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The structure and function of the cardio-respiratory system - Coggle…
The structure and function of the cardio-respiratory system
The pathway of Air
When we breathe in, air moves through our mouth and nose
It then travels down the trachea. The inner surface of the trachea is covered by thin hairs called
cilia
, which catches particles of dust, The trachea is kept open by
rings of cartilage.
Near the lungs, the trachea divides into two tubes called the
bronchi
( one enters left lungs one enters right )
Once in the lungs the bronchi split into smaller bronchi before dividing into even smaller tubes called bronchioles.
At the end of each bronchiole are openings to the alveoli. There are usually several alveoli coming from one bronchiole,
forming a little clump that resembles a cluster of grapes.
At the alveoli gaseous exchange occurs. Capillaries carrying blood surround each alveoli resulting in oxygen being passed
into the bloodstream from the alveoli in exchange for carbon dioxide which passes from the blood stream into the alveoli.
Gaseous exchange
We need to get oxygen from the air into the blood, and we need to remove waste carbon dioxide from the blood into the air. Moving gases like this is called gas exchange.
Features of alveoli
they give the lungs a really big surface area
they have moist, thin walls (just one cell thick)
they have a lot of tiny blood vessels called capillaries
The gases move by diffusion from where they have a high concentration to where they have a low concentration:
oxygen diffuses from the air in the alveoli into the blood
carbon dioxide diffuses from the blood into the air in the alveoli
Blood vessels
There are 3 types of blood vessel
Veins
Carry blood towards the heart
Most carry deoxygenated blood (carbon dioxide rich)
Thinner walls than arteries as blood is pumped through at a lower pressure
Have valves to prevent back flow of blood
Have large lumen to allow more blood to pass through them
Capillaries
Gaseous exchange takes place here
One cell thick - enabling cells to diffuse in and out of the bloodstream
Surround alveoli and tissues to enable gaseous exchange
Huge network throughout the body linking arteries and veins (large surface area for gaseous exchange to take place).
Arteries
Most arteries carry oxygenated blood
Thick walls due to higher pressure
Small/narrow lumen to force blood through at a higher rate
Strong elastic walls - can change diameter fast
Carry blood away from the heart
Structure of the Heart
Parts in the heart
Left / Right Atriums –
Upper Chambers
Left / Right Ventricles –
Lower Chambers
The heart contains valves to prevent the backflow of blood
Vena Cava –
Vein that brings deoxygenated blood back to the right side of the heart
Aorta –
Artery that takes oxygenated blood from the left side of the heart to the body tissues / cells
Pulmonary Artery –
only artery in the body that carries deoxygenated blood.
This artery takes the blood from the right side of the heart to the lungs.
Pulmonary Vein –
only vein in the body that carries oxygenated blood.
This vein takes blood from the lungs and returns it to the left side of the heart.
The pathway of blood
Deoxygenated blood enters right atrium, dark red now.
Right atrium pumps blood into the right ventricle through biscupid valve, opens due to pressure and closes to prevent backflow.
Right ventricle pumps blood through pulmonary artery to lungs, oxygen picked up and CO2 deposited. Blood colour changes to bright red as it is oxidised.
From the lungs the blood retruns to the left atrium through pulmonary vein
Cardiac output = stroke volume x heart rate
Cardiac output - amount of blood ejected from the heart in one minute
Stroke volume - amount of blood pumped out of the heart by each ventricle in one concentration
Heart rate - number of times heart beats, usually measured in bpm
Spirometer trace
It is a measure of lung volumes which includes;
tidal volume: volume of air inspired or expired/exchanged in each breath
inspiratory volume: amount of air breathed in after tidal volume
expiratory volume: amount of air could be breathed out after tidal volume
residual volume: amount of air left in lungs after maximal expiration
Mechanics of breathing
When inhaling
diaphragm flattens, moves downwards
intercoastal muscles contract
raise ribs up, making chest cavity larger
reduces air pressure causing air to be sucked into lungs
When exhaling
diaphragm becomes dome shaped makes chest chavity smaller