Control of blood water potential-structure of the nephron Flashcards Preview

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What is osmoregulation?-

-the amount of water and mineral ions we take in varies from day to day, as does the quantity we lose
-table 1 shows the daily balance between loss and gain of salts and water for a typical human
-in the blood, however, an optimum concentration of water and salts is maintainers to ensure a fairly constant water potential of blood plasma and tissue fluid
-the homeostasis control of water potential of the blood is called osmoregulation
-to understand osmoregulation, we must first understand the structure of the organ that carries it out, the kidney and in particular its functional unit - the nephron


What is the structure of the mammalian kidney?

-in mammals there are two kidneys found at the back of the abdominal cavity, one each side of the spinal cord


What is a kidney made up of?

-the fibrous capsule
-the cortex
-the medulla
-the renal pelvis
-the ureter
-the renal artery
-the renal vein


What is a fibrous capsule?

-an outer membrane that protects the kidney


What is a cortex?

-a lighter coloured outer region made up of renal (bowman's) capsules, convoluted tubules and blood vessels


What is a medulla?

-a darker coloured inner region made up of loops or Henle, collecting ducts and blood vessels


What is a renal pelvis?

-a funnel shaped cavity that collects urine into the ureter


What is a ureter?

-a tube that carries urine into the bladder


What is a renal artery?

-supplies the kidney with blood from the heart via the aorta


What is a renal vein?

-returned blood to the heart via the vena cave


What are nephrons?

-a microscopic examination of the cortex and medulla reveals around 1 million tiny tubular. Structures in each kidney
-these are the basic structural and functional units of the kidney - the nephrons


What is the structure of the nephron?

-the nephron is the functional; unit of the kidney
-it is a narrow tube up to 14mm long, closed at one end, with two twisted regions separated by a long hairpin loop


What is each nephron made up of?

-renal (bowman's) capsule
-proximal convoluted tubule
-loop of Henle
-distal convoluted tubule
-collecting duct


What is renal (bowman's) capsule?

-the closed end at the start of the nephron
-it is cup-shaped and surrounds a mass of blood capillaries known as the glomerulus
-the inner layer of the renal capsule is made up of specialised cells called podocytes


What is proximal convoluted tubule?

-a series of loops surrounded by blood capillaries
-its walls are made of epithelial cells which have microvilli


What is a loop of Henley?

-a long hairpin loop that extends from the cortex into the medulla of the kidney and back again
-it is surrounded b blood capillaries


What is distal convoluted tubule?

-a series of loops surrounded by blood capillaries
-its walls are made of epithelial cells, but it s surrounded by fewer capillaries than the proximal tubule


What is the collecting duct?

-a tube into which a number of distal convoluted tumbles from a number of nephrons empty
-it is lined by epithelial cells and becomes increasingly wide as it emptied into the pelvis of the kidney


Which blood vessels are associated with each nephron?

-affront arterial
-efferent arterial
-blood capillaries


What is affront arterial?

-a tiny vessel that ultimately arises from the renal artery and supplies the nephron with blood
-the afferent arteriole enters the renal capsule of the nephron where it forms the glomerulus


What is glomerulus?

-a many branched knot of capillaries from which fluid is forced out of the blood
-the glomerular capillaries recombine to form the efferent arterial
-in mammals the glomerulus is the only capillary bed in which an arterials (the afferent arterial) supplies it with blood and an arterial (the efferent arterial) also drains blood away
-in all other mammalian capillary beds it is a venule that drains away the blood


What is efferent arteriole?

-a tiny vessel that leaves the renal capsule
-it has a smaller diameter than the affront arterial and so causes an increase in blood pressure within the glomerulus
-the efferent arterial carries blood away from the renal capsule and later branches to form the blood capillaries


What are blood capillaries?

-a concentrated network of capillaries that surrounds the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule and from where they reabsorb mineral salts, glucose and water
-these capillaries merge together into venues (tiny veins) hat in turn merge together to form the renal vein