BSC2086L Lesson 9 PhysioEx 9 - Renal Physiology

How does kidney filter waste products out of our blood?

through the activity of millions of nephrons

How does waste get filtered?

filtration - blood pressure (hydrostatic pressure) 'forces' fluid and dissolved solutes (substances such as glucose, amino acids, ions, waste products, etc) out of the glomerular capillaries and into the Bowman's capsule

How does hydrostatic force work?

What is the relationship between the force and pressure?

hydrostatic force that 'pushes' fluid out of the glomerular capillaries influences the glomerular filtration rate (GFR) of the blood

the higher the pressure, the higher the glomerular filtration rate

How does the nutrients and H2O get reabsorbed?

reabsorption - nutrients (glucose, amino acids, etc) and H2O are reabsorbed by cells in the tubules and ultimately returned to the peritubular capillaries (and back into the circulatory system). The waste products (and some water) are not reabsorbed and stay within the tubules

How does urine become concentrated?

the fluid within the kidney medulla can contain high concentration of solutes (dissolved particles). This causes the interstitial fluid to have a high osmolarity (Omos). As the filtrate passes through the loop of Henle, H2O flows out of the loop of Henle and into the interstitial fluid (surrounding the loop) in the medulla

How does H2O flow?

from a solution that has less solutes to a solution that has more solutes (from an area of lower osmolarity to an area of greater osmolarity)

If you increase the osmolarity of the interstitial fluid surrounding the nephron tubules...

you can 'draw out' even more H2O from the filtrate thus concentrating the urine

What can alter interstitial fluid osmolarity?

certain hormones

How is the glomerular capillary pressure (GCP) and glomerular filtration rate (GFR) adjusted?

by adjusting the afferent or efferent arteriole radius

How does decreasing the radius of the afferent arteriole affect the glomerular capillary pressure (GCP) and glomerular filtration rate (GFR)?

decreases both

How does decreasing the radius of the efferent arteriole affect the glomerular capillary pressure (GCP) and glomerular filtration rate (GFR)?

increases both

During sympathetic activation, the sympathetic nerves innervating the kidneys cause ___________________ (increased/decreased) _________________ production by causing ___________________ (dilation/constriction) of the _____________________ (afferent/efferent) arteriole - less blood reaches the glomerulus and therefore _________ (more/less) blood is filtered which leads to ___________ (more/less) urine production.

If this persists too long, waste products and excess ions will ____________ ______ in blood and affect homeostasis.

decreased; urine; afferent; less; less; build up

If there is an increase in blood pressure, then the glomerular capillary pressure (GCP) and glomerular filtration rate (GFR) will ________________ (increase/decrease).

However, if someone has high blood pressure, the ____________ (high/low) hydrostatic pressure may damage kidney blood vessels and _______________ (increase/reduce) ability to filter ________________.

increase; high; reduce; blood

Blockage of the collecting duct will cause a(n) __________________ (increase/decrease) in hydrostatic pressure in the Bowman's capsule and result in a(n) _______________ (increase/decrease) in the GFR since that fluid pressure will _________________ (assist/oppose) filtration.

increase; decrease; oppose

During low blood pressure conditions, the body can react by ___________________ (dilating/constricting) the _________________ (afferent/efferent) arteriole and ___________________ (dilating/constricting) the _________________ (afferent/efferent) arteriole to maintain the GCP and GFR.

dilating; afferent; constricting; efferent

People with high blood pressure may be prescribed ________________ to cause a(n) ___________________ (increase/decrease) in urine production which with ________________ (increase/reduce) blood plasma volume and blood pressure.

diuretics; increase; reduce

As the solute gradient in the interstitial space is increased, the urine produced becomes _____________ (more/less) concentrated and ___________ (more/less) in volume.

more; less

The interstitial space solute gradient is what ___________ ___________ (pulls in/draws out) water from renal tubule. An increase in the interstitial solute gradient will cause a(n) ___________________ (increase/decrease) in H2O reabsorption (as seen in the juxtamedullary nephrons).

draws out; increase

Diuretics cause a(n) ___________________ (increase/decrease) in urine production. The urine produced is usually ________________ (higher/lower) in solute concentration. Diuretics work by either inhibiting ________________ secretion or by altering the ________________ ___________________ of the interstitial fluid (and thus affect the concentration and volume of the urine produced).

increase; lower; ADH; solute concentration

Organisms (such as deserts rats) living in arid conditions are able to concentrate their urine (and loss ____________ (more/less) H2O during urination) since the interstitial fluid solute gradient is very _________ (high/low).

less; high

Glucose is filtered out during the filtration process, but in a non-diabetic person, there are ________________ glucose carriers in the proximal convoluted tubules for the reabsorption of all the glucose in the filtrate.

In a diabetic that cannot regulate their blood glucose levels, ____________ (high/low) amounts of glucose might be found in blood. This will cause a(n) ___________________ (increase/decrease) in the amount of glucose filtered out at the glomerulus.

sufficient; high; increase

If there are excessive amounts of glucose in the filtrate, there will not be enough ________________ for the reabsorption of all the glucose in the filtrate. This will result in the presence of glucose in _____________.

carriers; urine

The addition of aldosterone and ADH to the distal convoluted tubule and collecting duct will cause a(n) ___________________ (increase/decrease) in urine volume.

decrease

In the presence of just aldosterone, urine volume ___________________ (increases/decreases) _______________ (slightly/significantly). The urine concentration _________________ (was/was not) affected.

In the presence of ADH, urine volume ___________________ (increases/decreases) _______________ (slightly/significantly). The urine concentration _________________ (was/was not) affected.

decreases; slightly; was not; decreases; significantly; was (significantly concentrated)

Ethanol consumption causes a(n) ___________________ (increase/decrease) in urine production by inhibiting ________________________ (ADH/aldosterone) release. Therefore ______________ (more/less) dilute urine is produced.

increase; ADH; more

People suffering from hypertension may be given ______________________ ___________________ enzyme inhibitors to ___________________ (increase/decrease) urine production which reduces blood volume and blood pressure. Remember, this enzyme converts ___________________ ______ to __________________ _____ which activates aldosterone and ADH. Therefore the enzyme inhibitor will inhibit aldosterone and ADH release.

angiotensin converting; increase; angiotensin I; angiotensin II