non specific immune response- lqc 4

Question 1

what are the main purposes of the 4 processes in the non specific immune response

Answer 1

to destroy, prevent the multiplication and spread of invading pathogens

Question 2

what happens if the processes fail

Answer 2

Bacteria can get carried away from the site in the blood or lymph. They travel to the lymph nodes, spleen & liver where they can undergo phagocytosis by macrophages. If this fails then there is widespread infection leading to septic shock (sepsis).

Question 3

inflammation is also known as an

Answer 3

inflammatory response

Question 4

describe the process of the inflammatory response

Answer 4

Damaged basophils and mast cells release histamine. This causes vasodilation of the arterioles to increase blood flow to the infected site – this brings more phagocytes to the area. It becomes red and hot. Histamine also makes the capillaries more leaky so that plasma, phagocytes and antibodies can enter the site. This causes oedema (swelling).

Question 5

where is the enzyme lysozyme found

Answer 5

tears, nasal secretions, saliva

Question 6

what is lysozymes substrate

Answer 6

the bacterial peptidoglycan cell wall

Question 7

what is the result of lysozymes action

Answer 7

the cell wall is broken down, water enters the cell, it bursts and the cell is destroyed

Question 8

what does the interferon protein provide defence against

Answer 8

mostly viruses, but also some bacteria and protozoa

Question 9

describe interferons mode of action

Answer 9

It is released from infected cells. It diffuses to and is taken up by surrounding cells where it prevents viral protein synthesis and therefore replication of new virus particles

Question 10

which cells carry out phagocytosis

Answer 10

phagocytes- neutrophils and macrophages

Question 11

describe the process of phagocytosis

Answer 11

Bacterium binds to membrane receptors on the phagocyte. Membrane processes surround the bacterium engulfing it into a {phagocytic vesicle / phagosome}. Lysosomes containing digestive enzymes fuse with the phagosome to form a phagolysosome and the bacterium is digested. A small vacuole buds off containing parts of the bacterium. The bacterial fragments bind to MHC receptors and are presented on the surface of the phagocyte to produce an antigen presenting cell (APC). The main phagolysosome fuses with the cell surface membrane to release the digested contents.

Question 12

what are the sequence of events that occur in the non specific immune response at the site of a cut

Answer 12

1) damaged basophil white blood cells and mast cells release histamine
2) arterioles in the area dilate and venules constrict sue to the presence of histamine
3) blood flow in the capillaries at the infected site increases. the site of the cut becomes red. it also becomes warm due to increased metabolic activity
4) capillaries become leaky as cells in the capillary walls separate slightly
5) plasma fluid, white blood cells and antibodies leak from the blood into the tissue causing oedema (swelling)
6) neutrophils, a type of white blood cell, engulf bacteria. each neutrophil engulfs between 5 and 20 bacteria before becoming inactive and dying
7) macrophages, another type of white blood cell, engulf bacteria, debris from damaged cells and foreign matter
8) pus collects at the site of the cut; this thick white liquid is made up of dead white blood cells
9) the pus gradually breaks down and is absorbed into the surrounding tissues
10) if viruses have infected cells at the side of the cut, the cells produce the protein interferon. this diffuses to the surrounding cells where it prevents viruses from multiplying by inhibiting viral protein synthesis