CHAPTER 50 Endocrine Systems. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

CHAPTER 50 Endocrine Systems Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Endocrine system All the endocrine glands and other organs with hormonesecreting cells Figure 50.1 Hypothalamus Anterior pituitary gland Posterior pituitary gland Heart Adrenal glands (medulla and cortex) Medulla (not visible) Pineal Parathyroids Cortex Thyroid Different organs and glands secrete Liver and kidneys different types of hormones Stomach and small intestine Pancreas Ovaries (in females) Adipose tissue Testes (in males)

Endocrine system Hormones - chemical signals produced by endocrine cells -travel through the blood stream and act on their target cells hormone Target cells Endocrine cells

Endocrine system Hormones - chemical signals produced by endocrine cells -travel through the blood stream and act on their target cells 3 types of hormones Amines Proteins/peptides : water soluble (except thyroid hormone) => unable to cross plasma membrane => signal through cell surface receptor Amines or proteins/peptide

Endocrine system Hormones - chemical signals produced by endocrine cells 3 types of hormones Amines Steroids -travel through the blood stream and act on their target cells Proteins/peptides : water soluble (except thyroid hormone) => unable to cross plasma membrane => signal through cell surface receptor : lipid soluble => cross plasma membrane => bind to either cytosolic or nuclear receptor

Endocrine system Hormones - chemical signals produced by endocrine cells -travel through the blood stream and act on their target cells Function in - Metabolism - Mineral Balance - Growth and Differentiation - Reproduction - Response to stress

Endocrine system Only cells having the proper receptors can respond to a hormone Hormones activate only specific cells Hormone interacts noncovalently and reversibly with the receptor Prevents cell from being permanently stimulated 8

Endocrine system

Link between Endocrine system and Nerve system Hypothalamus ( ) Pituitary ( ) Hypothalamus Hypothalamic nuclei 1) make neurohormones Infundibular stalk Arterial blood supply Anterior pituitary gland 2) Neurohormones are released from axon of hypothalamic neurons into capillaries Capillaries Portal veins Posterior pituitary gland 3) Travel through portal vein to anterior pituitary gland To venous circulation

Link between Endocrine system and Nerve system Hypothalamus (시상하부) Pituitary (뇌하수체) Hypothalamus Hypothalamic nuclei 1) make neurohormones 2) Neurones secrete neurohormones into capillaries Infundibular stalk Arterial blood supply Capillaries Anterior pituitary gland Posterior pituitary gland 3) Travel through portal vein to anterior pituitary gland neurohormones Portal veins To venous circulation 4) Anterior pituitary gland synthesize several hormones 5) Secrete into the circulation hormones

Hormonal Control of Metabolism and Energy Balance e.g., Thyroid hormone ( ) Increase Glucose metabolism Increase in heat production

Hormonal Control of Metabolism and Energy Balance e.g., Thyroid hormone (갑상선 호르몬) Fig 50.6 Hypothalamus T4 and T3 inhibit TRH secretion as well as expression of TRH precursor - TRH Anterior pituitary gland TSH Thyroid negative feedback Normal levels of T4 and T3 1) TRH (thyrotropin -releasing hormone) Is released from hypothalamus 2) TSH (thyroid-stimulating hormone) Is released from anterior pituitary gland 3) T4 and T3 (thyroid hormones) is released from thyroid Keeping balance 14

Hypothyroidism Diseases caused by too little or too much Thyroid Hormone 15

Diseases caused by too little or too much Thyroid Hormone Fig 50.6 Hypothyroidism :Low T3, T4 Hypothalamus T4 and T3 inhibit TRH secretion as well as expression of TRH precursor - TRH Anterior pituitary gland TSH Thyroid negative feedback Normal levels of T4 and T3 1) Decrease in TSH (thyroid-stimulating hormone) 2) Decrease in T4 and T3 (thyroid hormones) -most common cause of hypothyroidism => Weight gain, sensation of coldness Keeping balance 16

Diseases caused by too little or too much Thyroid Hormone Hypothyroidism e.g., Hashimoto s thyroiditis :autoimmune disease Hypothalamus T4 and T3 inhibit TRH secretion as well as expression of TRH precursor - TRH Anterior pituitary gland Increase in TSH (thyroid-stimulating hormone) Promote the abnormal growth of thyroid : Goiter TSH Thyroid negative feedback Normal levels of T4 and T3 Thyroid cells are destroyed by immune cells => Decrease in T4 and T3 (thyroid hormones) Fig 50.6 17

Diseases caused by too little or too much Thyroid Hormone Hyperthyroidism (overactive thyroid gland) Graves disease: - autoimmune disease -caused by hyperthyroidism Causes: Production of antibodies against TSH receptor present on Thyroid follicular cells => constitutively active receptor (TSH receptor is always active) => Excessive production of T3 T4 => weight loss, heat intolerance Protruding eyeballs

