Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > 6.3 Defence against infectious disease > Flashcards

6.3 Defence against infectious disease Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What happens when the skin is cut?

A

The blood vessels in it are severed and start to bleed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What process stops bleeding?

A

Clotting
* changes from a liquid to a semi-solid gel
* Seals up the wound and prevent further loss of blood and blood pressure
* Important because cuts breach the barrier to infection provided by the skin
* Clots prevent entry of pathogens until new tissue has grown to heal the cut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why do blood clots form?

A

To stop blood loss and stop entry of pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What release clotting factors in response to a wound?

A

Platelets (small cell fragments) along with damaged tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are platelets?

A
  • cellular fragments that circulate in the blood
  • They are smaller than either red or white blood cells
  • When a cur or other injury invovling damage to blood vessels occurs, platelets aggregate at the site forming a temporary plug.
  • They then release the clotting factors that trigger off the clotting process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does clotting factors cause?

A

A cascade of reaction, each of which produces a catalyst for the next reaction
Process ends with fibrin (a protein) fibres forming a mesh across the wound site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why must clotting be under strict control?

A

Because if it occurs inside blood vessels the resulting clots can cause blockages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does the cascade of reactions result in?

A

The rapid conversion of fibrinogen to fibrin by thrombin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Is fibrinogen and fibrin soluble?

A

Fibrinogen is soluble

Fibrin is insoluble (its fibrous)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is thrombin and what does it do?

A

It is an enzyme that is produced after the release of clotting factors from platelets that converts fibrinogen (soluble) into fibrin fibres (insoluble) that will form a mesh across the wound site to capture the red blood cells and prevent blood loss and entry of pathogens. The resulting clot is initially a gel, but if exposed to the air it dries to form a hard scab

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does atherosclerosis cause CHD (coronary heart disease)?

A

Atherosclerosis can lead to blood clots which cause coronary heart disease when they occur in coronary arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a thrombus?

A

A medical name for a blood clot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is coronary thrombosis?

A

The formation of blood clots in the coronary arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the consequences of coronary occlusion?

A
  • If a coronary artery becomes completely blocked, an acute myocardial infarction (heart attack) will result
  • This is because myocardial tissues require oxygen and nutrients transported via the coronary arteries in order to function
  • If the coronary arteries become blocked by a blood clot, part of the heart is deprived of oxygen and nutrients
  • Cardiac muscle cells are then unable to produce sufficient ATP by aerobic respiration and their contractions become irregular and uncoordinated
  • Fibrillation
  • This condition can prove fatal unless it resolves naturally or through medical intervention
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is fibrillation?

A

When the wall of the heart makes quivering movements that do not pump blood effectively.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What can atherosclerosis cause in coronary arteries?

A

Occlusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens to the endothelium of arteries when atheromas develop there?

A

Where atheroma develops the endothelium of the artarteries tends to become damaged and roughened; especially, the artery wall is hardened by deposition of calcium salts. Patches of atheroma sometimes rupture causing a lesion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What increase the risk of coronary thrombosis?

A
  • Coronary occlusion
  • Damage to the capillary epithelium
  • Hardening of arteries
  • Rupture of atheroma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are blockages of coronary arteries typically treated?

A

Can insert a closed stent into that artery then expand it with a balloon which widens the artery and compresses the plaque or by-pass surgery (redirecting the blood)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the stages of CHD?

A
  • Formation of atheroma
  • Rupture of atheroma
  • Platelets activates
  • Thrombin
  • Fibrinogen converted to fibrin
  • Clot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the risk factors of coronary heart disease?

A
  • Age – Blood vessels become less flexible with advancing age
  • Genetics – Having hypertension predispose individuals to developing CHD
  • Obesity – Being overweight places an additional strain on the heart
  • Diseases – Certain diseases increase the risk of CHD (e.g. diabetes)
  • Diet – Diets rich in saturated fats, salts and alcohol increases the risk
  • Exercise – Sedentary lifestyles increase the risk of developing CHD
  • Sex – Males are at a greater risk due to lower oestrogen levels
  • Smoking – Nicotine causes vasoconstriction, raising blood pressure

Mnemonic: A Goddess

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are some well-known factors that are correlated with an increased risk of coronary thrombosis and heart attacks: (6)

A
  • Smoking
  • High blood cholesterol concentration
  • High blood pressure
  • Diabetes
  • Obesity
  • Lack of exercise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are Erythrocytes?

