Cartilage
Rings of cartilage in the walls of trachea and bronchi provide support.its strong but flexible .it stops the trachea and bronchi collapsing when you breath in a the pressure drops
Ciliated epithelium
-cila hair like structure on the surface of epithelial cells lining .the airways they beat the mucus secreted by the goblet cells .thus moves the mucus upwards away from the alveoli towards the throat where it’s swallowed thus helps prevent lung infections
Goblet cells (lining in airways )
-secrete mucus the mucus traps microorganisms and dust particles in the inhaled air stopping them from reaching the alveoli
Smooth muscle
- smooth muscle in the walls of the trachea bronchi and bronchioles allow their donated to be controlled .during excerise the smooth muscles relaxes making the tubes wider . This means there’s less smooth muscle relaxes making the tubes wider meaning less resistance airflow and air moves in ans out more easily
Elastic fibres
-elastic fibres in the walls of the trachea bronchi bronchioles and alveoli help the process of breathing out . On breathing in the lungs inflate and the elastic fibres and streched . Then the fibres recoil to help push the air out when exhaling
How the alveolus is specialised for exchange
-many aveoli= large SA
-each alveolus is small , so large SA:V ratio
-inner surface moist and has pulmonary surfactant reduces surface tension and prevents collapse of aveoli
-very short diffusion distance
-single layer of squamous epithual cells ->5Mm thick
-surrounded by network of capillaries -> blood flow maintains concentration gradient
-contain elastic fibres that are streched during inhalation fibres recoil during exhalation
-inner surface patrolled by macrophages- engulfs and destroys pathogens and forging particle
What is ventilation?
The movement of air into and out of the lungs
Why is ventilation important important for gas exchange
-it maintains a steep concentration gradient of oxygen and carbon dioxide between alveoli ans blood
Where does gas exchange occur in the lungs
-in the aveloi
What structure separates the lungs from the abdomen
The diagram
Q: What happens to the diaphragm during inhalation?
The diaphragm contracts and flattens.
What happens to the external intercostal muscles during inhalation?
They contract
What happens to the rib cage during inhalation?
The ribs move upwards and outwards.
What happens to thoracic volume during inhalation
Throatic volume increases
What happens to pressure inside the lungs during inhalation
-pressure decreases below atmospheric pressure
Why does air enter the lungs during inhalation
Air moves down a pressure gradient from higher atmospheric pressure to lower pressure in the lungs.
What happens to the diaphragm during expiration?
The diaphragm relaxes and becomes dome-shaped
What happens to the external intercostal muscles during expiration?
They relax
Q: What happens to the rib cage during expiration?
The ribs move downwards and inward
What happens to thoracic volume during expiration?
Thoracic volume decreases.
What happens to pressure inside the lungs during expiration?
Pressure increases above atmospheric pressure.
Why does air leave the lungs during expiration?
Air moves down a pressure gradient from the lungs to the atmosphere.
What muscles are involved in forced expiration?
A: Internal intercostal muscles and abdominal muscles.
What do internal intercostal muscles do during forced expiration?
They contract, pulling ribs downwards and inwards.
