And then Pantagruel had a sudden, urgent need to piss. and he pissed all over their camp, so thoroughly and in such quantities, that his private and personal flood drowned everyone for ten miles around.
Francois Rabelais - Gargantua and Pantagruel

Excretion

Assignment

Audesirk, Audesirk & Byers Chapter 35

Today's musical selection
Frank Zappa and the Mothers of invention, Don't eat the yellow snow

Kidneys, transplantation, dialysis

Figure E35-2
Consider the work of the kidneys
Dialysis10 hr 2 times per week

Figure (chapter opener)
This is why transplant important, and there is difficulty getting a compatable donor

In the 1978 thriller movie Coma, unscrupulous doctors harvest organs from the amazing number of patients they have who slip into a coma for seemingly unexplained reasons.

Cell makes wastes go to plasma
heart pumps 7000 l/day (32 55 gal drums)
1/4 (8 55 gal drums) through kidneys
Glomerulus - Bowman's capsule 180 l/day filter
1 l urine/day

Osmoregulation

(for ions)
Hypertonic (concentrated), isotonic, hypotonic (dilute)
Nitrogenous waste is from catabolism of amino acids and nucleotides
Water animals - nitrogenous waste can be ammonia (toxic)

Comparative biology

Figure 35-1
There is a tradition in undergraduate biology to emphasize comparative aspects:
("nephron" is the term for "higher" organisms)
Protonephridia in planaria
earthworm has nephrostome with nephridiopore in each segment in close juxtaposition with vascular system.
Insect Malpighian tubule puts out uric acid and rectum recovers water and other molecules

Figure 35-8
Freshwater fish - gills leak water in, pump salt in, TRANSPARENCY Fig. 44.14 dilute urine
Salt water fish, gills lose water- pump salt out through gills, not much urine
(When we get to neurons, we will see how universal ion pumping is.)
Salmon (which move from fresh to salt to fresh water) must adapt
Cartilagenous fish keep urea in blood for equal tonicity- need to dialyse meat for preparation
Marine birds - nasal salt gland

Figure 35-9
Kangaroo rat - metabolic water, hypertonic urine
Uric acid (birds, reptiles, insects)

Nitrogen - An integrative story

Although 78% of the atmosphere is nitrogen in the form of N2, this is fairly unreactive.
Thus there are these important processes: N2 to NH3 nitrogen fixation, NH3 to NO3- (nitrate) nitrification, NO3 to NH3 (nitrate reduction) in plant roots.
Also nitrogen is recycled.
In Pacific, off the coast of Peru, the Humbolt current causes an upwelling of nutrients, anchovies thrive, bird droppings (guano) were used as fertilizer.
El Nino (the Child, named not for misbehavior but because it comes near Christmas) is a periodic climate misbehavior that disrupts this.


Human

Figure 35-3
kidney, ureter, bladder, urethra

Figure 35-4
Pelvis=basin; Medulla=marrow; Cortex=bark ("medulla" and "cortex" are terms used a lot, like in brain and in adrenal gland)
many blood vessels - kidney is supplied by major blood vessels
Renal artery and vein branches near eachother

Figure 35-5
each kidney has 1 million nephrons
Blood flow in glomeruli
Glomerulus - Bowman's capsule filter 180 l/day (throwing out the baby with the bath water)
blood and osmotic pressures drive
Glomerulus - capillaries a sieve
here is a picture from the histology course
another picture highlights glomerulus by dye injected into artery
large molecules dye do not pass
- small molecules dye passes through
blood proteins and cells do not pass
urinalysis strips test if blood, cells or protein is present

Figure 35-6
Need for resorption
Proximal Convvoluted tubule - bring back amino acids, glucose note active (NaCl) vs passive (water) transport

Figure E35-1
Na pump
6% of body's energy at rest
Countercurrant system
Ascending loop - salt resorbed but not water
Ascending loop of Henle - salt outward resorption is stimulated by aldosterone

Figure 35-7
ADH (vasopressin) makes water follow back into interstitial fluid which is hypertonic from salt
alcohol and caffeine inhibit ADH, hence diuresis (excessive urination)
regulation of ADH (from hypothalamus to pituitary) and relation to thirst

Posterior pituitary

Figure 37-8
(related to kidney coverage)
neurosecretion from hypothalamus (peptides)
oxytocin (milk, delivery)
(synthetic to induce labor)

Figure
Chapter 38 case study ("How do I love thee?")
hormones involved in love, oxytocin called the trust hormone