A

Red blood cells?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are Erythrocytes?

A

Red blood cells?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are microbes that cause disease called?

A

Pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the primary defence against infectious disease to the body?

A

The first line of defence against infectious disease are the surface barriers that prevent the entry of pathogens into the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the surface barriers that prevent the entry of pathogens into the body? (3)

A

Skin, mucous membranes, sebaceous glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What does the skin do in terms of defence against pathogens?

A

Outermost layer is tough and provides a** physical barrier** against the entry of pathogens and** protection against physical and chemical damage**

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does sebaceous glands do in terms of defence against pathogens?

A

Are associated with hair follicles and they secrete a chemical called sebum, which maintains skin moisture and slightly lowers skin pH. The lower pH inhibits the growth of bacteria and fungi.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where can mucous membranes be found on the human body?

A
  • Nasal passages and other airways
  • The head of a penis
  • Foreskin
  • Vagina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What does mucous membranes do in terms of defence against pathogens?

A

They are thinner and softer type of skin
* The mucus that these areas of skin secrete is a sticky solution of glycoproteins. Mucus acts as a physical barrier; pahogens and harmful particles are trapped in it and either swallowed or expelled. It also have antiseptic properties because of the presence of the anti-bacterial enzyme lysozyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Overview of Physical and chemical surface barriers

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is clotting (haemostasis)?

A

the mechanisms by which broken blood vessels are required when damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are some other primary defenses?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is coagulation cascade?

A

A complex set of reactions collectively in the process by which blood clots are formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What stimulates the coagulation cascade?

A

By clotting factors released fro damaged cells and platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the second line of defence against infectious disease?

A

White blood cells
The innate immune system, which is non-specific in its response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are the components of the second line of defence?

A

Principle component: phagocytic white blood cells engulf pathogens by endocytosis and digest them with enzymes from lysosomes

Other components of the innate immune system: inflammation, fever and antimicrobial chemicals (complement proteins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What results in the formation of a white liquid called pus?

A

When wounds become infected, large number of phagocytes are attracted, resulting in the formation of a white liquid called pus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are the two key properties of the innate immune system?

A
  • It does not differentiate between different types of pathogens (non-specific)
  • It responds to an infection the same way every time (non-adaptive)
41
Q

What is phagocytosis?

A

the process by which solid materials (such as pathogens) are ingested by a ell (i.e. cell ‘eating’ via endocytosis)

42
Q

Where do phagocytic leukocytes circulate in and where do they go in response to infection?

A

they circulate in the blood and move into the body tissue (extravasation) in response to infection

43
Q

How do damaged tissue draw white blood cells to the site of infection?

A

Damaged tissues release chemicals (e.g. histamine) which draw white blood cells to the site of infection (via chemotaxis)

44
Q

How are pathogens engulfed and digested?

A

During phagocytosis by leukocytes, pathogens are engulfed when cellular extensions (pseudopodia) surround the pathogen and then fuse to form an internal vesicle

Then the vesicle is then fused to a lysosome (forming a phagolysosome) and the pathogen is digested

45
Q

After pathogen is digested, fragments (antigen) may be present on the surface of the phagocyte in order to stimulate what?

A

The third line of defence

46
Q

What is the third line of defence against infectious disease?

A

the adaptive immune system, which is specific in its response

47
Q

What is the main difference in the response of the second and third line of defence against infectious disease?

A

2nd line: not specific

3rd: specific

48
Q

What can the third line of defence able to do that makes its response specific?

A
  • It can differentiate between particular pathogens and target a response that is specific to a given pathogen
  • It can respond rapidly upon re-exposure to a specific pathogen, preventing symptoms from developing (immunological memory)
49
Q

What are lympohcytes?

A

They are a class of leukocyte.

The adaptive immune system is coordinated by lymphocytes and results in the production of antibodies

50
Q

What are B cells and T cells?

A

B lymphocytes (B cells) are antibody-producing cells that recognise and target a particular pathogen fragment (antigen)

Helper T lymphocytes (T cells) are regulator cells that release chemicals (cytokines) to activate specific B lymphocytes

51
Q

What happens after a phagocyte leukocyte engulfs a pathogen and the digested fragments are left on their surface?

