Endocrine 3 Flashcards
where are the adrenal glands located?
a pair of small, triangular-shaped glands located on top of each kidney.
What are the functions of the hormones released by the adrenal glands?
Control
- Blood pressure
- Metabolism
- Stress response: The adrenal glands produce hormones that help the body respond to stress, such as adrenaline and noradrenaline. This is known as the “fight-or-flight” response.
- Salt and water balance
- Sex characteristics
- Immune system
what are the 2 parts of the adrenal glands?
the adrenal cortex and the adrenal medulla.
The adrenal cortex is subdivided into what 3 parts?
- Zona glomerulosa
○ Produces mineralocorticoids (e.g. aldosterone) - Zona fasciculata
○ Produces glucocorticoids (e.g. cortisol) - Zona reticularis
Produces androgens
What does the adrenal medulla produce?
- adrenaline and noradrenaline
what produces aldosterone?
the zona glomerulosa of the adrenal cortex
what is the function of aldosterone?
Salt and water regulation
- stimulates sodium reabsorption in the distal convoluted tubule of the kidney in exchange for potassium and hydrogen
- increases water reabsorption due to sodium reabsorptiion
Helps to control blood pressure
what hormone helps regulate blood pressure by balancing sodium and potassium levels in the blood?
aldesterone
how is aldosterone regulated?
- low blood volume stimulates the release of angiotensin II
- angiotensin II stimulates the adrenal cortex the produce aldosterone
- aldosterone has a number of different actions including Na reabsorption, H20 reabsorption, K excretion
- aldosterone, therefore, causes a net increase in blood volume
- increased blood volume inhibits the production of angiotension II via negative feedback
What drugs can be used to inhibit aldosterone to reduce high blood pressure?
ACE inhibitors (angiotensin-converting enzyme inhibitors) - inhibit angiotensin II
AT2 blockers (angiotension II receptor blockers)
what primary hormone is responsible for controlling your bodys response to stress
cortisol
What converts angiotensin into angiotensin I?
+ what organ releases this?
Renin released from the the kidney converts angiotensin
What stimulates the kidneys to release renin?
A drop in blood pressure/drop in fluid volume
What organ releases ACE (angiotensin-converting enzyme) to convert angiotensin I to angiotensin II?
The lungs
What organ releases aldesterone?
The adrenal glands
What organ does aldesterone act on to stimulate the reabsorption of NaCl and H20 (salt and water)
The kidneys
When do we have higher levels of cortisol?
highest in the morning and lowest at night
Where is cortisol produced?
In the zona fasciculata of the adrenal cortex
What are the physiological steroid effects of cortisol?
- Antagonist to insulin, raises blood glucose levels by inhibiting glucose uptake in the tissues and stimulating glucose production. Stimulates gluconeogenesis
- lowers immune reactivity (reduces inflammation and immune response)
- raises BP
- inhibits bone formation
How is cortisol regulated in the body?
- CRH (corticotropin-releasing hormone) is secreted by the hypothalamus (influenced by stress, time of day, and serum cortisol levels)
- CRH travels in the blood and binds to receptors on the pituitary gland - this increases the production of adrenocorticotropic hormone (ACTH)
- ACTH released into the blood stream, travels to the adrenal gland, where it binds to a receptor on the adrenal cortex
- stimulates the release of cortisol into blood stream where it has wide ranging effects
- increasing cortisol inhibits production of CRH and ACTH
what is the purpose of steroid medication?
Enhanced glucocorticoid effect
- immunosuppression
- anti-inflammatory
enhanced mineralocorticoid effect
- salt and water retention
- hypertension
What is cushing’s syndrome?
a condition caused by having excess glucocorticoid (cortisol)
What are the different types of cushing’s syndome?
- ACTH driven cushing’s syndome - (e.g. ACTH-secreting pituitary adenoma or ectopic ACTH secretion)
- ACTH independent cushing’s syndrome (e.g. adrenal adenoma, adrenal carcinoma, iatrogenic cushing’s syndrome (this is a result of long term corticosteroid therapy)
- Pseudo-cushings syndrome
what is the difference between cushing’s disease and cushing’s syndrome?
Cushing’s disease is a specific type of cushing’s syndrome caused by a benign tumour in the pituitary gland that produces too much ACTH = excess cortisol
Whereas cushing syndrome is a set of symptoms caused by prolonged exposure to high levels of cortisol. This can be caused by a number of things.
