12 The Endocrine System

Learning Outcomes Animal Organ-System and Its Functions: The ENDOCRINE System - STEM_BIO11/12- IVa-h-1 Give the functions of the Endocrine organ-system Identify the structures and functions of the Endocrine organs What are Hormones in the Body and their functions and evaluate how it works in the body Describe the Pathophysiology of the Endocrine System

(15 mins) Film Viewing https://www.youtube.com/watch?v=H2VkW9L5QSU   Buzz Session 1. What is the importance of the Endocrine System? 2. What is it made of? Structures and parts/functions? 3. What are Hormones in the Body and how does it work 4. What are disorders of the Endocrine system System? Describe.

Introduction The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood Regulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cells bloodstream to hormones into Glands secrete target tissues

Hormones Endocrine glands Ductless Release hormones Directly into target tissues Into bloodstream to be carried to target tissues Hormones – chemicals secreted by a cell that affect the functions of other cells

Hormones (cont.) Many are derived from steroids that easily cross the cell membrane Examples of steroidal hormones Estrogen Progesterone Testosterone Cortisol Hormones

Hormones (cont.) Nonsteroidal hormones Prostaglandins Made of amino acids or proteins and cannot cross the cell membrane easily Bind to receptors on the surface of the cells G-protein – activated by the hormone-receptor complex Activates enzymes inside cell Prostaglandins Local, or tissue, hormones Derived from lipid molecules Do not travel in the bloodstream Target tissues are located close by Produced by organs such as Kidneys Heart Stomach Uterus Brain

Feedback Loops Control hormone levels Negative feedback loop Hormone release stops in response to decrease in stimulus Stimulus (eating) raises blood glucose levels Pancreas releases insulin in response to elevated blood glucose Blood glucose decreases as it is used by the body or stored in the liver Insulin release stops as blood glucose levels normalize

Feedback Loops (cont.) Positive feedback loop As long as stimulus is present, action of hormone continues Infant nursing at mother’s breast  stimulates hypothalamus  stimulates posterior pituitary Oxytocin released  stimulates milk production and ejection from mammary glands Milk release continues as long as infant continues to nurse

Apply Your Knowledge VERY GOOD! ANSWER: Match the following: ___ Chemicals that effect cell function A. Nonsteroidal hormone ___ Easily cross cell membranes B. Steroidal hormone ___ Made of amino acids C. G-protein ___ Target nearby cells D. Prostaglandins ___ Activated by hormone-receptor E. Hormones complex ___ Cannot cross cell membranes easily ___ Estrogen and cortisol B A D C A B VERY GOOD!

Hypothalamus Hormones Oxytocin Antidiuretic hormone (ADH) Hormones transported to the posterior pituitary for storage Directs posterior pituitary to release hormones Glands

Pituitary Gland Controlled by the hypothalamus Located at the base of the brain Protected by a bony structure called the sella turcica The optic chiasm is located just above the pituitary gland Carries visual information to the brain for interpretation Two lobes Anterior lobe Posterior lobe Pituitary Gland Glands

Pituitary Gland (cont.) Growth hormone Stimulates milk production Prolactin Stimulates increase in size of muscles and bones Anterior Lobe Thyroid-stimulating (TSH) Luteinizing Stimulates the thyroid gland to release its hormones Females: stimulates ovulation and estrogen production Males: stimulates testosterone production Follicle-stimulating Adrenocorticotropic (ACTH) Females: stimulates estrogen production and maturation of the ova Males: stimulates sperm production Stimulates the adrenal cortex to release its hormones

Pituitary Gland (cont.) Oxytocin Posterior Lobe Females: causes contraction of the uterus and ejection of breast milk Males: stimulates contraction of the prostate and vas deferens during sexual arousal Antidiuretic hormone (ADH) Stimulates the kidneys to conserve water

Super! Apply Your Knowledge ANSWER: Match the following: D, E ANSWER: Match the following: ___ Stored in posterior pituitary A. Follicle-stimulating hormone ___ Milk production B. Prolactin ___ Produced by hypothalamus C. Luteinizing hormone ___ Stimulates sperm production D. ADH ___ Maturation of ova E. Oxytocin ___ Stimulates ovulation ___ Conservation of water ___ Production of testosterone ___ Contraction of uterus B D, E A A C Super! D C E

Thyroid Gland Calcitonin Thyroid hormones Located below the larynx Divided into follicles that store some of the hormones Major hormones Calcitonin Thyroid hormones T3 T4 Stimulate protein synthesis and increase cellular energy production Lowers blood calcium levels by activating osteoblasts that build new bone tissue Glands

Parathyroid Glands Four located on the posterior surface of the thyroid gland Secrete parathyroid hormone (PTH) Agonist to calcitonin by raising blood calcium levels through activation of osteoclasts (dissolve bone) As bone dissolves, calcium levels in blood increase Glands

Apply Your Knowledge Bravo! ANSWER: T F F F T T True or False: __ Thyroid hormones stimulate protein synthesis. __ The thyroid gland does not store hormones. __ PTH activates osteoblasts. __ Calcitonin increases cellular energy production. __ The four parathyroid glands are located on the thyroid gland. __ Calcitonin lowers blood calcium levels. ANSWER: T Thyroid follicles store some hormones. F F PTH activates osteoclasts. Thyroid hormone increases cellular energy production. F T T Bravo!

