ENDOCRINE SYSTEM Series of glands that produce hormones to help maintain homeostasis. Hormones: Chemical regulators that affect other parts of the body. Insulin Growth Hormone Gastrin Some glands produce one hormone, some produce many kinds and even other chemicals. Levels of hormones vary throughout the day.

COORDINATION The nervous system and the endocrine system work together to allow the body to function. Nervous System --> SHORT TERM corrections Endocrine System --> LONG TERM stability

HORMONES To be susceptible to the effects of a hormone, a cell must have a specific receptor. Two types of hormones: Steroid hormones: made from cholesterol, complex ring structures, fat soluble Sex hormones, cortisol Protein hormones: amino acid chains Insulin, growth hormone

Mechanism of Action Steroid Hormones: hormones diffuse out of blood stream and into the target cells combine with receptor molecules in cytoplasm hormone-receptor complex diffuses into nucleus attaches to chromosomes and activates a gene, initiating transcription and protein synthesis.

Mechanism of Action PROTEIN Hormones: hormones diffuse out of blood stream attach to receptors on the cell membranes of target cells the receptor-hormone complex activates the production of adenylyl cyclase, an enzyme that catalyzes the conversion of ATP into cyclic AMP (cAMP). The cAMP is a messenger that activates various enzymes inside the cell to begin their normal functions. (R-H complex activates an enzyme that converts ATP into cAMP, cAMP activates enzymes inside the cell to begin functioning)

PITUITARY GLAND This is known as the master gland because it controls a lot of other endocrine glands. A small sac connected to the hypothalamus. Pituitary gland stores hormones while the hypothalamus stimulates it to release them.

PITUITARY GLAND The pituitary gland has two lobes: The posterior lobe stores and releases hormones produced by the hypothalamus (ex. ADH, oxytocin) The anterior lobe produces and stores its own hormones (ex. TSH, prolactin)

PANCREAS pancreas cells produce: Digestive Enzymes Hormones: Insulin and Glucagon The hormones are produced in structures called the Islets of Langerhans (discovered by Paul Langerhans of Germany). approx islets in the pancreas each islet has 2 types of cells

INSULIN produced in the Beta cells released when blood sugar is high (after a meal)‏ Stimulates uptake of glucose by making muscles, liver and other organs more permeable to glucose so it can be stored Liver converts glucose to glycogen Result: Decreases blood sugar level.

GLUCAGON produced in the alpha cells released when blood sugar levels are low (fasting)‏ Stimulates release of glucose by organs into blood stream liver breaks down glycogen into glucose and releases it Result: Increase blood sugar level

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INSULIN RELEASED GLUCAGON RELEASED

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DIABETES Chronic disease caused by insufficient production of insulin Type I (juvenile) (insulin dependent) - 10% early degeneration of beta cells Type II (adult) (non-insulin dependent, NIDDM) – 90% decreased insulin production or ineffective use of insulin produced. Gestational temporary condition of pregnancy that increases risk of diabetes in both mom and child Banting and Best – isolated insulin for treatment p 383 #2-5

METABOLISM Thyroid Gland is located in front of the trachea. It produces hormones: Thyroxine (T4)‏ Calcitonin Triiodothyronine (T3)‏ T4 and T3 regulate body metabolism and growth and differentiation of tissues

METABOLISM Parathyroid Gland Parathyroid hormone Pituitary Gland Growth hormone (somatotropin)‏

THYROID HORMONES Thyroxine helps our body oxidize sugars and nutrients at a faster rate. All the energy of glucose is transferred to heat and ATP, and ATP is consumed during activity, therefore there is no weight gain. Hypothyroidism: low thyroid secretions glucose is not oxidized as quickly, and excess glucose is converted to glycogen and stored. once glycogen stores are filled, excess sugar is stored as fat.

REGULATION of METABOLISM Metabolic rate decreases Hypothalamus TRH Pituitary TSH Thyroid Thyroxine Increase metabolism inhibits Metabolic rate decreases hypothalamus sends thyroid releasing hormone (TRH) to the pituitary pituitary releases thyroid stimulating hormone (TSH)‏ TSH acts on thyroid to release thyroxine. thyroxine raises metabolism by increasing sugar usage by body tissues thyroxine levels feedback on TRH release

GOITER Lack of iodine for T4 and T3 Less T4 and T3 present TSH produced continuously Overstimulated thyroid enlarges

Other Metabolic Hormones Calcitonin Calcium absorption (bone formation)‏ Parathyroid Hormone Calcium release (from bones, reabsorption at kidneys, intestines)‏ Growth Hormone (somatotropin)‏ Dwarfism, gigantism, acromegaly Protein synthesis Breakdown of fats p 387 #3-7

STRESS Both the endocrine and nervous system make adjustments to stress to enable the body to cope. Nervous Response: quick, sudden. Increase heart rate Diversion of blood to needed muscles Endocrine Response: slow, prolonged More glucose available due to increased Epinephrine (increases blood sugar levels, heart rate and breathing rate)‏ increased Cortisol (converts proteins to glucose)‏ increased Glucagon (glycogen to glucose)‏ Decreased insulin* (decrease glycogen formation)‏ Lots of O 2 and glucose = more energy

STRESS and FLUID LEVELS Renin-Angiotesin-Aldosterone pathway (Nervous)‏ and ADH (Endocrine)‏ both are active to increase reabsorption to help maintain body fluid levels.

ADRENAL GLANDS located above each kidney made up of a cortex surrounding a medulla the cortex is regulated by hormones the medulla is regulated by nervous stimulation

MEDULLA produces the hormones: Epinephrine and Norepinephrine “Fight or Flight” In times of stress, EPI and NOREPI are released to Increase blood glucose levels by stimulating the break down of glycogen increase heart rate, breathing rate, metabolism dilate blood vessels and iris of eye

CORTEX produces hormones known as Glucocorticoids Ex. Cortisol also released in times of stress, cortisol increases amino acids (used by liver to convert into glucose, excess used to build proteins)‏ inhibits glucose uptake in many tissues (also helps increase blood levels).

LONG TERM STRESS Hypothalamus Pituitary ACTH Adrenal cortex Glucocorticoids Mineralocorticoids CortisolAldosterone hypothalamus sends a releasing hormone, ACTH (adrenocorticotropic hormone), into the blood ACTH stimulates adrenal cortex to release glucocorticoids and mineralocorticoids (hormones). cortisol - (see notes above)‏ aldosterone – increase Na+ and H 2 O reabsorption in kidneys (Negative feedback)‏

Problems with Prolonged Stress High blood sugar High blood pressure Increased water loss Rupture of vessels / clotting Increased Heart Rate (heart attack)‏ Hmwk p 383 #1,6-9; p 392 #1-4, 6*, 8*