B8.1 - Gas exchange Flashcards
Exchange surfaces are
surfaces that are adapted to maximize the efficiency of gas and solute exchange
Why do animals need to exchange gases
to supply oxygen for respiration in cells and to remove waste products of respiration i.e CO2
How are gases exchanged at surfaces
by diffusion
What increases gas exchange surface
a large surface area
A thin membrane so shorter distance that the substance has to diffuse
A good blood supply
Good ventilation to deliver more O2 and remove CO2 from the body
What is breathing
the process of ventilating the lungs with air
Name the steps to gas exchange within the lungs
Air enters through the nose and mouth
It passes over the larynx where it can be used to make sounds.
Air then travels down the trachea to the lungs
It divides into two tubes called bronchi
Bronchi divide into smaller bronchioles
There are a network of bronchioles
They divide and end up with tiny air sacs called alveoli
What are the features of the alveoli
Millions of small tiny air sacs
They are surrounded by a network of capillaries allowing O2 and CO2 to be exchanged between blood in capillaries and air in lungs
Describe how alveoli adapted for gas exchange?
Thin membranes one cell thick for shorter diffusion distance.
Good blood supply (surrounded by many capillaries) to maintain a low concentration of oxygen in blood
Large surface area in the lungs so more oxygen can diffuse into the blood at the same time
Kept clear by cilia removing mucus.
High concentration gradients for gases
What cells secrete mucus into the linings of the trachea, bronchi and bronchioles
goblet cells
Why are goblet cells necessary
they secrete mucus to trap microorganisms and dust particles that are breathed in and moisturize to keep vital organs from drying out
The lining of the trachea and bronchi are covered in tiny hairs called
cilia
What is the function of cilia
to sweep in a co-ordinated motion to move mucus up from the lungs up the trachea and back into the mouth where it can be swallowed.
Alveoli’s are where
oxygen and carbon dioxide diffuse into and out of the blood
In the lungs the blood absorbs
oxygen from inhaled air and circulate it around the body
The lungs absorb
carbon dioxide from the blood and exhale it into the air
describe what happens during inhalation
the internal intercostal muscles contract and external intercostal muscles relax
the ribcage moves upwards and outwards
The diaphragm contracts and becomes flattened and less dome shaped
these two both increase volume of thorax (chest cavity) making pressure inside lower than outside making air rush into the lungs
describe what happens during exhalation
the internal intercostal muscles relax and the external intercostal muscles contract
the ribcage moves downwards and inwards
The diaphragm relaxes and becomes more dome shaped
This decreases the volume in the thorax (chest cavity) making the pressure inside more than the outside
Why is the trachea made up of rings of cartilage
to stop the trachea from collapsing in on itself and closing
What are the percentages for inspired air
oxygen - 21%
carbon dioxide - 0.04%
water - variable
What are the percentages for expired air
oxygen 16%
carbon dioxide - 4.5%
water vapor - high
Explain why the composition of inspired and expired air is different
Oxygen we inspire is used in respiration so percentage of oxygen expired is lower
CO2 breathed in is less than expired as CO2 is produced by respiration so percentage of expiration increases
Water vapor concentration increases because water evaporates from the moist linings of the alveoli into the expired air as a result of warmth of the body so increase expired.
What investigation can be used to compare CO2 inspired and expired
A limewater test for CO2
Why is limewater used to test for comparing CO2 inspiration and expiration
Lime water is a clear solution
It reacts with CO2 and turns cloudy
The tubes in the experiment show that expired air contains more carbon dioxide than inspired air
Explain why breathing rate increase when exercising
It increase the rate of respiration in cells creating a higher concentration of CO2 in the blood.
If more CO2 is produced it needs to be removed quickly
The brain detects this and receptors send impulses in the lungs to cause breathing to become deeper and faster
This means more CO2 can be breathed out at a quicker rate and more oxygen and be breathed in
What piece of equipment can be used to test for rate and volume of someone’s breathing
spirometer
What are the steps for an investigation on the effect of exercise intensity on breathing rate
Set a timer for 15 seconds
Sit still and don’t move and measure your pulse for BPM.
You can do this by measuring your pulse from your neck or wrist
After the 15 seconds do the calculator 4 x amount of beats counted.
Now choose an intense exercise like high knees and set a metronome to 30 60 and 120 beats to measure the intensity of the exercise.
Do it for 2 minutes for each timed metronome and count how many beats in 15 seconds again.
Rest between to allow breathing rate to stabilize.
DV: The BPM measured
IV: The different intensity of exercise
CV: Same exercise used and same person for exercise,
Describe the trend for the effect of exercise intensity on breathing rate
As the intensity of exercise increases the breathing rate also increases
Why is tobacco smoke dangerous
Tobacco smoke contains mixtures of chemicals that are dangerous to the cells
Over time tobacco smoke can lead to diseases like
Chronic obstructive pulmonary disease (COPD) a collection of lung diseases that includes bronchitis, emphysema, lung cancer and coronary heart disease.
What are the effects of carbon monoxide on gas exchange
it can replace oxygen in hemoglobin and prevent the body from absorbing too much oxygen
What are the effects of nicotine on gas exchange
it is addictive and narrows blood vessels increasing blood pressure and the risk of coronary heart diseases (CHD)
What are the effects of tar on gas exchange
the sticky substance can coat cells of the trachea, bronchi and bronchioles leading to coughing and cell damage.
There is a decrease in rate of gas exchange and can lead to cancer of the lungs, throat and mouth