Execratory System Flashcards
animal life is challenged under changing environmental conditions – ____ ____ ____ compensate for changing conditions and maintain the internal environment within the relatively narrow limits that cells can tolerate
Homeostatic control system
Osmoregulation?
osmoregulation is the regulation of water and ion balance
Excretion do for body?
excretion helps maintain the body’s water and ion balance while ridding the body of metabolic wastes
Thermoregulation?
thermoregulation is the control of body temperature
living cells contain ____, are surrounded by ____, and constantly exchange ____ with their environment
water
What surrounds cell for simple animals?
What about for more complex animals?
for the simplest animals, water of the external environment directly surrounds cells – for more complex animals, an aqueous extracellular fluid (ECF) surrounds the cells
What does ECF contain in animals with a circulatory system?
in animals with a circulatory system, the ECF includes both interstitial fluid and blood plasma
What is osmosis?
in osmosis, water molecules diffuse across a selectively permeable membrane from a region of higher water concentration (low solute concentration) to a region of lower water concentration (high solute concentration)
What is osmolarity? What is it measured in?
the total solute concentration of a solution (osmolarity) is measured in osmoles – the number of solute molecules and ions (in moles) per liter of solution
What is normal human osmolarity?
the osmolarity of body fluids in humans and other mammals is about 300 mOsm/L
What is hypertonic?
the solution with higher osmolarity is hyperosmotic to the other solution
What is hypoosmotic solution?
the solution with lower osmolarity is hypoosmotic to the other solution
What is isosmotic?
if the solutions on either side of a membrane have the same osmolarity, they are isoosmotic
What must animals do to keep metabolic stability?
for metabolic stability, animals must keep their cellular fluids and ECFs isoosmotic
What are osmoconformers?
in osmoconformers, the osmolarity of cellular and extracellular solutions matches that of the environment
What are osmoregulators?
osmoregulators use control mechanisms to keep the osmolarity of cellular and extracellular fluids the same, but at levels that may differ from the osmolarity of the surroundings
What do animals do to control osmolarity?
animals control osmolarity by removing certain substances from body fluids and releasing them into the environment
animals control osmolarity by removing certain substances from body fluids and releasing them into the environment
animals excrete ____ ____, ____ ____ ____ ____, and ___________________________
excretion of ions and metabolic products is accompanied by ____ ____ – ____ is a solvent for those molecules
animals that take in large amounts of water may also excrete ____ to maintain osmolarity
animals control osmolarity by removing certain substances from body fluids and releasing them into the environment
animals excrete H+ ions, nitrogenous products of metabolism, and breakdown products of poisons and toxins
excretion of ions and metabolic products is accompanied by water excretion – water is a solvent for those molecules
animals that take in large amounts of water may also excrete water to maintain osmolarity
What carriers osmoregulation as a generality of all animals?
How are these structures set up?
microscopic tubules formed from a transport epithelium carry out osmoregulation and excretion
the tubules are immersed in body fluids at the proximal end, and open to the body exterior at the distal end
What are four components of osmoregulation?
1 Filtration:
Small molecules and ions from body fluids or blood nonselectively pass through narrow spaces between cells into the tubule.
2 Tubular reabsorption:
Nutrient molecules, some ions, and conserved water are returned to the body fluids or blood by transport epithelium
3 Tubular secretion:
Excess ions and toxic breakdown products are transported selectively from the body fluids or blood into the tubule.
4 Excretion:
Urine (nitrogenous wastes, some ions, toxic breakdown products, excreted water) is released into the environment.
What do transport proteins do to help with osmoregulation?
Where do they do this?
transport proteins move specific molecules and ions into and out of the tubule by either active or passive transport, depending on the substance and its concentration gradient
4 steps tubule function?
Filtration
Tubular reabsorption
Tubular secretion
Excretion
What is filtration?
Filtration is the nonselective movement of water and solutes, but not large molecules such as proteins, into the proximal end of the tubules through spaces between cells
What is tubular reabsorption?
Tubular reabsorption: Important molecules (e.g., glucose and amino acids) and ions are transported by the transport epithelium back into the ECF and eventually into the blood as the filtered solution moves through the excretory tubule