Respiration + Gas Exchange in Humans - Biology

Respiration

The chemical process that takes place in cells to breakdown glucose to release energy

ATP

a molecule that is produced during respiration in the mitochondria and provides energy in living organisms

Aerobic respiration

the breaking down on glucose to release energy in the presence of oxygen

anaerobic respiration

the breaking down of glucose to release energy in the absence of oxygen

detecting respiration - calcium hydroxide ( limewater)

Limewater goes from clear/colourless to cloudy white as it absorbs carbon dioxide

Detecting respiration: Hydrogen carbonate indicator

Yellow - High conc. CO2

orange - atmospheric air

pink/purple - Low conc. CO2

Detecting respiration: temperature increase

as energy is release during respiration, it is partially released as heat energy and warms up the cells surroundings

why use germinating seeds

doesn’t photosynthesis but it does respire

why wash the seeds in disinfectant ( bleach )

to kill any bacteria that may respire making results inaccurate

why use cotton buds to hold the seeds in the flasks

to allow the oxygen to reach the seeds so they can respire aerobically

Arteries

carry blood away from the heart ( oxygenated blood )

Veins

carry blood towards the heart ( deoxygenated the blood )

Gas exchange

The swapping of gases in the lungs, oxygen from the air enters the blood while carbon dioxide in the blood plasma enters the air in the lungs

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration, a passive process.

Breathing

the mechanical process of the diaphragm and intercostal muscles contracting and relaxing to change the size and shape of the lungs, it is how oxygen is taken in and carbon dioxide removed

Ventilation

The movement of air in and out of our lungs when we breath

adaptation of alveoli 1

Many alveoli - increase surface area of lungs and therefore increases the rate of diffusion

adaptation of alveoli 2

Thin - walls are only 1 cell thick this allows for a short diffusion distance as the blood capillaries surrounding the alveoli also have thin walls to increase rate of diffusion

Adaptations of alveoli 3

A moist lining allows the gases to dissolve

Adaptation of alveoli 4

A steep concentration gradient is maintained by a good blood supply in the capillaries this allows constant gas exchange due to ventilation bringing in more oxygen and removing more carbon dioxide, while circulation carries away the oxygenated blood and brings more deoxygenated blood

during intense exercise

An increased breathing rate meaning more oxygen is need by muscle cells for contraction this means higher rates of aerobic respiration to release more energy

after intense exercise

• aerobic respiration can’t supply all the oxygen needed during vigorous exercise so muscle cells start to respire anaerobically as well producing lactic acid.

• breathing rate remains high to repay the ‘oxygen debt‘ (EPOC), more oxygen allows for aerobic respiration to convert lactic acid back into glucose in the liver.

3 tips for a regular comment question

• compare patterns in data or describe trends in singular data

• suggest explanations

• comment on experimental design ( practical not repeated )

comment question on changes/ differences

• state the change

• compare the values given using comparatives (more/less)

• explain the reason for these changes/ differences

• do it for each difference

comment question on results from data or effect

• explain the trends seen in data

• fully explain why they would occur - referencing the biological processes involved

comment question on conclusion

• split your answers into reasons you agree and disagree with the conclusion

• give an explanation for each

Cancer

Chemicals in tar are carcinogenic, causing cells to divide uncontrollably and form a cancer, especially in the mouth, throat and lungs.

Chronic Bronchitis

Tar coats the cilia in the airways meaning sticky mucus builds up in the lungs rather than being removed, causing bacteria to grow in the sticky mucus causing bronchitis ( infection and inflammation of bronchi )

Emphysema

Continuous coughing to remove tar and mucus damages the alveoli, reducing their surface area this means gas exchange is less efficient , so patients struggle to breathe. this condition is called emphysema. there is no cure

Consequence of smoking - High blood pressure

stimulants like nicotine raise blood pressure, blood pressure is also increased because carbon monoxide in tobacco smoke reduces the amount of oxygen that blood can carry

consequence of smoking - cardiovascular disease/ coronary heart disease

tobacco smoke damages the lining of blood vessels, this causes cholesterol in the blood to stick on to the walls of the blood vessels. This reduce blood flow and can eventually lead to heart attack, stroke, deep vein thrombosis ( DVT ) or pulmonary embolism

Consequences of smoking - Carbon monoxide

Carbon monoxide is produced by the incomplete combustion of carbon-based fuels ( Vehicle exhausts are the main source in urban areas)

CO binds strongly to haemoglobin forming carboxyhaemoglobin, this reduces the amount of oxygen haemoglobin can carry, causing less O2 transport in the blood, less O2 delivered to cells, less aerobic respiration and less energy released. This can lead to low birth rate in babies whose mothers smoke, them having less O2 in their blood means less is delivered to the baby this means the baby will also have less O2 aerobic respiration, release less energy and will grow less.

acute CO poisoning can cause - headache, dizziness and confusion, sickness, convulsions, unconsciousness and death 

nicotine and smoking

An addictive drug and stimulant, smoking has many side effects such as increased risk of stroke, high blood pressure and blood clots. These blood clots are caused due to an increased number of platelets ( due to nicotine ) making them stickier and more prone to clumping.