The Nephron HSC Biology Maintaining a Balance Syllabus
The Nephron HSC Biology: Maintaining a Balance Syllabus link: explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition BEGIN
Instructions and notes The nephron is one of the more difficult concepts to understand in the Maintaining a Balance module of the HSC Biology course. This resource is designed to build upon your knowledge of the kidney, test your understanding of the nephron and be used as a study tool for your exams. Work through the questions slowly and don’t cheat – it’s not going to help you understand the concept! NEXT
Nephrons There about ________ in each mammalian kidney 10 000 nephrons 100 000 nephrons 1 000 nephrons 2 000 nephrons
Formation of urine The nephron is a small filtering unit in which urine is produced. The three processes in the formation of urine are: filtration, reabsorption and secretion. The kidneys process a large amount of blood, but produce a relatively small amount of urine. NEXT
BOM CHICKA WOW Excellent! There about one million nephrons in each kidney. NEXT
Errr… Not quite. Try re-watching the videos or check your textbook! TRY AGAIN
Label the nephron A H G D B E C F Label A, B & C Label D, E & F Label G & H
Label the nephron The parts of the nephron labelled A, B and C, respectively, are: Bowman’s capsule, distal convoluted tubule, collecting duct Bowman’s capsule, proximal convoluted tubule, collecting duct Glomerulus, loop of Henle, urethra Return to diagram
Ohh yeah! On to the next one…
Not quite… Try again!
Label the nephron The parts labelled D, E and F, respectively, are: Bowman’s capsule, loop of Henle, distal convoluted tubule Bowman’s capsule, proximal convoluted tubule, loop of Henle Glomerulus, loop of Henle, collecting duct Glomerulus, proximal convoluted tubule, loop of Henle Return to diagram
Ohh yeah! On to the next one…
Not quite… Try again!
Label the nephron The parts labelled G and H, respectively, are: Afferent arteriole, efferent arteriole Affluent arteriole, efferent arteriole Efferent arteriole, afferent arteriole Efferent duct, afferent duct Return to diagram
Not quite… Try again!
Finito! (except not)
Filtration, Reabsorption and Secretion Filtration is the removal of wastes from blood and other fluids through a semi permeable membrane. Reabsorption is an active process that requires energy. It is the movement of materials being reabsorbed into the blood. Secretion is: The body actively transporting substances from the nephron into the blood The body actively transporting substances from the blood into the nephron
Not quite… (Hint: It’s the other one)
Ohh yeah! On to the next one…
Blood comes to the kidneys via the: Renal vein Renal artery The ______ arteriole brings blood to the glomerulus. Efferent Afferent
One down… one to go!
Not quite. (Hint: it’s the other one)
Ohh yeah! On to the next one…
Not quite. (Hint: it’s the other one)
The Glomerulus The glomerulus is a ball of capillaries in which blood pressure is so high that some of the liquid from the blood is forced through the walls of the blood vessels into the Bowman’s capsule. This liquid does not have: Blood cells Sodium chloride (Na. Cl) Large proteins Blood cells AND large proteins
Not quite. Let’s give it another whirl!
Great work! The filtrate should not contain large proteins or blood cells but does contain: - Blood plasma - Water - Solutes: Na. Cl, K+, HCO 3 - Glucose and amino acids - Other ingested substances like penicillin and aspirin - Hormones - Nitrogenous waste products such as urea NEXT
Proximal tubule Reabsorption is an active process that requires energy. Click on the different substances to see if they are secreted into the nephron or reabsorbed into the blood. Amino acids Glucose K+ Drugs e. g. aspirin Water Na. Cl Bicarbonate ions Hydrogen ions NEXT
Amino acids are actively transported into transported from the proximal tubule into the blood. This is reabsorption. BACK
Glucose is actively transported into transported from the proximal tubule into the blood. This is reabsorption. BACK
As salt moves out of the tubule, water passes by osmosis back into the blood. This is reabsorption. BACK
Sodium ions are actively transported back into the blood and chloride ions follow passively. This is absorption. BACK
Most of the bicarbonate ions are actively reabsorbed in the proximal tubule. Some hydrogen ions may be secreted in order to keep the constant p. H of blood and body fluids. BACK
Drugs such as aspirin and penicillin and poisons identified by the liver are actively secreted into the tubule. BACK
Some hydrogen ions are secreted into the proximal tubule. This is done to maintain the constant p. H of blood and body fluids BACK
Potassium ions are actively transported into the blood. This is absorption. BACK
Reabsorption checkpoint Surrounding each tubule is a large capillary network. As the filtrate travels through the tubules and the loop of Henle, the substances that the body can re-use are reabsorbed into the blood. These substances include glucose, amino acids, vitamins, minerals, bicarbonate and water. NEXT
Loop of Henle The loop of Henle has a descending and an ascending limb. The walls of the loop of Henle are permeable to water but not to salt. Water passes across the membrane by: Diffusion Osmosis
Ohh yeah! On to the next one…
Not quite. (Hint: it’s the other one)
Loop of Henle In the ascending portion of the loop of Henle, the walls are permeable to salt not water. Salt passes out passively across a thin-walled section and then ______ across a thick-walled section. _______ is: actively passively
Ohh yeah! On to the next one…
Not quite. (Hint: it’s the other one)
Loop of Henle What part of the kidney does the loop of Henle mostly sit? cortex medulla pyramid pelvis Source: http: //www. comprehensive-kidney-facts. com/kidney-anatomy. html
Ohh yeah! On to the next one…
Not quite. Let’s try again, shall we?
Loop of Henle As water is removed from the loop of Henle in the descending limb, the concentration of salt in the medulla: Decreases Increases As salt is removed from the loop of Henle in the ascending limb, the concentration of salt: Decreases as it moves towards up to the cortex Increases as it moves up towards the cortex
BOO YAH! On to the next one. . .
Not quite. (Hint: it’s the other one)
Ohh yeah! NEXT!
Not quite (Hint: it’s the other one)
Source: http: //www. colorado. edu/intphys/iphy 3410 saul/resources/kidney. html As you can see in the diagram above, the concentration of salt is high in the bottom of the loop of Henle in the medullary region of the kidney. This is called an osmolarity gradient, where the solute concentration (sodium and urea in this case) increases from the cortex down to the inner medulla. NEXT
Distal tubule In the distal tubule, the p. H of the blood and the level of salts, in particular sodium and potassium, are adjusted by selective absorption and secretion. In the distal tube, small amounts of Na. Cl and H 2 O are reabsorbed and K+ and H+ ions are secreted. NEXT
Collecting Duct The collecting duct transports urine to the pelvis of the kidney which leads to the ureter. The walls of the collecting duct are permeable to water, but not salt which results in water passing out of the duct by osmosis. Urea and salt is also actively reabsorbed in the duct. This results in the formation of of urine. NEXT
FIN! Questions to ask yourself: • What do I know? • Where are the gaps in my knowledge? What do I need to study in order to understand this concept? This is a resource for you! So feel free to change it up, add things in and build upon your knowledge. This could be a very useful study tool for you!
- Slides: 55