Bio 11.3 & 6.6 (3-23-17)

11.3 A1- Consequences of dehydration and overhydration.

Dehydration or overhydration can cause the normally isotonic condition of the body to become hypertonic or hypotonic, respectively. Dehydration (not enough water intake) causes the body to become hypertonic because the lack of water intake results in a higher ratio of solutes to water. It causes thirst, low blood pressure, darker urine, exhaustion, and can lead to seizures. Overhydration (too much water intake) causes the body to become hypotonic because it cannot expel the excess water fast enough, resulting in a higher ratio of water to solutes than usual. It causes confusion, nausea, muscle cramps, exhaustion, and can also result in seizures.

11.3 S2- Annotation of diagrams of the nephron.

Fluids flow through the nephron in this order: 1. Bowman's capsule 2. proximal convoluted tubule 3. loop of Henle 4. distal convoluted tubule 5. collecting duct 6. exit to ureter There are millions of nephrons between the medulla and cortex of the kidneys, and all are used to filter out waste materials and excess water. "Checks and balances" allow for a reabsorption of water and substances if necessary.

11.3 A2- Treatment of kidney failure by hemodialysis or kidney transplaon.

Kidney failure can be caused when toxins build up in the kidneys and the solute concentrations can no longer be properly regulated by the kidneys. Hemodialysis is one method of treating it, in which blood is drawn out of the body and passed through a kidney-stimulating machine. This must be done for multiple hours multiple times a week. Kidney transplants are when someone receives a donor kidney, but it doesn't always work because the body might reject it if it is not the same blood type or has different tissues.

11.3 S1- Drawing and labelling a diagram of the human kidney.

Kidney has 3 parts: cortex, medulla, and pelvis. Renal artery goes in and renal vein exits. Nephrons are between the cortex and medulla. Waste gathers in the pelvis and exits through the ureter.

6.6 A2- Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.

Leptin injections were first tested on mice. The success shown made them move on to human subjects, where it began failing miserably. These injections rarely helped with obesity and caused skin irritation and swelling. In the few cases in which leptin injections caused a loss of body fat, it was gained back quickly after the trials.

6.6 U3- Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.

Leptin is secreted by adipose tissue and lowers appetite. It is a type of protein tissue and works in conjunction with insulin to regulate hunger.

6.6 U4- Melatonin is secreted by the pineal gland to control circadian rhythms.

Melatonin is secreted by the pineal gland and controls the body's circadian rhythm. This regulates sleep cycles. Melatonin levels increase in the evening and decrease in the morning to help make you fall asleep/wake up (respectively).

11.3 U1- Animals are either osmoregulators or osmoconformers.

Osmoregulators- not isootomic (isotonic) to their environment, so they must control their internal osmolarity (ie they expel excess water or take in water to offset water gain/loss due to a hypertonic or hypotonic environment). Osmoconfromers- issotomic (isotonic) to their environment. Includes most marine invertebrates and they have to live in water with stable conditions to survive.

11.3 U3- The composition of blood in the renal artery is different from that in the renal vein.

Renal arteries and veins are related to the kidneys, which are used for both osmoregulation and excretion by removing and excreting waste substances. The renal artery enters the kidney with high levels of O2 and urea, the urea is then filtered out and oxygen is given to the kidney. The Renal vein leaves the kidney with CO2 and lower levels of urea.

11.3 U2- The Malpighian tubule system in insects and the kidney carry out osmoregulation and removal of nitrogenous wastes.

The Malpighian tubes are tubes that branch off the intestinal tract of insects. waste products are transported by these tubes to be excreted and help osmoregulation. Osmoregulation is a way of maintaining homeostasis in the body by excreting waste products to keep the concentration of chemicals in the blood at a certain level.

11.3 U4- The ultrastructure of the glomerulus and Bowman's capsule facilitate ultrafiltration.

The glomerulus is a collection of capillaries. The capillaries are very small and have porous layers of tissue. The tissue allows some substances to diffuse through it, separating out smaller substances and allowing only very small particles through the capillaries. This method of separating particles/substances by size through porous tissue is called ultrafiltration. As liquid travels through Bowman's capsule, substances diffuse in and out, with a system of "checks and balances" in order to ensure that the body has the materials that it needs but excretes any waste unwanted by the body.

11.3 U6- The loop of Henle maintains hypertonic condition in the medulla.

The loop of Henle follows the proximal convoluted tubule in a nephron. Capillaries crisscross around the loop of Henle. As fluid flows through the loop of Henle, water diffuses out through osmosis on the downwards part of the loop. As the loop curves back up, various solutes move out through active transport and travel to surrounding tissues.

11.3 U8- The length of the loop of Henle is positively correlated with the need for water conservation in animals.

The loop of Henle varies in length in different species. In drier ecosystems, animals have longer loops of Henle to allow for more water reabsorption, thus increasing water conservation. Shorter loops of Henle allow animals who take in excess amounts of water to quickly and easily expel that water.

11.3 U5- The proximal convoluted tubule selectively reabsorbs useful substances by active transport.

The proximal convoluted tubule is part of nephrons. After Bowman's capsule, fluid flows through the proximal convoluted tubule. Substances needed by the body that diffused out of Bowman's capsule are reabsorbed by the proximal convoluted tubule.

11.3 U9- The type of nitrogenous waste in animals is correlated with evolutionary history and habitat.

There are 3 types of nitrogenous waste: Ammonia, urea, and uric acid. Ammonia is the most toxic and must be excreted quickly . This is produced by most marine invertebrates and bony fish. Urea is produced by the liver and is a combination of ammonia and CO2. It is the waste product of amino acid breakdown and is 100,000 times less toxic than ammonia, but requires energy to produce. It is produced by most mammals, amphibians, sharks, and turtles. Uric acid is mostly insoluble and requires the most energy to produce but also has very little water loss. This is produced by most birds, insects, snails, and reptiles.

6.6 U2- Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.

Thyroxin is a tyrosine derivative hormone that is secreted by thyroid glands to increase metabolic rate and help control body temperature.

6.6 A3- Causes of jet lag and use of melatonin to alleviate it.

Travelling quickly through time zones (ie flying) causes the body's natural circadian rhythm to be thrown off. This causes temporary insomnia, headaches, and exhaustion. Melatonin can be taken when it is time to sleep in the new time zone to help the body adjust quicker to the new time zone.

11.3 A3- Blood cells, glucose, proteins, and drugs are detected in urinary tests.

Urine tests can detect the various waste products that the body expels. The presence of blood cells in urine can be caused by various diseases or infections. The presence of glucose can be caused by diabetes. The presence of proteins (if in large concentrations) can be caused by kidney disease. Drugs will also be present in urine because the body often views them as waste.

11.3 U7- ADH controls reabsorption of water in the collecting duct.

When body fluid loses too much water and becomes too hypertonic, the pituitary gland secretes ADH, which tells the body that it needs to reabsorb more water and forces the collecting duct to increase in permeability to water in order to gain more water.