The Pituitary Gland And Its Disorders Flashcards
What is another name for the anterior lobe of the pituitary gland?
Adenohypophysis
What is another name for the posterior lobe of the pituitary gland?
Neurohypophysis
What is the dual blood supply to the pituitary gland?
Pituitary arteries and the hypophysial portal circulation
What does the hypophysial portal circulation begin as?
A capillary plexus round the arc
What are the three layers of the endocrine system?
Primary- end organ
Secondary - pituitary
Tertiary - hypothalamus
What is the role of the hypothalamus?
Takes inputs from the brainstem and senses and higher centres and converts them into hormones that give a particular state
How does the hypothalamus work in conjunction with the pituitary gland?
Hypothalamus secretes small amount of hormone into hypophysial vein which runs into the pituitary which amplifies the hormone to the rest of the body
What are the clinical features of pituitary tumours?
Hormone hypersecretion, space occupying lesion, hormone deficiency states
What do the space occupying lesions cause?
Headaches, visual loss and cavernous sinus invasion
What does excess TSH lead to?
Secondary thyrotoxicosis
What does excess LH/FSH lead to?
Non functioning pituitary tumour
What does excess PRL lead to?
Prolactinoma
What is the function of GH on liver?
Stimulates liver to produce IGF-1 -> acts on chondrocytes in long bones to promote linear growth
What does acral enlargement involve?
Spade like hands, increased shoe size, macroglossia (big tongue), carpal tunnel syndrome
Give some external effects of GH excess (acromegaly)
Increased skin thickness, sweating, skin tags and increased interdental spacing
Give the systemic effects of acromegaly
Impaired fasting glucose and glucose tolerance, diabetes mellitus, insulin resistance, reduced cholesterol, increased TGs and nitrogen retention
What are the actions of cortisol?
Increases plasma glucose levels and lipolysis, protein catabolis, sodium and water retention, anti-inflammatory and increased gastric acid production
What processes increase when cortisol increases plasma glucose levels?
Gluconeogenesis, glycogenesis and glycogen storage
Why does cortisol increases lipolysis?
Conserve glucose by using broken down fats as energy
What are the external symptoms of Cushing’s syndrome?
Change in body shape, central obesity, moon face, thin skin and easy bruising
What does the change in sex hormones in cushings lead to?
Excess hair growth, irregular periods, problems conceiving and impotence (ED)
What does prolactin inhibit?
LH and FSH
What feedback mechanism controls prolactinomas?
Positive
What does tonic release of DA inhibit?
PRL release
