The Excretory System

Purpose

Contributes to homeostasis Regulates internal environment by

eliminating metabolic waste products:VolumeElectrolyte compositionpH

Waste Products

Some are metabolicE.g. Water, salts, CO2, and ureaUrea is a toxic compound that is produced

when amino acids are used for energy (contain nitrogen).

Three Organs

Kidneys Lungs Skin

1. Kidneys Main organs of excretion. Remove excess water, urea & other

excess mineral wastes from the body.Act as filters to remove wastes that are

collected and transported by the blood.E.g. Surplus in water or electrolyte (salt) in

blood = kidneys excrete in the urine.

2. Lungs

Every time we exhale, we get rid of small amounts of water vapor and CO2.

CO2 is the waste product of cells that must be removed from the body so you can take in oxygen.

3. Skin

Excretes excess water, salts, and small amounts of urea through sweating.

The Urinary System

Made up of: Left and right kidneys Ureters Bladder Urethra

Removes wastes and toxins from the blood and produces urine.

Urine: made of water, excess salts, & urea

Kidney Structure

Bean shaped Either side of the spinal

column, near lower back Size of your fist Each are attached to a

renal artery & a renal vein

Renal Vessels Renal artery – blood from aorta

unfiltered and full of bodily wastes Renal vein – filtered blood

http://www.yoursurgery.com/ProcedureDetails.cfm?BR=1&Proc=69

11010

Ureters and Bladder Ureter leaves each kidney with fluid containing

excess water, salts, urea & other waste products Ureters lead to the bladder; liquid wastes are

deposited/stored here Expulsion of wastes controlled by specific

sphincter muscles – voluntary control.

http://www.emedicinehealth.com/prolapsed_bladder/page17_em.htmhttp://www.etsy.com/listing/70476539/kidneys-crochet-plush-with-ureters-and

Kidney Regions 2 distinct regions:

1. Inner Part: Renal Medulla

2. Outer Part: Renal Cortex

Nephrons In the renal cortex Working parts of

the kidney Each acts as an

individual unit of filtration About 1 million nephrons

per kidney

http://www.agefotostock.com/age/ingles/enam01b.asp?foto=13173541&key1=&foto_clave=BSI-3555309&famp=1

FYI

The kidneys receive approximately 10% of the blood that is pumped out of our heart every minute.

Adult kidneys filter approx. 180L of blood daily.

Filtration-Reabsorption-Secretion-Excretion

1. Filtration - Bowman’s Capsule (BC) -Hollow bulb surrounding ball of capillaries

(Glomerulus)

http://www.pitt.edu/~anat/Abdomen/Kidneys/Kidneys.htm

http://www.as.miami.edu/chemistry/2086/chap26/chapter%2026-new_part1.htm

Filtration (cont’d)

http://physrev.physiology.org/content/88/2/451

Blood enters via renal artery Blood filters through

permeable walls under pressure

Filtered materials (urea, glucose, salts, & some vitamins) are called filtrates.

Filtration (cont’d) Platelets, red and white blood cells remain in

the blood (too large to pass) Adult kidneys filter approx. 180L of blood daily.

Filtration-Reabsorption-Secretion-Excretion

2. Re-Absorption - Tubules Some filtrates reabsorbed by active

transportvaluable & can’t be lost

Water returns to blood through osmosis99% of the water that is filtered out of BC is

reabsorbed into your blood

Filtration-Reabsorption-Secretion-Excretion

3. Secretion - Tubules Excess fluid leaves BC & enters tubules

URINE. First part – Proximal Convoluted Tubule

(PCT).carries fluid down into the Loop of Henle

(LH).

3. Secretion - Tubules Urine concentrated in the tubule at the LH.

i.e.water reabsorbed Urine moves up Distal Convoluted Tubule

(DCT) & meets ureter

Filtration-Reabsorption-Secretion-Excretion

4. Excretion Purified blood returns to the body through

the renal vein, which runs to the Inferior Vena Cava

Urine moves from the nephrons to ureters and goes to the bladder for storage

Once urine is ready to leave the body, the urine will be expelled through the urethra.Stretch receptors in bladder

Recap:

http://www.as.miami.edu/chemistry/2086/chap26/chapter%2026-new_part1.htm

http://www.ask.com/wiki/Proximal_convoluted_tubule

http://www.colorado.edu/intphys/iphy3410saul/outlines08fall/nephron.gif

Kidney Failure

You have two kidneys in the body located on either side of the spine and extend a little below the ribs.

Your kidneys are bean-shaped organs and is about the size of a fist.

The kidneys receive approximately 10% of the blood that is pumped out of our heart every minute.

Your kidneys are responsible for the following:Regulate fluidsBalance chemicalsRemove wastesSecrete hormones

Condition Explanation:

Progressive in nature Anemia possible – lack of iron Malnutrition (lack of appetite) Decrease well-being Increased risk for heart disease

Toxins build up in blood Weight gain (excess fluids, swollen ankles,

puffiness) Fluid imbalances – dizziness – nausea

Treatment Options:

GeneralLimit fluid intake, high carb, low protein, low

potassium dietToo much potassium can cause irregular

heartbeat

HaemodialysisMost common methodUse of a machine (size of dishwasher) –

blood flow through special filter to remove and filter wastes

Clean blood returned to bodyStrict schedule – 3 times a week for 3 to 5

hours each time

Side effects Less energy Loss of time

Once a month blood is tested to see how effective dialysis is – may not work forever!

Peritoneal DialysisRemoves extra water, wastes, and chemicalsCleansing solution passed through catheter

into abdomenAfter a couple of hours the solution is drainedDoes not require a machineStrict dietMore recent advances, more flexibility (done

at home)

Kidney TransplantationReceive a healthy kidney from a living donor

or a recently deceased donorWhen effective recovers quality of health AND

lifeYields longer life expectancyCould be long waiting lists (shortage of

donors)Typical Surgery Risks (bleeding, infection,

etc.)Anti-rejection medications after surgery – may

weaken immune systemRisk of rejection (body doesn’t accept kidney)