Ice Man Climbed Mt Everest in shorts Scientists

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?

Functions of the Excretory System

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

Excretory System – removes excess water, H 2 O, urea, carbon dioxide, CO 2, 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, CO 2, from the blood. • Skin – excretes water, as sweat, which contains some trace chemical wastes, including urea.

Urinary System- The Liver • 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

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

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

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.

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?

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

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.

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.

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

Homework Questions 1. Explain how the excretory system works to maintain homeostasis 2. Do questions 1 -3 on pg. 348