6.3 Defence against infectious diseases Flashcards
What does the skin act as?
The skin acts as a barrier to infection
What is a pathogen?
A pathogen is a virus or organism that causes disease
What is the top layer of the skin called?
The epidermis is constantly being replaced as underlying dermal cells die and move upwards. The layer of dead cells is a good barrier against most pathogens
What is the bottom layer of the skin called?
The underneath layer is called the dermis and is alive. It contains sweat glands, capillaries, sensory receptors and dermal cells that give strength and structure to the skin.
What is the function of the biochemical agents in the skin?
The biochemical agents in the skin release acidic secretion to lower pH. The lower pH inhibits the growth of bacteria and fungi.
What is an example of a biochemical agent in the skin?
Sebaceous glands secrete chemicals which inhibit the growth of some bacteria.
What is the role of a mucous membrane?
Some pathogens enter into the that we breathe. The route of entry is lined with mucous membranes. Cells of mucous membranes produce and secrete a lining of sticky mucus. This can trap incoming pathogens and so prevent them from reaching cells they could infect. Some mucus membrane tissue is lined with cilia. Cilia are hair-like extensions capable of a wave like movement. This movement moves trapped pathogens up and out of mucus lined tissues. The cells that secrete mucus also secrete an enzyme called lysozome - which is capable of chemically damaging many pathogens.
What is the function of clotting?
Clotting prevents the loss of blood from broken vessels. Damaged cells and platelets release chemical signals called clotting factors which triggers a coagulation cascade.
What is a necessity for clotting to take place?
Platelets need to release clotting factors
Why is it important that blood clotting takes place under strict control?
If blood clotting takes place within blood vessels then the resulting clots can cause blockages.
What are platelets?
Platelets are cellular fragments that circulate in the blood.
