Hormones and The Excretory System

• ADH : controls water intake
• Thyroxine : growth and metabilism
• Adrenaline : increases and speeds reactions
• Insulin : controls blood glucose levels
• Oestrogen and Progesterone : controls eggs and uterus lining
• Testosterone : controls hormone levels at a balanced level
• Pancreas : produces insulin
• The body’s response to hormones is slower than response to nerves
• Homeostasis : the process of maintaining a constant internal environment
• Osmoregulation : a process which controls water content in the body
• Glucose is needed for respiration to occur
• After a meal containing glucose, it is absorbed across the ileum wall, into the bloodstream
• Insulin acts to reduce blood sugar by allowing more glucose to be absorbed into the cells which leads to an increase in respiration in the liver. The glucose is then converted to glycogen for storage.
• When blood glucose falls, the pancreas secreted less insulin
• Negative Feedback : a mechanism which constantly monitors levels, in other words a sequence of events to bring it back to normal
• Diabetes : when the control mechanism fails and the pancreas does not produce enough insulin
• Symptoms of Diabetes : high blood glucose, thirst, frequent urination, sugar in urine, tiredness and sudden weight loss
• Diabetes is treated by injections of insulin and a controlled diet
• Long Term effects of Diabetes : stroke, eye damage, heart attack, kidney damage
• Type 1 Diabetes : This can not be prevented, it shows in young people and is caused because of genes. The pancreas stops producing insulin
• Type 2 Diabetes : shows in older adults, it is caused because of high cholesterol and an unhealthy lifestyle. It can be predicted if you have obesity or a high blood pressure. Less insulin is produced by the pancreas. It can be treated by exercising more frequently and dietary changes.
• Excretion : elimination of metabolic waste products and toxic materials produced by cells
• Osmoregulation : maintenance of the water content of the body
• Water can be brought into the body by respiration, drinking and eating
• Water can be lost by exhaled air, urine, sweat and faeces
• When blood reaches the cortex, most of the liquid in the blood is filtered out.
• In the medulla, water is reabsorbed back into the blood in a controlled way until normal concentration are reached
• ADH in Osmoregulation : the water balance of the blood is detected by the brain, ADH increases the reabsorption of water from the urine to the blood so more water is reabsorbed
• When more water is absorbed : the final urine is concentrated and low volume
• When less water is absorbed : the final urine is dilute and high volume
• Plants can detect and respond to light, chemicals, water and gravity
• Tropism : directional growth response of a plant to a stimulus
• Auxin : produced at the tip of the plant
• When a plant is hit by a stimulus (light), the auxin at the tip diffuses down the shoot and causes the plant cells to elongate. However, when undirectional light is present, the auxin diffuses down the the shoot on the shaded side. It causes elongation on the shaded side, causing uneven growth which therefore leads in growth towards the light
• Positively Phototropic : a part of a plant which grows toward light
• Negatively Phototropic : a part of a plant which grows away from light