The Endocrine System 10/20/2014 Slowly but surely

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 Glands into 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 steroid hormones Estrogen Progesterone Testosterone Cortisol hormones

Hormones (cont.) Nonsteroidal hormones 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

Negative and Positive 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

Negative and Positive Feedback Loops (cont.) As long as stimulus is present, action of hormone continues Infant nursing  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! 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 E ANSWER: B A D C VERY GOOD! A B

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 Glands

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

Thyroid Gland and Parathyroid Glands (cont.) 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 osetoclasts (dissolve bone) As bone dissolves, calcium levels in blood increase Glands

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

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

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

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 Grave’s 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

In Summary The organs of the endocrine system secrete hormones directly into blood and other body fluids. Hormones secreted by the endocrine system control the functions of other cells. Endocrine organs Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Pineal body Thymus gland Gonads, stomach small intestine, heart, kidneys