1. Ice Man Climbed Mt. Everest in shorts!
Scientists are unclear on how this is possible
Found his brain does not send the same hormonal messages under cold stress
Other studies found many human proteins are better able to deal with cold stress than heat stress… Why do you think this is?

2. Functions of the Excretory System

3. Your body must eliminate wastes to remain healthy.
These systems function together as parts of your excretory system.

4. Excretory System – removes excess water, H2O, urea, carbon dioxide, CO2, and other wastes from our blood. Very important in regulating how much water we have in our body!
Kidneys – filter out excess water and urea
Lungs – filter out carbon dioxide, CO2, from the blood.
Skin – excretes water, as sweat, which contains some trace chemical wastes, including urea.

5. Urinary System- The Liver
Metabolizes toxins (alcohol) so kidney can excrete them
Processes harmful products from protein metabolism for kidneys to excrete as urea
Wastes are processed in the liver before being sent to the kidney through the bloodstream

6. Nitrogenous wastes
Amino acids are broken down to ammonia (highly toxic) which is converted into urea in the liver
Nucleic Acids are broken down into uric acid in the liver
Urea is the primary waste product in human urine

7. The Urinary System
The urinary system rids the blood of wastes produced by the cells.
The urinary system also controls blood volume by removing excess water
Gets rid of excess salts

8. Kidneys – filter wastes and excess water from the blood.
Ureters – tubes that take urine from the kidney to the urinary bladder.
Urinary Bladder – a sack that stores urine.
Urethra – small tube that leads urine out of the body.

9. Regulating Fluid Levels
The hypothalamus constantly monitors the amount of water in the blood.
When there is not enough water in the blood the hypothalmus releases Antidiuretic Hormone (ADH) this signals the kidney to return water to the blood
When the brain detects too much water in the blood, the hypothalamus releases a lesser amount of ADH
This signals the kidneys to return less water to the blood and increase the amount of wastewater, called urine, that is excreted.
When there is lots of ADH in your blood your pee is very yellow… why?

10. Organs of the Urinary System
The main organs of the urinary system are two bean-shaped kidneys.
The kidneys filter blood that contains wastes collected from cells.
It is made up of about 1 million tiny filtering units called nephrons

11. Approx. 2,000 L of blood is filtered daily by the kidneys.
Filtration in the Kidney
In approximately 5 min, all of the blood in your body passes through the kidneys
Approx. 2,000 L of blood is filtered daily by the kidneys.

12. Overview of the Urinary System
Blood enters the kidneys through the renal artery.
Blood enters the nephrons.
Water,sugar,salt and wastes in the blood enter a cuplike structure in nephron.
Capillaries reabsorb most of the water,sugar, and salt.
The renal vein returns purified blood to be circulated.
Urine drains from each collecting tubule into funnel shaped areas of the kidney
Urine flows from ureters to the urinary bladder
Urine flows from the bladder through the urethra and out of the body.

13. Nephron Structure & Function
The kidneys have three basic mechanisms for separating the various components of the blood:
filtration, reabsorption, and secretion.
The structure of the kidney is such that it allows for this function 13

14. Homework Questions
Explain how the excretory system works to maintain homeostasis
Do questions 1-3 on pg. 348