F. Kidney and the control of water balence Flashcards
What is the homeostatic control of water potential of the blood called
Osmoregulation
What is the structure that carries out osmoregulation
Nephron
Describe the structure of the mammalian kidney
- fibrous capsule
- cortex
- medulla
- renal pelvis
- ureter
- renal artery
- renal vein
What does renal mean
Relating to the kidney
What is the fibrous capsule
Outer membrane that protects the kidney
What is the cortex
Lighter coloured outer region made up if renal (Bowman’s capsule), convoluted tubles and blood vessels
What is the medulla
Darker coloured inner region made up of loops of Henle, collecting ducts and blood vessels
What is the renal pelvis
A funnel shaped cavity that collects urine into the ureter
What is the ureter
A tube that carries urine to the bladder
What is a renal artery
Supplies the kidney with blood from the heart via the aorta
What is the renal vein
Returns blood to the heart via the vena cava
Describe the structure of the nephron
- renal (Bowman’s) capsule
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubule
- collecting duct
What is a renal (Bowman’s capsule)
- the closed end at the start of the nephron
- cup shaped and surrounded by a mass of blood capillaries (the glomerulus)
- inner renal capsule is made of specialised cells called podocytes
What is a proximal convoluted tubule
- series of loops surrounded by blood capillaries
- walls made of epithelial cells which have microvilli
What is the loop of Henle
- long hairpin loop that extends from the cortex into the medulla of the kidney and back again
- surrounded by blood capillaries
What is the distal convoluted tubules
- series of loops surrounded by blood capillaries
- walls made of epithelial cells but less than the proximal tubule
What is the collecting duct
- tube into which a number of distal convoluted tubules from a number of nephrons empty
- lined by epithelial cells and becomes increasingly wide as it empties into the pelvis of the kidney
Name all the blood vessels associated with a single nephron
- afferent arteriole
- glomerulus
- efferent arteriole
- blood capillaries
What is an afferent arteriole
- tiny vessel that ultimately arises from the renal artery
- supplies the nephron with blood
- the afferent arteriole enters the renal capsule of the nephron where it forms the glomerulus
What is the glomerulus
- a many branched knot of capillaries from which fluid is forced out of the blood
- the glomerular capillaries recombine to form the efferent arteriole
What is the efferent arteriole
- tiny vessel that levels the renal capsule
- smaller diameter than the afferent arteriole so causes an increase in blood pressure within the glomerulus
- efferent arteriole carries blood away from the renal capsule and later branches to form the blood capillaries
What is the blood capillaries (within the nephron)
- concentrated network of capillaries that surrounds the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule
- from where they reabsorb mineral salts, glucose and water
- these capillaries merge together into venules (tiny veins) that in turn merge together to form the renal vein
Name an important function of the kidney
To maintain the water potential of plasma and hence tissue fluid (osmoregulation)
Name the series of stages of osmoregulation as carried out by the nephron
- the formation of glomerular filtrate by ultrafiltration
- reabsorption of glucose and water by the proximal convoluted tubule
- maintenance of a gradient of sodium ions in the medulla by the loop of Henle
- reabsorption of water by the distal convoluted tubule and collecting ducts
Describe the steps in the formation of glomerular filtrate by ultrafiltration
- blood enters kidney through renal artery which branches into many afferent arterioles
- each of which enters a renal (Bowman’s capsule) of a nephron
- walls of glomerular capillaries are made of endothelial cells with pores between them
- diameter of afferent arteriole is bigger than the efferent arteriole
- meaning there is a build up of hydrostatic pressure within the glomerulus
- water, glucose and mineral ions are squeezed out of the capillary to form the glomerular filtrate