Excretion, Osmoregulation, and Nitrogenous Wastes in the Urinary System

Excretion

the process of removing toxic metabolic wastes from an organism

What are some examples of toxic metabolic waste that is removed through excretion?

nitrogenous wastes, CO₂

Osmoregulation

maintaining the water and salt balance within an organism; regulates osmotic concentration

How is osmoregulation measured?

measured in osmoles per liter

Review: water always moves from the ___ side to the ___ side

hypotonic to hypertonic side

Review: water always moves from __ water potential to _ water potential

high to low water potential

Review: water always moves from __ water concentration to _ water concentration

high to low concentration

What are two modes of osmoregulation found in animals?

osmoconformers and osmoregulators

Osmoconformers

allow internal solute concentration to fluctuate with the water around them (conforms to the water around them)

Examples of osmoconformers

squid and jellyfish

What is a disadvantage for osmoconfromers?

concentration might not be ideal for body processes

Osmoregulators

maintain a constant internal solute concentration, no matter what’s happening externally

How do osmoregulators maintain homeostasis?

they excrete more or less urine (as needed)

What is a disadvantage for osmoregulators?

need energy

Example of an osmoregulator

mammals

Nitrogenous wastes are produced because of the…

breakdown of amino acids (from proteins)

How does different organisms removes waste differently? What is it dependent on?

different organisms produce different kinds of nitrogenous waste depending on their habitat

What are some examples of nitrogenous wastes?

Urea, Uric Acid, Ammonia

Rank the three nitrogenous discussed from low toxicity to high toxicity (or less soluble to more soluble)

uric acid→ urea→ ammonia

Is uric acid toxic?

Not toxic

Describe the solubility of uric acid in water

It’s partially soluble in water

What organisms mostly produce uric acid?

Mostly found in birds and insects (with small amounts in humans)

What is required for uric acid?

needs a little water

What is the purpose of uric acid for birds?

allows birds to stay in light for flight

Is ammonia toxic?

very toxic

Describe the solubility of ammonia in water

soluble in water

What is required for ammonia to be removed?

needs a lot of water to be removed

What type of organisms usually removed ammonia and why?

Freshwater organisms since it can be easily flushed

Is urea toxic?

somewhat toxic

Describe the solubility of urea in water

somewhat soluble

What type of organisms excrete urea as waste?

terrestrial mammals, marine mammals, and adult amphibians