Adrenal Function Flashcards
Wher are the adrenal glands located?
The adrenal glands are located abouve the kidneys, if either adrenal gland is removed, the other will double in size.
Name the two distinct parts of the adrenal gland
1) The outer cortex
2) The inner medulla
The cortex can be further subdivided into the….
Outer cortex - Zona glomerulosa cells are fund here
Inner cortex - Zona fasciculata and Zona Reticularis cells are found here
Describe the Zona Fasciculata
Zona Fasciculata consists of steroid hormone secreting cells that make steroid hormones.
Describe the Zona Reticularis
The Zona Reticularis cells are responsible for producing androgen hormones, such as DHEA and androstenedione.
Describe the cells found in the adrenal medulla - what hormones are found here?
The cells found in the adrenal medulla contain modified ganglion cells which are similar to modified nerve cells. They look completely different to the cells in the Zona Fasciculata that produce cortisol. Noradrenaline and adrenline are found here in vesicles to stimulate the sympathetic nervous system.
Describe the histology of the cells in the adrenal glands.
Outer capsule
Youngest - Glomerulosa matures to form the Fasciculate matures to form the Reticularis which matures to form the modified ganglion cells in the inner medulla.
State the intermediates when forming steroid hormones. For each intermediate, state the number of carbon atoms in each intermediate
Cholesterol (C27) —–> Pregnane derivatives such as progesterone, and corticoid derivatives (C21) —-> Androgens such as DHEA and androstenedione(C19) —-> Oestrogen derivatives (C18)
Describe the role of Aldosterone (ADST). Mention the site of synthesis, classification of the hormone function and the MOA
Site of synthesis: Zona Glomerulosa
Classification of the hormone: Mineralocorticoid
Function: Controls the balance of electrolytes to maintain homeostasis
MOA: ADST targets renal tubules, more K+ excreted, more Na+ reabsorbed —-> more water reabsorbed ————–> Higher BP. ADST release regulated by RAAS.
State the following about cortisol:
a) The site of synthesis
b) Classification of the hormone
c) Stimulus the body responds to
d) Effects on the body
A) Synthesised in the Zona Fasciculata in the Inner cortex
B) Glucocorticoid
C) Stress
D) Metabolism - increase glucose metabolism and protein catabolism, cardiovascualr system- increase blood flow for more 02 consumption and suppressing the inflammatory and immune system responses.
Describe the roles of androgens
They are responsible for the secondary sexual characteristics at pubety. They may be involved in preventing degenerate changes in ageing.
Describe the MOA of Aldosterone
Renin is an enzyme that is converts Angiotensinogen-Ag1. Ag1 is then converted to Ag2 by ACE. Ag2 acts on the zona glomerulosa cells where Ag2 receptors are found. Stimulation results in Alodsterone rlease which has a drirect effect on renal tubules. This promotes K+ excretion and Na+ reabsorption. Water follows Na+ —-> BP higher and aldosterone secretion stops when K+ is too low.
Describe the synthesis from the hypothalamus to Cortisol and its MOA
Hypothalamus sends CRH to the anterior pituitary. Corticotrophs release ACTH to the zona fasciculata in the adrenal cortex. The Zona Fasciculata releases cortisol into the blood. Cortisol has 3 main actions:
1) Increase protein catabolism + glucose production via gluconeogenesis, 2) Increase blood flow for more 02 and 3) reduces inflammation and the immune system responses.
Name and describe two adrenal deficiencies
1) Congenital adrenal hyperplasia - defiency of particular enzymes. There are no cholesterol converting enzymes, so they do not undergo sexual differentiation- possibly from birth defects.
2) Addison’s disease - bacterial infections like TB forming cysts in the adrenal glands or from autoimmune destrcution —> destroyed adrenals
Name and describe a condition where there are adrenal exesses
1) Cushing’s syndrome - the body produces excess cortisol possibly from tumours —> too much CRH or ACTH.
