Endocrine System Noadswood Science, 2016

Endocrine System To explain the functions of the endocrine system Saturday, April 14, 2018 Endocrine System To explain the functions of the endocrine system

Precise Learning Students should be able to describe the principles of hormonal coordination and control by the human endocrine system. The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream. The blood carries the hormone to a target organ where it produces an effect. Compared to the nervous system the effects are slower but act for longer. The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions. These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects. Students should be able to identify the position of the following on a diagram of the human body: pituitary gland pancreas thyroid adrenal gland ovary testes Students should be able to explain the roles of thyroxine and adrenaline in the body (higher tier only) Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’ (higher tier only) Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development (higher tier only) Thyroxine levels are controlled by negative feedback (higher tier only)

Hormones Hormones are chemical molecules released directly into the blood to regulate bodily processes (carried in blood plasma) affecting particular target organs Hormones are produced and secreted by various glands (endocrine glands) which make up the endocrine system

Glands Label the glands of the endocrine system

Target Organs The table shows the target organs and effects of the glands and hormones… Gland Hormone Target Organ Effect Adrenal gland Adrenalin Liver, heart etc… Fight or flight Ovary Oestrogen Progesterone Ovaries, uterus, pituitary gland Puberty, menstrual cycle Pancreas Insulin ADH (anti-diuretic hormone) Liver Kidney Blood sugar Water level control Pituitary gland FSH (follicle stimulating hormone) LH (luteinising hormone) Ovaries Egg maturation Egg release Testes Testosterone Male reproductive organs Puberty

Adrenaline Higher Tier

Adrenaline Higher Tier

Adrenaline Adrenaline is a hormone released by the adrenal glands (located above the kidneys) It is released in response to stressful or scary situations – the brain detects fear or stress and sends nervous impulses to the adrenal glands which secrete adrenaline Adrenaline prepares the body for a ‘fight or flight’ response by increasing oxygen and glucose to the cells in the brain and muscles Higher Tier

Thyroxine Thyroxine is a hormone released by the thyroid gland (found in the neck) It helps regulate basal metabolic rate as well as stimulating protein synthesis for growth and repair Thyroxine is released in response to thyroid stimulating hormone (TSH) which is released from the pituitary gland Higher Tier

Negative Feedback Levels of thyroxine can go above or below normal levels – this levels are brought back to their normal range by negative feedback Higher Tier

Negative Feedback When the level of thyroxine in the blood is too high secretion of thyroid stimulating hormone (TSH) is inhibited reducing the amount of thyroxine When the level of thyroxine in the blood is too low TSH starts up again and thyroxine levels increase Higher Tier

Practice Question Give two roles of thyroxine in the body Name the glands which release adrenaline What are hormones secreted from? Pierre is surprised when a dog jumps at him – his heart beats faster. Name the hormone causing this response and explain the purpose of it

Answers Give two roles of thyroxine in the body – regulating basal metabolic rate and stimulating protein for growth and development Name the glands which release adrenaline – adrenal glands What are hormones secreted from – endocrine glands Pierre is surprised when a dog jumps at him – his heart beats faster. Name the hormone causing this response and explain the purpose of it – adrenaline increases oxygen and glucose to cells ready for ‘fight or flight’