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Bio S3 2024 > Chapter 11: Infectious Diseases in Humans > Flashcards

Chapter 11: Infectious Diseases in Humans Flashcards

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Biology 101 flashcards
1
Q

What is a disease?

A

A disease is a condition that causes the body to function less effectively.

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2
Q

What is the difference between signs and symptoms of disease?

A
  • A sign of a disease can be observed or measured
  • A symptom of a disease can be described or felt by the patient
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3
Q

What are the differences between infectious diseases and non-infectious diseases?

A

Infectious disease-> Caused by pathogens
Non-infectious disease-> NOT caused by pathogens, could be caused by genetics, lifestyle or environmental factors

Infectious disease-> Can be spread from person to person
Non-infectious diseases-> Cannot be spread from person to person

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4
Q

Examples of infectious diseases?

A
  • Influenza
  • HIV
  • Pneumococcal disease
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5
Q

Examples of non-infectious diseases?
(and causes)

A
  • Excessive alcohol consumption-> Liver cirrhosis
  • Excessive consumption of polyunsaturated fats and trans fats-> Coronary heart disease
  • Cigarette smoking-> Atherosclerosis & Coronary heart disease
  • Type 2 diabetes
  • Sickle-cell anemia
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6
Q

How are infectious diseases spread?
(+description and examples)

A

1. Droplets in the air
- When a person coughs or sneezes, numerous tiny respiratory droplets are expelled
- These droplets may contain pathogens
- Anyone within a close range (ab 1m) may breathe in these droplets and become infected
- e.g. COVID-19, influenza, etc.

2. Direct contact
- Exchange of bodily fluids during sexual intercourse
- Breastfeeding
- Blood from an infected person coming into contact with another person’s mucous membranes or blood
-e.g. HIV, hepatitis B, syphilis, etc.

3. Contaminated food and water
- When improperly handled or stored, food and water can becontaminated with pathogens
- Prevention:
> Practising hygienic food preparations and storage
> Having good personal hygiene
> Maintaining a clean water supply
> Ensuring proper sewage treatment
- e.g. Cholera, etc.

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7
Q

Structure of a Bacterial Cell?

A
  • Does not have a membrane-bound organelle
  • No nucleus
  • Single circular DNA as genetic material
  • Has cell wall
  • Has cell membrane
  • Has cytoplasm
  • Has ribosomes
  • Has small circular DNA molecules called plasmids
  • Has one or more flagella
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8
Q

Structure of a Virus?

A
  • Has protein coat enclosing its genetic material, either DNA or RNA
  • Has living and non-living characteristics

> Does not have cellular structures, e.g. cell membrane, cytoplasm, organelles, etc. -(non-living)

> Does not grow, move, feed, respire or excrete -(non-living)

> Can reproduce, but only when it enters a living cell, which acts as a host [w/ necessary materials for reproduction, e.g. enzymes, ribosomes, etc.] -(living)

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9
Q

State the similarities between bacteria and viruses

A
  • Both have genetic material
  • Both have no nuclei
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10
Q

State the differences between bacteria and viruses

A

Bacteria-> Genetic material is DNA
Viruses-> Genetic material may not be DNA, could be DNA or RNA

Bacteria-> Has a cell wall and cell membrane
Viruses-> Has a protein coat

Bacteria-> Has ribosomes
Viruses-> Has no ribosomes

Bacteria-> Can reproduce by itself
Viruses-> Requires a host cell to reproduce

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11
Q

Describe influenza
(+description, cause, transmission & signs and symptoms)

A

DESCRIPTION:
- A disease that attacks the respiratory system
- Mostly able to recover within 2 weeks
- Sometimes, could lead to complications e.g. pneumonia

CAUSE:
- Influenza virus

HOW IT IS TRANSMITTED:
- Droplets through the air
- When a person touches an object/ surface contaminated w/ influenza virus and then touches their eyes, mouth or nose

SIGNS AND SYMPTOMS:
- High fever
- Headache
- Stuffy nose
- Cough
- Sore throat
- Muscle aches

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12
Q

Describe pneumococcal disease
(+description, cause, transmission & signs and symptoms)

A

DESCRIPTION:
- One of the major causes of death worldwide

CAUSE:
- Pneumococcus bacteria, a.k.a. Streptococcus pneumoniae

HOW IT IS TRANSMITTED:
- Through tiny respiratory droplets

SIGNS AND SYMPTOMS:
- Fever
- Headache
- Vomiting
- Cough
- Chest pain
- Rapid breathing

OTHER:
- The pneumococcus bacteria may attack different parts of the body
- e.g.
> Middle ear infection
> Lung infection (pneumonia)
> Inflammation of the membranes of the brain & spinal cord
> Infection of the blood

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13
Q

Methods to reduce the transmission of infectious diseases?
(6 pts.)

