all Flashcards
what materials does a cell take in during exchange?
oxygen, glucose, amino acids (and other nutrients), water and minerals
what materials does a cell need to get rid of during exchange?
waste such as urea and carbon dioxide
what is the surface area:volume ratio?
as surface area increases, volume decreases. the LARGER an organism, the SMALLER the SA/V ratio. the size/area of an animals body affects the SA/V. for every one unit of volume inside, there is less SA for material to diffuse into the organism
how can larger organisms exchange materials when they can’t rely on their surface?
lungs → alveoli (exchange of oxygen and CO₂)
gut → villi in small intestine (absorption of glucose)
kidneys → nephrons (release of excess water)
how are alveoli adapted for gas exchange by diffusion between air in the lungs and blood in the capillaries?
- LARGE SURFACE AREA of alveoli walls
- THIN WALLS (only one cell thick) = short diffusion distance
- RICH BLOOD SUPPLY that maintains a steep diffusion gradient
- LINED WITH LIQUID so that they are moist for dissolving gases
what are alveoli?
they are tiny air sacks in the lungs which are specialised to maximise the diffusion of oxygen and CO₂
how does temperature affect the rate of diffusion?
diffusion happens faster at higher temperatures
how does the concentration gradient affect the rate of diffusion?
the steeper/larger the concentration gradient, the faster the rate of diffusion
how does the diffusion distance affect the rate of diffusion?
the shorter the distance the molecules have to travel, the faster the rate of diffusion
how does the surface area affect the rate of diffusion?
the larger the surface area, the faster the rate of diffusion
how do you work out the rate of diffusion using Ficks Law?
rate of diffusion 𝑎 (surface area x concentration gradient) ➗ thickness of membrane
what are the tests for carbon dioxide?
- limewater : clear → cloudy
- hydrogen carbonate indicator : red → yellow
describe the structure and function of RED BLOOD CELLS (5 points)
- their job is to carry oxygen to all the cells in the body
- their shape allows maximum surface area for absorbing oxygen
- they contain haemoglobin which contains lots of iron
- when mixed with oxygen in the lungs, it becomes oxyhemoglobin
- they have no nucleus because they don’t need one so this allows more space for haemoglobin
describe the structure and function of WHITE BLOOD CELLS (5 points)
- their main role is to defend against disease
- they have a big nucleus
- they get rid of unfamiliar microorganisms
- they produce antibodies to fight bacteria
- they produce antitoxins to neutralise the toxins produced bacteria
describe the structure and function of PLASMA
- pale straw coloured liquid carries -RBC, WBC and platelets -nutrients such as glucose and amino acids -carbon dioxide -urea -hormones -antibodies and antitoxins
describe the structure and function of PLATELETS (3 points)
- small fragments of cells
- no nucleus
- they help blood to clot at a wound (to stop the entrance of microorganisms)
describe the structure and function of ARTERIES (6 points)
- they carry blood AWAY from the heart
- carry OXYGENATED blood
- NO VALVES blood has enough pressure from heart
- THICK MUSCLE to withstand pressure
- SMALL LUMEN
- blood flows at a HIGH PRESSURE
describe the structure and function of VEINS (6 points)
- carry blood TOWARDS the heart
- carry DEOXYGENATED BLOOD
- VALVES to prevent back flow of blood
- THIN MUSCLE
- LARGE LUMEN
- blood flows at a LOW PRESSURE due to the distance from the heart
describe the structure and function of CAPILLARIES (6 points)
- in between veins and arteries
- carry OXYGENATED and DEOXYGENATED blood
- NO VALVES
- THIN WALLS (one cell thick : short diffusion distance)
- TINY VESSELS
- LOW BLOOD PRESSURE and SLOW SPEED to allow exchange of materials
why are the walls of the LEFT VENTRICLE thicker than those of the RIGHT VENTRICLE?
the left ventricle has to push blood around the body and the right only has to take it to the lungs
what are the ATRIA?
smaller, less muscular upper chambers of the heart. they receive blood coming back to the heart from the veins
what are the VENTRICLES?
larger, more muscular lower chambers of the heart. they pump blood out of the heart
what are the coronary arteries and coronary veins?
these supply the hearts blood. it provides the muscle tissue with oxygen and glucose for respiration so the tit can contract
list in order the chambers and blood vessels when blood passes through them
vena cava → right atrium → tricuspid valve → right ventricle → semilunar valve → pulmonary artery
pulmonary vein → left atrium → bicuspid calve → left ventricle → semilunar valve → aorta
