Osmoregulation in Animals Chapter 44

Osmoconformers vs. Osmoregulators

How does a salmon survive? Usually osmoregulation uses about 5% of metabolism. Osmoregulation in extreme saline conditions: up to 30%

Compare and Contrast Osmoregulation in saltwater vs. freshwater fish!

Compare and Contrast the Following Excretory Organs Name of Structure Organisms How structure works Protonephrida Metanephridia Malphigian Tubules

The Pee Problem What happens to nutrients after they enter the body? What gets used? What gets stored? How is waste removed? Compare the elements contained in proteins to the elements in the storage molecules. What is it that doesn’t get stored?

Waste products affect water balance Habitat dictates the toxicity of waste that an animal can tolerate Energy cost to producing less toxic urea and insoluble uric acid

Diffusion, osmosis, & active transport in the body The Kidney & Dialysis Diffusion, osmosis, & active transport in the body

Gross Anatomy Posterior in the abdominal cavity Bean shaped Just below the rib cage Size of a fist

What do they do? Kidneys filter waste products and make urine Waste products from cells end up in the blood Blood circulates around the body including the kidneys Artery = away from the heart, into the kidney Capillaries = thin walls allow waste to leave Vein = leaves the kidney, back to the heart

Kidney Facts The rate of filtration is approximately 125 ml/min or 45 gallons (180 liters) each day. Considering that you have 7 to 8 liters of blood in your body, this means that your entire blood volume gets filtered approximately 20 to 25 times each day! www.how.stuffworks.com

A closer look

Nephron The repeating functional unit of the kidney A semi-permeable tube whose job is: Filtration Reabsorption Secretion

How is the nephron organized? Areas of the nephron: Glomerulus Bowman’s capsule Proximal Tubule Loop of Henle - ascending Descending Distal Tubule Collecting duct

Components of Blood

Filtration Plasma is the liquid portion of the blood Plasma contains water, ions, glucose, amino acids, and waste Blood pressure pushes plamsa out capillaries and into the nephron tube

Reabsorption Both active and passive transport move good molecules from the nephron tube back into the blood stream Sodium is pumped (actively transported) back into the capillaries Water follows  osmosis Bad stuff like waste is left in the tube headed to the bladder Anything that doesn’t get reabsorbed into the blood gets “peed” out (becomes urine)

Secretion Opposite of reabsorption Waste (H+ ions, drugs) are pumped from capillaries directly into the tube

Review of major processes

Recipe for urine?

Key Concept: Active transport drives the passive transport of water Counter-current multiplier system

How does structure meet function? Cells that make up the tube are different depending on their jobs!

Structure Meets Function Fluids must pass through transport epithelial cells for regulation Tight junctions force fluids to enter cells Semipermeable cell membranes (of transport epithelial) control the movement of solutes between internal fluids and the external environment by sorting, pumping, and secreting solutes

Hormonal Balance Two systems: What is the stimulus for each system? What hormones are involved? How do hormones cause a response?

ADH

RAAS

Reviewing Hormones Mini Case Study: Alcohol inhibits ADH. A college student was binge drinking. The student passed out and friends just figured they’d let him “sleep it off.” Knowing what you know about the feedback and osmoregulation, why is this a bad choice?

What if it doesn’t work? Kidney usage is usually measured in percent If you lose a kidney you can still filter 100% (you really only need one) When total kidney function drops below 20% it can be lethal Treatment- dialysis

Hemodialysis hemo = blood Internal filters don’t work, use an external filter Blood is filtered through an external machine

The dialyzer Nephron is to kidney as dialyzer is to hemodialysis Much simpler than the nephron Blood on one side, liquid on the other Semi-permeable membrane between

Why does it work? A waste product like urea is more concentrated in the blood than in the fluid (dialysate) so the urea passes through and is washed away

Life on dialysis Kidneys work 24/7 to get the job done Dialysis is periodic, not continuous Dialysis takes 4-5 hours Why can’t all the blood be filtered at once? Patients go to a clinic 3 times a week (MWF or THS)

Is hemodialysis just as good as a kidney? What do you think?

Hemodialysis Effectiveness About 10% as effective as normal kidneys Became available in the early 60s Some of the first patients are still alive Not a full life expectancy Without dialysis- certain death 20 million Americans

Be the doctor! Manipulating the dialysate In end-stage renal (kidney) failure potassium concentrations get really high This can cause big problems (Na+/K+ pump) What should you do to the concentration of potassium ions in the dialysate to fix this problem?