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The Kidney

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11.3.1 Define excretion

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The kidney

• Excretion is the removal from the body of waste products of metabolism

Urea is a waste

product.

Urea is a waste

product.

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Excretion

• Urea is a waste product from the metabolism of amino acids. Each amino acid must be deaminated (lose an amine group).

• It is the job of the kidneys to filter and cleanse the bloodstream of molecules like urea and other molecular wates.

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How do Kidneys work?

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11.3.2 Draw and label the structures of the kidney

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Excretory System filters blood and produces urine.

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The Kidney• Renal artery – takes

blood into the kidney• Renal vein – blood

drains out of the kidney• Renal pelvis – area

where urine collects• Ureter – takes urine to

bladder• Renal medulla –

surrounds renal pelvis

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11.3.3 Annotate a diagram of a glomerulus and associated nephron to show the the function of each part.

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Glomerulus

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Nephron

Kidneys made up of 1.25 million nephrons

Nephron = filtering unitCapillary bed = glomerulus Bowman’s capsule =

surrounds glomerulusProximal convoluted tubuleLoop of HenleDistal convoluted tubule

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11.3.4 Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement membrane

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The kidney is the blood’s filtration and balancing system

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Balancing the Blood

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Nephron

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Nephron

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Ultrafiltration – in the renal capsule

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Explain the process of ultrafiltration. (8 marks)

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Explain the process of ultrafiltration. (8 marks)

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11.3.5 Explain osmoregulation

• Osmoregulation is the control of the water balance of the blood, tissue or cytoplasm of a living organism

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Osmoregulation• Depends on:

– Total volume of water ingested recently as liquid & in solid foods

– Perspiration rate (exercise level & environmental temperature)

– Ventilation rate (breathing rate is largely dependent on exercise level

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11.3.6 Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of microvilli, osmosis and active transport.

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Selective ReabsorptionFiltrate leaving

Bowman’s capsule contain substances body needsWater, salt ions, glucose

Occurs in the proximal convoluted tubule

Returned to bloodstream in peritubular capillary bed

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Selective Reabsorption

Walls of the

prox. conv.

tubule is one cell

thick

Walls of the

prox. conv.

tubule is one cell

thick

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Selective Reabsorption

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Selective Reabsorption

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Selective Reabsorption

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Explain selective reabsorption in the kidney (8 marks)

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Explain selective reabsorption in the kidney. (8 marks)

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11.3. 7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH in maintaining the water balance of the blood

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Loop of Henle

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Loop of Henle

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Loop of Henle/medulla

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Collecting ducts

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Collecting DuctADH = antidiuretic

hormoneADH = antidiuretic

hormone

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Water concentration in the blood

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Explain osmoregulation in the kidney (8 marks)

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Explain osmoregulation in the kidney (8 marks)

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11.3. 8 Explain the differences in the concentration of proteins, glucose and urea between blood plasma, glomerular filtrate and urine

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Tables don’t have to be memorized

Fluids mentioned associated with the following locations.

Blood Plasma =

blood that enters

the glomerulus

originally from the

renal artery & no

filtering or

reabsorption has

yet occurred

Blood Plasma =

blood that enters

the glomerulus

originally from the

renal artery & no

filtering or

reabsorption has

yet occurred

Glomerular filtrate = fluid (now called

filtrate) which enters into the proximal

convoluted tubule after the ultrafiltration process within

Bowman’s capsule. No reabsorption has

occurred.

Glomerular filtrate = fluid (now called

filtrate) which enters into the proximal

convoluted tubule after the ultrafiltration process within

Bowman’s capsule. No reabsorption has

occurred.Urine = fluid which was the filtrate that has now undergone

reabsorption & osmoregulation

mechanisms & is taken to the

bladder

Urine = fluid which was the filtrate that has now undergone

reabsorption & osmoregulation

mechanisms & is taken to the

bladder

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Which nutrients are 100% reabsorbed? Glucose and amino acids

Where does this happen? selective reabsorption in the proximal convuluted tubule

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What is filtered, reclaimed and excreted by the kidney?

The concentration of uric acid is 12.5x greater in the urine than in the filtrate or the blood.How much more concentrated is urea in the urine than in the blood?

Why is such a large proportion of urea and uric acid excreted?

They are very toxic

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What is filtered, reclaimed and excreted by the kidney?

What percentage of the following are forced into the nephron by ultrafiltration?

urea – glucose – inorganic salts - proteins & macromolecules -

100%

100%100%

0%

Why the macromolecule result?

Too large for

ultrafiltration

Too large for

ultrafiltration

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Are there any other components not processed by ultrafiltration?

• Erythrocytes

• Lymphocytes

• platelets

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11.3.9 Explain the presence of glucose in the urine of untreated diabetic patients.

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Diabetes and the Kidney

• Type I : insulin not produced– Liver does not take up glucose from blood

Type II: insulin receptors inactive- Liver does not take up glucose from blood

Results: Blood sugar concentration remains high

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In the Kidney

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Diabetes & the Kidney

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From your heart to the Toilet