Title: Osmoregulation and Excretion: Sections 44.2,44.3, and 44.5 w/ some IB Topics
1Osmoregulation and ExcretionSections 44.2,44.3,
and 44.5 w/ some IB Topics
- Deanna, Stephanie, Christen
2Nitrogenous Wastes
- Breakdown products of proteins and nucleic acids
- Ammonia very soluble, highly toxic, tolerable
only at low concentrations excreted b/c animal
needs access to lots of water aquatic species
readily lost by diffusion across body surface /
thru gills to surrounding H2O - Urea terrestrial animals (b/c less access to
water for ammonia release) produced in the
vertebrate liver by a metabolic cycle that
combines ammonia w/ CO2 100,000x less toxic than
NH3 disadvantage must expend energy to produce
urea from NH3 - Uric Acid relatively nontoxic in insects, land
snails, reptiles, birds largely insoluble in
water excreted as semi-sold paste w/ lil water
loss adv for animals w/ lil water access but
lots of energy to produce (so lots of ATP needed)
3Pg. 927
4Influence of Evolution and Environment on
Nitrogenous Wastes
- Depends upon an animals evolutionary history and
habitat esp availability of water - Mode of reproduction affected which kind
- Shelled egg vs. shell-less egg or mammalian
embryo - Adjusting to environment
- Ex certain tortoise changes from urea to uric
acid when temp increases and water less available - Amount produced depends on energy budget type
of food - Ex endotherms eat more food so more wastes
5IB Syllabus!
Arrows pointing to the IB slides in this
presentation.
611.3.9 Explain the presence of glucose in urine
of untreated diabetic patients
- Glucose is often present in the urine of
untreated diabetic patients. This is because the
glucose concentration of blood rises much higher
than 90 mg per 100 ml, so the pumps in the
proximal convoluted tubule cant reabsorb all the
glucose that is filtered out into the glomerulus.
711.3.8 Explain the differences in concentration
of proteins, glucose and urea between blood
plasma, glomerular filtrate and urine.
Comparison of Fluid in the Kidney
Content (mg per 100mg of blood)
Blood in renal artery Urine Glomerular filtrate Blood in renal veins
Glucose 90 0 90 90
Urea 30 2000 30 24
Proteins 740 0 0 740
8- Remember drawing this from yesterday? The next
slide helps explain in more detail.
911.3.4 Explain the process of ultrafiltration,
including blood pressure, fenestrated blood
capillaries, and basement membrane.
- Function of glomerulus is production of filtrate
from blood by ultrafiltration - Blood plasma escape through walls of capillaries
remember video?, but in glomerulus 20 escapes
(more than usual) - Why this happens
- Blood pressure very high b/c efferent arteriole
is narrower than afferent arteriole - Capillaries in the glomerulus are fenestrated
(porous) - These pores are large enough to let any molecules
through, but on the outside of the capillary wall
is a basement membrane composed of a gel of
glycoprotein. It lets all substances in the blood
plasma through except plasma proteins. - The fluid produced by ultrafiltration is
collected by the Bowmans capsule and flows on
into the proximal convoluted tubule.
1011.3.7 Explain the roles of the loop of Henle,
medulla, collecting duct and ADH (vasopressin) in
maintaining the water balance of the blood.
(pg102)
11Survey of Excretory Systems - Intro
- Various excretory mechanisms have evolved in
animals for the purpose of osmoregulation and for
the removal of toxins. - Toxins include by-products of cellular
metabolism, such as the nitrogen wastes.
12Contractile Vacuoles
- Found in the cytoplasm of various protists, such
as paramecia and amoebas. - These vacuoles accumulate water, merge with the
plasma membrane, and release the water to the
environment.
13Flame Cells
- Aka protonephridium
- Flatworms.
- Network of dead-end tubules lacking internal
openings. The cells are distributed along a
branched tube system that permeates the flatworm.
