The villi provide a large surface area large surface area to volume ratio ventilated surface( large surface area, large surface area to volume ratio, ventilated surface ) with an extensive network of capillaries extensive network of arteries and veins extensive network of alveoli( extensive network of capillaries, extensive network of arteries and veins, extensive network of alveoli ) to absorb the products of digestion mineral ions in the blood oxygen in the blood excess water content in the blood( products of digestion, mineral ions in the blood, oxygen in the blood, excess water content in the blood ) by diffusion and active transport.

ACTIVE TRANSPORT - The movement of substances cells molecules atoms( substances, cells, molecules, atoms ) through a partially-permeable membrane concentration gradient( partially-permeable membrane, concentration gradient ) against a concentration gradient. partially-permeable membrane.( concentration gradient., partially-permeable membrane. ) This process requires the use of energy glucose water oxygen( energy, glucose, water, oxygen ) from respiration photosynthesis gas exchange( respiration, photosynthesis, gas exchange ), and enables cells the blood atoms( cells, the blood, atoms ) to absorb ions molecules oxygen water glucose( ions, molecules, oxygen, water, glucose ) from very dilute concentrated( dilute, concentrated ) solutions.

OSMOSIS - The diffusion movement( diffusion, movement ) of water oxygen minerals ions( water, oxygen, minerals, ions ) from a dilute concentrated( dilute, concentrated ) to a more concentrated dilute( concentrated, dilute ) solution through a partially-permeable membrane concentration gradient( partially-permeable membrane, concentration gradient ) that allows the passage of water molecules mineral ions oxygen molecules nutrients( water molecules, mineral ions, oxygen molecules, nutrients ).

As you breathe in out( in, out ), the diaphragm intercostal muscles abdomen( diaphragm, intercostal muscles, abdomen ) contracts expands contract expand( contracts, expands, contract, expand ) and becomes flatter thicker thinner( flatter, thicker, thinner ), and the intercostal muscles diaphragm abdomen( intercostal muscles, diaphragm, abdomen ) contract expand contracts expands( contract, expand, contracts, expands ), expanding the rib cage abdomen lungs bronchioles( rib cage, abdomen, lungs, bronchioles ) . This increases decreases( increases, decreases ) the volume of the thorax abdomen bronchioles( thorax, abdomen, bronchioles ), which causes the pressure in surface area of volume of( pressure in, surface area of, volume of ) the lungs to decrease increase( decrease, increase ) and allows air to be easily drawn in).
When breathing out in( out, in ), the intercostal muscles diaphragm abdomen( intercostal muscles, diaphragm, abdomen ) relax contract relaxes contracts( relax, contract, relaxes, contracts ), contracting the rib cage abdomen lungs diaphragm( rib cage, abdomen, lungs, diaphragm ), and the diaphragm intercostal muscles abdomen( diaphragm, intercostal muscles, abdomen ) also relaxes contracts relax contract( relaxes, contracts, relax, contract ) and moves up down( up, down ), increasing the pressure in surface area of volume of( pressure in, surface area of, volume of ) the lungs and expelling the air.

The rate of evaporation condensation diffusion photosynthesis( evaporation, condensation, diffusion, photosynthesis ) is increased decreased( increased, decreased ) when the conditions are hot cold( hot, cold ), dry wet( dry, wet ) and windy. calm.( windy., calm. )