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UAB BY 124 - How creatures keep homeostasis

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BY 124 1st Edition Lecture 21Outline of Last Lecture Chapter 11I. Cell communicationII. Signaling III. Figure 11.6IV. G-protein coupled receptorV. AmplificationVI. Phosphorylation Cascade VII. Second Messenger Systems VIII. Phospholipase C IX. Hormones X. Figure 11.18XI. Steroid Hormones XII. Cell death Chapter 45I. Hormone signalingII. Water vs Lipid solubleIII. EpinephrineIV. Pituitary GlandOutline of Current Lecture I. How creatures keep homeostasisII. Types of regulationIII. Types of excretory systems IV. Excretory organsa. Kidneys Current LectureChapter 44I. How creatures keep homeostasisa. Homeostasisb. Osmoregulationc. ExcretionII. Types of regulationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Isotonic – don’t have to do anything, animals are called osmoconformersb. Hypertonic – animals are called osmoregulators c. Hypotonic – animals are called osmoregulatorsIII. Types of excretory systems a. Flat worms (Figure 44.11)i. Flame cells, protonephridia – strictly rids body of waterii. Ammonia is rid of the body through the skin of the creatureb. Earthworms (Figure 44.12)i. Metanephridiumii. Waste leaves through external opening in a segmentc. Terrestrial insects (Figure 44.13)i. Malpighian tubule1. Water and nitrogenous wastes moves in these tubules and the things that are unwanted in the open circulatory system/body are excreted through the anusd. Tardigrades (Figure 44.5)i. Can go through anhydrobiosis – can live with severe lack of water e. Aquatic vertebrates (Figure 44.3)i. Use gills to get oxygen into bodyii. Salt water fish are hypertonic and therefore lose water1. Need to get water so drink it. To fix this issue (of drinking salt water and introducing more salt into body), they use transport epithelium (a single layer of cells that face external environment and connected by tight junctions) to secrete salt ions.a. Kidneys do not have to really worry about salt concentrations in the body and so do not urinate muchiii. Sharks/cartilaginous fishes1. Keep large amounts of urea in body and therefore act like freshwater fish – keep salt inside body – hypotonic 2. Loses salt to water so have to keep taking in water.iv. Freshwater fishes – see abovev. Mammals, most amphibians, freshwater fish1. Excrete urea2. Sea turtles can produce both urea and ammoniavi. Many reptiles, birds, insects1. Excrete uric acida. Decreases water lossIV. Excretory organs (Figure 44.14)a. Kidneysi. Nephron – functional unit of kidney1. Renal artery → afferent arteriole → efferent arteriole 2. Glomerulus – capillary 3. Tubules – capillaryii. Function (figure 44.10)1. Filtration (of blood)a. Once inside nephron it is called filtrate2. Reabsorption – things go back in blood3. Secretion – things in interstitial fluid move into nephron4. Excretion – waste leaves body as urineiii. Parts of a nephron (figure 4.15)1. Bowmann’s capsule – cup-like structure a. Filtration occurs hereb. Very efficientc. Contains little filters called podocytesd. Little things that can be transported passively will be transported into/out of nephrone. Bigger things like blood cells can’t pass passivelyi. Nutrients are transported out of nephron (want to get these back in body) – active transport ii. Salt 1. Water moves passively because it ends up following the salt concentrationf. Study figure!2. Moves to Proximal tubule 3. Then to Loop of Henle – countercurrent exchangea. Descending loop – only permeable to water i. Water leaves here passively in outer medulla b. Ascending loop – only permeable to salti. Salt leaves here passively in inner medulla1. Actively in outer medulla 4. Distal tubule is nexta. Most things leave tubule actively back to body because this allows for better controli. If you need to reabsorb some things then you can but if not then you don’t have to 5. Lastly is collecting duct that opens into renal ducta. Final collection placeb. Some urea reenters bodyc. Salt and urea create a solute concentration in outer medulla that allows the body/kidney to reabsorb more water rather than excrete too much of itd. Urea will eventually reach Bowmann’s capsule again and will be reabsorbed to be excretediv. Kidney regulation (Figure 44.16)1. ADH – made by hypothalamus and excreted by posterior pituitary2. Stimulus signals hypothalamus to create ADH due to increase in blood osmolarity (maybe blood is too thick)3. Causes you to get thirsty which makes you drink water and thus thin out blood a little bit4. Also the ADH increase leads to an increase in permeability in the distal tubule which prevents further osmolarity increase 5. Figure 44.20v. Figure 44.221. Juxtaglomerular apparatusa. Release renin when there is a low blood volume or blood pressure b. Renin activates Angiotensin I which is translated to Angiotensin II by ACEc. Angiotensin II activates adrenal gland to produce aldosterone which increases Na and water reabsorption in distal tubules which increases blood volume2. Atrial-natriuretic protein – opposite from abovevi. Threshold – things move into nephron from blood to help regulate “threshold”vii. Differences between other animal kidneys1. Desert animals have long loops of Henle because they need to reabsorb as much water as possible2. Whales and fish do not drink salt water so thus do not have to excrete as much water 3. Birds have nasal salt glands that release excess water and this is why they can drink salt water b. Ureter – connects kidneys to bladderc. Bladder holds wasteUrethra empties


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