GENBIO 2 - MOD 8

Ammonia

It is the direct waste produced by the metabolism of nitrogen-containing compounds like proteins and nucleic acids, during the catabolism (breakdown) of nitrogen-containing compounds, carbon, hydrogen, and oxygen are extracted and stored in the form of carbohydrates and fats

ammonotelic animals

Animals that secrete ammonia as the primary nitrogenous waste material are called

Urea

While aquatic animals can easily excrete ammonia into their watery surroundings, terrestrial animals have evolved special mechanisms to excrete nitrogenous wastes. Detoxification of ammonia occurs by converting it into a relatively non-toxic form such as urea or uric acid

ureotelic animals

Animals that secrete urea as the primary nitrogenous waste material are called

Uric Acid

is the major by product of ammonia metabolism in birds, insects and terrestrial reptiles. Mammals also form some uric acid as result of the breakdown of nucleic acids

uricoletic organisms

Organisms that secrete uric acid are called

Cell surface or cell membrane –

allows passage of wastes in unicellular organisms

Contractile Vacuole

fresh water protists (e.g. Paramecium) possess specialized cytoplasmic organelles that regulate water content of the cell

Protonephridia or Flame Bulb System

These are the simplest multicellular animals to have a dedicated excretory system. They excrete metabolic wastes in the form of ammonia by diffusion across its body surface

Flame Cell

is a specialized excretory cell found in the simplest freshwater invertebrates (e.g. Flatwor)

Metanephridia

For annelids (e.g. earthworms, leeches) and adult mollusks (e.g. snails, clams), waste is excreted through highly coiled tubular structures called ________. It is a more evolved excretory system compared to the flame cell

Malphigian Tubules –

extends from the digestive tracts of insects (e.g. bees, grasshoppers and cockroaches) and other terrestrial arthropods (e.g. spiders) to the exterior of the organisms. They remove wastes by producing urine and solid nitrogenous wastes, which are then secreted from the body

kidney

The primary organ for regulating body fluids in mammals is the _____. It plays an important role in osmoregulation and excretion

cortex

each kidney has two distinct sections: an outer section called

glomerulus

• consists of a network of capillaries between afferent arteriole and efferent arteriole and is enclosed by a cup-like capsule called Bowman’s capsule.

Water

is lost during excretion through the formation of urine

loop of Henle

of the nephron plays a key role in the conservation of water and is structurally modified for the production of hypertonic urine

Acid buffer systems

• These systems usually involve two or more chemicals that can combine with excess acids and bases. They typically combine with a strong acid (or base) and convert it into a weaker one. The stronger the acid, the more completely it will ionize and produce Hydrogen ions

Receptor

A body structure that monitors changes in a controlled condition and sends input to a control center. This pathway is called an afferent pathway since the information flows toward the control center

Control center

Sets the range of values within which a controlled condition should be maintained (set point), evaluates the input it receives from receptors, and generates output commands when they are needed

Effector

body structure that receives output from the control center and produces a response or effect that changes the controlled condition. Nearly every organ or tissue in the body can behave as an effector

Negative feedback system

A reaction in which the system responds in such a way as to reverse the direction of change

Positive feedback system

Tends to strengthen or reinforce a change in one of the body’s controlled conditions

Osmoregulation

• is the process by which living organisms regulate their body’s internal water and ionic balance (osmotic balance) across membranes within the body. It compensates for water loss avoids water gain and maintains he proper osmolarity of body fluids.

Isoosmotic

when two solutions separated by a selectively permeable membrane have the same osmotic pressure. When two solutions differ in osmolarity, the one with the greater concentration is referred to as hyperosmotic

Excretion

is the process by which organisms eliminate metabolic waste products including nitrogen wastes produced from the breakdown of proteins. _______ helps organisms’ control osmolarity and maintains acid-base balance

1. Osmoconformers

Marine animals such as the Starfish have body fluids that have similar osmolarity as seawater, so they gain and lose water at equal rates. If a starfish is placed in water that is more (or less) concentrated than seawater, their tissues will shrink (or swell) and the starfish will die because it cannot tolerate too much variation in environmental salinity.

stenohaline

unable to tolerate much variation in environmental salinity

2. Osmoregulators

Organisms that maintain a more or less stable internal osmolarity by actively controlling the salt concentrations within the body, irrespective of the salt concentration of the external environment

Marine osmoregulators

maintain an internal salinity lower than that of seawater, and freshwater osmoregulators maintain an internal salinity higher than that of freshwater