Session 9 (1) - Normal structure of Pituitary and Adrenal Glands Flashcards
Name 6 hormones produced from pituitatry, and the cells they stem from
TSH is produced in the Thyrotrophs
ACTH produced in the Corticotrophs
Growth hormone produced in the Somatotrophs (largest number of cells)
LH and FSH are produced in the Gonadotrophs
Prolactin is produced in the Lactotrophs
Where is the pituitary located?
Base of the brain suspended from the hypothalamus by a stalk
How do releasing factors travel from hypothalamus to pituitary gland?
Via hypohyseal portal system, a specialised series of blood vessels.
List the three types of hormones released from adrenal cortex and give examples of each
Mineralocorticoids
E.g. Aldosterone (C21 steroid)
Glucocorticoids
E.g. Cortisol and Corticosterone (C21 steroids) major steroids produced
Androgens
Give two parts of adrenal gland
Cortex and Medulla
What is the name for the three sections of the adrenal cortex, and what does each secrete?
Zona Glomerulosa --> Mineralocorticoids E.g. Aldosterone (C21 steroid) Zona Fasciculata --> Glucocorticoids E.g. Cortisol and Corticosterone (C21 steroids) major steroids produced Zona Reticularis --> Androgens
What is released from medulla?
Adrenaline
What is the function of TSH?
Stimulates secretion of thyroid hormones from thyroid
What is the function of growth hormone?
Affects metabolism, increasing muscle mass
What are the functions of LH and FSH?
Affects ovary and testis function
What is the function of prolactin?
Affects breast and milk development
What is the function of aldosterone?
Stimulates Na+ reabsorption in the kidney in exchange for K+ (or H+).
What does over secretion of aldosterone cause?
increases Na+ and water retention and loss of K+ causing hypertension and muscle weakness.
What does undersecretion of aldosterone cause?
Undersecretion decreases Na+ and water retention, increases K+. Causes hypotension.
What are the functions of androgens?
Stimulate growth and development of male genital tract and male secondary sexual characteristics. Anabolic.
Give an example of an androgen
Testosterone
What effect does over secretion of androgens have on females?
Hair growth, deepening voice, menstrual problems and acne.
What are the functions of Oestrogen?
Stimulate growth and development of female genital tract and female secondary sexual characteristics. Weakly anabolic.
(broad hips, accumulation of fat in breasts, body hair distribution)
How do steroids differ in structure from each other?
Number of C atoms
Presence of functional groups
Distribution of C=C bonds
Give two distinctive features of steroid hormones
Lipophillic
Synthesised from Cholesterol via progesterone
What is CRF secreted in response to, and where is it secreted from?
Physical (temperature, pain), chemical (hypoglycaemia) and emotional stressors.
Secreted from hypothalamus.
How is CRF secretion inhibited?
Negative feedback from glucocorticoids
What does CRF do?
Causes secretion of ACTH from anterior pituitary
What is the precursor for ACTH?
POMC
What does post translation processing of POMC produce?
a-melanocyte stimulating hormone
ACTH
B endorphins
What does ACTH cause pigmentation in body when present in large amounts?
MSH sequence contained with ACTH sequence, give ACTH some MSH like activity when in excess.
How does ACTH production relate to cortisol secretion rhythmn?
Secreted in pulses following circardian rhythmn
Where does ACTH bind and how? What does binding do?
Where
Zona fasiculata
Zona reticularis
How
Hydrophillic, interacts with high affinity receptors on cell surface.
Binding stimulates cholesterol esterase, which produces cholesterol from which cortisol produced.
What is the name of the receptor ACTH binds to?
Melanocortin receptor
What does over secretion of ACTH cause?
Pigmentation
Over-production of cortisol
What does under secretion of ACTH cause?
Symptoms related to lack of glucocorticoids
How is cortisol transported in plasma and why?
Bound to plasma proteins as it is lipophillic
Describe mechanism of action for cortisol on target cells
Cortisol can cross plasma membranes and bind to cytoplasmic receptors
The hormone/receptor complex enters nucleus and interacts with specific regions of DNA
This interaction changes rate of transcription of certain genes
Describe the functions of cortisol
1) Increase proteolysis (decreased amino acid uptake + protein synthesis)
2) Hepatic gluconeogenesis and glycogenolysis
3) Increased lipolysis in adipose tissue (HIGH cortisol results in lipogenesis)
4) Decreased peripheral uptake of glucose (ANTI-INSULIN)
How is adrenaline synthesised?
Tyrosine –> Dopamine –> Adrenaline
What type of hormone is adrenaline?
Amino acid derivative
Give four effects of adrenaline
- Cardiovascular system (increased cardiac output, increased blood supply to muscle)
- CNS (Increased mental alertness)
- Carb metabolism (increased glycogenolysis)
- Lipid metabolism (increased lipoysis in adipose tissue)
What is adrenaline secreted in response to?
Fright, fight or flight - stress situations
What can cause overproduction of adrenaline?
Tumour (phaechromocytoma) in adrenal medulla
What can overproduction of adrenaline cause?
Hypertensison, anxiety, palpitations, sweating and glucose intolerance
