BIOG 1440 Lecture Notes - Lecture 16: Metabolic Waste, List Of Lakes By Volume, Reabsorption

50 views5 pages
Objectives: How is excretion regulated? How does the kidney work?
Excretion
1. Regulation of water and salt in body fluids
a. Homeostasis is based on feedback loops. How to regulate volume,
concentration, and osmotic pressure?
b. Change in volume, concentration, osmotic pressure results in…
i. Regulation of water intake mechanism of thirst
ii. Regulation of water output regulation of excretion
2. Excretion: eliminate waste products of metabolism
a. Protein and nucleic acid metabolisms produce nitrogenous waste
b. Three forms of nitrogenous waste: ammonia, urea, uric acid
i. Ammonia: simplest form
ii. Animals also excrete urea and uric acid
1. Uric acid is common in many reptiles
c. Liver of mammals and most adult amphibians converts ammonia to less toxic
urea
d. Selective reabsorption by a filtration device
3. Eliminate waste products of the metabolism
a. Ammonia is released through whole body surface
i. Very toxic--must be removed quickly if the body is to release ammonia
b. Urea is released in urine, through kidney
c. Uric acid is secreted as a paste
4. Trade-offs of each nitrogenous compound...
Toxicity
Water volume
required
Energy Required
Ammonia
Highest
Highest
Lowest
Urea
Lower
Lower
Higher
Uric acid
Lowest
Lowest
Highest
5. Urine: allows for elimination of metabolic waste products, notably nitrogenous waste
a. Composition of urine
i. Water (95% by volume)
ii. Solutes
1. Ions
2. Nitrogenous waste
b. Try to minimize loss of water and ions
c. Eliminating waste comes with trade-off of losing fluids, meaning water and
ions.
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 5 pages and 3 million more documents.

Already have an account? Log in
i. → understanding the kidney is understanding how it reabsorbs most fluid
and ions AND how this reabsorption is regulated
6. Excretory systems are variations on a tubular theme
a. Protonephridia in flatworms
i. Network of dead end tubes
b. Metanephridia in earthworms
i. Each segment has tubes
c. Malpighian tubules in Insects
i. Tubes open on the hindgut
7. Excretion is reabsorption by a filtration device
a. Progressive refining of a filtrate produces urine
b. Functions
i. Filter body fluids (blood)
ii. Reclaim valuable solutes
iii. Reabsorb water
iv. Secrete wastes
c. Why a tube?
i. Sequential functions
ii. Filtrate moves down the tube, as water and solutes are reabsorbed
iii. Filtrate moves down tube as wastes are secreted
d. Excretion = filtration
i. - reabsorption (what the tube reabsorbs)
ii. + secretion
Organism
Excretory System
What it does
Picture
Flatworms
Protonephridia
Network of dead end
tubes
The Mammalian Kidney
1. Kidney Structure
a. Kidney is a retroperitoneal organ, 11-15cm
b. Bean-shaped structure, connected to renal artery and vein (20%
of cardiac output)
c. Each kidney feeds urine into bladder through ureter
d. Outer renal cortex
e. Inner renal medulla
i. Both have renal artery and vein for blood supply
ii. Excretory tubules within cortex/medulla to carry/process
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 5 pages and 3 million more documents.

Already have an account? Log in

Get access

Grade+
$40 USD/m
Billed monthly
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers
Class+
$30 USD/m
Billed monthly
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
7 Verified Answers

Related Documents

Related Questions