Chapter: 3 Movement in & out of Cells

Adrenaline

• There are two adrenal glands, one above each kidney.
• They make a hormone called adrenaline.
• When you are frightened , excited or keyed up , your brain sends impulses along a nerve to your adrenal glands.
• This makes them secrete adrenaline into the blood.
• Adrenaline has several effects which are designed to help you to cope with danger.
• These effects are known as the fight or flight response.
• For example , your heart beats faster, supplying oxygen to your brain and muscles more quickly.
• This allows your muscles to carry out aerobic respiration more quickly, giving them more energy for fighting or running away. Your breathing rate increases, so that more oxygen can enter the blood in the lungs.
• Adrenaline also causes the pupils in the eye to widen.
• This allows more light into the eye, which might help you to see the danger more clearly.
• Adrenaline causes the liver to release glucose into the blood.
• This extra glucose for the muscles, along with the extra oxygen provided by the increased breathing rate and heart rate, allows the muscles to increase their metabolic activity.

Ziad ahmed – IGCSE-AS-A-Level-IB Biology Teacher WhatsApp: [phone]

Ziad ahmed – IGCSE-AS-A-Level-IB Biology Teacher WhatsApp: [phone]