Human Gaseous Exchange System Flashcards
Nose/ Nasal Cavity
- large surface area with a good blood supply which warms the air to body temperature
- a hairy lining, which secretes mucus to trap dust and bacteria protecting delicate lung tissue from irritation and infection
- moist surfaces, which increase the humidity of the incoming air, reducing evaporation from the exchange surfaces
Trachea
It is a wide tube supported by C shaped ring of strong, flexible cartilage which stop the trachea from collapsing. The trachea and its branches are lined with a ciliated epithelium, with goblet cells between and below the epithelial cells.
Ciliated Cells
They are cells covered in tiny hair like structures which waft together. They move mucus containing trapped dust and microbes up to the throat
Bronchus
In the chest cavity the trachea divides to form the left bronchus and the right bronchus. They are similar in structure to the trachea, with the same supporting rings of cartilage, but they are smaller.
Bronchioles
In the lungs the bronchi divide to form many small bronchiole. Only the longest have cartilage. The walls of the bronchioles contain smooth muscle. When the smooth muscle contracts, the bronchioles constrict. When it relaxes, the bronchioles dilate. This changes the amount of air reaching the lungs. Bronchioles are lined with the thin layer of flattened epithelium, making some gaseous exchange possible.
Alveoli
They are thin-walled, moist air sacs in the lungs. They consist of a layer of thin, flattened epithelial cells, along with some college and elastic fibres. These elastic tissues allow the alveoli to stretch as air is drawn in. When they return to their resting size, they help to squeeze the air out. This is known as the elastic recoil of the lungs.
Ribs
Protect the lungs and have intercostal muscles between them to execute breathing/ ventilation.
External Intercostal Muscles
INHALATION: contracts to raise ribs
EXHALATION: relax to lower ribs
Internal Intercostal Muscles
INHALATION: ?
EXHALATION: contract further to force out more air
Diaphragm
INHALATION: flattens and contracts
EXHALATION: relaxes and is pushed up
Pulmonary vein
Thin walled blood vessel carrying blood at low pressure. Takes oxygenated blood from the lungs back to the heart
Pulmonary Artery
Thick walled blood vessel carrying blood at high pressure. Delivers deoxygenated blood to alveoli to exchange CO2 for O2 (only artery with deoxygenated blood).
Goblet Cells
Differentiated cells specialised to secrete mucus.
Surfactant
Chemical mixture containing phospholipids and both hydrophilic and hydrophobic proteins, which coats the surfaces of the alveoli and prevents them from collapsing after every breath.