chapter 11 - infectious diseases

Question 1

disease

Answer 1

condition that causes the body to function less effectively, producing specific signs or symptoms

Question 2

signs

Answer 2

can be observed/measured (eg. rashes, fever, coughing, vomiting)

Question 3

symptoms

Answer 3

can be described/felt (eg. headaches, fatigue, nausea)

Question 4

infectious diseases

Answer 4

influenza, pneumonia, covid-19, HIV/AIDS, malaria

Question 5

non-infectious diseases

Answer 5

asthma, diabetes, osteoporosis, dust allergy

Question 6

how are infectious disease spread?

Answer 6

• droplets : when an infected person coughs or sneezes, droplets of body fluid from respiratory tract will enter the air. the body and viruses in the droplets infects the uninfected host when they breathe in the droplets obtaining pathogens
• direct contact : by exchanging body fluids during sexual intercourse, an infectious disease can spread when skin or mucous membrane of an infected person comes into contact with an uninfected person
• contaminated food and water : might be contaminated with pathogens like bacteria that causes cholera, this can occur when food and water are not handled properly

Question 7

typical virus cell

Answer 7

a typical virus has a protein coat with specific receptors/antigens on its surface for attachment, enclosing its genetic material (DNA / RNA). it does not have any cellular structures such as cell membrane, cytoplasm or organelles. it does not grow, move, feed, respire or excrete and reproduces only in living host cells.

Question 8

typical bacterial cell

Answer 8

a typical bacterial cell has a cell wall, cell membrane, flagella, cytoplasm and ribosomes. a bacterial cell also contains DNA (linear - a single strand of genetic material & plasmids - circular DNA molecules) it does not have a membrane-bound nucleus. some are pathogenic (disease-causing) and some non-pathogenic.

Question 9

signs and symptoms of influenza and pneumococcal disease

Answer 9

• influenza – caused by the influenza virus
sore throat, chills, runny nose, muscle ache, fatigue, fever, headache, cough

• pneumococcal disease – caused by the bacteria, pneumococcus
shortness of breath, vomiting, photophobia, fever, headache, cough

Question 10

how are viruses transmitted?

Answer 10

the virus attaches to the host cell via its specific antigens/receptors and injects its viral DNA/ viral genetic material into the host cell. using the host cell’s reproduction mechanism, the virus reproduces and multiplies. these viruses break, or lyse, the cell and spread to other cells to continue the cycle.

Question 11

reduce transmission of viruses

Answer 11

• get respective vaccinations
• avoid close contact with people who have the flu
• cover mouth and nose with tissue when coughing or sneezing and dispose of the tissue properly
• wash hands with soap and water oftenly
• avoid touching hands, mouth and nose
• wear surgical mask when sick

Question 12

vaccine and how it works

Answer 12

vaccines contains an agent that resembles a pathogen and prevents infectious diseases by stimulating white blood cells to quickly produce antibodies when the pathogen invades. white blood cells bind to antigens on pathogens and the white blood cell is stimulated to divide. many antibodies are produced by the copies, and those antibodies help to destroy pathogens

Question 13

antibiotics

Answer 13

drugs to treat bacterial functions, made by microorganisms, used to kill and inhibit growth of bacteria, interferes with growth and metabolic activities of pathogens

Question 14

antibiotics inhibition of cellular structures

Answer 14

• inhibits synthesis of cell walls : when cell wall is weakened, water can enter the bacterial cell via osmosis, the cell expands and bursts
• inhibits synthesis of cell membrane : substances can freely move in and out of the bacterial cell and the cell is no longer protected from its environment
• inhibits synthesis of ribosomes : the antibiotics bind to bacterial ribosomes, preventing protein synthesis from taking place, inhibiting growth
• inhibits enzymes in cytoplasm : bacteria requires folic acid for growth. when antibiotics -inhibits the enzyme that synthesizes folic acid, the bacterial cell cannot grow

antibiotics cannot work on viruses as they don’t have cell wall, cell membrane or ribsomes

Question 15

overuse for antibiotics

Answer 15

the overuse of antibiotics will naturally select for bacteria that has become mutated to be resistant to the antibiotic, allowing them to survive, multiply and pass on their resistant genes. the spread of the antibiotic- resistant bacteria to others will allow the pathogen to survive, thus rendering that type of antibiotics to be now ineffective.