Homeostasis

Question 1

what does homeostasis involve?

Answer 1

it involves keeping conditions within tightly regulated physiological tolerance limits

Question 2

endocrine system

Answer 2

regulates most physiological systems associated with maintaining homeostasis

Question 3

is the fish endocrine system similar to that of other vertebrates?

Answer 3

yes

Question 4

endocrine disrupting compounds in fishes

Answer 4

synthetic estrogen in birth control

Question 5

primary concerns of homeostasis

Answer 5

• temperature
• osmoregulation

Question 6

autonomic nervous system

Answer 6

controls immediate involuntary functions

Question 7

functions controlled by the autonomic nervous system

Answer 7

• internal organ function
• heart rate & blood pressure
• blood flow through gills
• gas bladder volume

Question 8

temperature regulators

Answer 8

• ectotherms
• endotherms
• heterotherms

Question 9

ectothermic organisms

Answer 9

• most inverts
• fishes
• amphibians
• reptiles

Question 10

endothermic organisms

Answer 10

• birds
• mammals

Question 11

heterothermic organisms

Answer 11

large pelagic species

Question 12

heterothermy: heat generation

Answer 12

heat generated by swimming activity or heater organs

Question 13

heterothermy: heat retention

Answer 13

heat is retained by countercurrent exchange

Question 14

the special case of the Opah

Answer 14

• pectoral muscles & eye muscles to produce heat
• fatty layer insulates gills, internal organs, and head
• rete mirable isolates warm blood from cold gills

Question 15

how fish deal with low temperatures

Answer 15

• decreased metabolism & higher oxygen levels
• biological antifreeze molecules

Question 16

antifreeze molecules

Answer 16

proteins or glycoproteins bring the internal freezing point below zero

Question 17

low temperature fish

Answer 17

• antarctic fish
• smelt
• northern cod

Question 18

what do varying temperatures create a problem for?

Answer 18

protein structure

Question 19

heat shock proteins

Answer 19

keep proteins from denaturing at high temperatures

Question 20

isozymes

Answer 20

• alternative enzymes produced by different genes
• switched on or off at different temperatures

Question 21

allozymes

Answer 21

• alternative products produced by different alleles at the same gene
• different populations of a species may exhibit different allozymes that increase their fitness in regional temperatures

Question 22

thermal preference in fish

Answer 22

thermal preference drives fishes to select environmental temperatures at which they can function

Question 23

things affecting thermal preference

Answer 23

• power plant cooling systems
• hydroelectric dams affect this

Question 24

freshwater fish are generally _________ to their environment

Answer 24

hyperosmotic

Question 25

marine fish are generally _________ to their environment

Answer 25

hypo-osmotic

Question 26

stenohaline

Answer 26

tolerate a limited range of osmolarity (limited regulation)

Question 27

euryhaline

Answer 27

tolerate a wide range of osmolarity (osmoregulators)

Question 28

two systems for regulating osmolarity

Answer 28

- gills - kidneys

Question 29

gills regulating osmolarity

Answer 29

- especially important for nitrogenous wastes - chloride cells may also transport Cl- ions

Question 30

kidneys regulating osmolarity

Answer 30

regulation of water, salts, and ions

Question 31

renal tubule function

Answer 31

- filtration - selective reabsorption - selective secretion

Question 32

osmoconformers

Answer 32

- concentrations about the same as their environment - live in an osmotically & thermally stable environment

Question 33

example of osmoconformers

Answer 33

hagfishes

Question 34

salt supplementers

Answer 34

- high urea content & TMAO - low permeability to Na+, Cl-

Question 35

salt supplementers

Answer 35

marine elasmobranches

Question 36

sharks as salt supplementers

Answer 36

- sharks retain urea, which makes them hyper-osmotic to sea water - this causes water to diffuse in

Question 37

hyper-osmotics

Answer 37

- tend to loose water, replace via drinking & eating - chloride cells in gills pump out salts

Question 38

examples of hypo-osmotic organisms

Answer 38

marine teleosts

Question 39

hyperosmotics

Answer 39

- excrete large volumes of water - gill chloride cells pump in salts - often euryhaline

Question 40

hyperosmotic organisms

Answer 40

freshwater fish

Question 41

chloride cells in freshwater fish

Answer 41

remove divalent ions: bicarbonate and ammonium

Question 42

chloride cells in saltwater fish

Answer 42

larger chloride cells