Flashcards in Primary Defenses Against Disease. Deck (22)
What is inflammation?
Swelling and redness of tissue caused by infection.
What is the mucous membrane?
Specialised epithelial tissue that is covered by mucus.
Define primary defences.
Those that prevent pathogens entering the body.
What is the main primary defence?
What are the cells called in the outer layer of the skin (epidermis)?
Keratinocytes are produced by mitosis at the base of the epidermis. Then they migrate out to the surface of the skin. As they migrate, they dry out and the cytoplasm is replaced by the protein keratin.
How long does keratinisation take?
Clotting factors are released from platelets when a clot needs to be formed. What do the clotting factors cause?
An enzyme cascade.
What does clotting involve?
Calcium ions and at least 12 clotting factors.
Once the clot has formed it makes a scab. What is the importance of a scab?
A scab shrinks over time and bring the two side of the cut together. A scab is a kind of temporary seal for the body.
How does the skin repair itself?
Fibrous collagen deposited under scab.
Stem cells in epidermis divide by mitosis, new skin cells.
How is the new skin supplied with nutrients?
New blood vessels are formed to supply oxygen and nutrient to the new tissues.
Why is mucus used by the airways?
They are thinner there to facilitate diffusion and are therefore less well protected from pathogens.
How are the airways protected?
By the mucus membrane.
What are mucus secreting cells called?
How do the airways use mucus to combat pathogens?
The mucus traps the pathogens. The ciliated epithelium waft the layer of mucus in a coordinated fashion to the back of the throat where it is then either swallowed or coughed up by the animal.
Where else are mucous membranes found?
Gut, genital areas, anus, ears and nose.
What is the point of coughing or sneezing?
Coughing causes a sudden expulsion of air and with it the microorganisms which are irritating the body.
Specialised cells called mast cells are triggered by infection. What is the substance called that these cells release?
What does histamine do?
Causes vasodilation and makes the capillary walls more permeable to white blood cells and some proteins.
Blood plasma and phagocytic white blood cells leave the blood and enter the tissue fluid.
Why is it good that swelling occurs at the site of infection?
Swelling means that there is an increase in tissue fluid due to an influx in blood plasma and phagocytic WBC. The tissue fluid is then drained into the lymphatic system, where it can trigger an immune response, eventually killing the pathogen.