A
  • These antigen-presenting cells (dendritic cells) migrate to the lymph nodes and activate specific T cells
  • The helper T cells then release cytokines to activate the particular B cell capable of producing antibodies specific to the antigen
  • The activated B cell will divide and differentiate to form short-lived plasma cells that produce high amounts of specific antibody
  • Antibodies will target their specific antigen, enhancing the capacity of the immune system to recognise and destroy the pathogen
  • A small proportion of activated B cell (and activated TH cell) will develop into memory cells to provide long-lasting immunity
52
Q

What part of a pathogen is recognized as foreign by the body?

A

The proteins and other molecules on the surface of pathogens

53
Q

What are antigens?

A

An antigen is a substance that the body recognises as foreign and that will stimulate a specific immune response
* Any chemical that stimulates an immune respoinse is referred to as an antigen.

54
Q

What is specific immune response?

A

The production of antibodies in response to a particular pathogen

55
Q

What are antibodies? What are they made of?

A

An antibody is a protein produced by B lymphocytes (and plasma cells) that is specific to a given antigen and binds to an antigen on that pathogen

  • made of 4 polypeptide chains that are joined together by disulphide bonds to form Y-shaped molecules
56
Q

Even though each lymphocyte produces just one type of antibody, how do our bodes produce a vast array of different antibodies?

A

We have small numbers of lymphocytes for producing each of the many types of antibody. -> too few initially to produce enough antibodies to control a pathogen that has no previously infected the body

But antigens on the pathogen stimulate cell division of the small group of lympohocytes that produce the appropriate type of antibody. So then a large clone of lymphocytes called plasma cells are produced within a few days and they secrete large enough quantities of the antibody to control the pathogen and clear the infection

57
Q

What does the two functional regions of antibodies do?

A

A hypervariable region that binds to a specific antigen and another region that helps the body to fight the pathogen

58
Q

What are two ways antibodies help fight the pathogen?

A
  • Makring a pathogen more recognizable to phagocytes so they are more readily engulfed
  • Preventing a virus from docking to host cells so that they cannot enter the cells
59
Q

What happens to antibodies after the infection is over?

A
  • Antibodies only persist in the body for a few weeks or months and the plasma cells that produced them are also gradually lost, antigens associated with it are no longer present.
  • Some of the lumphocytes produced during an infection are not active plasma cells but instead become memory cells that are very long lived
  • These memory cells remain inactive unless the same pathogen infects the body again, in which case they become active and divide to produce plasma cells very rapidly
60
Q

What does having immunity mean?

A

To either have antibodies against the pathogens or memory cells that allow rapid production of the antibody

61
Q

What does it mean that antigen-antibody interactions are specific?

A

that each type of antibody recognises a unique antigen (like enzymes and substrates)

62
Q

What are the 3 lines of defence?

A

1st: Surface barriers
2nd: innate immune system (non specific)
3rd: adaptive immune system (specific)

63
Q

What are antibotics?

A

compounds that kill or inhibit the growth of microbes (specifically bacteria) by targeting prokaryotic metabolism

64
Q

What are some metabolic features that may be targetted by antibiotics?

A

key enzymes, 70S ribosomes and components of the cell wall

65
Q

Why do antibiotics target the pathogenic bacteria and not the infected host?

A

Because the metabolic features that may be targeted by antibiotics arent present in eukaryotic cells (e.g. 70s ribosome, cell wall etc)

66
Q

What do antibiotics do and what are they?

A
  • Block processes that occur in prokaryotic cells but not in eukaryotic cells
  • Therefore used to kill bacteria inside the body without causing harm to human cells.
  • A chemical that inhibits the growth of microorganisms.
  • Most antibiotics are antibacterial.
67
Q

What processes does antibiotic target in prokaryotes? (5)

A
  • Bacterial DNA replication
  • Transcription
  • Translation
  • Ribosome function
  • Cell wall formation
68
Q

What is a virus?

A
  • Non living
  • only reporoduce when they are inside living cells
  • Use chmical processes of a living host cell instead of having a metabolism of their own
  • Do not have their own means of transcription or protein synthesis
  • Rely on host cell’s enzymes for ATP synthesis and other metabolic pathways
  • These processes cannot be targeted by drugs as the host cell would also be damaged
69
Q

Why cant viral disease be treated using antibiotics?

