Gas Exchange (Humans) Flashcards
What is the pathway of air down the lungs?
It enters the mouth
It goes down the trachea
Into the bronchi
Into the bronchioles
Into the alveoli
It diffuses into the bloodstream
What is the process of inspiration?
The external intercostal muscles contract, internal intercostal muscles relax
The ribs are pulled up and out
The diaphragm contracts and flattens
The volume of the thorax increases
The pressure in the thorax decreases
Air is forced into the lungs due to the pressure difference
What is the process of expiration?
The external intercostal muscles relax, internal intercostal muscles contract
The ribs are pushed down and in
The diaphragm relaxes and returns to its dome shape
The volume of the thorax decreases
The pressure in the thorax increases
Air is forced out of the lungs due to the pressure difference
How are alveoli adapted for gas exchange?
High surface area to volume ratio for diffusion
1 cell thick alveolar wall for short diffusion distance
Good ventilation maintains a steep concentration gradient of high oxygen and low carbon dioxide in the air in the lungs, increasing the rate of diffusion
A rich blood supply due to dense capillary networks maintains a steep concentration gradient of high carbon dioxide and low oxygen in the blood supplied, increasing the rate of diffusion
How does smoking cause emphysema and what happens?
Smoking weakens alveoli walls
The alveoli are damaged and the walls of the alveoli collapse
This causes there to be less alveoli
This means that there is much less surface area for gas exchange, so less gas exchange occurs
The body receives less oxygen, and the individual can suffer from shortness of breath and fatigue
How does smoking cause bronchitis and what happens?
Chemicals in smoke damage cilia
The cilia stop working
Mucus cannot be wafted out of the airways
This causes a build up of mucus
Bacteria build up and reproduce
This leads to constant infections = Bronchitis
What is the effect of nicotine?
Narrows blood vessels, leading to increased blood pressure
It is also highly addictive
Can increase your risk of heart attack/stroke
What is the effect of carbon monoxide?
It binds to haemoglobin, reducing your capacity to carry blood
It means your heart and lungs have to work harder
This can increase your risk of heart attack/stroke
How does smoking cause lung cancer?
Carcinogens in smoke like tar cause mutations
These mutations lead to changes in DNA
These can lead to uncontrolled cell division, resulting in a tumour
What happens when a person has coronary heart disease and what causes it?
Cholesterol/fat builds up within artery walls, narrowing their lumens and increasing blood pressure
Blood clots form
The coronary artery is blocked
The heart receives less blood and oxygen, and an individual can experience angina
This causes the body to receive less oxygen
The body has to start respiring anaerobically, producing lactic acid
The heart muscle does not have enough oxygen to respire, leading to a heart attack
Outline an experiment to investigate the effects of exercise on breathing rate
Measure the number of breaths per minute for person A at rest
Have them exercise for a set time, and then immeadiately after measure their number of breaths per minute
Compare results
Repeat step 2 every minute after exercise to measure the rate that it returns to normal
Repeat this for different people, or wait until their breathing returns to normal and repeat for the same person
Why does breathing increase after exercise?
More muscular contractions
More respiration in muscle cells
More oxygen needed, and more carbon dioxide produced
More gas exchange must happen
This means more breathing must happen
Why does breathing still occur after exercising even though we have stopped?
Lactic acid built up needs to removed, which requires oxygen
More carbon dioxide needs to be removed
Oxygen debt
