Week 7: Microbes & Infection Flashcards
1
Q
T/F: The coat of a virus consists of protein.
A
True
2
Q
T/F: A “bacillus” is a spiral-shaped bacterium.
A
False
3
Q
T/F: A bacterial cell wall contains chitin.
A
False
4
Q
T/F: A prokaryotic cell is identified by the presence of ribosomes.
A
False - Ribosomes are found in both prokaryotic and eukaryotic cells.
5
Q
T/F: Viruses can transform host cells into tumor cells.
A
True
6
Q
T/F: Fungi are eukaryotic cells whose cell wall contains peptidoglycan.
A
False - The cell wall of fungi contains chitin. Peptidoglycan is found in bacterial cell walls.
7
Q
T/F: Bacteria feed off living matter only.
A
False
8
Q
T/F: The most common type of viral infection is lytic.
A
True
9
Q
T/F: Prokaryotic cells contain a nucleus but no membrane-bound organelles.
A
False - The nucleus is a membrane-bound organelle and thus is not present in prokaryotes.
10
Q
T/F: Fungi generally only cause mild, superficial infections in healthy hosts.
A
True
11
Q
In which symbiotic relationship does one partner benefit while the other is unaffected?
a Infection
b Parasitic
c Commensal
d Mutualistic
A
c Commensal
12
Q
What benefits do the normal flora receive from the host?
Nutrition
Prevent colonisation and infection of the host by pathogens
Provide nutrients such as vitamins B and K
Living space
A
Nutrition
Living space
13
Q
The normal flora can be found in/on which of the following:
upper respiratory tract (i.e. nose, pharynx)
lungs and uterus
urinary bladder
warmer, more damp areas of the skin
mouth and stomach
the upper reprodcutive tract
large, but not the small, intestine
A
upper respiratory tract (i.e. nose, pharynx)
warmer, more damp areas of the skin
mouth and stomach
14
Q
T/F: Transient microbes are unable to colonise body surfaces.
A
True
15
Q
A pathogen has a _____ relationship with the host.
a mutualistic
b transient
c commensal
d parasitic
A
d parasitic
16
Q
T/F: Infectious disease is transmissible disease.
A
False - “Infectious” refers to tissue damage caused by a pathogen, not an ability to be transmitted.
17
Q
Which terms have been correctly identified?
Infection = invasion of a body surface by a pathogen
Infectious disease = invasion of a body surface by a pathogen involving tissue damage
Colonisation = establishment and growth of a microbe on a body surface involving tissue damage
Infection = establishment and growth of a microbe on a body surface
Colonisation = establishment and growth of a microbe on a body surface
A
Infection = invasion of a body surface by a pathogen
Infectious disease = invasion of a body surface by a pathogen involving tissue damage
Colonisation = establishment and growth of a microbe on a body surface
18
Q
The normal flora can cause an opportunistic infection when:
their own defences are compromised
their ecological balance is upset and a specific population multiplies to high numbers
host defences are compromised
they penetrate a body surface and colonise deeper tissues
they are relocated to body areas they are normally excluded from
they colonise a body surface different to their usual location
they turn to the dark side
A
their ecological balance is upset and a specific population multiplies to high numbers
host defences are compromised
they penetrate a body surface and colonise deeper tissues
they are relocated to body areas they are normally excluded from
19
Q
T/F: Compromised surface barriers increase host susceptibility to infection.
A
True
20
Q
Opportunistic pathogens, that do not usually cause disease in otherwise healthy hosts, include:
transient microbes
conventional pathogens
environmental microbes
normal flora
A
transient microbes
environmental microbes
normal flora
21
Q
T/F: A more virulent microbe has a high infectious dose.
A
False - A more virulent microbe can establish an infection with a low number of organisms.
22
Q
T/F: A symptom is an objective change in a patient that can be observed and measured.
A
False - A symptom is the subjective patient experience.
23
Q
T/F: If a host has memory lymphocytes that recognise a particular pathogen they are likely to experience an asymptomatic or subclinical infection the next time they encounter that pathogen.
