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UC / Biology I Lab / Bio 3021 / Describe an aquatic habitat.

Describe an aquatic habitat.

Describe an aquatic habitat.


School: University of Cincinnati
Department: Biology I Lab
Course: Human/Comparative Physiology
Professor: Elke buschbeck
Term: Fall 2019
Tags: Physiology
Cost: 25
Name: Week 2 Notes
Description: These are the notes for week two fo Human/Comparative Physiology!
Uploaded: 09/09/2019
5 Pages 39 Views 4 Unlocks

 Walt and salt physiology in diff environments  

What is a aquatic habitat?

o Be able to apply water and salt physiology to a variety of diff  environments, and describe the common regulatory strategies for all  major environments

 Aquatic environments  

o Salinity= grams inorganic matter / kg water  

o Osm = osmol

o Seawater  

 Salinity 34-36 g/kg

 Osmolarity = 1000 mOsm

o Freshwater  

 Salinity <0.5 g/kg (avg 0.1-0.2)

 Osmolarity = 0.5-15 mOsm

o Brackish water (extremely variable)

 Salinity 0.5-3 g/kg  

 Osmolarity =  If you want to learn more check out What makes a testable prediction based on observations?

 2 ways to respond to changes in osmolarity  We also discuss several other topics like What is the difference between counseling and counseling psychology?

o Osmoregulation

 1- regulator  

 2- Conformer  

What does brackish water contain?

o Fig 27.3 ON EXAM

 Shrimp can keep its osmolarity both higher and lower

 Mussel is a conformer

 Crab keeps osmolarity higher than environment  

 Ex. Crab used to brakish water, if it is put in marine water the crab has lower  osmolarity than environment and it would shrink and therefore not break to  new shell/molt  

 Blood volume and osmolarity regulation

o Most fundamental role of kidneys is to regulate the composition of  blood plasma (by removing water, salts and other solutes)

o Other regulatory organs:

 gills (in dish and other aquatic animals)

 salt glands (birds and reptiles)

o Note that humans are left with kidneys ONLY (through salts are  excreted via the skin as well)  

How does the body regulate blood osmolality?

 The U/P ratio- urine/plasma; Osmotic pressure of urine/osmotic pressure of  blood plasma  

o Kidney regulates osmolarity  


o  If U/P < 1 = excrete water in urine = pref water  Don't forget about the age old question of What are the similarities and differences between homogeneous and heterogeneous mixtures?

 If U/P > 1 = excrete solutes = pref salts = holding water back   Mammals do both U/P while amphibians only do UP<1  

 Cell volume is regulated by solutes  


o Removing organic solutes to allow cell not to swell and allowing  electrochemical gradient to allow stability  

o Organic molecules can change the osmotic pressure without changing  electric charges  

 Note that concentration of inorganic ions remains constant  Don't forget about the age old question of What rights make an individual self-reliant and self-sufficient?

 Many cells alter their content of uncharged organic molecules to  achieve cell-volume regulation  

 Role of organic solutes  

o 4 different groups  

 Group A- marine invertebrates  

 Group B-marine sharks, skates, rays, etc

 Group C- fresh water terrestrial invertebrates  

 Group D- fresh water terrestrial vertebrates, marine vertebrates  o Constant proportion of ions except in marine environments   Typical problem of a freshwater animal  

o Fresh water- inside molarity larger than outside fresh water  Passively  

 Water passively diffuses into the animal  

 Organic molecules diffuse out  

 Active  

 Diluted urine – by antennal gland  

 Pump in salt; through gills  

 Gills are problem

 How to minimize negative effects  

 Lower permeability of integuments:

 Integuments of fresh water are only about 10% as that of  marine  

 But gills have large surface area, which are necessarily  

thin and permeable for O2 uptake  If you want to learn more check out What is selective attention and how does it relate to the cocktail party effect?
Don't forget about the age old question of What are the layers of the serous membrane?

 How to counteract negative effects

 Void excess volume of fluids; production of copious  

hypoosmotic urine. Although the level of NaCl of urine is

lower than that of blood, leads to net loss of salts  

 Active uptake of salts by gills  

 Volume and ion regulation are in conflict of each other  

 Freshwater teleost fish have same problem  

 Large amount of urine produced by kidneys instead of  

antennal gland  

 Teleost fish were once marine  

 Higher osmolarity than water  

o Marine- Inside molarity is smaller than outside marine  

 Water diffuses to the outside because  

 Mechanism of active salt transport

o Process is energetically costly! ATP is used  

o Uptake of Cl and Na are independent of each other  

o +ions for +ions and –ions for –ions; electroneutrality

o Bicarbonate (HCO3-) and H+ are metabolic byproducts which are  removed here

o Process also has impact on acid-base regulation (bicarbonate and H+  are players)  

o ****FIGURE 28.2 ON EXAM  


 ATP used indirectly  

 Freshwater overview

o Major phyla originated in the ocean- freshwater habitat is secondary o All freshwater animals are hyperosmotic regulators  

o They therefore continuously gain water through osmosis, loose ions by  diffusion

o Most of their solutes inorganic  

 Animals in the ocean- invertebrates  

o Life is thought to have originated in the ocean- life diversity

o Most marine invertebrates are isosmotic to seawater  o It does not mean that the ion composition is the same  o Most marine fish are hypoosmotic regulators  

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