Waste removal?!
Question: Waste removal!?
Outline the role of the kidney nephron in the formation of urine!.Www@Answer-Health@Com
Answers:
Nephrons are tiny tubules within the kidney that produce filtrate from the blood and remove waste products as urine!.
Nephrons (Greek nephros=kidney) are renal or kidney tubules!. Each kidney has over one million nephrons that are responsible for removing waste products from blood and maintaining water, salt and pH balance in the body!. This vital job results in the formation of urine!. How the nephrons maintain homeostasis is outlined below!. The structures responsible for specific nephron functions are illustrated in the following image!.
Afferent Arteriole: The afferent arteriole receives blood rich in oxygen from the renal artery!. This blood is transported to the glomerulus of the nephron where it is pressure filtered!.
Glomerulus
The glomerulus (Latin glomus=ball) is a knotted up capillary that contains small pores!. The plasma of the blood and the small molecules contained in plasma are pressure filtered into the Bowman's capsule!. Large blood proteins and formed elements like blood cells and platlets are too big to be pressure filtered and remain in the arteriole!.
Efferent Arteriole The efferent arteriole is smaller in diameter than the afferent arteriole and increases the pressure in the glomerulus aiding pressure filtration!. The blood entering the efferent arteriole is thicker, as plasma has entered the tubule, but still contains oxygen that is moved on to the peritubular network to provide for the metabolic needs of the tubule!.
Bowman's Capsule The filtrate produced in the glomerulus is collected in a bulblike start to the nephron called the glomerular capsule or Bowman's capsule (named for British surgeon Sir William Bowman)!. The plasma and its' dissolved molecules are transported from the Bowman's capsule into the lumen or inside of the nephron!.
Proximal Convoluted Tubule At this point in the nephron, the filtrate from the blood contains both waste molecules like urea and useful molecules like amino acids, glucose, and salt!. The filtering process in the glomerulus is not selective (except by size) so the proximal convoluted tubule works to actively transport nutrients (glucose, amino acids, and salts) back into the blood capillaries so they are not lost in the urine!. The tubule has a brush border with many villi to increase the surface area for this process of selective reabsorption!. The cells of the tubule also contain many mitochondria that produce the ATP required for the large amount of active transport taking place throughout the length of the tubule!.
Loop of Henle The Loop of Henle dips down into the hypertonic environment of the kidney medulla and is responsible for the reabsorption of water from the filtrate!. Water is drawn out of the descending limb of the loop, by osmosis, into the hypertonic medulla of the kidney!. This water can then move into the capillary network and back into circulation to maintain blood volume!. The ascending limb of the loop is impermeable to water and removes salt into the medulla of the kidney adding to the hypertonicity!.
Distal Convoluted Tubule The Distal Convoluted Tubule is the site of tubular secretion!. This process involves the active transport of materials from the blood directly into the tubule!. Examples of molecules that are secreted by the distal convoluted tubule are creatinine, drugs like penicillin, and hydrogen ions!. Tubular secretion of hydrogen ions along with the reabsorption of bicarbonate ions (a biological buffer) acts as a mechanism to control blood pH!.
Peritubular Capillary Network The Peritubular Capillary Network acts as the blood supply to the nephron!. The capillaries provide the nephron with glucose and oxygen to help with ATP production needed for active transport!. The nutrients and water that are reabsorbed by the nephron are taken up by the capillary network surrounding the tubules and carried back to the renal vein and the body!.
Collecting Duct The collecting duct receives filtrate from several nephrons!. The collecting duct will remove varying amount of additional water from the filtrate depending on the hydration state of the individual!. This results in a wide range of urine, from very dilute (lots of water remains) to very concentrated (most of the water was reabsorbed)!. The amount of water reabsorbed is controlled by a hormone called ADH and is the topic of a future lesson!. Once in the pelvis of the kidney the filtrate (now urine) contains substances that were pressure filtered and never reabsorbed such as urea, excess salt, water and other substances that were secreted from the blood such as hydrogen ions, drugs, or creatinine!.Www@Answer-Health@Com
Nephrons (Greek nephros=kidney) are renal or kidney tubules!. Each kidney has over one million nephrons that are responsible for removing waste products from blood and maintaining water, salt and pH balance in the body!. This vital job results in the formation of urine!. How the nephrons maintain homeostasis is outlined below!. The structures responsible for specific nephron functions are illustrated in the following image!.
