Unit A - The Endocrine System

Unit A - The Endocrine System Biology 30 Hormones and Homeostasis Nerves are not the only way the human body controls its activities. Hormones also contribute in a fashion similar to nerves. Typically, the response and action of hormones is much slower than the action of nerves. They are, however, last longer. Hormones in general Hormones Use Hormones are useful in the regulation of… - Metabolism Blood sugar Water regulation Sodium regulation Calcium regulation Growth Stress response (long term) General goal of hormones (and nerves) Homeostasis - —the body’s ability to keep a constant balance in a changing environment —endocrine system - consists of the hormone producing glands and tissues in the body What is a hormone? —Hormone – chemical messenger sent to many parts of the body to produce a specific effect on target cells or organs. Detecting Change Just like the nervous system, the endocrine system relies on sensory receptors to detect changes within the body. Typically these changes are chemical in nature (so use chemoreceptors) or are related to water and salt balance (so use baroreceptors or osmoreceptors) Feedback Systems To control the hormones, we rely on feedback systems… Negative feedback: mechanism that bring the body back to acceptable ranges —- most hormones are regulated by negative feedback systems —- prevent small changes from becoming too large VERY USEFUL SITEs https://www.visiblebody.com/learn/endocrine General Negative Feedback USEFUL PREFIXES/SUFFIXES HYPO- : MEANING LESS THAN NORMAL, or lower HYPER- : MEANING MORE THAN NORMAL, or higher -TROPIC : meaning affecting another area PARA- : meaning next to CORTICO- : meaning outer region of MEDULLA- : meaning inner region of ANTI- : meaning against HORMONES THAT AFFECT BLOOD SUGAR The pancreas is located behind the stomach and is connected to the small intestine via the common duct. — The pancreas contains hormone producing tissue called the islets of Langerhans These cells secrete two hormones: INSULIN and GLUCAGON Pancreas and Islets of Langerhans INSULIN —Secreted by beta cells of the pancreas —Action - Decreases the amount of glucose in the blood —Its release is triggered by the rise in glucose levels in the blood after meals —- Insulin makes cells more permeable to glucose —- The liver then converts glucose into glycogen —Once the levels of glucose have lowered the secretion of insulin is reduced After a sugar Binge!! Effects of Insulin Arrow = stimulation In addition to increasing glucose uptake, LIPOLYSIS and glucose production by the liver is inhibited. Glucagon —Secreted by alpha cells of the pancreas —Action - Increases the amount of glucose in the blood — - Its release is triggered by a drop of glucose levels (usually after fasting or hard exercise) —- Glucagon stimulates the liver to convert stored glycogen into glucose —Once the levels of glucose have been raised, the secretion of glucagon slows Other Effects of Glucagon Glucagon also - Decreases appetite - Decreases stomach activity - Increases energy expenditure - Increases metabolism of amino acids and lipids for forming ATP All together… (2 possible simple feedback loops) Also, another way to see it... Video Diabetes Mellitus —Occurs when the body does not produce enough insulin OR the body does not respond properly to insulin — → levels of blood glucose rise sharply after meals and remain high (hyperglycemia) SOLUTION - inject insulin in to the body to bring blood glucose levels down There are 2 types…. Effects of Diabetes ● ● ● ● —fatigue —use fats and proteins instead which are more difficult to break down; causes your breath and body to smell —kidneys cannot reabsorb all of the glucose -> much is lost in urine —If not treated this can lead to blindness, kidney failure, nerve damage and gangrene —Type 1 Diabetes (juvenile diabetes) ● —the immune system ● attacks the beta cells of the pancreas that produce insulin —Must take daily shots of insulin to live —Approximately 10% of people have this ● Type 1 Diabetes video Type 2 diabetes - Adult Onset ● ● ● ● ● —Develops gradually over time —Insulin receptors in body stop responding to insulin OR pancreas produces less insulin over time —Linked with unhealthy diets and being overweight —Usually diagnosed as an adult and controlled with diet, exercise and medication —90% of diabetic cases Type 2 Diabetes video Type 3 Diabetes - Gestational Diabetes ● —Temporary ● condition that occurs in 2%-4% of pregnancies —Increases the risk of type 2 diabetes in both mother and child Comparing Type 1 and Type 2 Diabetes Controlling the metabolism of Calcium WHY DO WE NEED TO CONTROL CALCIUM?? THe Thyroid Gland and Parathyroid Gland The Parathyroids - Releasing calcium —Parathyroids - Four small glands attached to the thyroid —→ Produce parathyroid hormone (PTH) —When calcium levels get too low in the blood PTH → stimulates the breakdown of bone material — → Stimulates the kidneys to reabsorb calcium from the urine — → Stimulates the absorption of calcium from food in the intestine Tumour affecting the parathyroids... The antagonistic effect Antagonist - doing the opposite effect Thyroid and the Metabolism of Calcium —CALCITONIN - Secreted from the thyroid — —→ Regulates the amount of calcium in our blood — → —If there is too much calcium in the blood calcitonin will stimulate uptake into the bones Calcitonin and PTH together influence calcium in blood and bones Feedback loop with both together Hypercalcemia - When there is too much calcium in the blood Hypocalcemia - When there is too little calcium in the blood WALK-THROUGH - Animated Tutorial calcium in the body The Master Glands Hypothalamus - Produces ADH and Oxytocin → move down portal system to posterior pituitary - Produces releasing and release-inhibiting hormones → move down axons to axon terminals The Pituitary Gland Has an anterior side and a posterior side. POSTERIOR= - does not produce any hormones stores and releases hormones •antidiuretic hormone (ADH) and oxytocin Anterior Pituitary Gland —The anterior pituitary produces six hormones: ● ● ● ● ● ● human Growth Hormone (hGH) thyroid-stimulating hormone (TSH) adrenocorticotropic hormone (ACTH) follicle-stimulating hormone (FSH) luteinizing hormone (LH) prolactin (PRL) Pituitary Gland - Summary Other thyroid hormones Thyroid Gland: —Lies below the larynx —Has two lobes; one on either side of the trachea —controlled by the anterior pituitary which releases thyroid stimulating hormone (TSH) — —Triiodothyronine (T3) & Thyroxine (T4) increases the rate at which the body metabolizes fats, proteins and carbs for energy — —TARGET ORGANS: heart, skeletal muscles, liver, kidney Effects of T3 and T4 Specific effects of T3 and T4 on different systems Negative Feedback Hypothyoidism Cretinism Occurs when the thyroid does not develop properly during childhood — —- Stocky and short —- Can have mental development delays —- Tired, slow pulse rate, puffy skin, hair loss and weight gain —- Very rare Hyperthyroidism —Overproduction of thyroxine — —Symptoms: anxiety, insomnia, heat intolerance, weight loss, irregular heart beat —Graves disease: extreme case – the immune system attacks the thyroid —Can be treated with medication or surgery to remove some or all of the thyroid http://amitahealth.adam.com/content.aspx?p roductId=117&pid=1&gid=000356 Thyroid and Iodine —The thyroid requires iodine in order to make thyroid hormones — —Insufficient iodine in one’s diet can cause thyroxine to not be made — —The body will continue to stimulate the thyroid gland and this can cause a goitre to form Hormonal Regulation of Stress —The adrenal glands are located on top of each kidney — —Each gland has two parts: —Adrenal medulla – inner layer —Adrenal cortex – outer layer Adrenal MEDULLA —Produces epinephrine (adrenaline) and norepinephrine (noradrenaline) —→ Regulate short term stress; works with the sympathetic nervous system —Results in increased: breathing rate, heart rate, blood pressure, blood flow to the heart and muscles, conversion of glycogen to glucose in the liver —→ Acts very quickly Medically these hormones are used to restart hearts or