1. Adrenal Glands
- Adrenal Gland is divided into two regions
- Cortex, Outer region - produces Steroid Hormones
- Medulla, Inner region - produces Amine Hormones
- Cortex divided into morphologically distinct outer, middle and inner regions
- Each produces a different set of hormones
Medullary Hormones
- Tyrosine-based Hormones
- Mainly Catecholamines
- Epinephrine (Adrenaline)
- Norepinephrine (Noradrenaline)
- Stress Response
- Fight Or Flight - by modulating metabolism and cardiac function
Catecholamines: Adrenaline and Noradrenaline
- Secreted by Chromaffin Cells (Modified postganglionic nerve cells)
- Secrete ~80% Adrenaline and ~20% Noradrenaline
- Directly activated by Sympathetic Nerves of Autonomic Nervous System
- Stress situations or sympathetic activity at the Adrenals cause the release of Catecholamines, leading to:
- Increased BP$\uparrow$
- Dilated airways
- Increased respiratory rate$\uparrow$
- Increased blood glucose level$\uparrow$
- Increased metabolic rate$\uparrow$
- Reinforce sympathetic Fight Or Flight response, but last longer
Cortical Hormones
- Adrenal Cortex is further divided:
- Zona Reticularis (R), Inner region - produces Androgen
- Sex hormones, important during puberty
- Zona Fasciculata (F), Middle region - produces Cortisol
- Function is in relation to stress, immune system development and organic metabolism
- Zona Glomerulosa (G), Outer region - produces Aldosterone
- Cat-ion excretion in the kidney and extracellular water balance
Androgens
- Production rises in late childhood in both sexes and is thought to play a role in the onset of puberty
- In young people contributes to pubic hair growth and pre-puberty growth spurt
- In male, negligible contribution compared to Androgens produces in testes
- In female contributes to Libido 性欲
- Converted to Oestrogens by other tissues
- After Menopause(when Ovarian Oestrogen production stops), all Oestrogen comes from Adrenal Androgen conversion
Control
Aldosterone