BIO 111, Week 4 Notes
BIO 111, Week 4 Notes BIOL 11100 - Fundamentals of Biology II
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BIOL 11100 - Fundamentals of Biology II
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This 6 page Class Notes was uploaded by Phoebe Notetaker on Friday February 5, 2016. The Class Notes belongs to BIOL 11100 - Fundamentals of Biology II at Purdue University taught by Dr. Athena Anderson in Winter 2016. Since its upload, it has received 11 views. For similar materials see Biology in Science at Purdue University.
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Date Created: 02/05/16
Week 4 2/2/16 Endocrine System Physiology & Homeostasis ● Complex/multicellular animals have a hierarchical organization of structures (think about last semester): ○ Cells are organized into tissue, which makes up organs, which is organized into organ systems, which all make up an entire organism. ○ Emergent properties appear at each new level (characteristics that are seen at the higher level that were not exhibited at the level below). ○ Complex living systems (warm blooded animals) exhibit homeostasis. Homeostasis ● The ability to maintain a constant internal environment despite fluctuating external environment; requires internal communication about the state of the organism. ● How does your blood know that it’s too cold? → Communication. ● Concentration of important molecules in body fluids have set points levels at which a physiological state is regulated. ● There’s a perfect spot that your body wants to stay regulated at and is unique to each organism. ○ Go above set point, response → lowering ○ Go below set point, response → raising ○ Ex: Thermostat in a house connected to heating and cooling systems. PRIMARY PURPOSE OF THE HYPOTHALAMUS IS TO REGULATE THE PITUITARY GLAND Signaling Molecules ● Different ways cells send signals: ○ Autocrine: Same cell type sends and receives the signal. ○ Paracrine: One cell type sends signal and another cell type receives signal. ● Recall the location of target: Close or distant. ○ Local signaling molecules (nerve cell to a muscle cell nearby): Neurotransmitters, histamines. ○ Distant signaling molecules: Hormones, growth factors. Endocrine System ● This system regulates the body’s “set points:” temperature, heart rate, metabolism, “fight or flight” response. ● Triggers important physiological events such as puberty and reproduction. ● Facilitates cell to cell communication: Glucose uptake, antihistamine and histamine release, “fight or flight.” Hormone ● A particular type of molecule/chemical secreted by an endocrine gland/organ into the blood for transport. ● Effective at very low concentrations (10^9 to 10^12M) ● Affect practically everything: growth, metabolism, development, and or homeostasis. ● Hormones are useful because it doesn’t take a lot of them to get your body’s response to its environment. Endocrine Gland ● A ductless gland or single cell that secretes a hormone, which travels through blood. ● Targets the cells or organs that have receptors for the hormone. Human endocrine glands: Hypothalamus, Pituitary, Thyroid, Thymus, Adrenal, Pancreas, Testes/Ovaries. Hypothalamus ● Maintains homeostasis by controlling the autonomic nervous system (the one you don’t have to think about); link b/w endocrine and nervous systems. Releases: 1. Neurotransmitters (epinephrine/fight or flight, serotonin). 2. Hormones that regulate anterior pituitary (thyrotropinreleasing hormone). 3. Hormones that are stored in posterior pituitary for later release (oxytocin/lactate inducing, vasopressin/controls blood vessel expansion or contraction). WHICH OF THE FOLLOWING GLANDS SECRETES CORTISOL? ADRENAL Pituitary Gland ● Structure below the hypothalamus which has two regions: ○ Posterior: Also part of the CNS receives neurohormones from hypothalamus and stores them until it’s time for them to be released. “Storage shed.” ○ Anterior: Not part of the CNS receives hormonal signals from the hypothalamus. Immediately reacts and does what the hormone tells it to do. No nerves in the anterior part. Memorize slide no. 11 and 12: very likely to have exam questions come from this chart. THYROID*** very likely to be on the exam. Classes of Hormones: 1. Steroids (derived from cholesterol). Ex: Cortisol, estrogen, testosterone. 2. Peptide (less than 40 amino acids). Ex: ACTH 3. Protein (greater than 40 amino acids). Ex: Growth hormone. 4. Glycoprotein. Ex: Thyroid stimulating hormone. Negative Feedback Loops ● Hormone regulation often involves negative feedback loops, where an increase in a hormone leads to the inhibition of that hormone. ○ The body senses that there is too much of a hormone and then it reverses in a sense, to make the body inhibit that hormone so that its concentration is regular again. ● Response to altered set point stops its own production: selflimiting. ○ Exceeds a set point in one direction and glands produce hormone, leading to response. ○ Exceeds in the opposite direction, and glands stop production, stopping the response. ● Ex: Level of glucose in blood. ● Controlled by two hormones, produced by islets of Langerhans cells in pancreas. ● Hormones have antagonistic effects: 1. Insulin responds to a raise in blood glucose by lowering 2. Glucagon responds to a decrease in blood glucose by raising ● After eating and blood glucose rises, 1. Stimulating insulin production by pancreas 2. Insulin lowers blood glucose a. Cells take up glucose b. Cells convert glucose to glycogen c. Slows gluconeogenesis (synthesis of carbohydrates from fat and protein) 3. Insulin production stops which leads to blood sugar dropping. ● Eating very sugary foods causes the “sugar crash” feeling of abrupt decrease in energy because it triggers quick decrease in blood sugar. ● B/w meals: 1. Blood glucose falls, stimulating glucagon production from the pancreas. 