Respiratory System

Stucture

allows for the efficient flow of air into and out of the lungs, so gas exchange can occur

Nasal Cavity

lined with a mucous membrane, so as air passes of the membranes, its warmed and humidified.

also has hairs and mucus, trapping debris

Mucous Membrane

in the nasal cavity and upper airways.

The epithelial lining has goblet cells that secrete mucus

Function is to trap debris before they enter the lungs

Pharynx

air travels through it before being divereted into the trachea by the epiglottis

Epiglottis

During inhalation, it covers the oesophagus guiding air into the trachea.

when swallowing, it covers the larynx preventing food from entering it

Larynx

cartilage structure joining the pharynx and trachea. Contains the vocal cords, which are mucous membranes that can vibrate when air passes of them.

Box-like structure constructed from 9 cartilages.

trachea

carries air in and out of the lungs. Made up of c-shaped cartilage rings that hold the structure open, ensuring air can always pass through. The rings prevent the tubes from collapsing during inhalation

epithelial tissue lining produces mucus, which can trap dust and debris. Cilia also line the trachea can move in wave0like motion to take the mucus and debris up to the pharynx, away from the lungs.

Bronchi

Trachea splits into 2 pirmiar bronchi for each lung. These then split into the secondary bronchi, which take the air into each lobe of the lung. The secondary bronchi continue to divide, forming tertiary bronchi.

Made up of c-shaped cartilage rings. They prevent the tubes from collapsing during inhalation

Bronchioles

When the tertiary bronchi divide, they from smaller airways (bronchioles), which continue to split until they end in millions of terminal bronchioles.

made of smooth muscles and elastin. Allowing the bronchioles to control the flow of air in the lungs, expanding when the body needs more oxygen

Lungs

each lung is divided into lobes. the left lung has 2, and the right 3. A membrane called the pleura covers the surface of the lungs, and lines the inside of the chest. Between the 2 layers of the membrane is a thin layer of pleural fluid.

Alveoli

each alveolus is surrounded by a network of blood capillaries. This is where gases move between the blood in the capillaries and the air in the alveoli. The alveoli are the functional units of the lungs. This makes it possible for them to be the surface for gas exchange

gas exchange

• structure suited for gas exchange

1. alveoli give the lungs a large internal surface area: volume, so that large amounts of gases can be exchanged in a relatively short time

2. each alveolus has lots of blood vessels so that as much blood as possible is able to receive. Continuous flow helps maintain the concentration gradient

3. the membrane that forms the wall of the alveoli is very thin, so many gas molecules don’t have to travel far when moving into/out the blood

gas exchange

Concentration gradient is required - maintained by the continous inspiraton of oxygen and the expiration of carbon dioxied. As well as the continous flow of blood to and from the blood capillaries

inspiration

the process of taking air into the lungs

diaphragm contracts, the internal intercostal muscles relax, external intercostal muscles contract. The volume of the chest cavity increases, therefore air pressure decreases

expiration

the process of removing air from the lungs.

Diaphragm relaxes, the internal intercostal muscles contract, external intercostal muscles relax. The volume of the chest cavity decreases and air pressure in the lungs decreases.

breathing

the process of moving air in and out of the lungs.

external and internal respiration

external - exchange of o2 and co2 between the lungs and blood

internal - the exchange of o2 and co2 between the blood and tissues

Disease

• Asthma

Chronic inflammatory disease of small bronchi and bronchioles

narrowing of the airways

• smooth muscles contract, narrowing airway

• inflammation causes the lining of airways the thicken, narrowing its diameter

• mucus fills the airways, narrowing the tube

Disease

• emphysema

caused by long-term exposure to irritating particles in the air taken into the lungs

the irritating particles cause damage to the alveoli. They lose their elasticity, and are often replaced with fibrous tissue, and may break down, reducing the internal surface area of the lung. because of the loss of elasticity of the lung tissue, the lungs are constantly inflated, and breathing out no longer occurs passively but requires voluntary effort