Chapter 9 - Protection Against Invaders Flashcards
(32 cards)
Are Bacteria harmful?
Nope, most of them are non-pathogenic.
What are Pathogens?
Disease-causing organisms.
Eg. Bacteria and viruses
What is a Bacteria?
Bacteria consist of a single cell and can be seen only with a microscope.
What are Viruses?
They are too small to be seen with an ordinary microscope, they have distinctive structures and differing sizes. Found to contain genetic material.
How do Viruses spread?
When the viruses infects a living cell, it’s DNA or RNA induces the cell to manufacture more virus particles. The new virus particles are then able to leave the host cell to infect others.
What are Bacteriophages?
Viruses that multiply in bacterial cells, causing the death of the bacterium.
What are Parasites?
Organisms that live on or in another living thing, the host, and gain food and shelter from it. They may cause the host little or much harm, depending on the nature of the relationship.
What’s the difference between non-specific and specific defences?
Non-specific defences are defences that work against ALL pathogens (skin), and Specific Defences are directed at a particular pathogen.
What is Sebum?
It is secreted by oil glands in the skin, contains substances that kill some pathogenic bacteria.
List some protective reflexes.
- Sneezing
- Coughing
- Vomiting
- Diarrhoea
What is the purpose of Blood Clotting?
Helps to minimize blood loss from the broken vessels and prevent the entry of infecting microorganisms.
How does Blood Clotting work?
- Constriction occurs immediately after injury to reduce blood flow.
- The internal walls of blood vessels are normally very smooth, but any damage creates a rough surface to which the platelets stick.
- The platelets release substances that act as vasoconstrictors which enhance and prolong the constriction of the damaged vessels.
What is Fibrin?
An insoluble protein formed from the complex series of reactions results in the formation of threads. The fibrin threads form a mesh work that traps blood cells platelets and plasma = clot.
Explain Clot Reaction.
A slow process which occurs after the formation of the blood clot. The network of threads contracts, becoming denser and stronger and pulling the edges of damaged blood vessels together. Serum is squeezed out.
What does a Phagocyte do?
A phagocyte is an internal non-specific defence that attack organisms that penetrate our external defence.
Cells that can engulf and digest micro-organisms and cell debris.
What role does the Leucocytes play?
Leucocytes are able to leave the blood capillaries and migrate through the tissues to places of infection or injury. Some secrete substances that destroy bacteria before they are engulfed, whereas others engulf live bacteria and digest them.
What are Macrophages?
They are large phagocytic cells that develop from some leucocytes. Some are “wandering” cells that move through the tissues looking for pathogens to come to them while some are fixed in one place.
What is the purpose of Inflammation?
Inflammation is a response to any damage to the tissues.
- Reduce the spread of any pathogens, to destroy them and prevent the entry of additional pathogens.
- Remove damaged tissue and cell debris.
- Begin the repair of the damaged tissues.
What are 4 signs of inflammation?
- Redness
- Swelling
- Heat
- Pain
Explain the Inflammatory Response.
- When the skin is broken, a non-specific inflammatory response is triggered.
- Most cells release histamine and heparin. Histamine diffuses into capillaries, causing them to dilate and become leaky. The area becomes red and swells. Heparin prevents clotting in the immediate area.
- Complement proteins are activated and attract phagocytes to the area, which engulf and digest dead cells and bacteria.
- The tissue heals when histamine and complement protein signaling finish and phagocytes are no longer attracted to the area.
What is a Histamine?
A substance which increases blood flow through the area and causes the walls of the blood capillaries to become more permeable so that fluid is filtered from the blood. It is the increased blood flow that causes the heat and redness associated with inflammation and the escape of sulks from the blood causes the swelling.
What is the role of the Heparin?
Prevents clotting so the release of heparin from the most cells prevents clotting in the immediate area if the injury. A cloth of the fluid around the damaged area does form and this slows the spread of the pathogen into healthy tissues.
What does the Lymphatic System consist of?
- A network of lymph capillaries joined to larger lymph vessels.
- Lymph nodes, which are located along the length of some lymph vessels.
What is the main function of the Lymphatic System?
To collect some of the fluid that escapes from the blood capillaries and return it to the circulatory system.