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Biology > Diseases - 4.1 > Flashcards

Diseases - 4.1 Flashcards

1
Q

What is a pathogen?

A

A microorganism that causes disease

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2
Q

What is a communicable disease

A

A disease that can be transmitted from one organism to another

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3
Q

What diseases are caused by bacteria?

A
  • Tuberculosis (A)
    -Meningitis(A)
    -Ring rot (P)
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4
Q

What diseases are caused by viruses?

A

-HIV (A)
-Influenza (A)
-Corona virus (A)
-Tobacco mosaic virus (P)

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5
Q

What diseases are caused by protostists?

A

-Malaria (A)
-Blight (P)

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6
Q

What diseases are caused by fungi?

A

-Athletes foot (A)
-Ringworm (A)
-Black sigatoka (P)

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7
Q

What is an antibiotic?

A

A drug that slows bacteria growth or kills bacteria

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8
Q

What are the primary reasons for the development of antibiotic resistance?

A

-Over prescription of antibiotics
-Patients not completing the course of antibiotics
-Routinely using antibiotics in farming

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9
Q

How are pathogens transmitted?

A
  • Direct physical contact (reduce by hand washing, cleaning surfaces, etc)
  • Faecal - oral transmission usually by eating food or water contaminated by the pathogen, eg cholera (reduce by washing fresh food and treatment of drinking water)
  • Droplet infection ( reduce by covering mouth when coughing, etc)
  • Transmission by spores - they can be carried in the air or in soil (reduce by washing hands after contact with soil)
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10
Q

What is a vector?

A

An organism that carries a pathogen from one host to another. This is indirect transmission- eg the plasmodium that causes malaria enters a host via a bite from a mosquito

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11
Q

What is the role of T helper cells?

A

Release cytokines that stimulates B cells to develop and stimulates phagocytosis by phagocytes

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12
Q

What is the role of T killer cells?

A

Attack and kill host body cells that display the foreign antigen

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13
Q

What is the role of T memory cells?

A

Provide long term immunity

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14
Q

What is the role of T regulator cells?

A

Shut down the immune response after the pathogen has been successfully removed. Also involved in preventing autoimmunity

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15
Q

What is the role of plasma cells?

A

Circulate in the blood to manufacture and release antibodies

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16
Q

What is the role of B memory cells?

A

Remain in the body for years and act as the immunological memory

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17
Q

What happens in clonal selection in the specific immune response?

A

The specific antigens on the pathogen are detected by T and B lymphocytes that carry a specific receptor molecule on their plasma membrane that is complimentary to the shape of the antigen. This is where a T helper cell is clonally selected

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18
Q

What happens in clonal expansion in the specific immune response?

A

Once the correct lymphocytes have been activated they must increase in number to become effective so divide by mitosis. The T helper cells also secretary cytokines which attract B cells

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19
Q

What happens during differentiation during the specific immune response?

A

T and B lymphocytes develop into a range of useful cells

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20
Q

What are the three main groups of antibodies?

A

-Agglutinins
-Opsonins
-Antitoxins

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21
Q

How do Opsonins work?

A

Bind to the antigens in a pathogen which acts as a binding site for phagocytic cells so they can bind more easily to destroy the pathogen

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22
Q

How do agglutinins work?

A

It cross links pathogens by binding an antigen in one pathogen with one binding site and then an antigen in another pathogen with its other binding site. This clumps together the pathogens which impedes them from carrying out some of their functions and makes it easier for them to be engulfed by phagocytosis

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23
Q

How do antitoxins work?

A

Directly bind to toxin molecules decreased by pathogen to neutralise them and prevent damage to cells

