34 terms

IGCSE Biology- Gas Exchange

Parts of the lungs
- larynx
- trachea
- right lung
- left lung
- bronchus (right and left)
- bronchioles
- intercostal muscles (external and internal)
- alveolus
- rib
- diaphragm
Order in which air passes through
trachea- bronchus-bronchioles- alveoli
Function of cartilaginous rings of the trachea
- stabilize trachea and keep it rigid while allowing the trachea to expand and lengthen when breathing
- If not supported- trachea would collapse due to the pressure in the chest
- betweeen 16-20- rings
- C- shaped because back of trachea presses against oesophagus- cartilage ring opens at the oesophagus and is replaced by connecting tissue and muscle- allows food to be swallowed easily
- Rings are stacked on top of each other- small space in between
Gas exchange system- label
- alveolus
- capillary
- oxygen
(see picture)
Features of the gas exchange surface
- large surface area
- thin surface/ less distance
- good blood supply
- good ventilation with air
How fast diffusion is achieved
- High surface area
- Short distance
- High concentration gradient
How a high surface area is maintained in gas exchange
Many alveoli and capillaries in the lungs
How a short distance is maintained in gas exchange
- Alveoli and blood capillaries have very thin walls
- Blood capillary- the diameter of a red blood cell
- Red blood cells have to squeeze through- short distance for diffusion
How gradients are maintained in gas exchange
- CO2 is taken away by the lungs
- O2 is taken away by blood flow
- Blood is constantly moving through capillaries- fast diffusion rate
Process of gas exchange
- Deoxygenated blood arrives at the alveoli in tiny blood capillaries
- Thin walls in capillaries and alveoli
- Deoxygenated blood- red blood cells are low in oxygen, plasma is high in CO2
- carbon dioxide diffuses from blood plasma into alveoli and into the air
- Oxygen diffuses from the air into the walls of the alveoli and into the red blood cells
Mechanism of breathing
- air is drawn into the lungs- gas exchange
- lungs are unable to draw air in on their own
- chest cavity where lungs are positioned is
- breathing in- diaphragm contracts
- volume of chest increased
- air is drawn into the lungs because pressure inside is less than the pressure outside
- Diaphragm is lowered
- internal intercostal muscles relax
- external intercostal muscles contract
- Rib cage is raised upwards and outwards
- Volume of thorax increases-pressure decreases- air is drawn into the lungs
- Diaphragm springs up- relaxes
- external intercostal muscles relax
- internal intercostal muscles contract
- Rib cage is pulled downwards and inwards
- lung volume decreases and air pressure inside increases
- air is pushed out
What makes us breathe?
Increased carbon dioxide levels, detected by the brain - the most important for homeostasis
The regulation of conditions in the body such as temperature, carbon dioxide and water content
Respiratory control
-The body picks up on certain changes- sends signals in return to adjust rate and depth of breathing to suit the body's needs
- controls the depth of inspiration and expiration
- controls the rate of breathing
Parts of the goblet and ciliated cells (label)
- cilia
- cilated cell
- mucus (released by goblet cell)
- nucleus
Function of goblet cells
- secrete mucus
- found scattered among the epithelial lining of organs, such as the intestinal and respiratory tracts
- found inside trachea, bronchus, larger bronchioles in the respiratory tract, small intestines and the colon
Function of cilia
- small hairs on the cells of the breathing system- keep dust and small particles out of the body
How do goblet cells and ciliated epithelial cells work together? (5 key points)
- Goblet cells are constantly secreting mucus
- This keeps the lining of the epithelial wet and traps foreign particles, eg dust, bacteria and viruses
- Cilia constantly move in a wavelike manner- wafts mucus and particles towards the throat
- prevents pathogens from entering the lungs
How smoking affects the respiratory system
- destroys the cilia
-goblet cells produce more mucus- more particles build up
- Bacteria and particles get caught in mucus but cannot be pushed out of the trachea
- Bacteria enter the lungs- live in the mucus
- Tar on the lungs- prevents the gases for diffusing
- Can lead to asthma- especially secondhand smoking in children
- Causes cancer and increased risk of heart disease
How air pollution affects the respiratory system
- similar effects to smoking- causes breathing problems
- Can also lead to asthma
Chronic inflammation of the lungs in which the airways (bronchi) are reversibly narrowed
Toxins in smoke (cigarettes)
- tar
- nicotine
- carbon monoxide
- smoke particles
Effects of tar on the lungs
- settles on the lining of the airways in the lungs
- Creates breathing difficulties- bronchitis and emphysema
- Bronchitis- tar in the airways leads to difficulty in breathing- coughing and wheezing- reduced oxygen intake and lack of energy
- Emphysema- permanent destruction to the alveoli
- Also causes lung cancer
Effect of carbon monoxide on the lungs
- binds tightly to haemoglobin
- less oxygen to the entire body, inefficient respiration
- less oxygen to the heart- puts a strain on the heart
Effects of nicotine
- Addictive drug
- stimulates nervous system, releases adrenalin
- Puts stress on the heart but reduces blood flow to tissues
- Increases the stickiness of platelets- higher risk of blood clotting and stroke
Effects of smoke particles on the lungs
- no longer filtered by cilia
- large particles can enter- causes irritation, bronchitis and asthma
- toxins and carcinogens can enter
Effects of smoking on the heart
- Arteriosclerosis- blockage of arteries (mainly caused by high cholesterol and fat diets, but smoking contributes)
- smoke particles can enter blood and cause hardening of arteries
- If the coronary artery is blocked, the heart loses oxygen and will result in a heart attack
Why people smoke
- peer pressure
- nicotine is addictive
- don't realise damage before its too late
atmospheric air/expired air
- N2- 78% in inspired/atmospheric air, none exhaled (not used)
- O2- 21% in inspired/atmospheric air, 15% exhaled (some used)
- used by cells for respiration, absorbed by gas exchange surface
- CO2- 0.035% in inspired/atmospheric air, 3.6% exhaled- lots exhaled
- carbon dioxide is a product of respiration of our cells- diffuses our across gas exchange surface
- H2O- percentage in inspired air varies, a lot is exhaled
Physical activity and breathing
- physical activity requires energy- energy comes from the respiration of glucose (or proteins and fats when glycogen is used up)
- respiration requires oxygen- heart rate needs to increase to increase blood flow- deliver respiring tissue with O2 and take away CO2
-breathing needs to be faster and deeper
Oxygen debt
- during vigorous exercise- we respire anaerobically and produce lactic acid
- oxygen is needed to remove the lactic acid build up
- we continue to breathe faster and deeper and our heart beats faster even after exercising (more detailed explanation in respiration unit)
- there's an experiment we need to know but i can't find a diagram so look at mr petes notes
- two tubes, A and B filled with limewater- tubes in both
- tubes are connected to one large tube (like a fork in a road)
- tube in A is shorter (above liquid), tube in B is submerged
- when breathing through the large tube, inhaled air will only go through A - easier path
- exhaled air will go through B- easiest path
- B will turn cloudy- carbon dioxide present
- A remains the same
- *make sure you understand the direction of air flow and the difference between inspired and expired air