1. The Endocrine System The Endocrine System Homeostasis Hormones Regulation of Metabolism Regulation of Metabolism Regulation of Glucose Regulation of Glucose Regulation of Water Regulation of Water General Adaptation Syndrome General Adaptation Syndrome Fight or Flight Responses Fight or Flight Responses

2. Homeostasis Homeostasis is the sum of all processes that attempt to maintain a steady internal state within an organismHomeostasis is the sum of all processes that attempt to maintain a steady internal state within an organism Homeostasis is accomplished through the use of receptors, a control centre, effectors and negative feedbackHomeostasis is accomplished through the use of receptors, a control centre, effectors and negative feedbackHomeostasis The nervous and endocrine systems work together to help maintain homeostasisThe nervous and endocrine systems work together to help maintain homeostasis

3. Hormones Hormones A hormone is a chemical secreted by cells that affect cells in other parts of the bodyA hormone is a chemical secreted by cells that affect cells in other parts of the bodyhormone Hormones are distributed by the circulatory systemHormones are distributed by the circulatory system Hormones have effects on target tissuesHormones have effects on target tissues There are two types of hormones:There are two types of hormones: 1.Steroid Hormones Steroid HormonesSteroid Hormones 2.Protein Hormones Protein HormonesProtein Hormones

4. Hormones Hormones Hormones are secreted by endocrine glandsHormones are secreted by endocrine glandsendocrine glandsendocrine glands An endocrine gland is a group of tissues that secrete hormones into the blood which carries them to the target tissuesAn endocrine gland is a group of tissues that secrete hormones into the blood which carries them to the target tissuesendocrine gland endocrine gland An exocrine gland is a group of tissues that secrete enzymes or other products directly to their target tissuesAn exocrine gland is a group of tissues that secrete enzymes or other products directly to their target tissuesexocrine gland exocrine gland The hypothalamus controls the activity of the pituitary glandThe hypothalamus controls the activity of the pituitary glandhypothalamus

5. Fight or Flight Responses Fight or Flight Responses In a stressful situation the adrenal gland secretes adrenalin and noradrenalin to initiate fight or flight responsesIn a stressful situation the adrenal gland secretes adrenalin and noradrenalin to initiate fight or flight responses Fight or flight responses are processes that enable the body to confront or avoid the stressFight or flight responses are processes that enable the body to confront or avoid the stress

6. Regulation of Metabolism Regulation of Metabolism The rate of metabolism is controlled by the pituitary gland and the thyroid glandThe rate of metabolism is controlled by the pituitary gland and the thyroid gland The hormone thyroxin directly controls the metabolic rate of cellsThe hormone thyroxin directly controls the metabolic rate of cells A feedback mechanism ensures that metabolic rate stays consistent by varying thyroxin levels in the blood A feedback mechanism ensures that metabolic rate stays consistent by varying thyroxin levels in the bloodfeedback mechanismfeedback mechanism

7. Regulation of Metabolism Regulation of Metabolism Hypothyroidism occurs when the thyroid gland makes not enough thyroxinHypothyroidism occurs when the thyroid gland makes not enough thyroxin Hyperthyroidism occurs when the thyroid gland maeks too much thyoxinHyperthyroidism occurs when the thyroid gland maeks too much thyoxinHyperthyroidism

8. Regulation of Glucose Regulation of Glucose The concentration of glucose in the blood is carefully regulatedThe concentration of glucose in the blood is carefully regulated Hyperglycemia: blood sugar too highHyperglycemia: blood sugar too highHyperglycemia Hypoglycemia: blood sugar too lowHypoglycemia: blood sugar too lowHypoglycemia When blood glucose levels are high the beta cells of the islets of langerhans of the pancreas secrete insulinWhen blood glucose levels are high the beta cells of the islets of langerhans of the pancreas secrete insulinislets of langerhans islets of langerhans

9. Regulation of Glucose Regulation of Glucose Insulin lowers blood glucose concentration by: Insulin lowers blood glucose concentration by: 1.Making cells more permeable to glucose 2.Causing liver and muscle cells to convert glucose to glycogen 3.Converts sugar to fat for storage 4.Facilitates cellular respiration in muscles

10. Regulation of Glucose Regulation of Glucose When blood glucose levels are low the alpha cells of the islets of langerhans of the pancreas secrete glucagon When blood glucose levels are low the alpha cells of the islets of langerhans of the pancreas secrete glucagonislets of langerhans islets of langerhans Glucagon raises blood glucose concentration by converting glycogen to glucoseGlucagon raises blood glucose concentration by converting glycogen to glucoseGlucagon The inability to properly control blood glucose concentration is called diabetes mellitusThe inability to properly control blood glucose concentration is called diabetes mellitusdiabetes mellitusdiabetes mellitus

11. Regulation of Glucose Regulation of Glucose There are three type of diabetes mellitus There are three type of diabetes mellitus 1.Type I: beta cells lack the ability to produce insulin Type IType I 2.Type II: beta cells produce insulin but body cells do not respond Type IIType II 3.Gestational: temporary form of diabetes that can occur during pregnancy Gestational

12. Regulation of Glucose Regulation of Glucose Other hormones that influence blood glucose concentration are Other hormones that influence blood glucose concentration are 1.Thyroxine: decreases blood glucose by increasing glucose usage for metabolism by cells 2.Adrenalin: increases blood glucose levels by rapidly converting glycogen to glucose in times of stress 3.Cortisol: increase blood glucose by converting protein to glucose

13. Regulation of Water Regulation of Water The concentration of water in the blood is carefully regulated by the kidneyThe concentration of water in the blood is carefully regulated by the kidneykidney Too much water in the blood raises blood pressureToo much water in the blood raises blood pressure Too little water in the blood lowers blood pressureToo little water in the blood lowers blood pressure

14. Regulation of Water Regulation of Water There are three chemical systems that affect water balanceThere are three chemical systems that affect water balance 1.Antidiuretic Hormone: retains water by increasing collecting duct permeability Antidiuretic HormoneAntidiuretic Hormone 2.Diuretics: remove water from the blood by inhibiting ADH production Diuretics 3.Aldosterone: retains water by increasing sodium concentration of the blood and kidney Aldosterone

15. General Adaptation Syndrome General Adaptation Syndrome The general adaptation syndrome is a model of how humans respond to repeated stressThe general adaptation syndrome is a model of how humans respond to repeated stressgeneral adaptation syndromegeneral adaptation syndrome The model consists of three stages The model consists of three stages 1.Alarm: Resistance to the stress is low so the adrenal gland secretes adrenalin to initiate fight or flight responses 2.Resistance: if the stress is not overwhelming the alarm response weakens 3.Exhaustion: if the stress persists the alarm response returns and stress related disease results