Covered in Excretion lecture: ADH action on kidney
vasopressin (ADH), H2O and blood pressure
alcohol, caffein inhibit anti [diuresis] hormone

Summary

Filter, resorb (salt and water)
Sweat pores not as good -which is why gatorade tastes good to athletes
especially bad in cystic fibrosis (salty sweat) molecular genetics shows a chloride channel defect
Kidney also secretes - pump out (penicillin)

Questions used in 2007 and 2008 related to this outline

Where does the ADH-dependent water resorption occur in the kidney?
(a) in the urethra
(b) in Bowman's capsule
(c) in the afferent arteriole
(d) in the bladder
*(e) in the collecting duct

To regulate osmolarity, salt water fish
(a) pump uric acid out through the fins.
(b) move water in through the gills by osmosis.
(c) have kidneys that excrete large amounts of dilute (hypotonic) urine.
*(d) pump salt out through the gills.
(e) move salt in through the gills by osmosis.

What is urea?
*(a) nitrogenous waste
(b) the tube connecting the kidney to the bladder
(c) the organ for excretion in the insect
(d) the hormone that helps the kidney maintain isotonic body fluids
(e) the unit of the kidney, 1 million per kidney

What happens in the proximal tubule of the nephron?
(a) Aldosterone is secreted.
(b) Filtration takes place.
*(c) Water and nutrients are resorbed.
(d) Memory cells of the immune system are stored.
(e) Urine exits from the bladder.

The Kangaroo rat, a desert animal
(a) is considered to be a producer by ecologists.
(b) uses dialysis.
(c) has diuresis.
*(d) excretes hypertonic urine.
(e) loses glucose through its urine.

What is the fundamental unit of the kidney in humans?
(a) oligodendroglia
(b) the polymorphonuclear granulocyte
*(c) the nephron
(d) the Malpighian tubule
(e) the urethra

"Secretion" (as opposed to excretion)
A) refers to active transport of water in the proximal tubule.
*B) refers to output of wastes in the distal tubule.
C) refers to the passive salt transport in the proximal tubule.
D) refers to the salt transport in the collecting duct.
E) refers to the filtration in the glomerulus.

What does the Humboldt current have to do with nitrogenous wastes?
A) The flame cell of the flatworm creates the Humboldt current.
B) This is the part of the nephron between proximal and distal tubules where there is a flow (current) of urine.
*C) Because it creates a rich marine environment, nitrogen-rich bird droppings are on the islands.
D) El nino is high in nitrogen.
E) The Humboldt current dilutes nitrogenous wastes in the kangaroo rat.

Where does ADH exert its influence in the kidney?
*A) collecting duct
B) loop of Henle
C) proximal tubule
D) distal tubule
E) glomerulus

After a salmon has returned to its mating area
A) it should need to pump salt out by active transport through its gills.
B) it should need to put out small amounts of salty urine.
C) its malpighian tubules would need to get rid of more urea.
*D) it should need to excrete copious amounts of dilute urine.
E) its osmoregulation would be no different than when it grew for 5 years in the ocean.

Why did they refer to the blood vessel returning blood from the glomerulus as an "arteriole?"
*A) because of the portal system
B) because the extracellular fluid in the kidney medulla is isotonic
C) because blood flows straight into the ureter
D) because it returns blood straight to the vena cava
E) because this is where water, salt and nutrients are secreted

What is the correct order of flow?
A) Bowman's capsule, urethra, loop of Henle
*B) proximal tubule, collecting duct, ureter
C) bladder, distal tubule, glomerulus
D) loop of Henle, collecting duct, proximal tubule
E) ureter, urethra, collecting duct

Where is dilute urine first formed by filtration of the blood?
A) the proximal tubule
B) the loop of Henle
C) the Purkinje cell
*D) the glomerulus
E) the kidney's medulla

ADH (antidiuretic hormone)
A) is no longer needed now that they add vitamins A and D to milk.
*B) is regulated by the hypothalamus that monitors your state of hydration.
C) is why you should soak shark meat in water before cooking and eating it.
D) is a hormone that tells your brain how hungry you should be.
E) has its effects on osteoclasts.

Which is NOT true about aldosterone?
A) It comes from the adrenal cortex.
B) The gland it comes from is near the kidney anatomically.
C) It has its effects in the kidney.
D) It mediates salt reuptake.
*E) It is a peptide.

return to Stark home page

Return to Bio 110 Syllabus

this page was last updated 6/30/09