Week 7: Endocrine Feedback Loops Flashcards
(62 cards)
1
Q
Describe hypothalamic and metabolic homeostasis
A
2
Q
ACTH AKA
A
- Adrenocorticotropic hormone
3
Q
GH AKA
A
growth hormone
or
STH (Somatotropic Hormone)
4
Q
TSH AKA
A
Thyroid-stimulating hormone
5
Q
Prl AKA
A
Prolactin
6
Q
LH AKA
A
Luteinizing hormone
7
Q
OT AKA
A
Oxytocin
8
Q
AVP
A
Arginine Vasopressin
9
Q
Posterior pituitary secretions and functions
A
- OT (Parturition & Lactation)
- AVP (Water balance)
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)
11
Q
Describe all Anterior & Posterior Pituitary secretions and functions
A
12
Q
Describe hypothalamic control of pituitary function
A
13
Q
List of pituitary disorders
A
- Hypopituitarism
- Hormone-producing Pituitary adenomas
- Growth Hormone Insensitivity
14
Q
Case discussion question
A
B Pituitary adenoma
can cause secretory dysfunction of the pituitary gland
15
Q
Hypopituitarism Pathophysiology/etiology
A
Ischemic damage to the pituitary gland or hypothalamic pituitary stalk during the peripartum period leads to Sheehan syndrome
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
17
Q
Hypopituitarism Clinical Manifestations
5 listed
A
- hypothyroidism
- adrenal insufficiency
- hypogonadism
- GH deficiency
- Hypoprolactinemia
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%)
19
Q
Etiology of GH Insensitivity
A
Growth failure can be the result of decreased GH release, decreased GH action or GH Insensitivity Syndrome
20
Q
GH Insensitivity Syndrome AKA
A
Laron Syndrome
21
Q
Laron Syndrome AKA
A
GH Insensitivity Syndrome
22
Q
Describe the Hypothalamus-pituitary-thyroid axis
A
23
Q
Describe the biosynthesis of thyroid hormones
A
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
25
Hypothalamus and metabolic regulation
* 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
Describe the mechanisms of how the hypothalamus controls pituitary function
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
STH AKA
GH
28
What is acromegaly?
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
Describe the Hypothalamus-pituitary-thyroid axis
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
Describe the biosynthesis of thyroid hormones
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
What stimulates thyroid hormone synthesis
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
Where are thyroid hormones synthesized
Follicular cells of the thyroid
33
Thyroid hormone precursors
Thyroglobulin & 2x Tyrosine
34
Describe the hypothalamus-pituitary-thyroid axis endocrine feedback loops
* 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
Wolff-Chaikoff effect
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
Describe the action of thyroid hormone
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
Thyroid hormone nuclear receptors
Different types regulating different gene sequences that are Cell type-specific
38
Thyroid hormone functions
9 listed
* Breathing
* Heart Rate
* Central and peripheral nervous system
* body weight
* menstruation
* muscle strength
* body temperature
* Cholesterol levels
* Body growth & metabolism
39
Thyroid hormone effects on breathing
40
Thyroid hormone effects on heart rate
41
Thyroid hormone effects on the CNS and PNS
42
Thyroid hormone effects on body weight
43
Thyroid hormone effects on menstruation
44
Thyroid hormone effects on muscle strength
45
Thyroid hormone effects on body temperature
46
Thyroid hormone effects on cholesterol levels
47
Thyroid hormone effects on growth & metabolism
48
Describe the biochemistry of thyroid hormone and metabolism
49
WAT VS BAT
* White adipose tissue (storage)
* Brown adipose tissue (burn and release heat)
50
BAT & Thyroid hormones
51
Hypothalamic effects of thyroid hormones
5 listed
T3 & T4 can activate neurons in different nuclei of the hypothalamus
52
Case discussion question
A. Graves disease
hyperthyroidism is a typical feature of graves disease
53
Describe the hypothalamus-pituitary-adrenal axis
Hypothalamus -CRH-\> anterior pituitary gland -ACTH-\> adrenal gland -glucocorticoids & catecholeamines-\> tissues
54
Hypothalamus-pituitary-adrenal axis organs targeted
immune system
Muscle
Liver
Fat cells
Heart rate
55
hypothalamus-pituitary-adrenal axis activation organs effects on the immune system
Altered
56
Hypothalamus-pituitary-adrenal axis activation organs effects on muscle
Net loss of amino acids for (glucose)
57
Hypothalamus-pituitary-adrenal axis activation organs effects on the liver
Deamination of proteins into amino acids and gluconeogenesis for (glucose)
58
Hypothalamus-pituitary-adrenal axis activation organs effects on fat cells
Free fatty acid mobilization
59
Hypothalamus-pituitary-adrenal axis activation organs effects on the heart rate
Increased
60
What is CRH?
Corticotropin-releasing hormone secreted by the hypothalamus to the pituitary to release ACTH to the adrenal glands
61
Describe the synthesis of steroid hormones in the adrenal cortex
62
