transport in animals Flashcards
3.1.2 (33 cards)
why do multicellular organisms need transport systems
- small surface area to volume ratio so diffusion distance is too large
- have a higher metabolic rate
- need to supply nutrients and oxygen rapidly to a lot of active cells
describe the fish’s single circulatory system
1- heart pumps blood to gills to pick up oxygen
2- blood flows from gills directly to rest of body to deliver oxygen
describe the mammalian double circulatory system
1- right side of heart pumps deoxygenated blood to the lungs to pick up oxygen
2- left side of heart pumps oxygenated blood to rest of body ( needs an extra push to deliver blood to distant tissues/organs that need higher pressures, eg kidney )
describe what type of circulatory system vertebrates have
closed circulatory system
- blood enclosed in vessels
- arteries generally distribute oxygenated blood
- veins generally return deoxygenated blood to heart
describe what type of circulatory system invertebrates have (eg insects)
open circulatory system
- blood flows freely through body cavity
- blood returns to heart through valves
- blood doesn’t just transport oxygen
describe the structure of the mammalian circulatory system
closed double system
systematic circulatory system:
- oxygenated blood pumped out of heart via aorta to most body tissues
- deoxygenated blood returned to heart via vena cava from body tissues
pulmonary circulatory system:
- deoxygenated blood pumped out via pulmonary artery to lungs
- oxygenated blood returned to heart via pulmonary vein from lungs
explain structure and function of arteries
- carry blood at high pressure away from heart
- outer layer (tunica adventitia/externa) of collagen provides strength to prevent bursting + to maintain shape
- middle layer (tunica media) of smooth muscle to contract and narrow (regulate blood flow) and thick elastic tissue to stretch and recoil (regulate blood pressure)
- inner layer (tunica intima) of endothelium that is one cell thick and smooth to reduce friction and folded to allow expansion
- narrow lumen to maintain high blood pressure
what are arterioles
- small blood vessels connecting arteries and capillaries that have a muscular layer contracting and narrowing to partially restrict blood flow to certain organs
- tunica media have larger lumen, less elastic tissue and more smooth muscle as they don’t need to withstand high pressures
explain structure and function of veins
- return blood to heart at lower pressures aided by contraction of nearby body muscles
- tunica interns is thinner ( little elastic and muscle tissue )
- collagen to provide strength and prevent bursting
- contain valves to prevent back flow
what are venules
- small blood vessels connecting veins and capillaries.
- very thin walls and very little smooth muscle
- contain valves like veins
explain the structure and function of capillaries
- connect arteries + veins and provides area for gases and nutrient as walls are porous
- narrow lumen so RBC’s closer to body cells
- thin one cell thick walls for short diffusion distance
- high branched for high surface area for diffusion
what’s the composition and function of blood
- plasma, RBC’S, WBC’S and platelets
- transports O2 and CO2, nutrients, waste for excretion, hormones, clotting factors etc
what is tissue fluid and what does it consist of
- fills spaces between cells
- made of small substances eg oxygen glucose and mineral ions, and also waste products eg co2, water and urea
- doesn’t contain big molecules like proteins or red blood cells and has les WBC’s as they cant leave the capillaries
explain the formation of tissue fluid
at arteriole end:
hydrostatic pressure > oncotic pressure, forcing fluids out of capillary down conc. gradient and into interstitial space
at venule end:
water potential is less inside capillary due to proteins and hydrostatic pressure is lower, so water moves back into capillary via osmosis down a water potential gradient
- excess tissue fluid drains into lymphatic system which eventually returns to bloodstream
describe the composition and transport of lymph
- similar to tissue fluid but with less oxygen and nutrients, but more fatty acids and WBC’s
- is transported through lymph vessels via muscle contractions and passes through lymph nodes, filtering pathogens
what is hydrostatic pressure
the force exerted by a liquid against the capillary walls coming from the pumping action of the heart
what is oncotic pressure
osmotic pressure exerted by plasma proteins pulling water into the capillaries
describe the pathway of blood in the circulatory system starting with the vena cava
- deoxygenated blood from vena cava
- enters right atrium then AV valve to right ventricle
- semilunar valve to pulmonary artery to lungs where blood gets oxygenated
- back into heart via pulmonary vein into left atrium
- AV valve into left ventricle, then semilunar valve out aorta to body where blood gets deoxygenated
describe the internal and external structure of the heart
- corona arteries surround heart to supply it blood
- atria and ventricles separated by AV valves, then go through semilunar valves
- septum runs down middle until apex
- left side is thicker to withstand pressure
explain a ‘lub-dub’ heartbeat sound
- caused by ventricles opening and closing
- slight delay to ensure all blood has been pushed out of the atria
what is the equation for cardiac output
cardiac output = heart rate X stroke volume
describe atrial systole
- ventricles relax, atria contract
- atrial pressure increases
- AV valves open
- blood flows into ventricles
describe ventricular systole
- ventricles contract, atria relax
- ventricular pressure increases
- semilunar valves open, AV valves shut
- blood flows into arteries
describe diastole
- ventricles and atria relaxed
- semilunar valves closed
- blood passively flows into atria