A

They lack a metabolism so they control the host cell completely. These processes that it uses cannot be targetted by drugs as the host cell would also be damaged

70
Q

What do virus do compared to pathogenic bacteria? What cant they be treated with antibiotics?

A

They do not possess a metabolism (they are not alive) and instead take over the cellular machinery of infected host cells

→ cant be treated with antibiotics and must be treated with specific antiviral agents

71
Q

What if a doctor prescribe antibiotics to viral infections?

A
  • It is inappropriate for doctors to prescribe them for a viral infection
  • Contributes to the overuse of antibiotics
  • Increases in antibiotic resistance in bacteria
72
Q

What are antivirals?

A

Drugs that can control viruses by having drugs target their viral enzymes

73
Q

What do antiviral agents target?

A

There are a few viral enzymes which can be used as targets for drugs to control vircuses without harming the host cell.
Only a few dugs have been discovered or developed to control viruses in this way. These are known as antivirals rather than antibiotics

74
Q

What two spectrum can antibiotics be?

A

Narrow spectrum: effective against specific bacteria

Broad spectrum: effective against many bacteria

75
Q

How may genes confer resistance?

A

By encoding traits that degrade the antibiotic, block its entry, increase its removal or alter the target

76
Q

What is the consequence of bacteria being able to reproduce at a rapid rate?

A

resistant strains of bacteria can proliferate very quickly following the initial mutation

77
Q

How may resistant strains be passed?

A

Resistance to the antibiotic spreads to more and more species of pathogenic bacteria
resistant strains can pass resistance genes to susceptible strains via bacterial conjugation (horizontal gene transfer)

78
Q

What causes the rapid evolution of antibiotic resistance?

A
  • Widespread use of antibiotics, both for treating diseases and in animals feeds used on farms
  • Bacteria can reproduce very rapidly, with a generation time of less than an hour
  • Populations of abcteria are often huge, increasing he chance of a gene for antibiotic resistance being formed by mutation
  • Bacteria can pass genes on to other bacteria in several ways, including using plasmids, which allow one species of bacteria to gain antibiotic resistance genes from another species
79
Q

How is the prevalence of resistant bacterial strains increasing rapidly with human populations?

What are 3 factors?

A
  • Antibiotics are often over-prescribed (particularly broad-spectrum drugs) or misused (e.g. given to treat a viral infection)
  • Many antibiotics are freely available without a prescription and certain antibiotics are commonly included in livestock feed
  • Multi-drug resistant bacteria are especially common in hospitals (i.e. nosocomial infections) where antibiotic use is high
80
Q

What are the measures required to avoid antibiotic resistance?

A
  • Doctors prescribing antibiotics only for serious bacterial infections
  • Patients completing courses of antibiotics to eliminate infections completely
  • Hospital staff maintaining high standards of hygiene to prevent cross-infection
  • Farmers not using antibiotics in animal feeds to stimulate groth
    Pharmaceutical companies developing new types of antibiotics - no new types have been introduced since the 1980s
81
Q

Until when are strains of bacteria with resistance a huge concern?

A

Strains of bacteria with resistance are usually discovered soon after the introduction of an antibiotic. This is not a huge concern unless a strain develops multiple resistance.

82
Q

What was the first chemical compound found to have antibiotic properties?

A

Penicillin - identified by Alexander Fleming in 1928

83
Q

Where were many antibacterial antibiotics found in? What is one of the examples?

A
  • Discovered in saprotrophic fungi
  • These fungi compete with saprotrophic bacteria for dead organic matter on which they both feed
  • By secreting antibacterial antibiotics, saprotrophic fungi inhibit the growth of their bacterial competitors

An example is penicillin
* Produced by some strains of the Penicillium fungus, but only when nutrients are scarce and compeition with bacteria would be harmful

84
Q

How was the discovery of penicillin a fortuitous accident?

A

it resulted from the unintended contamination of a dish containing S. aureus

  • A Penicillium mould began to grow on the plate and a halo of inhibited bacterial growth was observed around the mould
  • Alexander Fleming concluded that the mould was releasing a substance (penicillin) that was killing the nearby bacteria
85
Q

What method did Florey and Chain’s team develop on penicillin?

