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Cardio- respiratory system (The cardiac cycle and pathway of the blood…
Cardio- respiratory system
The pathway of air
Passage of air into the lungs
1) Air enters the body and is warmed as it travels through the mouth and nose.
2) It then enters the trachea.
3) The trachea divides into two bronchi. One bronchus enters each lung.
4) Each bronchus branches out into smaller tubes called bronchioles. Air travels through these bronchioles.
5) At the end of the bronchioles, the air enters one of the many millions of alveoli where gaseous exchange takes place.
Gaseous exchange
Gas exchange
Gas exchange occurs at the alveoli in the lungs and takes place by diffusion. The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries.
Diffusion is the movement of gas from an area of high concentration to an area of low concentration.
There is a high concentration of oxygen in the alveoli and a low concentration of oxygen in the blood, so oxygen diffuses from the alveoli into the blood.
There is a high concentration of carbon dioxide in the blood and a low concentration in the alveoli, so carbon dioxide diffuses from the blood into the alveoli.
Both oxygen and carbon dioxide are capable of combining with an iron-rich protein in the blood called haemoglobin. Haemoglobin carries oxygen to be exchanged at the working muscle and carbon dioxide to be exchanged at the lung.
Blood vessles
Key Terms:
Arteries = Any of the muscular-walled tubes forming part of the circulation system by which blood (mainly that which has been oxygenated) is conveyed from the heart to all parts of the body.
Veins = Any of the tubes forming part of the blood circulation system of the body, carrying in most cases oxygen-depleted blood towards the heart.
Capillaries = Any of the fine branching blood vessels that form a network between the arterioles and venules.
Atria = Upper chambers of the heart that collects blood from veins
Ventricles = Lower chambers of the heart that collect blood from veins
The pathway of blood :
The direction in which blood flows:
Deoxygenated blood enters the right atrium from the superior Vena Cava and into the inferior Vena Cava
Then passes through our valve to the right ventricle
The pulmonary artery transports deoxygenated blood to the lungs to the left atrium
Gaseous exchange occurs resulting in oxygenated blood
The pulmonary vein transport oxygenated blood from the lungs to the left atrium
It then then passes through a valve to the left ventricle
Oxygenated blood is ejected from the heart and is transported to the body via the aorta
Structure of the heart
The cardiac cycle and pathway of the blood
Pathway of the blood:
Oxygenated blood into the right atrium
then into the right ventricle
The pulmonary artery then transports deoxygenated blood to the lungs
Gas exchange occurs (blood is oxygenated)
Pulmonary vein transports oxygenated blood back to the left atrium
then into the left ventricle
before oxygenated blood is ejected and transported to the body via the aorta
Cardiac output, stroke volume and heart rate
Cardiac Output = stroke volume x heart rate
Mechanics of breathing
Inhaling (at rest):
Intercostals = Situated between the ribs
Rib cage = Protects vital organs
Diaphragm = a dome-shaped muscular partition separating the thorax from the abdomen in mammals. It plays a major role in breathing, as its contraction increases the volume of the thorax and so inflates the lungs.
Interpertation of a spirometer trace
Tidal volume = The lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied
Expiatory reserve volume = The additional amount of air that can be expired from the lungs by determined effort after normal expiration
Inspiratory reserve volume = The maximal amount of additional air that can be drawn into the lungs by determined effort after normal inspiration
Key terms
Vital capacity = The greatest volume of air that can be expelled from the lungs after taking the deepest possible breath.
Residual volume = The amount of air that remains in a person's lungs after fully exhaling. Doctors use tests to measure a person's residual air volume to help check how well the lungs are functioning