Adrenal Glands Located on top of each kidney Divided into the adrenal medulla and adrenal cortex Adrenal medulla Central portion Hormones Epinephrine Norepinephrine Same effects as sympathetic nervous system Glands

Adrenal Glands (cont.) Adrenal cortex Outermost portion Secretes many hormones, but main ones are Aldosterone Stimulates body to retain sodium and water Important in maintaining BP Cortisol Released when stressed Decreases protein synthesis, resulting in slowed tissue repair Decreases inflammation

Excellent! Apply Your Knowledge ANSWER: Match the following: ____ Adrenal medulla A. Cortisol ____ Sodium retention B. Epinephrine ____ Decreases inflammation C. Aldosterone ____ Sympathetic effects D. Norepinephrine ____ Maintains blood pressure ____ Released during stress ____ Adrenal cortex B, D C A B, D C A Excellent! A, C

Pancreas Located behind the stomach Both exocrine gland and endocrine gland Exocrine – secretes digestive enzymes into a duct leading to the small intestine Endocrine – secretes hormones into bloodstream Glands

Pancreas (cont.) Insulin Glucagon Islets of Langerhans secrete hormones into bloodstream Alpha cells secrete glucagon Beta cells secrete insulin Insulin Glucagon Blood glucose concentrations Blood glucose concentrations Protein synthesis Protein synthesis

Apply Your Knowledge What are the effects of insulin and glucagon? ANSWER: Insulin decreases blood glucose concentration and increases protein synthesis. Glucagon does just the opposite. It increases blood glucose and decreases protein synthesis. Yippee!

Other Hormone-Producing Organs Pineal body Small gland Located between cerebral hemispheres Melatonin Regulates circadian rhythms May play a role in onset of puberty Thymus gland Located between lungs Thymosin Promotes production of T lymphocytes Glands

Other Hormone-Producing Organs (cont.) The gonads Ovaries Estrogen Progesterone Testes Testosterone Stomach Gastrin Small intestine Secretin Cholecystokinin Heart Atrial natriuretic peptide – regulates BP Kidneys Erythropoietin – stimulates blood cell production Glands

Back Back

Apply Your Knowledge Good Job! ANSWER: Match the following: ___ Between lungs A. Pineal body ___ Melatonin B. Heart ___ Estrogen/testosterone C. Kidneys ___ Gastrin D. Thymus gland ___ Secretin E. Small intestine ___ Erythropoietin F. Stomach ___ Atrial natriuretic peptide G. Gonads ___ Thymosin ___ Cholecystokinin D A G F E C B D Good Job! E

The Stress Response Stressor Any stimulus that produces stress Types Physical factors Psychological factors Positive stimuli

The Stress Response (cont.) Physiologic response to stress caused by hormone release General stress syndrome Increased heart rate, respiratory rate, and BP Increase in glucose and fatty acids in blood, which leads to weight loss Increase in cortisol if stress prolonged Decreased body repair Susceptibility to illness

Apply Your Knowledge Very Good! ANSWER: Match the following: ___ Extreme heat A. Physical stress ___ Death of friend B. Psychological stress ___ Fractured leg C. Positive stimulus ___ Wedding ___ Exam ___ Hearing an explosion nearby ___ “A” on an exam ___ Flu ___ Car stolen A B A C B Very Good! B C A B

Common Diseases and Disorders Disease/Disorder Description Acromegaly Too much growth hormone produced in adults; enlargement of bones and thickened skin Addison’s disease Adrenal gland fails to produce enough corticosteroids Cretinism Extreme form of hypothyroidism present prior to or soon after birth Cushing’s disease Hypercortisolism; over-production of cortisol Diabetes insipidus Kidneys fail to reabsorb water, resulting in excessive urination; hyposecretion of ADH

Common Diseases and Disorders (cont.) Disease/Disorder Description Diabetes mellitus Type I Type II Gestational Chronic disease characterized by elevated blood glucose levels Insulin-dependent diabetes mellitus; usually develops in childhood Noninsulin-dependent diabetes mellitus; primarily in adults but increased incidence in teens Occurs during pregnancy; usually temporary Dwarfism Too little growth hormone (somatotropin) produced during childhood

Common Diseases and Disorders (cont.) Disease/Disorder Description Gigantism Too much growth hormone produced during childhood Goiter Enlargement of thyroid gland, causing swelling in neck; deficiency of iodine in diet Graves’ disease Hyperthyroidism; antibodies attach to thyroid gland, causing it to produce too much thyroid hormone Myxedema Thyroid gland produces inadequate amounts of thyroid hormone; common in females over 50

Apply Your Knowledge ANSWER: True or False: Correct! True or False: ___ Acromegaly develops as a result of too much growth hormone in a child. ___ In diabetes insipidus, the kidneys fail to reabsorb water. ___ Too little growth hormone in childhood results in dwarfism. ___ Myxedema is the result of hyperthyroidism. ___ Addison’s disease is the result of too little corticosteroid. ___ Cushing’s disease is the result of too little ACTH. ___ Cretinism is an extreme form of hyperthyroidism present at birth. ANSWER: F in an adult T T F hypothyroidism T F too much ACTH F hypothyroidism

End of Chapter 12 Its not stress that kills us, it is our reaction to it. ~ Hans Selye