2.1 The Effects Of CF On The Lungs Flashcards
Goblet cells
Mucus-producing cell.
Cilia
Tiny hair-like extensions (singular cilium) of the cell surface membrane. Ciliated epithelial cells line the airways of the lungs. Small particles of dust in the air we breathe in are trapped in the mucus that lines these airways. The beating action of the cilia continuously wafts this mucus and the 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.
Epithelium
Tissue which forms the outer surface of many animals. Epithelial cells also line the cavities of organs such as the gut and lungs. The epithelium consists of one or more layers of cells sitting on a basement membrane. These cells may be flat (squamous or pavement epithelium) or tall in shape (columnar epithelium).
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.
Tissue
A group of cells which have a similar structure, and together carry out a particular function. Epithelial tissue, for example, forms the outer surface of many animals. It also lines the cavities of organs such as the gut and lungs. Plants are also made up of different types of tissues including vascular tissue. Vascular tissues transport substances through the plant.
Basement membrane
Epithelial cells are cells which form the outer surface of many animals. They also line cavities inside organs. Epithelial cells sit on a membrane formed from protein fibres held in a jelly-like substance. This membrane is called a basement membrane.
Pathogens
A general term used to describe a microorganism that causes disease. Campylobacter and Helicobacter are examples of pathogenic bacteria. Viruses are also pathogens, as are the fungi which cause diseases such as athlete’s foot and thrush.
Diffusion
The movement of molecules from where they are in a high concentration to where they are in a lower concentration. Small molecules such as oxygen diffuse through cell membranes into cells. Other molecules cross cell membranes with the aid of proteins. This form of diffusion is called facilitated diffusion. Osmosis is a special form of diffusion involving water molecules.
Gas exchange surface
The layer across which oxygen and carbon dioxide are exchanged.
Features:
- Large surface area of the alveoli
-Numerous capillaries around the alveoli
- thin walls of the alveoli and capillaries meaning a short distance between the alveolar air and blood in the capillaries
Alveolus, alveoli
One of the tiny air sacs in the lungs where gas exchange takes place. The alveoli are lined by a layer of cells known as squamous epithelium. These cells are very thin and this helps to ensure efficient diffusion of oxygen from the alveoli into the blood, and of carbon dioxide from the blood into the alveoli. The total surface area of all the alveoli in the lungs is very large. This large surface area also helps to ensure efficient diffusion.
Rate of diffusion
Dependent on
- Surface area-> directly proportional
- Concentration gradient -> directly proportional
- Thickness of the gas exchange surface -> indirectly proportional
Fick’s law
A law which relates some of the factors affecting the rate of diffusion across a gas exchange surface. Fick’s law states that rate of diffusion is proportional to: surface area × difference in concentration / thickness of gas exchange surface
Cystic fibrosis
Cystic fibrosis transmembrane regulator An inherited condition in which a faulty gene results in the production of a faulty transport protein in cell membranes. The CFTR (cystic fibrosis transmembrane regulator) protein transports chloride ions across the membrane. A person with cystic fibrosis has a faulty CFTR protein, so produces thick, sticky mucus. This leads to problems with digestion and gas exchange.
Surface area
The area (measured in units such as mm2 or m2) of a surface, e.g. the outside of an alveolus.
Concentration gradient
A concentration gradient occurs when a substance (e.g. oxygen) exists at a higher concentration in one place than another, with intermediate concentrations in between.
