topic 11: human health and physiology 11.3 the kidney
TRANSCRIPT
11.3.1 Define excretion
11.3.2 Draw and label a diagram of the kidney
11.3.3 Annotate a diagram of a
glomerulus and associated nephron to
show the function of each part
11.3.4 Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement membrane
11.3.5 Define osmoregulation
11.3.6 Explain the reabsorption of
glucose, water and salts in the proximal
convoluted tubule, including the roles of
microvilli, osmosis and active transport.
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water balance of the blood
11.3.8 Explain the difference in the
concentration of proteins, glucose and
urea between the blood plasma,
glomerular filtrate and urine
11.3.9 Explain the presence of glucose in untreated diabetic patience
11.3.1 Define excretion
11.3.5 Define osmoregulation
Excretion - the removal of waste products that are a result of metabolic processes • characteristic of all living things
Osmoregulation - The control of water balance of the blood, tissue and cytoplasm of an organism
Water moves from the filtrate into the body tissue in two places• The Loop Henle – through
osmosis• The collecting duct –
hormonally controlled
11.3.3 Annotate a diagram of a glomerulus and associated nephron to show the function of each part
afferent vessel – takes blood to the glomerulus
efferent vessel – takes blood away from the glomerulus
glomerulus – performs ultrafiltration
Bowman's capsule – receives the filtrate from the glomerulus
proximal convoluted tubule – the location of most of the reabsorption of water, glucose and salt
Loop of Henle – location of the reabsorption water and transport of salts
distal convoluted tubule – the reabsorption of salt
collecting duct – reabsorption of urea, salt and water. Regulated by the hormone ADH
11.3.4 Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement
membrane
The main purposes of the nephron are: • Ultrafiltration • Selective reabsorption• secretion
Ultrafiltration • in the glomerulus, water and small useful molecules
(glucose, amino acids, ions) are forced out of the capillaries and into the lumen of the bowman’s capsule
• The force is cause by blood pressure because the afferent capillary (input) is larger than the efferent capillary (output).
11.3.4 Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement
membrane
The capillaries are called fenestrated capillaries because they have small holes to allow some substances to pass through• Glucose, water, salts, urea, amino acids
and proteins CAN pass through• Erythrocytes, leucocytes and platelets
CANNOT pass through
There is a second layer called the basement membrane and the third layer is composed of cells called podcytes. They are also fenestrated
This is the second level of filtration and do not let larger plasma proteins to pass into the filtrate.
The filtrate continues through the nephron where selective reabsorption occurs.
11.3.6 Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of microvilli,
osmosis and active transport. The fluid in the proximal convoluted tubule is very similar to the blood plasma (glucose, amino acids, vitamins, hormones, urea, salt, ions and water)
Most reabsorption takes place here
All of the following are reabsorbed into the blood: • Glucose • Hormones • amino acids • Vitamins • Water• Salts
11.3.6 Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of microvilli,
osmosis and active transport. Osmosis is the force that allows water to be reabsorbed • It follows the active transport of
glucose and Na+ • Glucose and amino acids follow by
co-transport • Cl- is passively transported
There are many mitochondria to supply the energy needed for active transport
The interior of the proximal convoluted tubule contain microvilli to increase surface area and to maximize reabsorption
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodLoop of Henle
The Loop of Henle consists of the descending and ascending limb
In the descending portion of the loop of Henle water exits the nephron by osmosis due to the increasing concentration of salt.
The walls of the descending limb are impermeable to Na+
This water is immediately passed into the capillaries and taken from the kidneys
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodThe ascending limb of the loop of Henle is impermeable to water
Salt is passed into the medulla from the filtrate by active transport
The amount of salt that is actively transported in the ascending limb is more than diffuses into the descending limb
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodThe salt remains in the medulla in this area of the loop of Henle to maintain the concentration gradient in the medulla
The filtrate that leaves the loop of Henle is less concentrated than the tissue in the medulla
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodMedulla
The concentration gradient of the medulla is maintained by “vasa recta countercurrent exchange”
There is no direct exchange between filtrate and blood, but instead, the substances pass through the interstitial region of the medulla
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodCollecting duct
Collecting duct is where the water content of the blood is regulated by the hormone ADH (antidiuretic hormone).
When water content in the blood is low antidiuretic hormone (ADH) is secreted from the posterior lobe of the pituitary gland
When water content is high no ADH is secreted
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodCollecting duct
Collecting duct is where the water content of the blood is regulated by the hormone ADH (antidiuretic hormone).
The walls of the collecting duct are variably permeable caused by the presence of ADH
When water content in the blood is low (you’re thirsty) antidiuretic hormone (ADH) is secreted from the posterior lobe of the pituitary gland. Aquaporin channels in the cells of the
collecting duct open and allow water to enter back into the blood (keep blood in your body)
11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water
balance of the bloodWhen water content is high (you drank too much water) no ADH is secreted by the pituitary gland
A large amount of dilute urine is formed
If you drink too much alcohol it suppresses ADH secretion and you have to pee.
11.3.8 Explain the difference in the concentration of proteins, glucose and urea between the blood plasma, glomerular
filtrate and urine
The composition of our urine is very variable depending on things like diet, exercise, environmental conditions, etc...
However, blood must stay at a constant composition
11.3.8 Explain the difference in the concentration of proteins, glucose and urea between the blood plasma, glomerular
filtrate and urine
Blood
Blood in the renal artery contains more salts, urea and sometimes water than is necessary
Blood leaving the kidney from the renal vein contains optimum amounts of water, salts, and little urea
11.3.8 Explain the difference in the concentration of proteins, glucose and urea between the blood plasma, glomerular
filtrate and urine
Glomerular filtrate
Similar to blood plasma minus the large proteins
11.3.8 Explain the difference in the concentration of proteins, glucose and urea between the blood plasma, glomerular
filtrate and urine
Urine
Urine contains less water, less salt and no proteins, no glucose and no amino acids
But contains more urea than the glomerular filtrate