2. Glucagon raises blood glucose. a. Glucose released by liver cells. b. Glycogen is converted to glucose. c. Increases gluconeogenesis Glucagon production stops which leads to blood glucose rising Diabetes: A disease that disrupts insulin/glucose regulation. ● Type I: Genetic, pancreas doesn’t produce enough insulin, treated w/ insulin injection, 10%. ● Type II: Usually acquired through lifestyle, pancreas can’t make enough insulin to keep blood glucose down, 90%. ○ How much sugar you eat, amount of exercise, health habits, etc. ● Associated risks: Heart disease, nerve, eye, kidney, foot damage, skin conditions, hearing impairment, Alzheimer’s disease. ○ It’s very likely to have issues w/ feet. 2/4/16 Fight or Flight Response 1. Brain tells the hypothalamus that a threat is perceived. 2. Hypothalamus signals pituitary to release ACTH. 3. ACTH signals adrenal gland to release epinephrine (adrenalin) and cortisol. 4. Together, they increase blood pressure & sugar, increase gluconeogenesis, & metabolism of protein & fat to glucose. 5. The result is a burst of energy to muscles, to prepare the body to fight or flee. Pupils dilate, tunnel vision, hearing loss, digestion slows, shaking, blood flow diverted from extremities to muscles, etc. Slide 26. Effects of Chronic Stress ● Some stress is good (eustress); keeps you alert and engaged in activities. ● Constant high stress (distress) keeps the body in “fight or flight” mode. ● Chronic pain also causes chronic stress. ● Side effects of chronic stress: ○ Decreased productivity, difficulty thinking, high blood pressure, stroke, heart disease, insomnia, decreased immunity, depression, anxiety, obesity, fatigue, increased risk of substance abuse. → College students are at high risk of chronic stress. Thyroid: Controls metabolism, affects temperature, heart rate, growth. Produces two hormones: 1. Triiodothyronine (T ). 3 2. Thyroxine (T 4. Have similar effects, but 3made from T4and more potent. Hypothyroidism: Caused when the thyroid doesn’t produce enough T 3or T4 Slide 2. ● It can take years for a correct diagnosis, often discounted as “all in your head.” ● 10% of women have some degree of thyroid issues. ● Can have “normal” levels of TSH, T3 and T4and still suffer from this. Goiter: Enlarged thyroid gland, can be caused by numerous conditions: Iodine deficiency, hyperthyroidism, nodules, cancer, pregnancy, inflammation. Most common in developing countries where iodine is less present and iodine deficiency is more likely. Thymus ● Only active during youth, before puberty. Starts to atrophy at puberty and turns into fat. ● Produces Tcells (essential for immune function) and thymosin which causes maturation of T cells. ● Both endocrine and immune function. Sjörgens Syndrome: “Showgrins,” equally affects all ethnic groups. ● Autoimmune disease, thought to come from Tcells that aren’t trained in thymus long enough. ● Causes range of symptoms, especially fatigue and drying of body’s moistureproducing glands. ○ Ex: Venus Williams Adrenal Glands [sit on to of the kidneys] ● Produces many hormones: ○ Estrogen & progesterone → female sex hormones ○ Cortisol & cortisone → antiinflammatory, stimulates gluconeogenesis ○ Epinephrine & norepinephrine → Increased heart rate, sugar metabolism, threat response ○ Dopamine → Neurotransmitter which gives happy feeling from awar seeking behavior, counters norepinephrine Addison’s Disease: Causes severe fatigue, weight loss, vomiting, pain, depression. Adrenal glands produce insufficient cortisol. Pancreas: Produces insulin and glucagon to regulate blood glucose levels. Also produces enzymes that help w/ digestion. Testes/Ovaries ● Testes: Male gonads, produce testosterone and other androgens. ● Ovaries: Female gonads, produce estrogen and progesterone. ● Up to 6 weeks, post fertilization, male and female gonads are indistinguishable. ● Wolffian ducts (male) will inhibit Mullerian ducts (female) when Sertoli cells in testes secrete Mullerian inhibiting substance (MIS). ● If not inhibited by sex determining substances from Y chromosome, Mullerian system develops. Acromegaly: Caused by an overproduction of GH from the pituitary gland. Causes elongation of legs, feet, arms, hands, jaw. ● 90% of sufferers have a pituitary tumor; grows continuously. ● Associated risks: Type II diabetes, high blood pressure, arthritis, cardiovascular disease. Cushing’s Syndrome: Most often caused by overuse of glucocorticosteroid medication, which mimics cortisol. Tumors are most commonly a natural cause. Hormones and Development ● Hormones control normal development in all complex animals. ● Molting in insects is caused by hormone ecdysone, a steroid secreted by glands in the thorax. ● Metamorphosis in amphibians is stimulated by release of Tfrom the thyroid. 3 Endocrine Disruptors (EDs): Environmental chemicals that interfere with normal endocrine signaling; mimic effects of steroid hormones. Ex: 1. Diethylstilbestrol (DES) ● A nonsteroidal estrogen mimic, synthesized in 1938. The FDA approved its use for menopause symptoms in 1941 & to prevent miscarriage in 1947. In 1953 the first study suggested that it was not effective for preventing miscarriage. In 1971 the first published study linked it to vaginal cancer in female offspring of mothers who used it. ○ Risks of exposure to DES during fetal development: ■ In males: Feminization of reproductive organs, undescended testes, abnormal development of penis and urethra. ■ In females: Increased risk of uterine and cervical cancer, abnormal development of uterus. 2. Bisphenol A (BPA) ● Used in production of plastics, exhibits hormonelike properties. Risks of exposure to BPA during fetal development. ○ In males: Increased probability of abnormal development of penis, testes, and prostate. ○ In females: In rats it causes suppression of ‘Hox A’ genes, which regulates uterine development. Alters uterine lining and progesterone sensitivity in adults. Slide 21
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