Temperature, Osmotic Regulation and the Urinary System

PowerPoint for this section is in Secret Readings.

Thermoregulation

More on Dinosaur Thermoregulation

Velociraptors  from Jurassic Park I (A) and a male from Jurassic Park III. Note pin feathers. Recent research indicates that Velociraptors  were heavily feathered and MUCH smaller than depicted in the movies. Feathers were probably first used for thermoregulation and then later evolved to the addition function of communication.

More on dinosaur feathers (click me)!

During hot, dry spells bees will leave the hive to avoid overheating and killing the brood. More on behavioral insect thermoregulation is here. A BBC movie on termites and their mounds is HERE (8 min). A movie of a Dragonfly hand standing is HERE.

A ball python brooding her eggs by shivering.

Garter snakes hibernate in a mass underground and collectively produce heat (Left). Red sided garter snakes soon after leaving hibernation (right). It's still cool, so they remain in a ball while mating. Most of these are males with only a few females at the center. More on garter snake hybernation. General info on garter snakes is HERE.

Capillary beds in rabbit ears

Surface to Volume Ratio Considerations

Control of temperature by the hypothalamus (use this for study)

Osmoregulation

Osmoconformers vs. Osmoregulators

Contractile Vacuoles are osmo-regulators

Protonephridia of a planarian (Left), Flame cells in Philodia (a rotifer; center); Philodina (Right)

Nephridia of the earthworm. (A) general structure not the the nephrostome collects fluids from an adjacent coelom. (B) earthworm cs (C) location of nephridia in a dissection

Malpighian Tubules

Salt glands: Top left- Sea Tortoise at rear of eye. Top right: Galapagos iguana (nose). Bottom left: Albatross (beak). Bottom right: lizard (nose) 

Kidney Function

Location of Kidney and Gross Kidney Structure.

The important stuff here is blood flow in and out, two-layers in the kidney, where the nephrons are loccated, ureter->baldder->urethra.

Relationship between gross kidney structure and nephrons

Tubular system of nephron

• Know this anatomy.
• Urine formation starts at the filtrate within Bowman's capsule.
• The loop of Henle is where urine concentration (mostly amount of water) is controlled.
  • Long loops cause the body to retain water and form a concentrated (hypertonic) urine. These are seen in desert animals and saltwater fish.
  • Short loops cause the body to lose water and cause the formation of a watery (hypotonic) urine. Seen in animals that live in a watery environment (freshwater fish).
• The collecting duct is connected to hundreds of nephrons. Formed urine collects here and eventually it flows out of the kidney at the ureter.

Capillary system of nephron

• The afferent arteriol brings "dirty" blood to the nephron.

• The juxtaglomerular apparatus responds to Antidiruretic hormone (ADH).

  • In the presence of ADH less, more concentrated urine is formed by the nephron (you pee less).

  • Low levels of ADH cause higher quantities of less-concentrated urine to be produced by the nephron (you pee more).

• Materials like salt, water, glucose, ammonia, hydrogen ions, and other good/bad stuff leaves the blood at the glomerulus and enters Bowman's capsule. This is the start of urine formation.

• Weird and spooky blood with strange and frightening ionic concentrations, otherworldly osmotic pressure, and questionable parentage crawls (NO! SLITHERS!) from the glomerulus and Bowman's capsule on its unholy campaign to the nether regions of the nephron by way of the efferent arteriol.

• Peritubular capillaries snuggle up to the proximal and distal convoluted tubules. Depending on the ion or other substance, chemicals can be passively/actively removed or added to the blood.

• The vasa recta is a set of capillaries that lie close to the loop of Henle. Substances can be actively/passively added/removed from/to the blood as needed. Good stuff moves to the vasa recta.  

Setting up the concentration gradient

• The loop of Henle is largely responsible for setting up the concentration gradient (Low (hypotonic) at the top of the loop, high (hypertonic) at the bottom). This is shown by the color gradient and is represented by the numbers.

• The concentration gradient is responsible for setting up the passive diffusion of water, salts, and other goodies/nasties.

• Depending where you are on the tubular system, some materials are actively transported to/from the tubular system.

• Different portions of the tubular system react differently to ions (absorbing/secreting) and water. This causes the formation of urine.

Simplified diagram of ion flow

• Most of the water is retained in the blood (for animals like us).

• Most potassium and sodium is retained in the blood (for animals like us).

• Nutrients like glucose are retained in the blood.

• Hydrogen ions are eliminated in the urine as are ammonia-like compounds.

Animation and explanation of kidney function (CLICK FOR LINK)
DON'T FOLLOW THIS LINK!!!