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Today:. Hormones and the Endocrine System cont’d Case Study Into to Homeostasis?. Reminder: Next week’s group quiz moved to Thursday!. Vertebrate Coordination of Endocrine and Nervous Systems. Hypothalmus : endocrine gland in the brain of vertebrates.
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Today: Hormones and the Endocrine System cont’d Case Study Into to Homeostasis? Reminder: Next week’s group quiz moved to Thursday!
Vertebrate Coordination of Endocrine and Nervous Systems Hypothalmus: endocrine gland in the brain of vertebrates
Vertebrate Coordination of Endocrine and Nervous Systems Oxytocin: Positive-feedback mechanism involved in release of milk from mammary glands and uterine contraction
Vertebrate Coordination of Endocrine and Nervous Systems: ADH What would an Anti-Diuretic Hormone (ADH) do? When would I produce it?
Vertebrate Coordination of Endocrine and Nervous Systems: ADH
Vertebrate Coordination of Endocrine and Nervous Systems • Anterior pituitary produces a variety of tropic and nontropic hormones • Tropic hormones regulate the function of endocrine cells or glands. Example: TSH • Nontropic hormones target nonendocrine tissues. Example: MSH
Vertebrate Coordination of Endocrine and Nervous Systems These impacts make GH tempting for adult athletes to abuse! A few hormones, like Growth Hormone (GH) have both tropic and nontropic effects
LONDON – In a major breakthrough in the fight against doping, a British rugby league player has become the first athlete to be suspended for using human growth hormone. Terry Newton admitted taking the substance in a statement released by his attorneys on Friday. The United Kingdom Anti-Doping authority announced a two-year ban on Monday after Newton was fired by his club, Wakefield. "It's the first time and very significant," WADA director general David Howman said. "It shows the people who say that HGH cannot be detected that it can. The sports people who said it can't be detected are fooling themselves." Rugby player makes history with growth hormone ban By ROBERT MILLWARD, AP Sports Writer Robert Millward, Ap Sports Writer – Mon Feb 22, 2010 2:48 pm ET
Functions of the Thyroid Hormone Involved in both homeostasis (blood pressure, heart rate, etc.) and development Excessive secretion = hyperthyroidism (high temp, high blood pressure, weight loss) Insufficient production = hypothyroidism (weight gain, lethargy, intolerance to cold)
Iodine was added to salt in 1924 when up to a third of US adults suffered from goiter!
Next in Homeostasis Survey:OSMOREGULATION Osmoregulation: management of body’s water and solute content www.pbs.org
Transport Epithelia Most animals use layers of specialized epithelial cells to regulate solute movements. (Remember our tight junctions??)
Transport Epithelium Example: Salt excretion in marine birds
Osmoregulation: Metabolic Wastes Most wastes (except CO2) must be dissolved in water to be eliminated, including nitrogenous wastes. Breakdown of proteins produces ammonia (soluble but very toxic)
Osmoregulation: Metabolic Wastes To secrete ammonia directly, must have access to lots of water! So what kinds of animals would you expect to secrete ammonia directly?
Osmoregulation: Metabolic Wastes Not an efficient strategy for land animals! Most mammals, amphibians, marine fish, turtles, etc., excrete mainly urea Urea is much less toxic, but requires energy to produce
Osmoregulation: Metabolic Wastes Option #3: Uric Acid Land snails, insects, birds, and some reptiles use uric acid to eliminate nitrogenous waste Uric Acid is also relatively nontoxic, but insoluble in water! (And even more expensive to produce!) So why bother??
Water Balance All animals must balance the rate of water uptake and water loss Two solutions: osmoconformers and osmoregulators! Where do you expect to find each of these?
Measuring Osmolarity Osmolarity = total solute concentration expressed as moles of solute per liter Common unit in biology = milliosmoles per liter (mosm/L)
Osmoregulation has Energetic Costs “Expense” depends on: • Concentration gradient between animal and environment • Permeability of surface to water and solutes • Energetic cost of membrane-transport work
General Strategies: Saltwater Animals Invertebrates: Most have body fluids that are isoosmotic to the surrounding environment Note: This is not as easy as it seems! Nudibranch, Photo: Robbie Wong, MSU
General Strategies: Saltwater Animals Vertebrates: Most have body fluids that are hypoosmotic compared to the surrounding environment. So which way does water move?
Data courtesy of Professor Balment, University of Manchester
Exceptions to the “Rule”: Marine Sharks (Chondrichthyes) • Internal salt concentration low • Kidneys remove some of this salt; rest is excreted by the rectal gland or in feces However, net diffusion of water is inward!! Photo: Pisces Conservation LTD
General Strategies: Saltwater Animals • Marine reptiles and birds drink seawater to replace lost water. • Kidneys cannot produce concentrated urine and excess salts are excreted using special glands. Photo: BBC News
General Strategies: Freshwater Animals Net movement of water? Salt issues?
General Strategies: Freshwater Animals • Opposite problem! Water is constantly diffusing in as salts are lost • Many freshwater animals cope by excreting large amounts of very dilute urine, replacing salts through food and active transport from the environment
General Strategies: Freshwater Animals What about the salmon?? Ocean-going salmon drink seawater and excrete excess salt from the gills After migrating to freshwater, they stop drinking and produce lots of dilute urine
Also Problematic: Temporary Waters Animals inhabiting temporary waters must have mechanisms for preventing the effects of desiccation (anhydrobiosis) Ditylenchus larvae in anhydrobiosis(photo M.McClure)
General Strategies: Terrestrial Animals Desiccation is a serious regulatory challenge! Many adaptations: • waxy coverings • nocturnal lifestyle • kidneys! A Kangaroo (desert) Rat Example: This Kangaroo Rat doesn’t drink! Potential sources of water??
Excretion Most systems share a two-step process: 1. Fluid collection 2. Content adjusted by selective reabsorption or secretion
Excretion Step 1: Fluid Collection Typically involves filtration through membranes of transport epithelia Membranes retain cells and large molecules (proteins); water and small solutes end up in the filtrate This process is non-selective!
Excretion Step 2: Selective Reabsorption or Secretion Useful solutes (glucose, some salts, amino acids) are reabsorbed; nonessential solutes and wastes are left or actively transported into the filtrate
Animal Survey Stop 1: Flatworms Planaria utilize simple excretory systems called protonephridia This system is a network of dead-end tubules branching through the body; cilia draw fluid in through the flame bulb into the tubule system
Animal Survey Stop 2: Annelids Most annelids utilize metanephridium Each segment has a pair of metanephridia immersed in coelomic fluid; fluid is collected in a ciliated funnel and then passed through the collecting tubule and out the nephridiopore Photo: Dr. Frederic Janzen, ISU
Animal Survey Stop 3: Insects Insects and terrestrial arthropods utilize malpighian tubules to remove nitrogenous wastes (and osmoregulation) Outfoldings of the digestive tract secrete wastes and salts from the hemolymph into the lumen
Survey Stop 4: Mammalian Kidneys Mammals have two kidneys, each supplied with LOTS of blood flow via the renal artery; as a result, all blood is filtered ~every 30 minutes Our kidneys can excrete urine 4X as concentrated (1,200 mosm/L) as our blood! Image: The Biology Project
Survey Stop 4: Mammalian Kidneys Functional Unit = the Nephron (single long tubule with a ball of capillaries) Kidneys are compacted bundles of nephrons (~1.3 million) all draining, eventually, into the ureter Image: The Biology Project
Kidney Function • Blood Pressure forces fluid from the blood (glomerulus) into the lumen of Bowman’s capsule • Non-selective!! (~180 L of filtrate/day)