Afferent Arteriole: The afferent arteriole receives blood rich in oxygen from the renal artery!. This blood is transported to the glomerulus of the nephron where it is pressure filtered!.
Glomerulus
The glomerulus (Latin glomus=ball) is a knotted up capillary that contains small pores!. The plasma of the blood and the small molecules contained in plasma are pressure filtered into the Bowman's capsule!. Large blood proteins and formed elements like blood cells and platlets are too big to be pressure filtered and remain in the arteriole!.
Efferent Arteriole The efferent arteriole is smaller in diameter than the afferent arteriole and increases the pressure in the glomerulus aiding pressure filtration!. The blood entering the efferent arteriole is thicker, as plasma has entered the tubule, but still contains oxygen that is moved on to the peritubular network to provide for the metabolic needs of the tubule!.
Bowman's Capsule The filtrate produced in the glomerulus is collected in a bulblike start to the nephron called the glomerular capsule or Bowman's capsule (named for British surgeon Sir William Bowman)!. The plasma and its' dissolved molecules are transported from the Bowman's capsule into the lumen or inside of the nephron!.
Proximal Convoluted Tubule At this point in the nephron, the filtrate from the blood contains both waste molecules like urea and useful molecules like amino acids, glucose, and salt!. The filtering process in the glomerulus is not selective (except by size) so the proximal convoluted tubule works to actively transport nutrients (glucose, amino acids, and salts) back into the blood capillaries so they are not lost in the urine!. The tubule has a brush border with many villi to increase the surface area for this process of selective reabsorption!. The cells of the tubule also contain many mitochondria that produce the ATP required for the large amount of active transport taking place throughout the length of the tubule!.
Loop of Henle The Loop of Henle dips down into the hypertonic environment of the kidney medulla and is responsible for the reabsorption of water from the filtrate!. Water is drawn out of the descending limb of the loop, by osmosis, into the hypertonic medulla of the kidney!. This water can then move into the capillary network and back into circulation to maintain blood volume!. The ascending limb of the loop is impermeable to water and removes salt into the medulla of the kidney adding to the hypertonicity!.
Distal Convoluted Tubule The Distal Convoluted Tubule is the site of tubular secretion!. This process involves the active transport of materials from the blood directly into the tubule!. Examples of molecules that are secreted by the distal convoluted tubule are creatinine, drugs like penicillin, and hydrogen ions!. Tubular secretion of hydrogen ions along with the reabsorption of bicarbonate ions (a biological buffer) acts as a mechanism to control blood pH!.
Peritubular Capillary Network The Peritubular Capillary Network acts as the blood supply to the nephron!. The capillaries provide the nephron with glucose and oxygen to help with ATP production needed for active transport!. The nutrients and water that are reabsorbed by the nephron are taken up by the capillary network surrounding the tubules and carried back to the renal vein and the body!.
Collecting Duct The collecting duct receives filtrate from several nephrons!. The collecting duct will remove varying amount of additional water from the filtrate depending on the hydration state of the individual!. This results in a wide range of urine, from very dilute (lots of water remains) to very concentrated (most of the water was reabsorbed)!. The amount of water reabsorbed is controlled by a hormone called ADH and is the topic of a future lesson!. Once in the pelvis of the kidney the filtrate (now urine) contains substances that were pressure filtered and never reabsorbed such as urea, excess salt, water and other substances that were secreted from the blood such as hydrogen ions, drugs, or creatinine!.Www@Answer-Health@Com