Excretory SystemMaddie, 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 (

http://training.seer.cancer.gov/images/anatomy/urinary/urinary_system.jpg)

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: http://4.bp.blogspot.com/_rSpBEx_JXa0/TSEcdlvs9fI/AAAAAAAAAUA/3i4Pmbmqnjg/s640/nephron.gif

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 nephrono 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+, HCO3

-), 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: http://waynesword.palomar.edu/images/osmosi2.gif http://droualb.faculty.mjc.edu/Course%20Materials/Physiology%20101/Chapter%20Notes/Fall%202007/figure_18_15_labeled.jpg

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 needsimages from: http://droualb.faculty.mjc.edu/Course%20Materials/Elementary%20Anatomy%20and%20Physiology%2050/Lecture%20outlines/15_05Figure-L.jpg

http://content.answcdn.com/main/content/img/elsevier/vet/gr277.jpg

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?

Bibliography1. Taggart, Ralph. Cecie Starr. "Urinary System of Mammals." The Unity and Diversity of Life. Ninth

edition. Publisher.: Brooks/Cole, 2001. pg 750-752. Print. Biology2. "Excretory System." ScienceDaily. ScienceDaily, n.d. Web. 03 Nov. 2013.

<http://www.sciencedaily.com/articles/e/excretory_system.htm>.

3. Freudenrich, Craig. "Kidney Filtration." HowStuffWorks. HowStuffWorks, n.d. Web. 03 Nov. 2013. <http://science.howstuffworks.com/life/human-biology/kidney2.htm>.

4. " Excretory System." Excretory System Worksheet. N.p., 1998. Web. 03 Nov. 2013. <http://www.pleasanton.k12.ca.us/avhsweb/thiel/apbio/review/excretory.html>.

5. Chapter 25: Physiology of Glomerular Filtration. N.p., n.d. Web. 3 Nov. 2013. <http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2020/2020%20Exam%20Reviews/Exam%204/CH25%20Physiology%20of%20Glomerular%20Filtration.htm>.

6. "Urinary System." Urinary System. N.p., n.d. Web. 03 Nov. 2013. <http://www.augustatech.edu/anatomy/chapter_26.htm>.

7. "The Urinary System." The Urinary System. N.p., n.d. Web. 03 Nov. 2013. <http://classes.midlandstech.edu/carterp/Courses/bio211/chap26/index.htm>