Excretory System Maddie, Jess, Monica, Alyssa

The Urinary System (1, 2) Consists of: 2 kidneys, 2 ureters, 1 urinary bladder, and 1 urethra Function: To maintain homeostasis (a stable internal environment) in the body by getting rid of excess water and waste image from (

The Kidney (5) ●Kidney contains millions of nephrons which perform the functions of the Kidney: ○eliminate waste products ○regulate water & what kind of chemicals are in blood/body ○maintains balance between water/salt and acids/bases ● Which becomes urine Image from source 1

The Nephron (1) Parts of Nephron: Glomerulus (G & R) o Bowman’s capsule (G) + blood capillaries (R) = Glomerulus Proximal tubule (G) Loop of Henle (B) Distal tubule (P) Collecting duct (Y) Each part of Nephron involved in either transporting substances into or out of the blood capillaries (R) which surround the nephron. Image from:

Processes (1) Urine forms in nephrons by 3 process: o Filtration:  separation of a liquid from some or all of the undissolved particles through a selectively permeable membrane o Tubular Reabsorption:  movement of substances out of nephron and into the blood capillaries o Tubular Secretion:  process by which substances move into the distal and collecting tubules from blood capillaries

Nephron: Glomerulus (3, 5) Function: filters out solutes (except proteins) & water from blood into the nephron o raises blood pressure = forces molecules into Bowman’s capsule o process called filtration This fluid (called filtrate) made up of: water, urea, salts (e.g. NaCl) ions (e.g. H+, K+, HCO 3 - ), glucose, amino acids, vitamins, & (possibly) drugs/poisons Photo is from source 5 Bowman’s capsule (yellow) + blood capillaries (pale beige) = Glomerulus

Nephron: Proximal Tubule (4, 6) Function: Tubular reabsorption (nutrients and other substances returned to blood) o active tubular reabsorption  Movement of sodium, etc, by transport proteins o passive tubular reabsorption  Osmosis  Substances in filtrate move out into blood as well images from:

Nephron: Loop of Henle (6, 7) descending part of loop = outside fluid hypertonic with sodium, therefore water leaves by osmosis as water leaves = sodium concentration in tubule increases o that’s why on ascending part of loop = sodium leaves tubule by diffusion - > contents of tubule become more dilute Key: = sodium Function: sodium & water selectively reabsorbed in order to keep constant concentration NaCl

Nephron: Distal Tubule (6) Tubular Secretion: Solutes in blood capillaries are accepted and secreted into the nephron Solutes are mainly H + and K + o Regulates sodium, potassium, pH Prevents foreign substances (drugs) from accumulating in blood

Nephron Collecting Duct (6) Function: Controls how much water is reabsorbed into the blood Aldosterone allows for sodium to be absorbed by blood capillaries by stimulating sodium pumps = creates L to H gradient need for osmosis ●ADH makes tubule more permeable for water & w/ osmotic gradient = allow more water in the filtrate to be reabsorbed into the blood ●Amount of secretion of each based on what the body needs images from:

How does urine formation help maintain homeostasis? (7) pH- kidneys help excrete extra hydrogen (h+ ions) from the blood into urine through active transport Ions- the excess ions such as sodium or calcium leave the body in the urine The Loops of Henle balances concentrations by osmosis Collecting Duct - keeps more water in body or allows it to leave the body All information on slide is from readings cited 1 and 4

Questions?

Bibliography 1.Taggart, Ralph. Cecie Starr. "Urinary System of Mammals." The Unity and Diversity of Life. Ninth edition. Publisher.: Brooks/Cole, pg Print. Biology 2."Excretory System." ScienceDaily. ScienceDaily, n.d. Web. 03 Nov Freudenrich, Craig. "Kidney Filtration." HowStuffWorks. HowStuffWorks, n.d. Web. 03 Nov " Excretory System." Excretory System Worksheet. N.p., Web. 03 Nov Chapter 25: Physiology of Glomerular Filtration. N.p., n.d. Web. 3 Nov "Urinary System." Urinary System. N.p., n.d. Web. 03 Nov "The Urinary System." The Urinary System. N.p., n.d. Web. 03 Nov