Liver removes amine groups from proteins

Called deamination Ammonia is a highly toxic by-product...

0.005mg can kill a human!! Liver combines Ammonia and CO2 to form

Urea. Uric Acid is formed by the breakdown of

nucleic acids. See page 342

Anatomy of the Urinary System

Kidneys(urine formation)

Lower Urinary TractUreters (2)Bladder (1)Urethra (1)

(urine collection, storage, excretion)

Filters blood and removes cellular waste products.

Also a major homeostatic organ. They control water balance, pH and levels

of sodium, potassium, bicarbonate and calcium ions in the blood.

Secrete erythropoietin...a hormone that stimulates red blood cell production and they activate vitamin D production in the skin

3 sections – Cortex, Medulla and Pelvis Within the Cortex and Medulla are ~1million

Nephrons. Nephrons -

-Bowman’s capsule, proximal tubule, loop of Henle, distal tubule & collecting duct.

Each nephron is surrounded by cells and a network of blood vessels

By controlling what stays & leaves in the nephrons, the kidneys keep levels of water, ions and other materials constant within the limits necessary to maintain homeostatis.

CortexGlomeruli

MedullaRenal tubules

UreterTakes urine to bladder

Blood carried to the kidney by the renal

artery and taken away by the renal vein.

Cortex

Medulla

Renal artery

Renal vein

Renal pelvis

Ureter

Renal hilum

Each nephron consists of a:GLOMERULUS (found in cortex)

forms a protein-free filtrate from bloodTUBULE (found in medulla)

processes the filtrate to form urine

Each TUBULE consists of several segments:Proximal tubuleLoop of HenleDistal Tubule

Collecting Ducts.

Functional Unit of the Kidney is the NEPHRON

Glomerulus (inside Bowman’s capsule)

Proximal Tubule

Loop of Henle

Distal Tubule

Collecting Duct

http://www.youtube.com/watch?v=aQZaNXNroVY&feature=related

P 345 #1-3 P348 #1-4

Is accomplished by movement of fluids from blood into Bowman’s capsule. Each nephron of kidney has its own blood

supply Materials move from high [ ] to low [ ]

generally

Involves the transfer of essential solutes and water from the nephron back to the blood About 600mL fluid flows through kidneys every minute About 20% filtered into nephrons 1mL of urine formed for every 120mL of fluid filtered

into nephron (remainder reabsorbed) selective Reabsorption both active and passive carrier molecules move Na+ ions over across cell

membranes of cells which line the nephron Negative ions (Cl-, HCO3

-) follow Na+ by charge attraction

Excess NaCl remains in nephron and excreted in urine when reabsorption reaches the threshold level (max amount of material that can be moved across the nephron.

Proteins in the bloodstream draw water from the interstitial fluid (fluid that surrounds the body cells) into the blood

Involves movement of materials from blood back to nephron N-containing wastes, excess H+ ions, and

minerals such as K+ are examples of substances secreted

Even drugs (e.g. penicillin) can be secreted Molecules are shuttled (active tran) from

blood to nephron

http://www.sumanasinc.com/webcontent/animations/content/kidney.html

Involves the interaction of the body’s two communication systems Nervous system Endocrine system

Antidiuretic hormone (ADH) helps regulate osmotic pressure of body fluids

by causing kidneys to increase water reabsorption

when ADH released, more concentrated urine is produced (therefore conserving water)

ADH produced by hypothalamus and moves to pituitary gland (via specialized fibres) which stores and releases ADH into blood

Osmoreceptors located in hypothalamus detect changes in osmotic pressure Decrease of water [ ] causes blood solutes to

increase in [ ], thereby increasing blood’s osmotic pressure Water then moves into bloodstream causing

hypothalamus cells to shrink and sensation of thirst Causes signalling the release of ADH from pituitary,

carried by bloodstream to kidneys Kidneys reabsorb more water, thereby creating

more concentrated urine, preventing increase of osmotic pressure of body fluids.

If sensation of thirst causes intake of water, if more water is taken in, it is absorbed by blood and [ ] of solutes in blood decreases.

Greater amount of H2O taken in, lower osmotic pressure of blood.

Blood becomes more dilute, fluids move to hypothalamus cells and they swell.

Nerve messages to pituitary stop. Less ADH released, less H2O reabsorbed from

nephrons.  

Dec. Blood pressure or blood volume (from dehydration, blood loss) can cause a reduction in the delivery of oxygen nutrients to tissues.

Blood pressure receptors in the Juxtaglomerular Apparatus (found near the glomerulus) detect this low BP

Specialized cells in the J.A. then release Renin

Renin is an enyme that converts Angiotensinogen (a plasma Protein produced by the liver) into Angiotensin (active form)

Angiotensin causes constriction of blood vessels; this increases Blood Pressure.

It also stimulates the release of Aldosterone (from the Adrenal Glands above each kidney)

It acts on the Nephrons to increase Na+ reabsorption

This increases the osmotic gradient, so water moves out of the Nephron by osmosis back into the bloodstream.

This increase Blood Volume

Kidneys maintain pH balance pH of human body remains relatively

constant (7.3-7.5) pH may lower during Cell Resp – Acids

produced Acid-base balance maintained by buffer

systems that absorb excess H+ ions. Buffer systems maintain Acid-Base

balance

Bicarbonate ions buffer excess H+ ions, producing carbonic acid

Carbonic acid is a weak acid that breaks down into CO2 and goes to the lungs and is exhaled.

This rxn is reversed in the kidneys CO2 is actively transported from capillaries into

the cells that line the nephron. Here CO2 combines with water to initiate the

reverse rxn generating HCO3- H+ ions

The ions diffuse back into the blood, restoring the buffer

The H+ ions left recombine with the phosphate ions or ammonia and are excreted with the nephric filtrate

Make short note on...1. Diabetes Mellitus2. Diabetes Insipitus3. Bright’s Disease4. Kidney Stones5. Dialysis Technology6. Kidney Transplants and Xenotransplants

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