Endocrinology Anatomy Flashcards
What is the anatomical position of the adrenal glands?
Superiomedially between the superior pole of the kidney and the crus of the diaphragm
What is the embryological origin of the cortex?
Mesoderm (similar to the gonads)
What is the embryological origin of the medulla?
Ectoderm (similar to the SNS)
What does the adrenal cortex secrete?
Steroid hormones
Mineralocorticoids (aldosterone)- electrolyte and fluid homeostasis
Glucocorticoids (cortisol) - CHO, protein, and lipid metabolism
Sex hormones - testosterone and oestrogen
What does the adrenal medulla secrete?
Catecholamines: (nor)adrenaline
What regulates glucocorticoid secretion?
Anterior pituitary adrenocorticotropic hormone (ACTH)
What regulates mineralocorticoid secretion?
RAAS and [K]plasma
What regulates secretion of medullary catecholamines?
SNS
Chromaffin cells
Thorcacic splanchnic nerves
Coeliac Plexus
What the the two layers of the adrenal gland?
Outer cortex
Inner Medulla
What invests the adrenal gland?
Dense fibrous capsule
What are the 3 layers of the adrenal cortex and what are their functions?
Remember GFR
- Zona Glomerulosa: large amounts of sER and mito; secretes mineralcorticoid hormones (aldosterone) controlled by RAAS and [K]plasma, RAAS is regulated by the macula densa
- Zona Fasciculate: middle and broadest; cytoplasm rich in sER, mito, and lipids; secretes glucocorticoids (cortisol); Also secretes sex hormones
Zona Reticularis: inner most; fewer lipid droplets; secretes small quantities of androgens and glucocorticoids
How is aldosterone release triggered?
- Decreased arterial pressure
- Decreased GFR
- Decreased macula densa NaCl
- Increased renin production
- RAAS pathway
Where, in the kidney, does aldosterone act on?
Renal tubules
Increases Na+ and H2O retention
In turn increasing ECF volume and arterial BP
Can aldosterone secretion be triggered by ACTH?
No
What controls cortisol secretion?
Hypothalamus (CRH) –> Anterior Pituitary (ACTH) –> Adrenal Cortex (Cortisol)
Hypothalamus stimulus: stress, time of day, illness
What is the medulla composed of?
Closely packed clusters of secretory cells
What does the medulla secrete?
Catecholamines: (nor)adrenaline
What forms the endocrine pancreas?
Islets of Langerhans
Where are the islet of Langerhans found?
Scattered throughout the exocrine glandular tissue
Vary in size
MOST NUMEROUS in tail of pancreas
What cells comprise the endocrine pancreas?
B-cells (70%) - secrete insulin in response to hyperglycaemia –> Promotes glucose uptake by GLUT4
A-cells (25%) - secretes glucagon –> respond to hypoglycaemia
D-cells (4%) - secrete somatostatin –> GI Function + inhibit alpha and beta-secretion
PP-cells (1%) - secrete polypeptide hormone
What kind of hormone is insulin?
Peptide
Where is insulin synthesised?
Describe the pathway
- b-cells of pancreas
- at eER as preproinsulin
- preproinsulin is cleaved to form proinsulin
- proinsulin is then cleaved at the Golgi to form insulin
- insulin is then packages in vesicles and remains in the cytoplasm for secretion
Where does the pancreas lie?
Retroperitoneal
Transversely across the posterior abdominal wall
Posterior to the stomach
Between the duodenum on the right and the spleen on the left
What lies on the anterior margin of the pancreas?
Root of the transverse mesocolon