1. Part 3 Kidney and Excretion
Ch. 14
Part 3
Kidney and Excretion

2. Major Organs to Know Kidney Liver producing hormones
absorbing minerals
filtering blood
producing urine
Liver
Detoxification of blood

3. Excretion Removal of unwanted metabolic products made in body cells
Toxic
Excess molecules
2 biggest waste products:
Carbon Dioxide
Review respiratory
Produced by AEROBIC respiration
Dissolves in water  weak acid (carbonic acid)
Too much = decrease pH = BAD
Carried to lungs in blood plasma and expired and released when we breath out
Nitrogenous Excretory Products
Urea
From catabolism of protein
Produced in liver
Carried in blood plasma to liver
Leaves in urine
Creatinine
From breakdown product of creatine phosphate in muscle
Made from Creatine (produced in liver using certain amino acids)
Most used in muscles as creatine phosphate as ENERGY STORE
Excess creatine converted to creatinine and excreted
Uric Acid
From Catabolism of nucleic acids
made from break down of PURINES from nucleotides

4. Urea Adults produce 25 – 30 grams per day Made from excess amino acids
DEAMINATION in liver occurs
Removal of amine group form amino acid
Amino Acid  Keto acid and Ammonia
Keto acid Carbon skeleton of AA
Enters KREBS CYCLE for respiration
Changed to: glucose, glycogen, or fat
Ammonia Soluble and Toxic (build up in blood BAD)
What happens to amine group?
Hydrogen atom added to Amine group (NH2) to make it NH3 (ammonia)
Ammonia immediately converted to UREA (via Urea cycle)
Ammonia + Carbon Dioxide = Urea

6. Step 1
In Liver…
Step 2
In Liver…now urea can be carried in blood to kidney
Urea will be dissolved with water and leave body as urine…once out of body, it will degrade back to AMMONIA
Step 3

8. Kidney “Renal” pertaining to kidneys MAIN Function
process the plasma portion of blood by removing substances from it (or adding)
Variety of other Functions:
Regulation of Water and inorganic ion balance
Removal of metabolic wastes from blood and excrete through urine
Removal of foreign chemicals from blood and excretion through urine
Gluconeogenesis
Production of hormones/enzymes (endocrine glands)

9. The Kidney Every minute 1300 mL of blood enter the kidneys
1299 mL leave the kidney
1 mL leaves as urine.
Location:
Posterior (back)
Outside the abdominal cavity
Behind the peritoneum of abdominal cavity

10. Structure of Kidney Renal Artery delivers blood TO the kidney
Renal Vein blood LEAVES the kidney from here
Ureter narrow tube that caries URINE away from kidney to bladder
Urethra tube from bladder to outside of body
Contains about 1 MILLION subunits called nephrons
Nephrons contain:
Renal corpuscle

11. Major Areas of Kidney Capsule Cortex Medulla Pelvis
Tough outermost covering of kidney
Cortex
Beneath outer capsule
Contains cup-shaped beginning structure of nephron called the renal capsule
contains about one million blood filtering nephrons
Medulla
Central area of kidney
Very SALTY!!!! (Hypertonic)
 inner region of the kidney contains 8-12 renal pyramids
pyramids empty into the calyx
Medullary pyramids – formed by the collecting ducts, inner part of the kidney
Pelvis
basin-like area that collects urine from the nephrons
narrows into the upper end of the ureter
Calyx – extension of the renal pelvis; they channel urine from the pyramids to the renal pelvis

13. Nephron Glomerulus Bowmans Capsule Afferent arteriole
Special type of network of capillaries
Only oxygenated blood here
Components of blood ill be squeezed out through these capillary walls
FILTRATE
No RBCs or small proteins leave
Bowmans Capsule
C-shaped structure that surrounds the glomerulus
Receives filtrate
Beginning of nephron tubes
Afferent arteriole
Brings blood to glomerulus
Efferent arteriole
Leaves the glomerulus
Leads to there peritubular capillaries (go all around all the tubules of the nephron)

16. Reabsorption = when molecules LEAVE nephron and go back onto blood
Proximal Convoluted Tubule (PCT)
In CORTEX of kidney
Receives filtrate Bowman’s Capsule
Reabsorption of many molecules occurs here
Water, glucose, ions, amino acids
Sodium-Potassium pump important (Na-K)
Co-Transport Symport important (Glucose)
Loop of Henle (LOH)
Dips into MEDULLA
Descending LOH
Water reabsorption
Passive transport of water
Ascending LOH
Ion reabsorption (Na and Cl)
Active transport
Important in osmolarity
Distal Convoluted Tubule (DCT)
Back in CORTEX
Receives filtrate from LOH
More reabsorption
Important in maintaining blood pressure
Collecting Duct
Dips back into MEDULLA and eventually into the PELVIS of kidney
Receives filtrate from MANY DCT
Reabsorption of water
Reabsorption of some UREA (to maintain osmolarity of medulla)

18. How We Make Urine 2 Stages Ultrafiltration Selective Reabsorption
Involves filtering small molecules out of blood and into Bowman’s Capsule
Molecules flow through nephron and to ureter
Selective Reabsorption
When useful molecules (amino acids, glucose. Ions) are taken back from filtrate fluid and into the blood