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Transcript of The Kidney
Topic 11.3 at this stage the filtrate = hypotonic
If this volume of water were to consistently leave the body as urine, the individual would need a very high water intake - not losing any by any other means... ADH and the collecting duct Appreciation of what happens when blood is filtered by the kidneys 11.3.1- Define excretion
11.3.2- Draw and label the structure of a kidney
11.3.3- Annotate a diagram of a glomerulus and associated nephron to show the function of each part.
11.3.4- Explain the process of ultrafiltration, including blood pressure, fenestrated blood capilaries and basement membrane.
11.3.5- Define osmoregulation
11.3.6- Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of micovilla, osmosis and active transport.
11.3.7- Explain the roles of the loop of Henle, medulla, collecting duct, and ADH in mainting the water balance of the blood.
11.3.8- Explain the differences in the concentrations of proteins, glucose, and urea between blood plasma, glomerular filtrate and urine.
11.3.9- Explain the presence of glucose in the urine of untreated diabetic patients. Topic 11.3
Assessment Statements Function of the kidney:
to filter waste products from the blood. Key Terms Blood Stream-
Acts to supply needed substances to metabolism
Removes molecular waste products from the tissues Metabolism-
All of your collective reactions within your body cells. CONSTANT ADDITION OF WASTE INTO THE BLOOD STREAM (EX. UREA) BLOOD STREAM NEEDS TO BE FILTERED AND CLEANSED 11.3.1 -
Define "Excretion" The removal from the body of the waste products of metabolic pathways THE KIDNEYS 11.3.2 Draw and label the structure of a kidney RENAL ARTERY-
Takes blood into each of the kidneys
Drains blood away from the kidneys
The fluid produced by the kidneys
Urine then goes to the urinary bladder
Layer of tissue around renal pelvis
Layer of tissue around the medulla
Filtering units within the kidney Nephrons ANATOMY OF A KIDNEY (1.25 million in each kindey) COMPONENTS OF A NEPHRON GLOMERULUS-
a capillary bed
filters various substances from the blood
capsule surrounding the glomerulus
a small tube
extends from Bowman's capsule
has parts: Proximal convoluted tubule, loop of Henle and distal convoluted tube.
PERITUBULAR CAPILLARY BED-
a second capillary bed
surrounds the three part tubule above 11.3.3- Annotate a diagram of a glomerulus and associated nephron to show the function of each part 11.3.3- Annotate a diagram of a glomerulus and associated nephron to show the function of each part Why can diabetes lead to the presence of glucose in urine? "100% of the glucose in the filtrate is reabsorbed into the peritubular capillary bed by active transport..." ULTRAFILTRATON Efferent Arteriole Afferent Arteriole BOWMAN'S CAPSULE Filtrate Beginning of Proximal Convoluted Tubule Basement Membrane Glomerulus
(fenestrated capillary bed) 11.3.4- Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries, and basement membrane. Ultrafiltration:
the term used to describe the process by which various substances are filtered through the glomerulus and its fenestrations under the abnormally high blood pressure in this capillary bed. Fluid that is ultrafiltrated through the glomerulus and its fenestrations Passes through the basement membrane
Helps to prevent large molecules from becoming part of the filtrate (ex. proteins) Proximal convoluted tubule Afferent Arteriole brings unfiltered blood plasma into the glomerulus Molecules that did not become part of the filtrate exit Bowman's capsule by the Efferent Arteriole Reabsorption Proximal Convoluted Tubule GLOMERULUS NOW - the filtrate has been filtered, but still contains many substances that the body can not afford to lose in the urine (ex. salt ions, glucose and LOTS of water) These need to be reabsorbed into the blood stream. Several mechanisms are used. 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 Salt-
Not all, but the majority of the salt ions must return to bloodstream.
FIRST actively transported into the tubule cells and THEN into the intercellular fluid. FINAL:LY taken into the peritubular capillary bed.,
Movement of salt induces the movement of water by OSMOSIS.
Hypotonic --> Hypertonic region.
Active Transport of glucose allows for 100% of glucose to be removed from the filtrate. (Diffusion - highest %=50%)
No glucose in the urine = nephrons that function correctly. The Loop of Henle Much of the water from the original filtrate still remains even after the proximal tubule. Osmoregulation 11.3.5 Define Osmoregulation THE BODY'S RESPONSE MECHANISMS WHICH ATTEMPT TO MAINTAIN HOMEOSTATIC LEVELS Total amount of water that leaves the body in urine everyday depends on many physiological factors. a) total volume of water ingested-
or in solid foods.
c) ventilation rate-
breathing rate is largely dependent on exercise level
significant amount of water is lost when we breathe out) permeable to salt ions
impermeable to water permeable to water
impermeable to salt ions Medulla Region
Hypertonic (many ions) 11.3.7- Explain the role of the loop of Henle, medulla, collecting duct and ADH in maintaining the water balance of the blood. 11.3.7- Explain the role of the loop of Henle, medulla, collecting duct and ADH in maintaining the water balance of the blood. the collecting ducts becomes permeable to water
water moves by osmosis out into the medulla region
water then enters the peritubular capillary bed
returned to blood stream collecting ducts become impermeable to water
water stays in collecting duct
leaves in the urine
urine is more dilute Collecting duct - differentially permeable to water ADH - Anti-diuretic hormone
Secreted from the posterior lobe of pituitary gland and circulates the blood stream
FINAL DESTINATION: KIDNEY COLLECTING DUCTS ADH absent ADH present Molecule Amount in blood plasma Amount in glomular filtrate Amount in urine Proteins Glucose Urea >700 in mg 100m/l in mg 100m/l in mg 100m/l 0 0 >90 >90 0 30 30 >1800 11.3.8- Explain the differences in concentrations of proteins, glucose, and urea between blood plasma, glomular filtrate and urine. PROTEINS-
too large to fit through the basement membrane in the glomerulus
Proteins do not become a part of the filtrate.
part of the filtrate
active transport out of the proximal convoluted tube allows for 100% of glucose to return to the blood stream
No glucose in urine.
not toxic unless its concentration is too high in the blood plasma.
high concentration in the urine (compared to proteins and glucose) is due to the reabsorption of water. 11.3.9- Explain the presence of glucose in the urine of untreated diabetic patients. Diabetic's blood sugar level is not being regulated properly Abnormally high levels of glucose dissolved in their blood plasma "high blood sugar"
"Hyperglycaemic" NOT IN DIABETICS Active transport mechanisms have a maximum rate at which they can reabsorb Diabetics = have HIGH LEVELS of glucose in their blood plasma, and then their filtrate...... ... and the mechanisms OVERLOAD and can not reabsorb the glucose and some remains in the urine. Proximal Convoluted Tube Loop of Henle ABSENT PRESENT