Gas Exchange and Respiration Flashcards
Describe the changes occurring during inhalation and exhalation.
Breathing In
- Intercostals and diaphragm contract
- Thorax volume increases
- Air is drawn in because of decreased pressure
Breathing Out
- Intercostals and diaphragm relax
- Thorax volume decreases
- Air is forced out
How is oxygen transported to the tissues?
- The blood is carried to the lungs and the oxygen diffuses into it. The haemoglobin in the RBCs reacts with it and forms oxyhaemoglobin
- When the blood reaches the cells, oxygen is released from oxyhaemoglobin in RBCs and diffuses in to the body
- At the same time, CO2 diffuses into the blood (plasma) to be carried back to the lungs
- THEN……CO2 dissolves in water to form carbonic acid. This is poisonous as it can denature blood proteins including haemoglobin
- SO……receptors in the brain detect the fall in the pH and increase the breathing rate.
Explain how physical activities increase respiration rate and why?
- As physical activity increase, rate of respiration increases
- More O2 is used up and more CO2 is released.
- CO2 dissolves in tissue fluid and plasma forming carbonic acid.
- This can cause a fall in pH and denature blood proteins
- The brain (medula) detects this fall in pH before any harm can be caused.
- Breathing rate and depth is increased in order to remove the CO2
State the composition of inhaled and exhaled air.
AIR IN Nitrogen - 79% Oxygen - 21% Carbon dioxide - 0.04% Water vapour - varies
AIR OUT Nitrogen - 79% Oxygen - 16% Carbon dioxide - 4% Water vapour - loads
What problems can the inhaled dirt particles cause and why are there more chances of pathogens growing in the lungs?
Inhaled dirt particles can potentially block air spaces in the lungs.
Airborne pathogens give rise to infections, as the lungs provide a warm, moist environment ideal for their growth
How are the lungs adapted to prevent dirt particles and pathogens from entering the organ?
- The entry of dirt particles and pathogens are reduced by the ciliated epithelium which lines the trachea, bronchi and bronchioles.
- Goblet cells secrete a sticky mucus which lines these airways. Dirt and microbes adhere to the mucus.
- Beating cilia then transfer/transport the mucus up to the back of the throat.
- From here it can be swallowed, the mucus and any microbes it contains, being digested into simple, harmless substances
What is the job of the lung and the alveoli?
How is the alveoli adapted to its function?
JOB
- The job of the lungs is to transfer oxygen to the blood and remove waste CO2 from it.
- To do this the lungs contain millions of alveoli where gas exchange takes place.
ADAPTATION OF ALVEOLI
- Have enormous surface area (70 m2 in total)
- A moist lining for dissolving gases
- Very thin walls
- Copious blood supply to maintain the concentration gradient
What problems are caused by smoking?
- Cancer, chemicals in cigarettes can damage cells
- Peripheral vascular disease
- Blocks the aorta
- Tar in cigarettes paralyse cilia
- For pregnant women, the chemicals can harm the foetus
- Causes emphysema
What is respiration?
It goes on in every cell in our body. Controlled process of converting glucose to energy. Takes place in plants too. All living things respire to convert food (glucose) into energy.
What is the energy from respiration in animals used for?
- Muscle contraction
- Protein synthesis
- Active transport
- Growth
- Transmission of nerve impulses
- Maintaining a constant body temperature
What is aerobic respiration?
What is anaerobic respiration?
Aerobic respiration
- Happens when there is plenty of O2 available
- ‘Aerobic’ means ‘with air’ and it’s ideal way of converting glucose to energy
- No toxic waste produced
- Huge amount of energy produced
C6H12O6 + 6O2 –> 6CO2 + 6H20 +Energy
Anaerobic respiration - Happens when no oxygen is available - 'Anaerobic' means 'without air' - Not best way to produce oxygen - Poisonous waste product produced (lactic acid) C6H12O6 --> 2C3H6O3 +Energy
What is oxygen debt?
- Lactic acid generated in mucus
- Faster heart rate = more C3H6O3 moved from blood - liver
- Trigger : pH changes in blood act as receptor cells in the brain (medula) to increase heart rate.
- Even after lactic acid is removed the breathing rate is high
- Oxygen debt - the increased breathing rate supplies oxygen for aerobic respiration of lactic acid
Compare anaerobic respiration in humans and microbes?
- Both start-off with glucose
- Both release same amount of less energy
- Both happen in absence of O2
- In humans : produces lactic acid, in microbes : produces alcohol
Explain the process of bread making.
- Yeast is used in making bread, the CO2 from fermentation makes bubbles in the bread dough making the bread light in texture
- Flour, water, salt and oil are mixed to make the dough. No enzymes for yeast, but addition of water activates the maltose in dough. This digests some of the starch to sugar. Yeast then oxidises sugar to ethanol and CO2
- Gluten (protein) added to make the dough sticky and like plastic to hold the bubbles. It is repeatedly folded and stretched
- Then left for an hour (at 40˚C) for the yeast to act, accumulating CO2 bubbles which raises the dough, doubling its volume.
- It is then baked at 160˚C, this temp makes the bubbles burst, kills the yeast and evaps the small quantities of ethanol before dough turns into bread.
