Chapter 33 Pituitary Flashcards
Describe the biological function of ADH
It has two effects on the body, one on the kidney and one on the vascular system
ON the kidney
-It conserves body water by reducing the loss of water in urine
-To maintain a normal plasma osmolality (solute concentration by increasing water reabsorption by the kidney
On the Vascular system
Vasoconstriction leading to increase in systemic vascular resistance and increase in blood pressure
Describe the regulation of ADH secretion by plasma osmolality
Water deprivation leads to increase in plasma osmolality which then effects the osmoreceptors neurons in the hypothalamus to detect that the plasma osmolality is higher than normal so it stimulates and increases ADH secretion which leads to more water reabsorption and it returns to the normal plasma osmolality
Describe the regulation of ADH secretion by blood pressure and blood volume
When both blood pressure and blood volume decreases, the drop is detected by the baroreceptors and stretch receptor so that stimulates the hypothalamus ADH neuron which then stimulates the increase in ADH secretion which then causes both the Blood pressure and blood volume to increase and return to the normal range
Describe abnormally increased hormone secretion caused by pituitary adenoma
It is a hormone secreting adenoma that secrets 4 major hormones
Name 3 major hormones that are secreted by pituitary adenoma
Prolactin secreting adenoma (prolactinoma)-most common
Growth hormone
ACTH
Describe how the mass effect of pituitary adenoma causes visual field defects
The mass causes compression on the optic nerve which effects the vision
Describe how the mass effect of pituitary adenoma causes hypopituitarism
Because the destruction of pituitary happens and lose of one or more pituitary hormones occurs due to the compression of the pituitary cells
Describe 2 clinical consequences of hyperprolactinemia
Galactorrhea
-which is the production and discharge milk or a milk like liquid, unrelate to breast feeding
Impaired reproductive function
-Amenorrhea, irregular menses, infertility
Describe the pharmacological treatment (medication) for hyperprolactinemia
As mentioned before prolactin secretion is inhibited by Dopamine so,
The dopamine agonists bind to the dopamine receptors in the anterior pituitary and decrease prolactin synthesis, limits cell multiplication and reduce tumour size
Describe the major cause of and clinical consequences of excessive secretion of GH
Gigantism and Acromegaly
Describe the difference between acromegaly and gigantism
Gigantism happens before puberty and acromegaly happens between the ages of 20-40
Describe the 3 possible complications of acromegaly
Sleep apnoea
type 2 diabetes
Heart disease
Describe the treatment options for acromegaly
-Surgery (removal of tumor)
- Radiation therapy
- Medications: Somatostatin analogue- which helps inhibit growth hormone
Describe the causes of hypopituitarism
- Most common cause is pituitary adenoma (mass effect)
- Head injury , brain surgery , radiation treatment , etc.
- Genetic mutations (genes involved in endocrine cell development )
Describe the clinical consequences of GH deficiency ( in children and adults)
Children : dwarfism and delayed puberty
Adults : Low bone density , decreased muscle mass and strength