The human gas exchange system Flashcards
What is inspiration? When does this occur?
Inhalation - When the air pressure is greater than the air pressure inside the lungs, air is forced into the lungs.
What is expiration?
Exhalation - When the air pressure in the lungs is greater than that of the atmosphere, air is forced out of the lungs.
Pressure changes within the lungs is brought about by the movement of 3 sets of muscles, what are the 3 muscles?
The diaphragm - a sheet of muscle that separates the thorax from the abdomen,
the internal intercostal muscles - contract leading to expiration,
the external intercostal muscles - contract leading to inspiration.
What happens during inspiration?
The external intercostal muscles contract and the internal intercostal muscles relax
The ribcage is pulled upwards and outwards, increasing the volume of the thorax
The diaphragm muscles contract causing it to flatten, increasing the volume of the thorax
The increased volume of the thorax causes reduction of pressure in the lungs
The atmospheric pressure is now greater than the pulmonary pressure and so air is forced out of the lungs.
What happens during expiration?
The internal intercostal muscles contract and the external intercostal muscles relax
the ribs move downwards and inwards, decreasing the volume of the thorax
the diaphragm muscles relax and so it’s pushed up again by the contents of the abdomen that were compressed during inspiration. The volume of the thorax i further decreased
Decreased vol of thorax increases the pressure in the lungs
Pulmonary pressure is now greater than the atmospheric pressure and so air is forced out of the lungs.
When do the internal intercostal muscles contract?
expiration
When do the external intercostal muscles contract?
inspiration
Why is a constant supply of oxygen needed in the body?
In order to release energy in the form of ATP during respiration.
Why is the volume of oxygen absorbed and the volume of carbon dioxide removed in mammals large?
because…
they’re relatively large organisms with a large volume of living cells
they maintain a high body temp which is related to them having high metabolic and respiratory rates.
What are lungs?
A pair of lobed structures made up of a series of highly branched tubules called bronchioles, which end in tiny air sacs called alveoli.
What is the trachea?
A flexible airway that is supported by rings of cartilage that prevents the trachea from collapsing as the pressure inside it falls when breathing. The walls of the trachea are made of muscle lined with cilialted epithelium and goblet cells.
What are bronchi?
2 divisions of the trachea, each leading to 1 lung. Similar in structure to trachea. Also produce mucus and have cilia to move mucus towards throat. Larger bronchi supported by cartilage, amount gets smaller as bronchi is smaller.
What are bronchioles?
Series of branching subdivisions of the bronchi. Their walls are made of muscle lined with epithelial cells. Muscles allow them to constrict so they can control the flow of air into and out of the alveoli.
What is alveoli?
Minute air sacs at end of bronchioles. Between alveoli there is some collagen and elastic fibres. Lined with epithelium. The elastic fibers allow alveoli to stretch as they fill with air when breathing in. They then spring back during breathing out in order to expel carbon dioxide rich air. Alveolar membrane is gas exchange surface.