- Body fluids are filtered across the flame cells
whose internal cilia move the fluids through the
tube system. - Wastes (water and salts) are excreted from the
tubule system through pores that exit the body. - Tubules reabsorb most solutes before the urine
exits the body so the urine is dilute.
14Nephridia
- Aka Metanephridia
- Unlike previous, has internal openings
- Earthworms.
- Occur in pairs within each segment of the
earthworm. Interstitial fluids enter through a
cilated opening called a nephrostome. - Fluids concentrated as they pass through the
collecting tubule which includes a storage
bladder that opens to the outside through a
pores. - As urine moves along the tubule, most solutes are
reabsorbed and returned to the blood in the
capillaries. Nitrogenous wastes remain and are
excreted outside. - Live in damp soil and absorb water through
osmosis. They balance water influx by making
diluted urine.
15Malpighian Tubules
- Insects and other terrestrial arthropods.
- Tubes attached to the midsection of the digestive
tract collect body fluids from the hemolymph that
bathe the cells. - Fluids which include both nitrogen wastes and
materials to be retained (salts and water), are
deposited to the midsection.
- As fluids pass near the rectum, most solutes are
pumped back into the hemolymph. - The nitrogenous wastes are eliminated as nearly
dry matter along with the feces.
16Kidney
- The last one..
- Kidneys.
- But you all should be experts on that now.
Teehee.
17Regulation of Kidney Functions Hormones
- These hormones influence osmoregulation by
regulating the concentration of salts in the
urine - ADH
- JGA
- Angiotensin II
- Aldosterone
- ANF
18Antidiuretic Hormone (ADH)
- Increases the reabsorption of water by the body
and increases the concentration of salts in the
urine. - It does this by increasing the permeability of
the collecting duct to water. - Urine becomes more concentrated as water diffuses
out of the collecting duct as the filtrate
descends into the renal pelvis. - Recall its position Posterior Pituitary
- Recall process of Feedback Inhibition
19Juxtaglomerular Apparatus (JGA) to Angiotensin II
- Location near afferent arteriole that supplies
blood to the glomerulus - When blood pressure/volume drops, an enzyme
(renin) aids in producing a peptide called
angiotensin II. - This hormone raises blood pressure by
constricting arterioles, decreasing blood flow to
many capillaries, like in the kidney. - Also stimulates the proximal tubules of the
nephrons to reabosorb more NaCL and water which
reduces the amount of both in the urine.
20Aldosterone
- This hormone acts on the nephrons distal tubules
making them reaborb more sodium (Na) and water
allowing for further increase of blood
volume/pressure - It does this by increasing the permeability of
the distal tubule and collecting duct to Na - As a result, more Na diffuses out of this tubule
and duct allowing for water to passive flow.
21In summary so far, RAAS
- Starting basically from the JGA to Aldosterone,
that whole process is called RAAS - When blood pressure drops, JGA is released and
aids in rising it again with angiotensin II and
aldosterone. - So, the first hormone ADH and the RAAS process
raise blood pressure. Isnt this a bit redundant?
22ADH vs RAAS
- Both increase water reabsorption, but counter
different osmoregulatory proglems. - ADH is a response to body dehydration.
- A loss of both salt and body fluids such as an
injury or severe diarrhea will reduce blood
volume without increasing osmolarity. - This will not induce a change in ADH release but
RAAS will respond by increasing water and Na
reabsorption.
23Atrial Natriuretic Factor (ANF)
- This hormone opposes the former RAAS
- Recall renin, the enzyme that helped make JGA
- ANG inhibits the release of renin, inhibits NaCl
reabsorption by the collecting ducts, and reduces
aldosterone release. - This basically lowers blood volume/pressure.
- Thus, ADH, RAAS, and ANF is basically a
biological check and balance system
24Guess what?!
- No more new info! Review if time.
- Enjoy your 3 day weekend!
-
- Study away for those exams./