A
  • Developed a method of growing the fungus Penicillium in liquid culture in conditions that stimulated it to secrete penicillin
  • They also developed methods for produing reasonably pure samples of penicillin from the cultures
86
Q

How were the medical applications demonstrated by an Australian scientist, Sir Howard Florey, in 1940?

A
  • Working with another scientist (Ernst Chain) and a team of researchers, Florey tested penicillin on 8 deliberately infected mice
  • Eight mice were injected with streptococci bacteria that cause death from pneumonia and four of these mice were subsequently injected with doses of penicillin
  • The untreated mice died of bacterial infection while those treated with penicillin all survived – demonstrating its antibiotic potential
  • Tested on a 43 year old policeman
  • Has a life-threatening bacterial infection caused by a scratch on his face
  • Given penecillin for 4 days and his condition improved considerably
  • Penecillin supply ran out and suffered a relapse and died from the infection
  • Larger quantities were produced
  • 5 more patients
  • All cured but one died
  • Small child had infection behind the eye and it weakened the wall of the artery carrying blood to the brain
  • Alothought cured from infection, the child died of brain hemorrhage when the artery burst
87
Q

Why would Florey and Chain not be allowed to carry out the tests on penicillin today?

A
  • Strict protocals in minimize risks
  • They tested the drug on human patients after only a very brief period of animal testing
  • Samples of penicillin were not pure and there could have been side effects from the impurities
  • But the patients were all on the point of death and several were cured as a result of the experimental treatment
88
Q

What is HIV and what does it infect?

A

The Human Immunodeficiency Virus (HIV) is a retrovirus that infects helper T cells, disabling the body’s adaptive immune system
* A retrovirus that has genes made of RNA and uses reverse transcriptase to make DNA copies of its genes once it enters a host cell

89
Q

What is a syndrome?

A

A collection of several diseases or conditions existing together

90
Q

What is AIDS? How does it spread?

A

Acquitred immune deficiency syndrome (AIDS)
* When the syndrome of conditions due to HIV is present, the person is said to have acquired immune deficiency syndrome (AIDS)

It spreads by HIV infection. Normally only occurs if there is blood to blood contact with an infected person

91
Q

What are the effects of HIV?

A
  • HIV specifically targets the helper T lymphocytes which regulate the adaptive immune system
  • The consequence is a progressive loss of the capacity to produce antibodies.
  • With a reduction in the number of helper T cells, antibodies are unable to be produced, resulting in a lowered immunity
  • Eventually antibody production becomes so ineffective that a group of opportunistic infections strike
  • The body becomes susceptible to opportunistic infections, eventually resulting in death if the condition is not managed
92
Q

How can the rate at which helper T-cells are destroyed by HIV be slowed down?

A

Using anti-retroviral drugs

93
Q

What is meant when a person is said to be HIV-positve?

A

If antibodies made by the immune systen in the early stages of infection against HIV is detected in a person’s body.

94
Q

How can HIV be transmitted? (4)

A
  • exchange of body fluids (including unprotected sex, blood transfusions, breastfeeding, etc.)
  • Sexual intercourse, during which abrasions to the mucous membranes of the penis and vagina can cause minor bleeding (i.e. use condoms)
  • Transfusion of infected blood, or blood products such as Factor VIII
  • Sharing of hypodermic needles by intravenous drug users
95
Q

How may people be immune to HIV infection?

A
  • A small minority of people are immune to HIV infection (they lack the CD4+ receptor on TH cells that HIV requires for docking)

CD4 is a receptor for HIV

96
Q

How transnational is HIV and where is it particularly prevalent?

A
  • HIV is a global issue, but is particularly prevalent in poorer nations with poor education and health systems
97
Q

What is a pathogen? What are the 2 category they can be in?

A

A pathogen is a disease causing agent that disrupts the normal physiology of the infected organism

Pathogens can be cellular (e.g. parasites, protozoa, bacteria) or acellular (viruses and prions)

98
Q

Where can mucous membranes be found on the human body?

A
  • Nasal passages and other airways
  • The head of a penis
  • Foreskin
  • Vagina

Biology (57 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions