Adrenal Gland — the Emergency Hormone

What you do

• Name the two parts of the adrenal gland and one hormone from each.
• Say which cortical disorder follows hyposecretion of cortisone and which follows hypersecretion.
• Explain the dry mouth and thumping heart you feel before making a speech.

Challenges to clear

• Step through the whole emergency response.
• Reach the stage that explains why a frightened person turns pale.
• Raise the danger until adrenaline floods the blood.

The task

A fright arrives. Step through what adrenaline does to the body.

What this lesson covers

• Danger appears — A sudden fright, anger or emotional stress. Nerve endings of the autonomic nervous system stimulate the adrenal gland, which sits like a cap on the top of each kidney.
• Medulla releases adrenaline — The central medulla of the adrenal pours adrenaline into the blood. This is the emergency hormone, preparing the body to fight or to flee.
• Heart and breathing speed up — The heart beats faster and blood pressure rises, and breathing becomes faster and deeper, so more glucose and oxygen reach the muscles and carbon dioxide is removed quickly. You feel a thumping heart and you pant.
• Blood is redirected — The arterioles of the skin and of the digestive system constrict, so less blood goes to them and more is available to the muscles. The person turns pale and the mouth goes dry.
• Fuel is released — The liver converts glycogen into glucose and fat deposits are converted into fatty acids, putting energy into the blood for muscle contraction — like putting more fuel into the engine.
• Body ready for action — The muscles tense ready for immediate action, the pupil of the eye dilates and the clotting capacity of the blood increases. The final dash to win a race is under the influence of adrenaline.
• At rest only a trace of adrenaline circulates and the body stays calm.
• In real danger the medulla floods the blood with adrenaline, which is biologically active even at 1 part in 300,000,000.

Hint

Adrenaline comes from the MEDULLA, the inner part of the adrenal; the CORTEX, the outer part, makes the corticoids including cortisone. The effects hang together: more blood to the muscles means less to skin and gut, which is exactly why fright brings a pale face and a dry mouth.