Diseases caused by too little or too much Thyroid Hormone Diet can affect production of thyroid hormone : Iodine is required for T4, T3 production Hypothalamus 4)Excess TRH 6)Enlarged thyroid Anterior pituitary gland 5)Excess TSH & overstimulation of thyroid Thyroid 2) Low T4 and T3 due to lack of iodine 3) Reduced negative feedback 1) Reduced iodine intake 19

Glucose Homeostasis Two hormones involved in Glc Homeostasis glucagon Insulin =>Produced in pancreas Small intestine Pancreas Pancreatic islets of Langerhans :spherical clusters of endocrine cells Alpha cells produce glucagon Beta cells produce insulin

Glucose Homeostasis Homeostasis : body s tendency to maintain relatively constant internal condition

Glucose Homeostasis 2) Stimulate secretion of insulin from Pancreas 1) Glucose level Increases above normal (eating) 3) insulin stimulate glucose uptake into cells (mainly in adipose or skeletal muscle Cells) Normal blood glucose level

Glucose Homeostasis 2) Stimulate secretion of insulin from Pancreas 3) insulin stimulate glucose uptake into cells (mainly in adipose or skeletal muscle Cells- express glucose transporter GLUT ) Most of GLUTs are located membrane bound vesicles inside the cells And only a few are present in plasms membrane. 1) Glucose level Increases above normal (eating) Without insulin Glucose molecule GLUT (glucose transporter) Insulin receptor

Glucose Homeostasis 4)Blood glucose level increases. Normal blood glucose level 1) Glucose level decreases above normal (fasting) 3) High Glucagon Liver Glycogen Glucose 3)Glucagon stimulates glycogenolysis Noncarbo hydrates 2) glucose-monitoring regions in the hypothalamus stimulate production of glucagon from Pancreas Gluconeogenesis (generation of Glc) Glucose

Glucose Homeostasis Insulin from pancreas Blood glucose level increases. When blood glucose level increases. Normal blood glucose level Blood glucose level decreases. When blood glucose level decreases. Glucagon from pancreas

Glucose Homeostasis Insulin from pancreas Blood glucose level increases. When blood glucose level increases. Normal blood glucose level What happens if this system doesn t work? Blood glucose level decreases. When blood glucose level decreases. Glucagon from pancreas

Diabetes Type 1 Diabetes mellitus (T1DM) Type 2 Diabetes mellitus (T2DM)

Diabetes Type 1 Diabetes mellitus (T1DM) Autoimmune disease where immune system destroyes beta cells => can not produce insulin when blood glc increases => no insulin production => accumulation of Glc in blood Also called juvenile diabetes (usually diagnosed in children and Young adults) Treated by administration of insulin

Diabetes Type 1 Diabetes mellitus (T1DM)

Diabetes Type 2 Diabetes mellitus (T2DM) Most common form of diabetes 1) Pancreas do not produce enough insulin (but not by the attack of immune cells) 2) cells of the body lose much of their ability to respond to insulin Insulin resistance Constant high blood Glc level 1) Insulin can t signal to Glucose transporter 2) Diminished Glc uptake

Diabetes Type 2 Diabetes mellitus (T2DM) Many life style factors are important in development of Type 2 diabetes : High level of Physical activity Healthy diet Keeping normal weight no smoking => 89% lower chance to get type II diabetes Obesity is cause for over than 1/2 of type II diabetes

Diabetes Type 2 Diabetes mellitus (T2DM)

Control of growth and differentiation anterior pituitary Produces Growth hormone (GH) Gonadal hormone : seal growth plate ( ) Liver Produces IGF1 (insulin like growth factor-1) Elongation of bones during puberty

Control of growth and differentiation When a person develop a tumor causing the production of excessive GH during childhood -> becomes very tall -> Pituitary giant If a person develop a tumor causing the production of excessive GH after puberty, -> develops a condition called Acromegaly (enlargement and thickening of feet and hands) 2

Control of growth and differentiation low amount of GH produced => Short stature Can be treated by injection of GH e.g, Lionel (Leo) Messi 3

Stress Hormone Hypothalamus Stress Anterior pitutiary Secete Releasing factor ACTH released into blood Acute stress (Table 50.3) Adrenal cortex 1. Increase heart rate to maximize blood pumping 2. Maximize oxygen intake 3. Increase production of glucose to provide energy to muscle cells 4. Increase alertness Cortisol (a member of glucocorticoids) 4

Stress Hormone Hypothalamus Stress Anterior pitutiary Secete Releasing factor Adrenal cortex ACTH released into dlood Cortisol (a member of glucocorticoids) Exposure to Chronic stress 1. Lower immune systems 2. Slow down thinking 3. Create blood sugar imbalances 4. Raise your blood pressure 5. Weaken muscle tissue 6. Decrease bone density 7. Craving for sweets and carbohydrates 8. Increase fat to stomach areas 5