to open air passages during an allergic reaction Adrenal Cortex —Produces three types of hormones: the glucocorticoids (cortisol), the mineralocorticoids (aldosterone), and gonadocorticoids (small amounts of sex hormones) ● ● ● —Involved in long term stress response —Glucocorticoids will increase blood sugar —Mineralocorticoids will increase blood pressure Cortisol (a glucocorticoid) —Hypothalamus stimulates the anterior pituitary gland to secrete adrenocorticotropic hormone (ACTH) which stimulates the adrenal cortex to release cortisol — Hypothalamus → anterior pituitary → ACTH → adrenal cortex → cortisol —Purpose of cortisol is to raise blood glucose levels Cortisol and blood glucose Raised glucose is achieved by ● ● promoting the breakdown of protein into amino acids which are made into glucose in the liver promotes the breakdown of fat tissue to be made into glucose Over the short term, this is good. Effects of Cortisol Long term stress and high glucose levels —Long term (chronic stress) or Cushing’s disease (increased prod. due to tumor) ● ● ● ● ● ● —impaired thinking —damage to the heart —high blood pressure —Diabetes —increased susceptibility to infection —cause early death Review of Nephron action in kidney Aldosterone - a mineralcorticoroid —Primary mineralcorticoid secreted by the adrenal cortex ● ● ● —Stimulates the kidneys to increase sodium absorption into the bloodstream —allows more water to move in through osmosis —increases blood pressure Better feedback loop : Aldosterone (including ACTH) Even Better (but complex) Solid line = stimulates Dashed line = inhibition Aldosterone effect on kidney Addison’s disease —Addison’s disease: ● —Damage done to the adrenal cortex ● —Body secretes inadequate amount of mineralocorticoids and glucocorticoids —Symptoms: —Hypoglycemia —Na+ and K+ imbalances —Rapid weight loss —Weakness —Drop in blood pressure ● ● ● ● ● ● Other hormone affecting the kidney ADH is another hormone that affects the kidney… —Is released in response to low blood volume, low blood pressure, dehydration (ie. increased ion concentration) —TARGET ORGAN: kidneys — —Stimulates the kidneys to reabsorb water back into the blood for hydration — —Inhibited by hydration, increased levels of blood, alcohol and caffeine ADH feedback Loop ADH effect on nephron Diabetes Insipidus —Central diabetes insipidus = lack of ADH —Nephrogenic diabetes insipidus = kidneys do not respond to ADH ● —CDI – caused by damage to hypothalamus or ● pituitary gland —NDI – there is a defect in the parts of the kidney involved in reabsorption Symptoms of Diabetes Insipidus —Excessive thirst —May be intense or uncontrollable — —Excessive urine volume General Blood Pressure Regulation Human Growth Hormone Released from - Anterior Pituitary Gland —Affects nearly every body tissue — —will affect some tissues by direct stimulation but the majority of tissues it affects is by acting as a tropic hormone (Liver release growth factors) —TARGET ORGANS: liver, muscle, bone, cartilage and other tissue for growth Effects of hGH —Causes an increase in: Protein synthesis ● Cell division and growth (bones and muscle) ● Fat usage ● Glucose synthesis ● - If there are low levels of hGH in the blood secretions are stimulated by growth hormone releasing hormone (GHRH) and is inhibited by growth hormone inhibiting hormone (GHIH) when there are high levels of hGH About insulin-like growth factor 1 Too much growth hormone as a child —Too much hGH before your growth plates have fused = gigantism —Symptoms —very tall —Large muscles and organs —Delayed puberty —Headache —Sweating —Irregular menstrual cycles Large hands and feet with thick fingers and toes Gigantism —Robert Wadlow – 8ft 11 in —Died at age 22 Too little hGH as a child = dwarfism Too much hGH as an adult... —Overproduction of hGH can lead to acromegaly —Bones and soft tissues of the body widen —Ribs thicken —Face widens —Feet and hands enlarge —Can also cause cardiovascular diseases, sugar intolerance (diabetes), breathing problems, muscle weakness or colon cancer hGH, IGF and bodybuilding