Transcript Chapter 15
Chapter 15 Hormones Objectives Students should be able to: – Define a hormone as a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver – Explain what is meant by a endocrine gland, with reference to the islets of Langerhans in the pancreas State the role of the hormone adrenaline in boosting blood glucose levels and give examples of situations in which this may occur Explain how the glucose concentration is regulated by insulin and glucagon as a homeostatic mechanism Describe the signs such as an increased blood glucose level and glucose in urine, and the treatment of diabetes mellitus using insulin Living with stress Butterflies in your stomach? Increase in pulse rate? Sweaty hands which feel cold and clammy? – Why? – Because we are nervous and our body is preparing for action Such symptoms are induced by the hormone ADRENALINE Adrenaline: – Increases the heart rate – Increases the rate of breathing – Causes vasoconstriction of the blood vessels around the intestine (why?) – Raises the metabolic rate? – Dilates the pupils 15.1 Hormones A hormone is a chemical substance produced in minute quantities by an endocrine gland. It is transported in the bloodstream to target organ(s) where it exerts its effects Hormones influence the growth, development and activity of an organism Some hormones also exercise control over other glands or muscles Where are hormones produced? Hormones are produced by glands Hormones are produced by ductless glands. This means that the hormones which the glands produce passes directly into the bloodstream which then distributes the hormones round the body Some glands are purely endocrine glands producing only hormones (e.g. adrenal gland produces only adrenaline) There are glands that produce both hormones and other secretions. Can you think of one? Hormones production must be balanced to ensure that body functions normally After hormones have performed their functions, they are eventually destroyed by the liver and excreted by the kidneys Chapter 15 Hormones Glands and Their Hormonal Secretions 18 July 2015 Glands and Their Hormonal Secretions Hypothalamus An endocrine gland that regulates the secretion of some pituitary hormones. Glands and Their Hormonal Secretions Hypothalamus Pituitary gland Plays an important role as a ‘controller’. It secretes a number of hormones, which control the functions of several other endocrine glands. This is why the pituitary gland is often referred to as the ‘master gland’. The pituitary gland also secretes antidiuretic hormone (ADH). An endocrine gland that regulates the secretion of some pituitary hormones. Glands and Their Hormonal Secretions Pituitary gland Plays an important role as a ‘controller’. It secretes a number of hormones, which control the functions of several other endocrine glands. This is why the pituitary gland is often referred to as the ‘master gland’. The pituitary gland also secretes antidiuretic hormone (ADH). Hypothalamus An endocrine gland that regulates the secretion of some pituitary hormones. Thyroid gland Secretes thyroxine. Thyroxine controls the rate of metabolism and influences physical development. Glands and Their Hormonal Secretions Pituitary gland Plays an important role as a ‘controller’. It secretes a number of hormones, which control the functions of several other endocrine glands. This is why the pituitary gland is often referred to as the ‘master gland’. The pituitary gland also secretes antidiuretic hormone (ADH). kidney Hypothalamus An endocrine gland that regulates the secretion of some pituitary hormones. Thyroid gland Secretes thyroxine. Thyroxine controls the rate of metabolism and influences physical development. Adrenal gland (medulla) Secretes adrenaline. Adrenaline has wideranging effects that prepare the body for ‘fight or flight’ situations. Glands and Their Hormonal Secretions Pituitary gland Plays an important role as a ‘controller’. It secretes a number of hormones, which control the functions of several other endocrine glands. This is why the pituitary gland is often referred to as the ‘master gland’. The pituitary gland also secretes antidiuretic hormone (ADH). kidney Hypothalamus An endocrine gland that regulates the secretion of some pituitary hormones. Thyroid gland Secretes thyroxine. Thyroxine controls the rate of metabolism and influences physical development. Adrenal gland (medulla) Secretes adrenaline. Adrenaline has wide-ranging effects that prepare the body for ‘fight or flight’ situations. Pancreas Islets of Langerhans in the pancreas secrete insulin and glucagon that regulate the blood glucose concentration. Glands and Their Hormonal Secretions Pituitary gland Plays an important role as a ‘controller’. It secretes a number of hormones, which control the functions of several other endocrine glands. This is why the pituitary gland is often referred to as the ‘master gland’. The pituitary gland also secretes antidiuretic hormone (ADH). kidney Ovaries (in females) Secretes oestrogen and progesterone. Hypothalamus An endocrine gland that regulates the secretion of some pituitary hormones. Thyroid gland Secretes thyroxine. Thyroxine controls the rate of metabolism and influences physical development. Adrenal gland (medulla) Secretes adrenaline. Adrenaline has wide-ranging effects that prepare the body for ‘fight or flight’ situations. Pancreas Islets of Langerhans in the pancreas secrete insulin and glucagon that regulate the blood glucose concentration. Glands and Their Hormonal Secretions Pituitary gland Plays an important role as a ‘controller’. It