A
  1. Get the respective vaccination for the disease
  2. Avoid close contact with those with the disease
  3. If you are sick, cover your mouth and nose with a tissue when coughing or sneezing and dispose of the used tissue properly
  4. Wash your hands with soap and water or rub with disinfectant
  5. Avoid touching your eyes, nose and mouth
  6. Wear a surgical mask if feeling unwell

FOR VIRUS: Take prescribed antiviral drugs
FOR BACTERIA: Take the full course of prescribed antibiotics

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14
Q

What are antigens?
(in the context of Infectious Diseases)

A
  • Antigens on red blood cells trigger the production of antibodies
  • Proteins on the surfaces of pathogens (i.e. bacteria and viruses) are examples of antigens
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15
Q

What are white blood cells?
(in the context of Infectious Diseases)

A
  • White blood cells can have many types of receptors on its surface
  • Receptors on certain white blood cells are complementary to certain antigens on pathogens
  • Some of the stimulated white blood cells remain as memory cells
  • Memory cells can recognise the same pathogen in the future and quickly destroy it
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16
Q

What are antibodies?
(in the context of Infectious Diseases)

A
  • Antibodies are proteins that are produced by white blood cells to destroy a specific pathogen
  • Antibodies specific to destroy one type of pathogen will be ineffective against any other type of pathogen
  • Antibodies can also tag a pathogen for destruction by white blood cells
17
Q

How do vaccines work?
(5 pts.)

A
  1. Vaccines contain agents that resemble pathogens (and therefore the antigens)
  2. When these agents enter the body, they bind to receptors on white blood cells and stimulate them to divide and produce many antibodies
  3. These antibodies help to destroy the agent in the vaccine
  4. Some white blood cells remain in the bloodstream for a long time as memory cells
  5. In the future, if the same pathogen enters the body, these memory cells will recognise it and quickly produce antibodies to destroy the pathogen before it can infect our cells
18
Q

What are antibiotics?

A
  • Drugs used to treat bacterial infections
  • Naturally made by microorganisms
  • Used to kill or inhibit growth and metabolic activities of bacteria
  • Many antibiotics are chemically modified to make them more effective in treating disease
19
Q

How do antibiotics work?
(4 pts.)

A

1. Inhibits synthesis of bacterial cell walls
- When bacterial cell walls are weakened, water enters the cells by osmosis through the partially permeable cell membrane
- The bacterial cell expands, bursts and dies

2. Inhibits cell membrane function
- Bacterial cell membrane is broken up
- Without cell membrane, bacterial cell is no longer protected from its environment as any substance can now move into the cell

3. Inhibits protein synthesis in ribosomes
- Antibiotics bind to bacterial ribosomes, preventing ribosomes from taking part in protein synthesis
- This thereby inhibits bacterial growth

4. Inhibits enzyme action in cytoplasm
- Bacteria require a vitamin called folic acid for growth
- Antibiotics inhibit the enzyme needed for folic acid synthesis
- This thereby inhibits bacterial growth

20
Q

Why are antibiotics ineffective against viruses?

A
  1. Antibiotics inhibit synthesis of cell walls.
    Viruses do not have cell walls.
  2. Antibiotics break up cell membranes.
    Viruses do not have cell membranes.
  3. Antibiotics prevent ribosomes from taking part in protein synthesis.
    Viruses do not have ribosomes.
  4. Antibiotics inhibit growth.
    Viruses do not grow.
21
Q

How are viral infections treated?

A
  • Antiviral drugs
  • Rest
  • Body will recover from the infection with time
22
Q

How does antibiotic resistance come about?

A
  • When bacteria are exposed to certain chemicals or other mutagenic agents, their genes may change
  • This mutation may make bacteria resistant to certain antibiotics
23
Q

Describe what happens to bacteria cells in the body during a course of antibiotics, if the course is not completed

A

Start:
- Many bacteria cells in the body, most of which are normal but there is a small proportion that are more resistant to antibiotics

e.g. First-Second dose:
- More and more of normal bacteria cells are killed, until only the more antibiotic-resistant cells remain

When course is stopped:
- Remaining antibiotic-resistant cells reproduce to form more antibiotic-resistant cells

24
Q

How can antibiotic resistance be reduced?

A
  • Do not misuse or overuse antibiotics
  • Complete full prescribed course of antibiotics so that all bacteria are killed
  • Use antibiotics only when necessary

Bio S3 2024 (9 decks)

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