Respiratory System & Physiology Flashcards
Components, Inhalation/Exhalation & Control of Breathing
Role of the respiratory system
To intake Oxygen (required by the body for respiration) and remove unwanted gaseous waste products (Carbon Dioxide).
This process is also known as gas exchange.
What is the thoracic cavity?
The space in the body where the lungs are
Lungs
Two in each human contain bronchi, bronchioles and alveoli.
Have a light, spongy texture as they contain a large proportion ofgases (used for gas exchange).
What is the pathway of air INTO the body?
Mouth (Buccal/ Oral Cavity)
Trachea (windpipe)
Bronchi
Bronchioles
Alveoli
Bloodstream (cappilaries)
What is the difference between the trachea, bronchi & bronchioles?
The trachea is the windpipe found at the end of the mouth (and rinds down the neck).
This then branches off into two bronchi, one of which goes in each lung.
The bronchi then branch off into many bronchioles, the alveoli are found at the very end of the bronchioles.
Cartilage in the airways
Strong and flexible rings of cartilage surround the airways.
This helps to hold the airways open (during inhalation)
Ciliated epithelia
Found in the inner surface of the trachea and bronchi.
They waft mucus produced by goblet cells out of the airways (into the oesophagus)
What happens during inhalation?
The diaphragm contracts and flattens and external intercostal muscles contract. This causes the volume of the thoracic cavity to increase
Pressure in the lungs is reduced (to lower than the atmosphere), therefore air is forced into the lungs down a pressure gradient.
What happens during exhalation?
The diaphragm relaxes and domes up and the external intercostal muscles relax. This causes the volume of the thoracic cavity to decrease.
Pressure in the lungs is increased above the atmosphere and air is forced out of the lungs down a pressure gradient.
What happens during forced exhalation?
The diaphragm relaxes and domes back up, the internal intercostal muscles contract, pulling the ribs down and in. This causes the volume of the thoracic cavity to decrease.
Pressure increases above the atmosphere and moves out, down its concentration gradient.
Control of Breathing (increase)
Breathing rate is increased when high levels of carbon dioxide are detected in the blood.
Nerve impulses from the brain are sent to internal intercostal muscles and the diaphragm to increase contractions and therefore the breathing rate
Control of Breathing (decrease)
Stretch receptors (in the wall of the alveoli) detect an increased volume of blood so the breathing rate needs to decrease.
Nerve impulses are sent from the brain to internal intercostal muscles and the diaphragm to decrease contractions and therefore the breathing rate.
What are the alveoli?
Microscopic sacks, which is where gas is exchanged (in and out) between the blood and the bronchioles/air
There are millions of alveoli in each lung.
Pulmonnary Surfactant
Fluid secreted by the alveoli which helps to reduce surface attention of the pulmonary fluids and prevent the alveoli from collapsing during expiration
Pathway of air INTO capillaries (alveoli)
Alveolar Space
Alveolar epithelium
Capillary endothelium
Capillaries (blood)
Adaptations of the Alveoli
They have a thin exchange surface (one cell thick) to provide a short diffusion pathway to speed up the rate of diffusion.
They have a large SA (as there’s many of them) to provide a faster rate of diffusion.
There is a good blood supply which provides a steep concentration gradient of oxygen and carbon dioxide. This helps to increase the rate of diffusion as it relies on different in concentration.
Capillary (lumen) in relation to gas exchange
The lumen of the capillary only allows one red blood cell to pass through at a time.
This helps to drastically decrease the pressure and the speed of blood flow which allows for gas (and ion) exchange to take place more efficiently.
What is the diaphragm?
A dome shaped sheet of muscle found under the lungs