A
True - Memory lymphocytes will mediate a secondary immune response that prevents, or reduces the severity of, an infection.
24
Q
T/F: Whether an infection occurs depends on host susceptibility, pathogen virulence and environmental conditions.
A
True
25
T/F: A major cause of tissue damage by the host can be the process of inflammation.
True
26
T/F: Viruses generally kill a host cells upon exit, causing tissue damage and promoting inflammation.
True
27
T/F: Most pathogens can use multiple portals of entry into the body.
False - Most pathogens have a preferred portal of entry.
28
The most common portal of entry is the:
a respiratory tract
b urinary tract
c gastrointestinal tract
d skin
a respiratory tract
29
In order to establish an infection, a pathogen must first
a be able to use the host as a food resource
b avoid host defences
c attach to a body surface
d multiply to a critical population size
c attach to a body surface
30
Pathogens can overcome host INNATE defences by:
- using enzymes to break though surface barriers
- using enzymes to destroy host anitbodies
- killing phagocytes with toxins
- changing their surface proteins
- degrading phagocyte digestive enzymes with their own enzymes
- using enzymes to break though surface barriers
- killing phagocytes with toxins
- degrading phagocyte digestive enzymes with their own enzymes`
31
Damage to the host can be caused:
- indirectly by the activity of the pathogen
- directly by the activity of the host defences
- by perforins and granzymes from cytotoxic T cells or NK cells
- through the lytic activity of viruses
- by enzymes dervied from the pathogen or from host phagocytes
- by toxins that kill host cells
- by perforins and granzymes from cytotoxic T cells or NK cells
- through the lytic activity of viruses
- by enzymes dervied from the pathogen or from host phagocytes
- by toxins that kill host cells
32
Pathogens most commonly exit the host via the:
a respiratory or gastrointestinal tracts
b secretions from the eyes and nose
c urine and faeces
d skin
a respiratory or gastrointestinal tracts
33
T/F: Viruses, but not bacteria, can overcome host defences by changing their surface antigens.
False- Both viruses and bacteria can undergo antigenic variation.
34
T/F: Bacteria release enzymes that can kill phagocytes.
True
35
T/F: In an acute infection, host defences are never able to clear the pathogen.
False
36
T/F: Pathogens cannot be transmitted during the incubation period of an infection.
False - Pathogens can be transmitted during any period, as long as the pathogen is multiplying.
37
T/F: During the latent period of a chronic infection, the pathogen does not multiply and cannot be transmitted and the host is asymptomatic.
False - A chronic infection does not have a latent period.
38
The phases of an acute infection occur in the following order:
a disease, incubation, prodromal, recovery
b recovery, prodromal, disease, incubation
c prodromal, recovery, incubation, disease
d incubation, prodromal, disease, recovery
d incubation, prodromal, disease, recovery
39
A chronic infection generally results in:
a no tissue damage after a chronic period of time
b a dormant period when the pathogen does not multiply or cause tissue damage
c ongoing, long-term tissue damage
d recurrent periods of acute, symptomatic disease
c ongoing, long-term tissue damage
40
T/F: Herpes viruses cause latent infections and cannot be transmitted in the latent period becasue the virus is not multiplying.
True
41
# Define:
Microbes
Microorganisms, including bacteria, viruses, fungi, and protozoa, that can live in and on the human body, influencing health in both positive and negative ways.
42
# Define:
Microbes
Microscopic organisms, including bacteria, fungi, viruses, protozoa, and algae, that can only be seen with a microscope. They make up a significant portion of Earth's biomass.
43
# Define:
Bacteria
Single-celled prokaryotic organisms that lack membrane-bound organelles. They are found in various environments, including the human body.
44
# Define:
Fungi
Eukaryotic organisms that can exist as single cells or multicellular forms, such as molds and yeasts. They can produce toxins and antibiotics, like penicillin.
45
# Define:
Viruses
Acellular microbes that do not have all the components necessary for independent cell function and metabolism. They are not considered living organisms outside of a host.
