BIOL 2312 Week 6 Class Notes
BIOL 2312 Week 6 Class Notes Biol 2312
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This 8 page Class Notes was uploaded by Sarah Westermann on Thursday September 29, 2016. The Class Notes belongs to Biol 2312 at University of Texas at Dallas taught by Michelle Wilson in Fall 2016. Since its upload, it has received 12 views.
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Date Created: 09/29/16
September 27, 2016 Endocrine System o Includes all organs and tissues that secrete hormones o Endocrine Ductless Secreted into extracellular fluid Carried in blood o Exocrine Duct Secrete product into a duct Create a quantity based on the stimulus and deliver it to a specific area o Only targets with receptors are able to respond Pituitary gland (hypophysis) o At base of hypothalamus o Physical extension of hypothalamus o Runs the show o Known as the “master gland” o 2 visual regions Anterior side (Anterior Pituitary) Front Appear glandular Developed from pouch of epithelial tissue of embryo’s mouth Very compact, uniform look Does all the work for the pituitary Produces and secretes 7 essential hormones o No back-up mechanisms in the body if these hormones can’t be produced Controlled by hormones from hypothalamus Glands need regulation Example: hormone delivered by the hypothalamohypophyseal portal system o Portal Vessel system - capillary bed to another capillary bed but does not go through the heart Acts like a duct Negative feedback and feedback inhibition Posterior side (Posterior Pituitary) Back Appear fibrous Storage container Doesn’t produce anything Stores and releases 2 hormones - neuroendocrine reflex o Antidiuretic Hormone (ADH) Peptide hormone Usually produced during dehydration Stimulates water reabsorption by the kidney Inhibits diuresis (urine production) Intricate balance between kidney and ADH Makes you thirsty, inhibits sweating Heat Stroke: thirsty, sweating inhibited, pass out (due to drop in blood pressure - blood volume depleted) o Oxytocin Positive feedback Composed of 9 amino acids (very small) Peptide hormone Only shows up in milk ejection and labor contractions Both males and females have this hormone Still unsure why males have it The two have different embryonic origins o If the pituitary glands has problems; everything else has problems Tropic hormones (tropins) o Act on another gland o 3 categories Peptides Hormones Very small Not much structural complexity ACTH o Works in adrenal cortex gland MSH o Makes melanin (pigment) for hair and skin Protein Hormones Much larger and more complex than peptide hormones Single chain of ~200 amino acids GH o Disorders Over- or undergrowth Gigantism versus pituitary dwarfism Acromegaly Affects protein, lipid, and carb metabolism PRL o Positive feedback o Milk production Glycoprotein Hormones Very complex Dimers (2 identical subunits) o Contain alpha and beta subunits TSH o Tropic LH o Gonads o Ovulation (in females) o Help other cells nurture sperm (in males) FSH o Gonads o Develops the egg (in females) o Develops sperm (in males) FSH and LH named after function in women Hypothalamus o Produces 2 hormones o Stores them in posterior pituitary gland Thyroid o Front of the neck; can feel it when you swallow o Goiter Enlargement of thyroid Lack of iodine Thyroid hormones can’t be produced without iodine Try to compensate by getting bigger Resolved by intake of iodine (table salt) o In the thyroid gland (lipophilic) T4 Precursor Similar function as T3 T3 More active form Intracellular receptors in nucleus o Hypothyroidism (slow metabolism) vs hyperthyroidism (fast metabolism) o TSH (in frogs) activated when limbs begin to grow and tails are lost o Calcitonin Stimulates uptake of Ca2+ into bones Lowers blood Ca2+ levels Not the only thing that regulates calcium blood levels Calcitonin is usually one of the last options Parathyroid o Behind thyroid o 4 small glands attached to thyroid o Produce PTH Antagonist of calcitonin Stimulated by drops in Ca2+ blood level Can take calcium from intestines, kidneys, and bone o Vitamin D Parathyroid controls conversion from nonfunctional to functional Thymus o Immune driven Heart o Secondary hormone function September 29, 2016 Parathyroid o Acts as antagonist - parathyroid hormone to calcitonin o Raises blood Ca2+ levels Gets calcium from ingestion, calcium pulled back from urine in kidneys, can also be pulled from bones Pulling calcium from bones is usually a last resort since it would weaken the bones Adrenal Glands o Located on top of kidneys o Also known as “super-renals” o One on top of each kidney o Medulla (inner region) Innervated directly Stimulated by sympathetic NS “fight or flight” Secretes epinephrine and norepinephrine Effector: Catecholamine Hormones Short-term stress response o Cortex (outer region) Stimulated by ACTH Turns on production of corticosteroids Cortex has 3 layers, each layer produces a different hormone Cortisol Stress Manages sugar Weight gain or loss Aldosterone Mineralocorticoids Mineral balance regulation Effector: glucocorticoids Long-term stress response Pancreas o Exocrine and endocrine glands o Connected to duodenum of small intestine o Cluster of cells unique to pancreas - islets of Langerhans o Insulin Produced by beta cells Gets rid of high glucose blood levels by storing blood glucose in receptors o Glucagon Produced by alpha cells Promotes hydrolysis of glycogen Once we exhaust this we begin burning fat o Insulin and glucagon are antagonistic o Diabetes Type I Beta cells do not function properly or are not there at all Genetic; hereditary Type II Beta cells function just fine; insulin production works Cells won’t take in sugar Insulin receptors reject the sugar Low number of insulin receptors Insulin receptors can be brought back with a healthy diet and exercise Gonads o Ovaries and testes in vertebrates o Sex steroids are produced o Females: estrogen and progesterone o Males: androgens (includes testosterone) Androgens are a class of hormones Pineal Gland o Secretes melatonin Synchronizes sleep/wake cycles (circadian rhythm) o Can detect light on its own o Sometimes referred to as the “third eye” Other Hormones o Production of hormones in these organs serves as a secondary function o Atrial Natriuretic Hormone Secreted by the right atrium in the heart Helps monitor high blood pressure Promotes salt and water secretion Water always follows salt o Erythropoietin Secreted by kidneys Makes more red blood cells Which allows for more oxygen in blood Good for muscles Used for doping purposes sometimes Insect Hormones o Molting Organism just growing larger Sheds exoskeleton for new one o Metamorphosis Transformation point High levels of brain hormones cause molting o Juvenile hormones Run the show Appears in molting phases only Insect won’t metamorphosize if juvenile hormones are present Musculoskeletal system o Form (skeletal) and function (muscular) o Pulling mechanism - works in pairs (when one contracts another relaxes) Pulls against skeletal frame Myofibrils => Muscle Fibers => Bundles => Muscles o Myofibrils Made of actin and myosin (contractions occur at this level) Thick (myosin) filament When multiple myosin molecules are wrapped together Myosin heads talk to actin binding point Ratio of actin is higher when compared to myosin Actin molecules attach to Z-Disk Z-line contraction unit (unit contracts as a whole) ATP is important in this process o Muscle Fibers Multiple cells fuse together o Bundles Multiple muscle fibers come together o Muscles Multiple bundles o Multiple layers allow for good control