Flashcards in Metabolism - Pituitary And Adrenal Glands Deck (56)
What are the 5 cell types and hormones they produce in the anterior pituitary?
Gonadotrophs - LH/FSH
Lactotrophs - Prolactin
Corticotrophs - ACTH
Thyrotrophs - TSH
Somatotrophs - GH
What hormones are released from the posterior pituitary?
How is GH released?
Pulsation fashion through day but peaks at night.
How does GH cause an effect?
Stimulates the production of IGF-1 by the liver
Acts on cell surface receptors to activate secondary messenger cAMP.
What mediates GH?
Mediated by IGF–1
What are the functions of GH?
Increased muscle strength
Quality of life
What will the effects of a deficiency in GH be?
Short stature if in children
What will be the effect of excess GH?
Gigantism in children
Acromegaly in adults
--> coarse features
What stimulates ACTH?
CRH and stress
How are CRH and ACTH released?
In a pulsatile fashion with 9am being peak
What is the function of ACTH?
It controls cortisol levels which increase glucose production and use.
What controls TSH release?
Negative feedback from T3/4 and TRH
What is the function of TSH?
Activates follicular cells to produce T3/4
What occurs in primary gland failure of TSH?
The thyroid fails
= little T3/4 and lots of TSH
= lots T3/4 and little TSH
What occurs in secondary gland failure of TSH?
The pituitary gland fails
= little TSH, little T3/4, normal TRH
= lots of TSH, lots of T3/4
What stimulates prolactin?
Oestrogen and a little TRH.
What inhibits and controls prolactin release?
Dopamine under tonic inhibitory control (NOT UNDER PITUITARY CONTROL)
What do high levels of prolactin cause and how does this occur?
Causes menstrual disturbance and lactation
- Polycystic ovaries
- Pituitary problem
What is the function of ADH and how does it achieve this?
It acts on the kidneys to recycle water when the body is becoming dehydrated.
Osmoreceptors in the pituitary gland control release of ADH
- if blood is more concentrated, secrete ADH = more water retained.
- a lower blood concentration or alcohol intake inhibit release of ADH
How is prolactin released?
Pulsatile fashion but greater amounts at night.
What is the anatomy of the pituitary gland?
Held by the pituitary stalk below the optic chiasma and in the middle of cranial nerves.
Where does the pituitary gland develop from?
Posterior = down growth of neural tissue
Anterior = up growth of primitive gut tissue
What is the hypothalamo-pituitary axis?
The link between the body's endocrine and nervous systems.
What are the 2 types of tumour that can affect the pituitary hormones?
1). Pituitary tumour
2). Endocrine hypersecretion
What effect would a pituitary tumour have and what are its symptoms?
Symptoms may include lack of peripheral/blurred vision (press on optic chiasma) or cranial nerve palsied (cavernous sinus invasion).
It will decrease the secretion of all the hormones except prolactin, as this is not under pituitary control = hypopituitarism.
What are endocrine hypersecretion tumour and how will they affect the pituitary hormones?
Where a tumour elsewhere in the body secretes that hormone.
- high TSH = high T3/4
- can also be lost by loss of dopamine secretion
- shrink using dopamine
- infertility (inhibits LH/FSH)
GH secreting tumour
- acromegaly (coarse features, headaches, high BP, sweating)
- high sex steroids
- high LH/FSH
How is LH/FSH released?
What stimulates LH/FSH release?
How does LH/FSH affect men and women?
LH - testosterone production
FSH - sperm production
Works by simple negative feedback
Slight circadian rhythm
LH - oestrogen and progesterone release
FSH - follicle development
Works on simple positive feedback