Pituitary gland and its disorders Flashcards
What hormones does the anterior pituitary produce?
→ ACTH → TSH → GH → LH/FSH → Prolactin
What hormones does the posterior pituitary produce?
→ oxytocin
→ ADH
What does oxytocin do?
→ uterine contractions
→ breast milk expression
What are the three layers of the endocrine system?
→ end organ is the primary layer
→ the secondary layer is the pituitary
→ third layer is the hypothalamus
What are the 2 functions of the hypothalamus?
→ it takes sensory input - electrical signal
→ and produces hormones to adapt to the physical state - chemical signal
In what blood vessel do the hormones get released into?
→ hypophyseal portal blood vessel
What is the negative feedback system in endocrinology?
→ The production of the end hormone stops the pituitary and hypothalamus producing more
What happens when you get pituitary tumors?
→ Hormone hypersecretion
→ Space occupying lesion- visual loss
→ Hormone deficiency states
What is excess growth hormone?
→ acromegaly
What is too much ACTH?
→ Cushings disease
What is excess TSH?
→ secondary thyrotoxicosis
What is excess LH and FSH?
→ Non functioning pituitary tumor
What is excess prolactin?
→ prolactinoma
Describe the growth hormone circulation
→ GF acts on the liver to produce IGF
→ IGF acts on bones to stimulate chondrocytes to grow which form new bone
→ it reduces body fat
What are symptoms of acromegaly?
→ hands grow
→ Macroglossia
→ Carpal tunnel
→ Change of appearance
Why do people with acromegaly get polyps or cancer?
→ skin and bowel tissue turns over a lot
What are the actions of cortisol?
→ increases plasma glucose levels → increases lipolysis → Proteins are catabolized → Na+ and H2O retention to maintain BP → increase glycogenolysis
What are visible changes in cushings?
→ change body shape → central obesity → moon face → thin skin → excess hair growth → irregular periods → High BP
How is prolactin controlled?
→ The stimulus to production of milk is an external signal
→ Intrinsic high production of prolactin from the pituitary
→ Tonic inhibitory dopamine signal from the hypothalamus to the pituitary
How does lactation occur?
→ mechanical stimulation of the nipple sends a neuronal signal to the brain
→ goes to the hypothalamus
→ switches off dopamine production
What happens if you have excess prolactin?
→ Infertility
→ No periods - amenorrhoea
What drugs would interfere with prolactin formation?
→ drugs that interfere with dopamine such as antiemetics and antipsychotics
What is the treatment for excess prolactin?
→ Dopamine agonists
→ bromocriptine
→ Cabergoline
Why do non functioning pituitary tumors cause problems?
→ Pressure on the surrounding structures
→ no syndromes
→ headache - visual field defects
Why do we have front facing eyes?
→ Humans are predators
→ Gives depth vision
What is homologous vision?
→ Nasal fibres from the same side cross and line up with temporal fibres on the other side
→ Go into one piece back to the brain for interpretation
Where is the optic chiasm?
→ Above the pituitary
What is bitemporal hemianopia?
→ Partial blindness
→ Vision is missing in the outer half of both right and left visual field
In what order are the hormones lost in when the tumor grows?
1) sex hormones
2) growth hormones
3) metabolic
4) Survival
What rises when a tumor is made?
→ prolactin
→ obstructs the pituitary and stops dopamine coming in the brain
What are the treatments for pituitary adenomas?
→ Transsphenoidal surgery
→ Radiotherapy
→ Drugs - block hormone production, stops hormone release
What are the causes of pituitary failure?
→ Tumor → Trauma → Infection → Inflammation - sarcoidosis → Iatrogenic
What happens if you don’t produce enough thyroid hormone?
→ Bradycardia → Weight gain → Cold intolerance → Hypothermia → Constipation
What happens when you don’t produce enough sex steroids?
→ Oligomenorrhoea
→ Reduced libido
→ Hot flushes
→ Less body hair
What happens if you have reduced cortisol?
→ Tiredness → Weakness → Anorexia → Postural hypotension → Myalgia
What happens if you have reduced GH?
→ Tiredness
→ Central weight gain
What is the treatment for underproduction of thyroid hormone?
→ Thyroxine
What is the treatment for underproduction of sex steroids?
→ Testosterone
→ Estrogen
What is the treatment for reduced hydrocortisol?
→ Hydrocortisone
What is the treatment for reduced GH?
→ Growth hormone
What is the action of ADH?
→ Collecting ducts
→ Increases permeability for H2O
→ Reabsorption of free water
→ Vasoconstriction
How is ADH stimulated?
→ Increased osmolality
→ Decreased blood pressure
→ Decrease in O2
→ Increase in CO2
What is the cause of syndrome of inappropriate ADH production?
→ Brain injury
→ Lung cancer
→ Metabolic - hypothyroidism, Addisons
How do you diagnose SIADH?
→ Dilute plasma
→ Concentrated urine
What happens during diabetes insipidus?
→ Cranial
→ Lack of production of ADH
→ Nephrogenic
- receptor doesnt respond to it
What is a symptom of SIADH?
→ Urinating a lot
What is the water deprivation test?
→ Checking if someone is dehydrated when depriving them of water
