Hormones Objectives: *Define hormone and state the role of adrenalin in controlling body metabolism ** Compare nervous and endocrine system ***Discuss the use of hormones in food production

The role of hormones in our body Hormones are chemicals produced in endocrine glands and released straight into the blood stream rather than into a duct. They then travel around the body in the blood to the target organs or tissues which recognise and respond to them. Hormones coordinate the activities of the body differently from nervous system. Once they have performed their function they are broken down by liver

Hormone controls. Hormones control: Growth Sexual development Sugar levels ( Homeostasis) Mood Metabolism Can you think of any problems that can be caused by these not working?

Endocrine glands. 2)Pituitary gland Secretes ADH which control the water balance in the body 3)Thyroid gland The thyroid gland in our neck makes a hormone called thyroxine.This regulates the rate of metabolism. Too little the chemical reactions are too slow 5)Adrenal gland makes adrenaline when you are frightened or angry it helps your body cope with an emergency 6)Pancreas makes insulin and glucagon insulin lowers blood sugar concentration and glucagon increases it) 7)Ovary makes oestrogen and progesterone in female. They control menstrual cycle and stimulate development of secondary sexual features during puberty 8)Testis makes testosterone in males and stimulate development of testes and secondary sexual features during puberty

Adrenaline Adrenaline stimulates: Liver cells to convert glycogen to glucose which diffuses into the blood. This means more glucose to muscles for contraction needed for sudden action. Increase in heart rateso more glucose and oxygen is delivered to muscles for energy release Dilation of the airways so more air reaches the alveoli in the lungs for more gas exchange Vasodilation of arterioles in brains and muscles so more glucose and oxygen is delivered to them Vasoconstriction of arterioles in the gut and other organs allowing blood to be diverted to the muscles

Comparing Endocrine and nervous System FeatureNervous systemEndocrine system StructuresnervesGlands containing secretory cells Forms of informationElectrical impulseHormones (chemicals) pathwaysAlong neuronesIn the blood Speed of information transferFastSlow although response to adrenaline is rapid Duration of effectsShort eg. Muscle contract for a short time Long lasting Target areaLocalised – only the area immediately at the end of a neurone Whole tissue or organs or even the whole body ResponseMuscle contraction or secretion by gland Many responses as conversion of glucose to glycogen, protein synthesis, rate of respiration

Hormones in food production BST ( Bovine somatotropin ) is a protein hormone produced by cows. The dairy cows if given extra quantities of these hormone produce more milk. Farmers use this hormone to increase milk yield to make more profit and also it keep their costs down by having less number of cows. Hormones are also used to increase growth. The problems Some are concerned about drinking milk from treated cows as a tiny quantity get into milk which is harmless and digested into amino acids in the gut Cows can become infertile after the treatment Most likely to get mastitis ( an inflammation of the udder) due to abnormally large quantities of milk produced. There is a surplus of milk in some parts of the world. So EU imposed a quota but with increased demand from India and China this is now scrapped. They have banned use of BST so has New Zealand but USA still uses it.

Quick Quiz - hormones 1.How do hormones move around the body? 2.What is the meaning of “target organ”? 3.List 3 endocrine glands. 4.Where is urine produced? 5.What is the chemical name and symbol for common salt? 6.Why are marathon runners in danger of loosing too much salt?

The role of hormones in our body HormoneEndocrine gland Target Organ Effect Insulin Glucagon Thyroxine ADH