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Biology > 6.3 - Defence Against Infectious Diseases > Flashcards

6.3 - Defence Against Infectious Diseases Flashcards

1
Q

Name 7 methods of skin/body protection

A 
Tears
Saliva
Skin
Large intestine 
Bladder
Stomach 
Respiratory tract
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2
Q

Tears

A

Wash away irritants and microbes, lysosome kills bacteria

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3
Q

Saliva

A

Washes microbes from the mouth and teeth

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4
Q

Skin

A

Physical barrier

Acidic pH discourages growth

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5
Q

Large intestine

A

Bacterial inhabitants outcompete invaders

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6
Q

Bladder

A

Urea washes microbes from the urethra

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7
Q

Stomach

A

Acid kills microbes

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8
Q

Respiratory tract

A

Mucus traps microbes

Cilia sweep away microbes

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9
Q

Phagocytes (5)

A
  • white blood cells
  • ingest pathogens by endocytosis
  • contain lysosomes, which contain digestive enzymes
  • identify pathogens by detecting foreign proteins on the pathogen surface
  • assisted by antibodies attached to pathogens
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10
Q

Phagocytosis (6)

A
  1. microbe attached to surface of phagocyte (microphage)
  2. detects it as non-self by antibodies
  3. ingested by endocytosis
  4. surrounded by pseudopods
  5. within, a lysosome secrets digestive enzymes which breaks down the microbes (now inside a phagosome)
  6. waste material produced then ejected by exocytosis
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11
Q

Blood clotting (2)

A
  • needs to happen incredibly rapidly at the right time, in a controlled way
  • helps to prevent entry of microorganisms
  • blood contains a soluble protein called fibrinogen
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12
Q

Blood clotting steps (7)

A
  • Process of clotting converts soluble fibrinogen into insoluble fibrin
  • Chemicals released by damaged cells or clotting factors released by platelets initiate a cascade of enzyme catalysed reactions
  • Eventually leads to prothrombin (inactive enzyme) being converted into thrombin (active enzyme)
  • Thrombin converts fibrinogen into fibrin
  • Fibrin forms a mesh, trapping blood cells into a clot
  • External and internal clots prevent blood loss
  • Clot dries and forms a scab
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13
Q

How does HIV cause AIDS? (7)

A
  • Virus inserts RNA into specific lymphocyte called a helper T-cell
  • Enzyme reverse transcriptase makes copies of genes in form of DNA
  • Helper T-cell uses DNA to produce more viruses
  • Viruses destroy helper T-cells
  • Knock-on effect on B-cells, decrease in number and produce fewer antibodies
  • Lack of antibodies means infection cannot be fought (AIDS)
  • Infected individual cannot fight off pathogens
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14
Q

Transmission of HIV (7)

Hint: BOB DUCA

A

B reast feeding
O ral sex
B lood transfusion

D uring birth
U nprotected sexual intercourse
C ontaminated needles
A cross placenta

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15
Q

Antibiotics (4)

A
  • Act against specific chemicals or chemical pathways in prokaryotes, do not affect eukaryotes
  • Target these processes: translation, replication, transcription, ribosome function, cell wall formation
  • Some bacteria have evolved genes that confer resistance to specific antibiotics or multiple antibiotic resistance
  • EG: penicillin
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16
Q

Florey and Chain (2)

A
  • Act against specific chemicals or chemical pathways in prokaryotes, do not affect eukaryotes
  • Target these processes: translation, replication, transcription, ribosome function, cell wall formation
  • Some bacteria have evolved genes that confer resistance to specific antibiotics or multiple antibiotic resistance
  • EG penicillin
17
Q

Florey and Chain testing (5+2)

A
  • injected healthy mice to test toxicity (not toxic)
  • a group of mice injected with haemolytic streptococci bacteria
  • half injected with penicillin
  • several hrs later, mice that received penicillin were alive, others were dead
  • first human patient 1941
    • injected and showed immediate signs of recovery
      • died due to lack of penicillin
18
Q

Florey and Chain testing problems (3)

A

Penicillin used when side effects not known
Source was impure
Human testing after only some mice

19
Q

Viruses (4)

A
  • Use the chemical processes of the host cell
  • Do not have a metabolism of their own
  • When treated, there is no effect and their resistance increases
  • Some antiviral drugs exist which do not damage the host cell
20
Q

Antibiotic resistance (5)

A
  • Doctors only giving prescriptions when necessary
  • Patients finishing prescriptions to fully kill the bacteria
  • Farmers not using antibacterial drugs in food
  • Hospitals preventing contamination
  • Introduction of new drugs
21
Q

Antigen

A

Molecule, usually a protein, which is foreign to body and stimulates the production of a specific antibody

22
Q

Antibody

A

Specific protein produced by the body in response to a specific antigen

23
Q

Lymphocytes (2)

A

Antibody-producing cells

Can only produce one specific type of antibody

24
Q

Lysosome

A

An organelle in the cytoplasm of eukaryotic cells containing digestive enzymes enclosed in a membrane

Biology (9 decks)

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