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24
Q

State three factors that would affect the speed of transmission in plants

A

-climate change
-wind
-overcrowding of crops
-warm humid conditions

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25
How is influenza virus most likely to be transmitted between humans?
Respiratory droplets
26
Sate four different types of vector that can transmit a communicable disease
-water -wind -animals (mosquitos) -humans
27
State three passive physical defences that prevent plants being infected by pathogen
-cellulose cell wall -bark -waxy cuticle -thorns
28
State three active physical defences a plant would use against a invading pathogen
- Callose synthesised and deposited between plasma membrane and cell wall (callose blocks sieve plates in phloem) - callose deposited in plasmodesmata between infected cells and their neighbours -lignin added to cell walls -tyloses block xylem vessels
29
State three chemical defences a plant would use against an invading pathogen
- hydrolytic enzymes (chitinases , tannins, etc) - antibacterial compounds ( phenols, alkaloids, etc)
30
Describe the role of the skin as a primary non specific defence
-dead outer layer of keratin prevents pathogen entry -skin flora outcompete pathogens for space -oil secretions inhibit pathogenic growth
31
Describe the role of mucus membranes as a primary non-specific defence
- mucus traps pathogen -mucus contains lysosomes -phagocytes engulf and digest pathogens in mucus
32
What enzyme catalyses the conversion of prothrombin to thrombin?
Thromboplastin
33
Describe the role of thrombin in the clotting process
Causes the conversion of fibrinogen into insolvable fibrin fibres to block the wound
34
Describe the process of inflammation as a secondary non-specific response
-mast cells release histamines -histamines increase the permiability of capillaries so that plasma leaks into tissue fluid (causes pain and swelling) -arterioles vasodilation so more blood can reach the infected area (causes heat and redness) -neutrophils are attracted to the area so more phagocytosis happens
35
Describe the process of phagocytosis
Phagocyte engulfs pathogen into a phagosome. Lysosomes fuse with the phagosome to form a phagolysosome. Enzymes, hydrogen peroxide and nitric acid break down the pathogen
36
What is the name of small proteins that act as cell signalling compounds?
Cytokines
37
How are neutrophils adapted for their role?
-Have a lobed nucleus so they can squeeze through capillaries -Plasma membrane have receptors for opsonins -Many mitochondria for respiration -Many ribosomes to make enzymes -Many lysosomes -Many Golgi apparatus
38
Why are opsonins non-specific?
So that opsonins can attach to any type of pathogen to help phagocytosis so the phagocyte has something to bind to. They have to be non-specific to bind to many different pathogens
39
Define autoimmunity
The destruction of self tissue as the body’s immune system mistakes its own healthy tissues as foreign and attacks them
40
Give examples of autoimmune diseases
-Rheumatoid arthritis -Lupus -Type 1 diabetes
41
What is the role of T regulatory cells
Dampen down the immune response (stops it). Prevents autoimmunity
42
How does an antigen presenting cell lead to a large number of T helper cells?
Antigen presenting cell binds specifically to Th cell (clinal selection) This selected Th cell then increases in number by mitosis (clonal expansion)
43
How are B lymphocytes activated and what is their role?
A T helper cell binds specifically to a B lymphocyte, B lymphocyte differentiates into plasma cell Plasma cells release antibodies specific to particular antigen
44
How do T killer cells destroy a virally infected cell?
They release performing which punch holes in membranes of infected cell. It then floods in hydrolytic enzymes , nitric acid and hydrogen peroxide
45
What is the difference between an antigen and an antibody
An antigen is found on the surface of a pathogen and antibodies are produced by plasma cells - they are specific to the antigen
46
How are plasma cells specialised for their role?
They produce antibodies - they ave lots of ribosomes, Golgi, RER and mitochondria
47
How do opsonins function
They bind to an antigen on the pathogen which creates a binding site for the pathogen to attach to so it is marked for destruction by a neutrophil which binds to the constant region of the opsonin so the pathogen can be destroyed by phagocytosis
48
How do agglutinins function?
One of the binding sites on the antibody binds to one antigen on a pathogen and the other binding site binds to a different antigen which cross links them. This clumps them together so they are easier to phagocytose
49
How do antitoxins function?
They bind specifically to toxins produced by the pathogen so they neutralise them
50
How does the structure of an antibody enable it to preform its function?
-It has variable regions specific to antigen (shape complimentary to shape of antigen) -Has a hinge region so it is flexible to bind with more than one antigen -The disulphide bridges hold the four polypeptide chains together -The constant region may have a shape that can be recognised by neutrophils
51
Why does it take several days for the primary immune response to become effective?
After infection the pathogen must be detected and attacked by macrophages, clonal selection must take place of T and B cells, they must then reproduce in clonal expansion, hen they must differentiate into plasma cells to produce specific antibodies to the antigens. Each step takes time
52
Why is the secondary immune response so much faster than the primary immune response?
There are already T memory and B memory cells in the blood meaning that the correct T and B memory cells are clonal lay selected and can differentiate very quickly into the correct T helper, T killer and plasma cells, meaning plasma cells can produce antibodies faster and in greater quantity. This means pathogen is wiped out before symptoms are experienced and the levels of antibodies stayed higher for longer
53
What is natural active immunity - give example
The body’s own response to a new pathogen so memory cells are produced - antibodies made in immune system in response to infection
54
What is natural passive immunity - give example
Antibodies provided through placenta and breast milk so no memory cells produced
55
What is artificial active immunity - give example
The injection of an antigen so immune response occurs meaning memory cells produced
56
What is artificial passive immunity - give example
ANTIBODIES are injected that have been made by another organism so no memory cells produced
57
Why does passive immunity only provide short term immunity?
Antibodies are supplied which are proteins so will to last long in body and may be attacked by our own antibodies from our immune system
58
What is an epidemic?
A rapid spread of disease through a high proportion of the population
59
What is the difference between heard vaccination and ring vaccination?
-Heard vaccination is where almost everyone is vaccinated -Ring vaccination only vaccinates people around the site of the outbreak to prevent spread of disease to the whole population
60
How can a microorganism become resistant to an antibiotic?
Bacteria that survive a treatment will be slightly resistant to the antibiotic and the antibiotic will select the resistant individuals which can reproduce. Some of their offspring may be more resistant so resistance evolves
61
parasite definition
An organism that lives inside a host and gets its nutrition at the expense of that organism

Biology (16 decks)

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