Ch 32 Homeostasis of internal fluids

intracellular fluid

contains cells that hold water

extracellular fluid

present as blood plasma and interstitial fluid in vertebrates

Importance of maintenance of normal body water levels

• water allows dissolved solutes to participate in chemical reactions

• water transports oxygen and nutrients to cells and removes wastes

• dehydration stops the functions of the circulatory system and ability to regulate body temp

Important of ion balance

• useful for muscle contraction & communication in the nervous system

• dehydration → ion imbalance

• osmolarity : measure of solute concentration

Vital process

these have the potential to disturb ion/water balance and are obligatory, requiring extra energy

• food ingestion

• respiration

• metabolism

• body temp regulation

• removal of wastes

food ingestion

food introduces salt and H2O

respiration

water vapor exits during breathing

metabolism

cells produce H2O during metabolism

removal of wastes

ions and H2O are lost in feces and urine

body temperature regulation

H2O is lost by evaporation

nitrogenous wastes

generated when proteins and nucleic acids are broken down and metabolized

• toxic in high concentrations and need to be eliminated

Respiration: lungs

significant water loss

Respiration: water breathing

• complex

• water and ions move across gills

Fresh water fish respiration

• hypotonic environment

• hyperosmotic body : body has more salt than outside

• doesn’t drink water

• H2O enters gills by osmosis

• intakes ions and H2O from food

• takes in Na+ and Cl-

• dilute large amount of urine with few ions

Seawater fish respiration

• hypertonic environment

• hyposmotic body : body has more water than outside

• drinks seawater

• H2O leaves gills by osmosis

• intakes ions and H2O from food

• releases Na+ and Cl-

• small amount of urine with lots of ions