2.1 Flashcards
What is mucus?
A thick slimy fluid secreted by the cells lining many organs.
Mucus is produced, for example, by cells in the gas-exchange system, the digestive system and the reproductive system.
Apart from water, its main component is a protein called mucin.
Mucus acts as a lubricant and as a protective layer.
What are cilia?
Tiny hair-like extensions of the cell surface membrane.
Ciliated epithelial cells line the airways of the lungs.
The beating action of the cilia continuously wafts mucus and trapped particles up into the throat where it is swallowed.
Ciliated epithelial cells also waft egg cells down the Fallopian tube from the ovary to the uterus.
What are epithelial cells?
Cells which form the outer surface of many animals, line cavities and tubes, and cover the surface of internal organs.
What are columnar epithelium?
Column-shaped epithelial cells, often with microvilli on free surface.
What are the properties of the trachea?
1) kept open by ‘C’ shaped rings of cartilage
2) smooth muscle in its wall
3) ciliated lining
What are the properties of the bronchus?
1) Cartilaginous plates
2) smooth muscle in its walls
3) ciliated lining
4) mucus producing cells
What is the diaphragm?
A thin sheet of muscle situated between the lungs and the abdominal organs of a mammal. Contraction of this muscle causes the diaphragm to flatten and air to be drawn into the lungs.
What is a pathogen?
An organism capable of causing disease
What is Fick’s Law?
Relates to the factors affecting rate of diffusion
Diffusion is proportional to: surface area x conc. differece / thickness of gas exchange surface
What are the structures of a healthy alveolus that help maintain efficient gas exchange?
1) Large SA:Vol ratio. SA is directly proportional to the rate of diffusion
2) Thin walls for short diffusion distances
3) Good network of capillaries maintain a high concentration gradient
4) Thin layer of moisture on the surface which allows gases to dissolve before diffusing
What reduces surface tension and stops the alveoli collapsing?
The soapy surfactant, found in the water which diffuses from alveoli cells, which contains a mixture of lipid molecules.
What type of epithelium do alveoli have?
Squamous for short diffusion distances
Which type of cells produce mucus?
Goblet
What is cystic fibrosis?
An inherited condition in which a faulty gene results in the production of a faulty transport protein in cell membranes.
A person with cystic fibrosis has a faulty CFTR protein, so produces thick, sticky mucus. This leads to problems with digestion and gas exchange.
What problems does the sticky mucus in CF patients cause?
1) Increases chances of lung infections as pathogens become trapped in the thick mucus which is hard to cough up.
There are low levels of oxygen in the mucus (as it diffuses slowly into it and CF epithelial cells use up more oxygen than normal). Bacteria can thrive in these anaerobic conditions.
2) Reduces gas exchange - slow diffusion and a greater diffusion distance