46
# Define:
Protozoa
Single-celled eukaryotic organisms that can live alone or in colonies, typically found in water. Examples include amoebas.
47
# Define:
Algae
Photosynthetic eukaryotic organisms that can be single-celled or multicellular, found mainly in aquatic environments.
48
# Define:
Eukaryotic cells
Cells with membrane-bound organelles, including a nucleus, Golgi apparatus, lysosomes, and mitochondria. Found in animals, plants, fungi, protozoa, and algae.
49
# Define:
Prokaryotic cells
Simpler cells that lack membrane-bound organelles and a nucleus. All bacteria are prokaryotes.
50
# Define:
Bacilli
Rod-shaped bacteria. The term is used in the names of rod-shaped bacterial species.
51
# Define:
Cocci
Spherical-shaped bacteria. The term is used in the names of spherical bacterial species.
52
# Define:
Spirilla
Spiral-shaped bacteria. This term is used for bacteria with a spiral shape.
53
# Define:
Spirochete
A specific type of spiral-shaped bacteria with a unique corkscrew motion.
54
# Define:
Vibrio
A comma-shaped or curved rod-shaped bacteria.
55
# Define:
Cell envelope
The outer layers surrounding a bacterial cell, including the cell membrane and cell wall.
56
# Define:
Peptidoglycan
A glycoprotein consisting of protein and carbohydrate groups that forms a mesh-like layer in the bacterial cell wall, targeted by certain antibiotics.
57
# Define:
Capsule
An additional outer layer found in some bacteria, which can be sticky or slippery and aids in host colonization.
58
# Define:
Pili
Hair-like structures on the surface of bacteria used for genetic material exchange and adherence to surfaces.
59
# Define:
Flagellum (Plural: Flagella)
A whip-like structure used by bacteria for locomotion and sometimes as a receptor for environmental changes.
60
# Define:
Nucleoid
A region within a bacterial cell where the genetic material, a single circular DNA chromosome, is located.
61
# Define:
Binary fission
The process of bacterial reproduction where a single bacterium divides into two identical daughter cells after DNA replication.
62
# Define:
Obligate parasites
Organisms that can only reproduce inside a host cell, relying on the host's cellular machinery for replication.
63
# Define:
Naked viruses
Viruses that have a protein coat called a capsid surrounding their genetic material but lack an outer lipid envelope.
64
# Define:
Enveloped viruses
Viruses that have a phospholipid bilayer derived from the host cell’s plasma membrane surrounding their capsid, which may contain embedded proteins for host cell attachment.
65
# Define:
Capsid
A protein coat surrounding the genetic material of a virus. It helps protect the viral genome and facilitates attachment to host cells.
66
# Define:
Envelope
An outer lipid bilayer surrounding some viruses, derived from the host cell's membrane, which may contain viral proteins that assist in infection.
67
# Define:
Lytic infection
A type of viral infection that results in the destruction (lysis) of the host cell, releasing new viral particles.
68
# Define:
Endocytosis
A process by which cells take in external substances, such as viruses, by engulfing them in a vesicle.
69
# Define:
Fusion
The process by which an enveloped virus merges its lipid envelope with the host cell membrane to gain entry into the cell.
70
# Define:
Exocytosis
The process by which viruses exit the host cell, often involving the budding off of new viral particles from the cell membrane.
71
# Define:
SARS-CoV-2
The virus responsible for COVID-19, characterized as an enveloped virus with spike proteins that facilitate attachment and entry into host cells.
72
# Define:
Spike proteins
Surface proteins on some viruses, such as SARS-CoV-2, that enable the virus to bind to specific receptors on the host cell, facilitating infection.
73
# Define:
Chronic or persistent infection
A type of viral infection where the virus is released slowly from the host cell without killing it, leading to a prolonged presence in the host.
74
# Define:
Latent state
A condition in which a virus remains dormant inside a host cell without replicating, potentially becoming reactivated later.
