Biology Chapter 32: Osmotic Regulation and Excretion

Osmosis

The movement of water molecules from a higher concentration to a lower concentration through a selective semi-permeable membrane

Diffusion

The net movement of components from a higher concentration to a lower concentration; may or may not occurs through a membrane

Osmotic regulation

Process of keeping mineral salts (ions) and water in balance across a membrane

Osmotic homeostasis

The process of osmotic regulation under extreme influences, such as body temperature, diet, activity, and weather conditions

Osmotic pressure

The minimum pressure needed to prevent the inward flow of a pure solvent across the membrane

Hypertonic

Concentration of solute is greater outside the cell

Isotonic

Concentration of solute is equal inside and outside the cell

Hypotonic

Concentration of solute is greater inside the cell

Osmoconformers

Animals whose internal osmolarity is the same as the external environment. All these animals are marine

Osmoregulators

Animals that control their osmolarity independent of the external environment. These animals are terrestrial or live in fresh water

Transport epithelia

Specialized cells that transport solute in one direction

Nitrogenous waste

A toxic metabolic produced by the breakdown of nitrogenous compounds (proteins/nucleic acids)

Excretion

The process of getting rid of nitrogenous waste compounds

Ammonia

Toxic nitrogenous waste, so it can only be tolerated at low concentration. Usually found in aquatic animals

Urea

Nitrogenous waste with low toxicity, so it can be tolerated in higher concentration and requires less water as a dilutent. Requires energy to make and is usually found in terrestrial animals

Uric acid

Nontoxic nitrogenous waste that is insoluble in water and secreted as a paste; requires lots of energy to make and is usually produced in birds and reptiles

Kidneys

Pair of bean shaped organs that filter blood and remove waste and extra water; also produce hormones that help maintain/control blood pressure

Nephron

Functional unit of the kidney, in which the filtration takes place

Cortical nephron

Nephron type that is limited to the cortex of the kidney

Juxtamedullary nephron

Nephron type that extends down into the medulla as well

Renal pyramid

Contains the nephrons

Renal pelvis

Collects urine that empties into the ureter

Filtrate

Formation of this occurs when blood pressure forces fluid from blood vessels into the lumen of the Bowman’s capsule

Bowman’s capsule

Small blood vessels where filtration takes place; filled with fenestrations

First step of filtration

Filtrate passes through the proximal convoluted tube, in which HCO3, NaCl, H2O, nutrients, and K are removed from the fluid, and H and NH3 are added to the fluid

Second step of filtration

Filtrate passes through the loop of Henle, in which H2O and NaCl are removed from the fluid

Descending loop

Section of the loop of Henle that is permeable to water and aids in the removal of water from the filtrate

Ascending loop of Henle

Section of the loop of Henle that is not permeable to water and aids in the removal of NaCl from the filtrate

Third step of filtration

Filtrate travels through the distal convoluted tube, in which NaCl, H2O, and HCO3 are removed from the fluid, and K and H are added to the fluid

Final step of filtration

Filtrate travels through the collecting duct, which receives the processed filtrate and sends it to be removed from the body