Exchange and transport system

Insect tracheal system

Tracheae, tracheoles, spiracles

Counter-current mechanism

Blood and water flow in opposite direction

Blood always passing water with higher oxygen concentration

Maintain a constant gradient of oxygen to diffuse along the gills

Inhale

Diaphragm contracts and flatten

External intercostal muscle contract and ribcage pulled out

Increase the volume and reduce the pressure in thoracic cavity

Exhale

Diaphragm relax and moves up

external intercostal muscle relax and ribcage moves in

Decrease the volume and increasing the pressure in the thoracic cavity

Large organism

Smaller SA:V so a shorter diffusion pathway

Smaller organisms

Large SA:V so more heat is lost and a faster rate of metabolic releasing

Fish

Gils, gil lamellae, gils filaments

Insect gas exchange

body can be move to move air so maintain concentraton gradient for oxygen

fluid in the end of tracheoles that moves out during exercise so faster diffusion through air to gas exchange surface

tracheoles have thin walls so short diffusion pathway to cell

large number of traheoles so large surface area and short diffuse distance

Amylase

hydrolysis of starch to maltose

secreted by salivary glands and pancreas

Endopeptidase

Hydrolysis of peptide bond in the middle of polypeptide

Exopeptidase

Hydrolysis of peptide bond at the end of polypeptide

Dipeptidase

Hydrolysis of peptide bond between two amino acid

Lipase

Hydrolysis of ester bond in lipids

Bile salt

emulsify lipids into smaller droplets to increase surface area for lipase to react faster

Micelles

contain bile salt and fatty acid

make fatty acid more soluble in water

bring fatty acid to lining of ileum

maintain higher concentration of fatty acid to lining

fatty acid absorbed by diffusion

Absorption and transport of digested lipid

micelles contain bile salt and fatty acid

make fatty acid more soluble in water

fatty acid absorb by diffusion

triglycerides reformed in cell

vesicles move in cell membrane