75
# Define:
Chitin
A carbohydrate derivative of glucose that forms a tough, protective shell around fungal cells, similar to the exoskeletons of insects and crustaceans.
76
# Define:
Yeast
Single-celled fungi that reproduce by budding. They are oval-shaped and can be found in various environments.
77
# Define:
Budding
A form of asexual reproduction in yeast where a new cell develops from an outgrowth or bud on the parent cell.
78
# Define:
Molds
Multicellular fungi that form a network of cells known as mycelium. They often appear as fuzzy or thread-like structures and are commonly seen on spoiled food.
79
# Define:
Mycelium
A network of fungal cells that forms the vegetative part of a fungus, such as mold. It helps in nutrient absorption and growth.
80
# Define:
Tinea
A type of fungal infection commonly known as athlete's foot, which affects the skin between the toes.
81
# Define:
Candidiasis
A fungal infection caused by Candida species, which can occur in areas such as the mouth (thrush) or other mucosal surfaces.
82
# Define:
Immunocompromised
Individuals with weakened immune systems, such as those with HIV/AIDS, undergoing immunosuppressive treatments, or having chronic conditions like cancer or diabetes, who are more susceptible to severe fungal infections.
83
# Define:
Symbiosis
A relationship between two organisms living together in close association. In the context of microbes and humans, it refers to how microbes interact with humans, either beneficially, neutrally, or harmfully.
84
# Define:
Normal flora
Also known as resident flora, microbiota, or the microbiome. These are the microorganisms that regularly inhabit various parts of the human body and usually benefit the host by outcompeting harmful pathogens and assisting in various bodily functions.
85
# Define:
Transient microbes
Microorganisms that temporarily inhabit the body but do not establish a permanent presence. They may be picked up from the environment and do not necessarily contribute to the body’s normal flora.
86
# Define:
Commensalism
A type of symbiotic relationship where the microbe benefits from the interaction, while the host is unaffected (neither helped nor harmed).
87
# Define:
Mutualism
A symbiotic relationship where both the microbe and the host benefit from the interaction.
88
# Define:
Parasitism
A symbiotic relationship where the microbe benefits at the expense of the host, potentially causing harm or disease to the host.
89
# Define:
Communicable
Refers to diseases that can be transmitted from one person to another. Infectious diseases are not always communicable, as some, like tooth decay, do not spread between individuals.
90
# Define:
Lactobacillus
A type of bacteria found in the gastrointestinal tract and vagina. They metabolize glycogen to produce lactic acid, which maintains an acidic environment that inhibits the growth of harmful microbes.
91
# Define:
Escherichia coli (E. coli)
A bacterium commonly found in the large intestine. It helps with the metabolism of waste products and the production of essential vitamins, such as B-group vitamins and vitamin K, which are crucial for various bodily functions.
92
# Define:
Vitamin K
A vitamin produced by intestinal bacteria, essential for normal blood clotting. Infants are often given a injection at birth to ensure proper clotting until their gut flora is established.
93
# Define:
Butyrate
A fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine. It supports cell health and reduces the risk of colon cancer by enhancing blood flow and immune function.
94
# Define:
Innate immune defenses
The body's initial, non-specific defense mechanisms that respond quickly to pathogens. It includes physical barriers like skin and mucous membranes, as well as various immune cells and proteins.
95
# Define:
Adaptive immune defenses
The part of the immune system that develops a specific response to pathogens and improves its response with each exposure. It involves specialized cells and antibodies.
96
# Define:
Sign
An objective change in the body that can be observed or measured by a healthcare provider, such as a fever.
97
# Define:
Symptom
A subjective experience reported by the patient, such as pain or fatigue, which cannot be directly measured but indicates an underlying condition.
98
# Define:
Subclinical disease
An infection or disease that does not produce noticeable symptoms, often because the immune system has successfully contained the pathogen.
99
# Define:
Virulence
The capacity of a microbe to cause disease. It measures how harmful the microbe is and affects the severity of the disease it can cause.
