B8 - Exchange and Transport in Animals

relationship between sa:v and size of organism

as organism gets bigger, sa:v decreases

why do smaller animals not need transport systems

they have small sa:v ratio and are able to diffuse in any neccessary gas

relationship between organism size and diffusion distance

as organism size increases, so does diffusion distance

alveoli

in lungs exchange o₂and co₂

villi

in small intestine, absorb nutrients

root hair cells

absorb water and minerals

leaves

absorb co₂

how does a large sa:v help exchange surfaces

more molecules are able to diffuse at once, so rate of diffusion is faster

how does thin exchange surfaces assist exchange surfaces

smaller diffusion distance

how does a blood supply assist a specialised exchange surface

maintains a concentration gradient

how does a good supply of external medium assist specialised exchange surfaces

maintains a concentration gradient

What happens within the lungs

when blood arrives, it is deoxygenated, so o2 diffuses into haemoglobin, and co2 is diffused from blood stream into alveoli

how are the lungs adapted for gas exchange

air travels into lungs from trachea into bronchi, into alveoli, which have very short diffusion distsanecs between capillaries and membranes, as well as large sa:v and moist walls

root of oxygenated blood in heart

pulmonary vein → left atrium → left ventricle → aorta → body

root of deoxygenated blood in heart

vena cava → right atrium → right ventricle → pulmonary artery → lungs

capillaries

exchange nutrients and oxygen; one cell thick; permeable (allowing for easy diffusion); small lumen, however total cross sectional area very large so low pressure

veins

carry blood to heart; large lumens and thin walls so low pressure; valves prevent blood flowing backwards

arteries

carry blood away from heart; blood is high pressure; walls are thick and small lumen; walls made of elastic and muscle tissue

platelets

fragments of cell which clot blood when cut, and prevent microogranisms entering, and blood exiting

plasma

straw colored liquid makes blood flow, carries: amino acids, nutrients, glucose

white blood cells

immune system, includes lymphocytes, phagocytes and antitoxins

red blood cells

carry oxygen in haemoglobin. biconcave disk so large surface area, no nucleus so more space for oxygen

aerobic respiration reaction

glucose + oxygen → CO₂ + water

when and where does aerobic respiration take place

in mitochondria, continuously

anaerobic respiration reaction

glucose → lactic acid

when and where does anaerobic respiration take place

takes place in cytoplasm, when there is an insufficient supply of oxygen e.g. when exercising

why is anerobic respiration less good than aerobic

it is inefficient as incomplete breakdown of glucose. also lactic acid is very damaging to bodily tissues, so must be removed quickly

why must humans respire

release energy used for:

• building larger organisms

• muscle contraction

• maintains body temp

• part of metabolism

ficks law