Primary Defences Against Disease Flashcards
What is a primary defence?
Those that prevent pathogens entering the body
How does the skin act as a physical barrier?
Outer layer is called the epidermis, consists of layers of cells known as keratinocytes. This produced by mitosis at the base of the epidermis. As They migrate out to the surface of the skin, They dry out and cytoplasm is replaced by a protein (keratin). This is called keratinisation, this takes 30 days. When the cells reach the surface, they die.
What are the clotting factors
1) Damage to blood vessel wall exposes collagen and releases clotting factors.
2) Platelets bind to collagen and release clotting factors.
- ) 1+2 can create temporary platelet plug
3) if 1,2 join with inactive thrombokinase (factor x) it creates an active thrombokinase (an enzyme)
4) active thrombokinase + prothrombin in blood and calcium creates active thrombin (enzyme)
5) active thrombin + soluble fibrinogen in plasma creates insoluble fibrin (this is what stops blood from passing through open wound.
6) fibres attach to platelets in plug replaced the temporary platelet plug formed from 1+2.
7) red blood cells and platelets are trapped.
8) this forms a clot
How does mucous membranes protect us?
Bacteria gets trapped in mucus and prevents it from getting into the blood stream.
How does coughing and sneezing protect us?
It releases those toxins out of the body. These are a form of reflexes.
How does inflammation help protect our body
Inflammation is when tissue becomes red and swollen, may be filled with puss. May be hot and painful. When a microorganism is detected by tissue, histamine will vasodilate, making the capillary walls more permeable to white blood cells and some proteins. They enter the tissue fluid, causing swelling and excess fluid. Fluid is drained into lymphatic system, increasing chance of pathogens coming into contact with lymphocytes.
How do the eyes, ear canal and female reproductive system
Eyes; protected by antibodies and enzymes in tear fluid
Ear canal; lined by wax, traps pathogens.
Reproductive system; protected by mucus plug in cervix and acidic conditions in vagina