100
# Define:
Infectious dose
The minimum number of pathogens required to cause an infection. A lower infectious dose indicates higher virulence.
101
# Define:
Conventional pathogens
Microbes that cause disease in individuals with normal immune defenses. Examples include viruses like the measles virus and bacteria like Neisseria gonorrhoeae.
102
# Define:
Opportunistic pathogens
Microbes that usually do not cause disease in healthy individuals but can lead to infections when the host’s immune defenses are compromised or when they colonize an unusual body site.
103
# Define:
Ecological imbalance
A disruption in the normal balance of microbes, allowing opportunistic pathogens to overgrow. For instance, the reduction of Lactobacillus bacteria can lead to the overgrowth of Candida albicans.
104
# Define:
Relocation
When normal flora microbes move to a part of the body where they are not typically found, potentially causing infections. For example, E. coli from the large intestine causing a urinary tract infection.
105
# Define:
Compromised host defenses
When the immune system or physical barriers are weakened, making the host more susceptible to infections. Factors include preexisting conditions, age, and compromised immune systems.
106
# Define:
Aspergillus
A genus of fungus found in various environments, such as damp hay, which can cause respiratory infections in immunocompromised individuals.
107
# Define:
Primary immune response
The initial reaction of the immune system to a pathogen, aimed at eliminating it and leading to recovery.
108
# Define:
Secondary immune response
A faster and more effective immune response that occurs upon subsequent exposure to a pathogen, often preventing disease or reducing its severity.
109
# Define:
Portal of Entry
The site through which a pathogen enters the body. Different pathogens may have preferred entry points for effective infection.
110
# Define:
Skin and Mucous Membranes
Physical barriers of the body that act as the first line of defense against pathogens. Pathogens may enter through openings in the skin or mucous membranes.
111
# Define:
Glycocalyx
A sticky substance secreted by some bacteria that helps them adhere to body surfaces and can contribute to the formation of biofilms, such as dental plaque.
112
# Define:
Viral Attachment
The process by which viruses bind to specific molecules on the surface of target cells to facilitate infection.
113
# Define:
Extracellular pathogens
Microbes that obtain nutrients from extracellular fluids and do not need to enter host cells to cause disease.
114
# Define:
Intracellular pathogens
Microbes that obtain nutrients from within host cells, causing disease by infecting and replicating inside these cells.
115
# Define:
Virulence factors
Traits or abilities of a pathogen that enable it to evade host defenses, cause damage, or persist within the host.
116
# Define:
Surface Barriers
Physical and chemical defenses of the body, such as the skin and mucous membranes, that prevent microbial entry and infection.
117
# Define:
Antigenic Variation
A mechanism by which pathogens alter their surface proteins to evade recognition by the immune system, leading to ongoing or repeated infections.
118
# Define:
Cytopathic Effects
Direct damage caused by pathogens, particularly viruses, which leads to the death of host cells.
119
# Define:
Fibrosis
Formation of excess fibrous connective tissue in response to chronic inflammation, leading to scarring and loss of function.
120
# Define:
Portal of Exit
The route through which a pathogen exits the host's body to spread to new hosts, commonly through respiratory or digestive tracts.
121
# Define:
Acute Infection
An infection characterized by a rapid onset of symptoms and a relatively short duration, typically resolved once the pathogen is eliminated.
122
# Define:
Chronic Infection
An infection that begins acutely but persists over a long period, often with slow multiplication of the pathogen and progressive tissue damage.
123
# Define:
Latent Infection
An infection where the pathogen remains dormant within the host after an initial acute phase, not causing symptoms or being transmissible until reactivation.
124
# Define:
Prodromal Period
The phase of an infection characterized by mild or nonspecific symptoms that precede the onset of more severe symptoms.
125
# Define:
Disease Period
The phase of an infection marked by the peak of symptoms and tissue damage, defining the disease's impact on the host.
126
# Define:
Recovery Period
The phase following the peak of an infection where symptoms decrease as the host's defenses overcome the pathogen.