secretes a number of hormones, which control the functions of several other endocrine glands. This is why the pituitary gland is often referred to as the ‘master gland’. The pituitary gland also secretes antidiuretic hormone (ADH). kidney Ovaries (in females) Secretes oestrogen and progesterone. Testes (in males) Secretes testosterone. Hypothalamus An endocrine gland that regulates the secretion of some pituitary hormones. Thyroid gland Secretes thyroxine. Thyroxine controls the rate of metabolism and influences physical development. Adrenal gland (medulla) Secretes adrenaline. Adrenaline has wide-ranging effects that prepare the body for ‘fight or flight’ situations. Pancreas Islets of Langerhans in the pancreas secrete insulin and glucagon that regulate the blood glucose concentration. Chapter 15 Hormones How Adrenal Medulla Responds to Stimuli 18 July 2015 How Adrenal Medulla Responds to Stimuli 1 Stimuli Fear, anger, anxiety, stress, etc Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2015 20 How Adrenal Medulla Responds to Stimuli 2 1 Stimuli Receptor Hypothalamus stimulated Fear, anger, anxiety, stress, etc Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2015 21 How Adrenal Medulla Responds to Stimuli 2 1 Stimuli Receptor Hypothalamus stimulated Fear, anger, anxiety, stress, etc Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 3 sensory neurone Certain sensory neurones in the hypothalamus are activated 18 July 2015 22 How Adrenal Medulla Responds to Stimuli 2 1 3 Receptor Hypothalamus stimulated Stimuli sensory neurone 4 Fear, anger, anxiety, stress, etc Nerve impulses are transmitted to the spinal cord spinal cord Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2015 23 How Adrenal Medulla Responds to Stimuli 2 1 Stimuli Fear, anger, anxiety, stress, etc 3 Receptor Hypothalamus stimulated sensory neurone 4 5 Nerve spinal cord impulses leave the spinal cord to adrenal medulla Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. adrenal medulla 18 July 2015 24 How Adrenal Medulla Responds to Stimuli 2 1 Stimuli 3 Receptor Hypothalamus stimulated sensory neurone 4 Fear, anger, anxiety, stress, etc 5 spinal cord Adrenal medulla is stimulate, producing adrenaline. 6 adrenal medulla Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2015 25 How Adrenal Medulla Responds to Stimuli 2 1 3 Receptor Hypothalamus stimulated Stimuli sensory neurone 4 Fear, anger, anxiety, stress, etc 5 6 spinal cord adrenal medulla Adrenaline is carried in blood Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 7 18 July 2015 26 How Adrenal Medulla Responds to Stimuli 2 1 Stimuli 3 Receptor Hypothalamus stimulated sensory neurone 4 Fear, anger, anxiety, stress, etc 5 6 spinal cord adrenal medulla 8 Adrenaline reaches target organs in various parts of the body. It brings about short-term responses that prepare the body for ‘fight or flight’. Adrenaline is carried in blood Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 7 18 July 2015 27 Effects of adrenaline secretion Increases blood glucose levels by speeding up the breakdown of glycogen to glucose in the liver and muscles Increases metabolic rate (more energy released) Increases rate of heartbeat Constricts arteries in skin Causes pupils to dilate to enhance vision Contracts hair muscles producing ‘goose pimples’ Effects of Insulin Secreted by Islets of Langerhans in pancreas Secretion caused by an increase in concentration of blood glucose above the normal level Effect(s): – Decrease in blood glucose concentration by: Increasing the permeability of cell membranes to glucose thereby increasing the rate of glucose uptake by cells Causing the conversion of glucose to glycogen for storage in liver and muscles Causing an increased oxidation of glucose during tissue respiration – This leads to an overall increase in the utilization of glucose by cells Lack of secretion: – Glucose cannot be utilized by cells, some lost in urine => diabetes mellitus – Muscle cells no reserves of glycogen, body weakness flows and then loss of weight – Body oxidizes fats instead of glucose to produce energy resulting in poisonous substances formed Effects of Oversecretion – Abnormal decrease in blood sugar concentration – Shock HAPPENS – Coma and death may follow Diabetes mellitus A disease where the body is unable to control its blood glucose concentration so that it remains within normal limits. Kidneys unable to reabsorb all the glucose, hence some gets excreted in the urine 2 Types of diabetes: Type 1: – Juvenile diabetes. Inability of the pancreas to produce insulin Type 2: – Occurs later in life. Overweight people seem more prone to it. May be due to a decrease in the production of insulin by the pancreas or a failure of the target cells to respond well to it. Signs – Persistently high blood glucose level – Glucose in urine after a meal – Healing of wounds is slow or difficult Treatment – Measure blood glucose concentrations and test urine regularly – Watch their diet, take less carbohydrates – Inject insulin into veins (Type 1) – Control intake of carbohydrate (Type 2) Glucagon Produced by islets of Langerhans when the concentration of blood glucose decreases below the normal levels Target organ of glucagon is Liver Glucagon increases the blood glucose concentration by stimulating: – The conversion of glycogen into glucose – The conversion of fats and amino acids into glucose – The conversion of lactic acid into glucose Hormonal & Nervous Control Both serve as a means of co-ordination within the body There are differences between the 2 systems though: