Endocrinology of the adrenal gland Flashcards
What are the adrenal glands?
Triangular glands located craniomedially to each kidney
What are the two parts of the adrenal glands?
The outer cortex and the inner medulla
Where does the cortex develop from?
It develops from mesodermal tissue and secretes steroid hormones
Where does the medulla develop from?
The medulla develops from neuronal tissue and releases catecholamine hormones like adrenaline and noradrenaline
What are the three zones that the adrenal cortex can be divided into?
Zona glomerulosa, Zona reticularis and Zona fasciculata
What is the end product hormone of the zona glomerulosa?
aldosterone
What is the end product hormone of the zona fasciculata?
Cortisol
What is the end product hormone of the zona reticularis?
androstenedione and testosterone
What is the starting point of all hormones in the adrenal cortex?
Cholesterol
What is the first step of hormone synthesis?
Removal of the cholesterol side chain in order to produce pregnenolone
Where does the first step of synthesis occur?
In the mitochondria of adrenocortical cells
Which hormone is released from the hypothalamus when stress is the primary stimulus annd what is its function?
Cortico-releasing hormone or ACTH releasing hormone, it is delivered to the anterior pituitary via the hypothalamic-pituitary portal system and then stimulates the release of ACTH from the anterior pituitary
What happens when ACTH acts on the zona fasciculata?
Increases the uptake of cholesterol into cells and increases the conc of cholesterol being converted into glucocorticoids/androgens
Where is renin produced and released from?
The juxtaglomerular cells
Where does angiontensin I get converted to angiotensin II?
By angiotension converting enzyme in pulmonary capillaries
What are the two effects of angiotensin II on the body?
It acts on the zona glomerulosa of the adrenal cortex and stimulates the production of aldosterone
What are mineralcorticoids?
Mineralcorticoids have crucial effects on the homeostasis of important ions eg Na+
What system regulates the secretion of ACTH?
The renin angiotensin system
What is the ‘most important’ glucocorticoid? in mammals?
Cortisol
What effect does cortisol have during times of stress?
Increases plasma levels of glucose (stimulates gluconeogenesis)
What is DHEA and where is it secreted?
DHEA is secreted from the zona reticularis and has important functions in libido and hair growth in females
What is the function of the adrenal medulla?
To synthesise and secrete catecholamines such as adrenaline or noradrenaline
What are Chromaffin cells?
Cells that produce neurohormones
What is hyperadrenocorticism?
Cushings disease/ over production of glucocorticoids
