

Altered

56
Q

Hypothalamus-pituitary-adrenal axis activation organs effects on muscle

A

Net loss of amino acids for (glucose)

57
Q

Hypothalamus-pituitary-adrenal axis activation organs effects on the liver

A

Deamination of proteins into amino acids and gluconeogenesis for (glucose)

58
Q

Hypothalamus-pituitary-adrenal axis activation organs effects on fat cells

A

Free fatty acid mobilization

59
Q

Hypothalamus-pituitary-adrenal axis activation organs effects on the heart rate

A

Increased

60
Q

What is CRH?

A

Corticotropin-releasing hormone secreted by the hypothalamus to the pituitary to release ACTH to the adrenal glands

61
Q

Describe the synthesis of steroid hormones in the adrenal cortex

A
62
Q
A