Gas exchange and respiration Flashcards
What features do all gas exchange surfaces have in common that maximise the rate of gas exchange?
- Large surface area, to allow faster diffusion of gases across the surface
- Thin walls- so that diffusion distance remains short
- Good ventilations with air so that diffusion gradient can be maintained
- Good blood supply to maintain a high concentration gradient so diffusion can occur faster.
what are alveolus
Tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs).
What process occurs at the alveoli?
The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.
How many alveoli does each lung contain approximatly?
Around 250 million alveoli
What are the features that all exchange surfaces have in common? ex. villi, root hair cells
- Large surface area
- Good blood supply
- Steep concentration gradient
These features allow the efficient movement of substances across their surface by diffusion, active transport and osmosis
Ribs
Bone structure that protects internal organs such as the lungs
Intercostal muscle
Muscle between the ribs which control their movement causing inhalation and exhalation
Diaphragm
Sheet of connective tissues and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation
Trachea
Windpipe that connects the mouth and nose to the lungs
Larynx
Also known as the voice box, when air passes across here we are able to make sounds
Bronchi (PL)
Large tubes branching off the trachea with one bronchus (SIN)
Bronchioles
Bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli
Alveoli
Tiny air sacs where gas exchange takes place
Clavicle
Collar bone
Why is the composition of inhaled air different to the one of exhaled air?
Air that is inhaled differs in gas composition to air that is exhaled, this is due to the process known as gas exchange that takes place in the alveoli.
What happens during gas exchange in the alveoli?
During gas exchange in the alveoli, oxygen enters the blood from the alveoli and CO2 and water vapour leave the blood to enter the alveoli
What is the composition of inhaled air?
Inhaled air contains around 21% of oxygen, 0.04% of CO2, 0.2-4 % water vapour and 78% nitrogen
What is the composition of exhaled air?
Exhaled air contains 16% of oxygen, 4% CO2, 5-7 % of water vapour and 78% of Nitrogen
Why are there two sets of intercostal muscles?
Muscles are only able to pull on bones, not push them. This means that there must be two sets of intercostal muscles, one to pull the rib cage up and another to pull it down
Where can the intercostal muscles be found?
One set of them can be found outside of the ribcage (external intercostal muscle) and the other set is found inside the ribcage (internal intercostal muscle)
What does cartilage surround?
The trachea and the bronchi
What is the function of the cartilage?
To support the airways and keep them open during breathing
What could happen if cartilage wasn’t present?
If they were not present then the sides could collapse inwards when the air pressure inside the tubes drops.
What is the function of the diaphram?
It is a thin sheet of muscle that separates chest activity from the abdomen. It is responsible for controlling ventilation in the lungs.
What happens when the diaphragm contracts?
When the diaphram contracts, it flattens and this increases the volume of the chest cavity (thorax), which leads to decreased air pressure inside the lungs (thorax) , relative to outside the body, drawing air in. This process is known as inhalation, during this process, the external set of intercostal muscles contract to expand the ribcage.
What happens when the diaphragm relaxes? exhalation OR expiration
When the diaphragm relaxes, it moves up, becoming dome- shaped , which causes an increase in pressure in the lungs (thorax), a decrease in volume of the thorax and causes air to be forced out of lungs. The external intercostal muscles relax, allowing the ribcage to drop inwards and downwards.
Why is there a diffrence in concentration of oxygen levels in inspired and expired air?
Oxygen is removed from the blood by respiring cells so blood returning to lungs has a lower oxygen concentration than the air in the alveoli which means oxygen diffuses into the blood in the lungs
Why is there a difference in the concentration of CO2 in expired and inspired air?
Carbon dioxide is produced by respiration and diffuses into the blood from respiring cells; The blood transports the carbon dioxide to the lungs where it diffuses into the alveoli as theres a higher concentration in the blood than in the air of the alveoli.
Why is there a diffrence in the concentration of water vapour in expired and inspired air?
Water evaporates from the moist lining of the alveoli into expired air as a result of the warmth of the body.
Why are the levels of nitrogen the same in expired and inspired air?
Nitrogen gas is very stable and so cannot be used by the body, for this reason its concentration does not change in inspired or expired air
Why does frequency of breathing increase during exersice?
Because muscles are working harder and aerobically, respiring more and they need more oxygen to be delivered to them (and Co2) to keep up with the energy demand.
What happens when the aerobic respiration can’t meet the energy demands?
If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid.
What happens to lactic acid after exercise has finished?
The lactic acid that has built up in muscles needs to removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions. It can only be removed by combining it with oxygen, this is known as “repaying the oxygen debt”
What happens after Co2 is produced as a product of aerobic respiration?
Co2 levels increase in the muscle cells, this co2 diffuses out of the cells into the blood plasma, this causes a slight drop in pH so the blood becomes slightly more acidic.
Where does the blood with CO2 from aerobic respiration flow?
The blood flows around the circulatory system and passes to the brain where the increased CO2 levels are detected by chemoreceptors in the brain
What are chemoreceptors, where are they located?
Chemoreceptors are cells that detect chemical changes in the body, they can detect changes in blood gas levels, as well as changes in pH. They are located in the medulla oblongata of the brain
What does the brain do to increase the rate and depth of muscle contraction?
The brain sends nerve impulses to the diaphragm and the intercostal muscles to increase the rate and depth of muscle contraction. The rate of inspiration increases, along with the volume of air moved in and out with each breath. This results in greater absorption of oxygen and removal rate of co2. This supports the increased rate of respiration
Which processes require enzymes?
Aerobic respiration, anaerobic respiration in yeast and animals, all catabolic reactions
why does anaerobic respiration of glucose release less energy in muscle cells than aerobic respiration?
In aerobic respiration, glucose is completely broken down into carbon dioxide and water. However, in anaerobic respiration, the breakdown of glucose is incomplete. The end product of anaerobic respiration is lactic acid instead of carbon dioxide and water.
What helps oxygen to be absorbed rapidly in the lungs?
Alveoli have thin walls and a large surface area
which materials are excreted by kidneys
The kidney regulates/controls the water and salt content and removes urea. It is excreted in urine.. The filtered excess water, salts and urea form a liquid called urine
which process uses the greatest amount of energy
Respiration is the process uses the greatest amount of energy.
how is an effective oxygen supply maintained between the alveoli and the lung capillaries
Effective oxygen supply between the alveoli and lung capillaries is maintained by (large surface area, thin diffusion barrier) and (high blood flow, steep diffusion gradient, hemoglobin binding). These factors ensure a continuous and efficient oxygen supply to the blood while
removing carbon dioxide.
