L16 - Adrenal gland physiology Flashcards
Describe the histological zonation of the adrenal, starting from the outer capsule –> cortex –> medulla
- Zona glomerulosa - mineralocorticoids (aldosterone)
- Zona fasciculata - glucocorticoids (cortisol)
- Zona reticularis - Androgens (DHEA)
- Catecholamines
Describe the steroid hormones in adrenal insufficiency
- Glucocorticoid deficiency
- Mineralocorticoid deficiency
- Adrenal androgen deficiency
Describe the steroid hormones in Cushing’s syndrome
Glucocorticoid excess
Describe the steroid hormones in Conn’s syndrome
Mineralocorticoid excess
Describe the steroid hormones in Pharchromocytoma
Catecholamine excess
What is phaeochromocytoma?
- Rare tumour of adrenal gland tissue
- Release too much adrenaline or noradrenaline –> prod excess adrenaline
What conditions could result in an excess of steroid hormones from adrenal cortex/ medulla?
- Cushing’s syndrome
- Conn’s syndrome
- Phaeochromocytoma
- Adrenal tumours
- Congenital adrenal hyperplasia
What are corticosteroids?
- Lipid solible (therefore able to pass through biological memb)
- Bind to specific intracellular receptors
- Exact action depends on structure, ability to bind to specific receptors
- Alter gene transcription directly or indirectly
What are the actions of glucocorticoids?
ESSENTIAL TO LIFE
- Important in homeostasis
- Have actions on most tissues
- Many actions are permissive
- PERMISSIVE ACTIONS ONLY APPARENT WITH DEFICIENCY
What is a permissive action?
- Seen by glucocorticoids
- Do not directly initiate but allow to occur in presence of other factors
- PERMISSIVE ACTIONS ONLY APPARENT WITH DEFICIENCY
Give an example of a permissive action
The effects of catecholamines on vascular tone
What are the effects of excess glucocorticoids on the body tissues and systems?
- Glaucoma
- LH, FSH release
- TSH release
- Peptic ulcerations
- Promotes centreal obesity
- Salt and water retention
- Hypertension
- Skin thinning
- Muscular atrophy
- Bone formation
- Bone mass and osteoporosis
What are the actions of glucocorticoids?
- Inc glc mobilisation
- Augment gluconeogenesis
- aa generation
- Inc lipolysis - Maintenance of circulation
- Vascular tone
- Salt and water balance - Immunomodulation
- Dampen IR
What is gluconeogenesis?
Prod of new glc from non-CBH sources
- e.g. prod of glc by liver cells from glycerol, fatty acids, aa and lactate
What is glycogenolysis?
Hydrolysis of stored glycogen in skeletal muscle sand liver
