C4. The Kidneys Flashcards
Excretion of waste products
Blood enters the _____through the ______artery and then passes through ___________in the ______(outer layer) of the kidneys. As the blood passes through capillaries in the cortex, substances are ___________out of the blood and into _____ __________that surround the capillaries. This process is called ________________. Useful substances, such as __________and the right amount of water, are then __________________back into the blood. This process is called _______reabsorption. The remaining unwanted substances pass along to the __________and are ___________as urine.
Blood enters the kidney through the renal artery and then passes through capillaries in the cortex (outer layer) of the kidneys. As the blood passes through capillaries in the cortex, substances are filtered out of the blood and into long tubules that surround the capillaries. This process is called ultrafiltration. Useful substances, such as glucose and the right amount of water, are then reabsorbed back into the blood. This process is called selective reabsorption. The remaining unwanted substances pass along to the bladder and are excreted as urine.
Figure 1: Diagram to show the location of the kidneys - with the gross structure of the kidneys, their blood vessels and the bladder enlarged.
The nephrons
The long tubules along with the bundles of ___________where the blood is ___________are called nephrons- there are around one million nephrons in each kidney.
The long tubules along with the bundles of capillaries where the blood is filtered are called nephrons- there are around one million nephrons in each kidney.
Ultrafiltration PT1
Blood from the _____ artery enters ________ __________in the ________of the kidney. Each ____________splits into a structure called a ____________, a bundle of capillaries looped inside a hollow ball called a ____________ __________.This is where ultrafiltration takes place.
Ultrafiltration PT1
Blood from the renal artery enters smaller arterioles in the cortex of the kidney. Each arteriole splits into a structure called a glomerulus (plural, glomeruli) a bundle of capillaries looped inside a hollow ball called a Bowman’s capsule. This is where ultrafiltration takes place.
Ultrafiltration PT2
The arteriole that takes blood into each _______________is called the ____________arteriole, and the arteriole that takes the filtered blood away from the glomerulus is called the _____________arteriole. The efferent arteriole is __________in diameter than the afferent arteriole, so the blood in the glomerulus is under ____pressure. The high pressure forces liquid and small molecules in the blood out of the capillary and into the __________ _________.
The liquid and small molecules pass through three layers to get into the Bowman’s capsule and enter the nephron tubules-the _________ _____________, the _____________ ______________ and the _____________of the Bowman’s capsule
Ultrafiltration PT2
The arteriole that takes blood into each glomerulus is called the afferent arteriole, and the arteriole that takes the filtered blood away from the glomerulus is called the efferent arteriole. The efferent arteriole is smaller in diameter than the afferent arteriole, so the blood in the glomerulus is under high pressure. The high pressure forces liquid and small molecules in the blood out of the capillary and into the Bowman’s capsule.
The liquid and small molecules pass through three layers to get into the Bowman’s capsule and enter the nephron tubules-the capillary endothelium, the basement membrane and the epithelium of the Bowman’s capsule
Ultrafiltration PT3
Larger molecules like _________and _______cells can’t pass through so stay in the _______. The substances that enter the Bowman’s capsule are known as the ____________ _________. The glomerular filtrate passes along the rest of the _________and useful substances are _____________along the way. Finally, the filtrate flows through the ____________ ______and passes out of the kidney along the ________.
Ultrafiltration PT3
Larger molecules like proteins and blood cells can’t pass through so stay in the blood. The substances that enter the Bowman’s capsule are known as the glomerular filtrate. The glomerular filtrate passes along the rest of the nephron and useful substances are reabsorbed along the way. Finally, the filtrate flows through the collecting duct and passes out of the kidney along the ureter.
Figure 3: The location and structure of one nephron. Ultrafiltration takes place in the glomerulus and Bowman’s capsule (highlighted in blue).
Ultrafiltration - in 4 steps
1) Blood from the renal artery passes through smaller arterioles in the cortex
2) The blood flows into the afferent arteriole and then through the efferent arteriole which forces out molecules as it puts it under pressure from the smaller diameter and forces small molecules into the Bowman’s Capsule
3) The filtered blood passes through the bowmans capsule where larger molecules like proteins and blood cells can’t pass through as it goes through the bowman’s capsule epithelium, the basement membrane and the capillary endothelium
4) This is now called the glomeular filtrate and use substances are reabsorbed along the way and it passes through the collecting duct
Figure 4: Diagram to show the three layers separating the glomerular capillary and the Bowman’s capsule.
Figure 5: Diagram to show the structure of one nephron. Selective reabsorption takes place in the areas highlighted in yellow.
Selective reabsorption PT1
Selective reabsorption of useful substances takes place as the _____________ _________flows along the ____________convoluted tubule (_CT), through the loop of ________, and along the _______convoluted tubule (_CT)—see Figure 5. Useful substances leave the tubules of the ____________and enter the __________network that’s wrapped around them.
Selective reabsorption PT1
Selective reabsorption of useful substances takes place as the glomerular filtrate flows along the proximal convoluted tubule (PCT), through the loop of Henle, and along the distal convoluted tubule (DCT)—see Figure 5. Useful substances leave the tubules of the nephrons and enter the capillary network that’s wrapped around them.
Selective reabsorption PT2
The epithelium of the wall of the ____has ____________to provide a large surface area for the reabsorption of useful materials from the ___________ _________(in the tubules) into the blood (in the capillaries). Useful solutes, like ________, are reabsorbed along the ___by _______transport and _____________ __________.
Selective reabsorption PT2
The epithelium of the wall of the PCT has microvilli to provide a large surface area for the reabsorption of useful materials from the glomerular filtrate (in the tubules) into the blood (in the capillaries) -. Useful solutes, like glucose, are reabsorbed along the PCT by active transport and facilitated diffusion.
Selective reabsorption PT3
Water enters the ________by _________because the water potential of the blood is _______than that of the ________. Water is ___________from the ___, loop of __________, ___and the ___________ ______.The filtrate that remains is ______, which passes along the ureter to the ___________.
Selective reabsorbtion PT3
Water enters the blood by osmosis because the water potential of the blood is lower than that of the filtrate. Water is reabsorbed from the PCT, loop of Henle, DCT and the collecting duct. The filtrate that remains is urine, which passes along the ureter to the bladder.
Selective Reabsorption - in 3 steps
1) The proximal convoluted tubule has microvilli to increase surface are so useful solutes like glucose can be reabsorbed via active transport and facilitated diffusion
2) Water moves from filtrate to blood via osmosis as blood has a lower water potential
3) Water is reabsorbed from the convoluted tubules, the collecting duct and the Loop of Henle and the rest is urine
Tip: The cells that make up the epithelium of the Bowman’s capsule are called…
podocytes
Figure 7: Epithelial wall of the proximal convoluted tubule (PCT).
