exchange and transport

• factors that effect rate of diffusion are surface area, difference in concentration and length
• Oxygenated blood leaves the left side of the heart via the aorta.
• Blood then travels back to the heart through pulmonary veins.
• surface area is the amount of space available to allow molecules to move through
• difference in concentration is how much more or less there is on one side compared to another
• Deoxygenated blood returns to the right atrium from all parts of the body except lungs.
• The pulmonary artery carries deoxygenated blood away from the heart to the lungs.
• Pulmonary vein brings oxygenated blood back into the heart from the lungs.
• the greater the surface area, the faster the rate of diffusion
• Oxygenated blood leaves the left ventricle via the aorta, which branches out into smaller vessels called arteries that carry it throughout the body.
• The right ventricle pumps deoxygenated blood into lungs via pulmonary artery.
• in insects gas goes from spiracles to trachea to tracheoles to the fluid filled ends of tracheoles to muscle fibres
• spiracles are openings on the sides of the insects head that allow air to enter and exit the trachea
• chitin


  rings of muscle that support the trachea
• insects speed up the process of diffusion in their body by pumping their abdomen
• gas exchange in fish happens in the gills located behind the head
• gills are located in between the mouth cavity and the operculum
• gills are composed of filaments which are covered in lamallae
• lamallae increase surface area and contain many blood capillaries to maximise diffusion
• countercurrent flow is when blood and water move in opposite directions to maximise diffusion across length of whole gill
• alveoli are surrounded by a network of capillaries that allow for the exchange of gases
• alveoli are lined with epithelium and have a large surface area to volume ratio
• inspiration happens when the diaphragm contracts and the intercostal muscles contract
• inspiration increases volume of thorax and decreases pressure in lungs
• expiration is when the diaphragm relaxes and intercostal muscles relax
• expiration decreases volume of thorax and increases pressure of lungs
• chemoreceptors are stimulated by rise in CO2 and decrease in pH
• in the ileum there is villi and microvilli these increase surface area for absorption
• amylase in saliva breaks glycosidic bond in starch to form maltose
• sucrase breaks down starch into glucose and fructose
• lactase breaks down lactose into glucose and galactose
• lipases breaks down the ester bond in the lipids into fatty acids and glycerol
• peptidases breaks down peptide bonds in proteins to form amino acids
• the three types of peptidases are endopeptidases (middle) exopeptidases (outer) dipeptidases (between two amino acids)
• villi have thin walls so there is a shorter diffusion distance
• both amino acids and monosaccharides are moved from ileum into the blood by diffusion and co-transport
• bile salts emulsify fats making them more soluble
• when fats are emulsified into bile they form droplets called micelles
• micelles move through the ileum and come into contact with epithelial cells
• micelles get broken down and release monoglycerides and fatty acids