127
# Define:
Immune Complex
A combination of antigens and antibodies that can deposit in tissues, activating complement proteins and attracting phagocytes.
128
# Define:
Complement Proteins
Proteins in the blood that assist in the immune response by marking pathogens for destruction and attracting phagocytes.
129
# Define:
Flaccid Paralysis
A condition where muscles become weak and limp due to the inability to contract, often caused by toxins affecting neuromuscular junctions.
130
# Define:
Tetany
Sustained muscle contractions due to a disruption in normal nervous system function, often caused by certain toxins.
131
# Define:
Shingles
A reactivation of the varicella-zoster virus that causes a painful rash, usually along the path of a spinal nerve.
132
# Define:
Herpes Viruses
A group of viruses that can cause latent infections and reactivate later, such as varicella-zoster virus which causes both chickenpox and shingles.
133
# What is...
Microorganisms, including bacteria, viruses, fungi, and protozoa, that can live in and on the human body, influencing health in both positive and negative ways.
Microbes
134
# What is...
Microscopic organisms, including bacteria, fungi, viruses, protozoa, and algae, that can only be seen with a microscope. They make up a significant portion of Earth's biomass.
Microbes
135
# What is...
Single-celled prokaryotic organisms that lack membrane-bound organelles. They are found in various environments, including the human body.
Bacteria
136
# What is...
Eukaryotic organisms that can exist as single cells or multicellular forms, such as molds and yeasts. They can produce toxins and antibiotics, like penicillin.
Fungi
137
# What is...
Acellular microbes that do not have all the components necessary for independent cell function and metabolism. They are not considered living organisms outside of a host.
Viruses
138
# What is...
Single-celled eukaryotic organisms that can live alone or in colonies, typically found in water. Examples include amoebas.
Protozoa
139
# What is...
Photosynthetic eukaryotic organisms that can be single-celled or multicellular, found mainly in aquatic environments.
Algae
140
# What is...
Cells with membrane-bound organelles, including a nucleus, Golgi apparatus, lysosomes, and mitochondria. Found in animals, plants, fungi, protozoa, and algae.
Eukaryotic cells
141
# What is...
Simpler cells that lack membrane-bound organelles and a nucleus. All bacteria are prokaryotes.
Prokaryotic cells
142
# What is...
Rod-shaped bacteria. The term is used in the names of rod-shaped bacterial species.
Bacilli
143
# What is...
Spherical-shaped bacteria. The term is used in the names of spherical bacterial species.
Cocci
144
# What is...
Spiral-shaped bacteria. This term is used for bacteria with a spiral shape.
Spirilla
145
# What is...
A specific type of spiral-shaped bacteria with a unique corkscrew motion.
Spirochete
146
# What is...
A comma-shaped or curved rod-shaped bacteria.
Vibrio
147
# What is...
The outer layers surrounding a bacterial cell, including the cell membrane and cell wall.
Cell envelope
148
# What is...
A glycoprotein consisting of protein and carbohydrate groups that forms a mesh-like layer in the bacterial cell wall, targeted by certain antibiotics.
Peptidoglycan
149
# What is...
An additional outer layer found in some bacteria, which can be sticky or slippery and aids in host colonization.
Capsule
150
# What is...
Hair-like structures on the surface of bacteria used for genetic material exchange and adherence to surfaces.
Pili
151
# What is...
A whip-like structure used by bacteria for locomotion and sometimes as a receptor for environmental changes.
Flagellum (Plural: Flagella)
152
# What is...
A region within a bacterial cell where the genetic material, a single circular DNA chromosome, is located.
Nucleoid
153
# What is...
The process of bacterial reproduction where a single bacterium divides into two identical daughter cells after DNA replication.
Binary fission
154
# What is...
Organisms that can only reproduce inside a host cell, relying on the host's cellular machinery for replication.
Obligate parasites
155
# What is...
Viruses that have a protein coat called a capsid surrounding their genetic material but lack an outer lipid envelope.
Naked viruses
156
# What is...
Viruses that have a phospholipid bilayer derived from the host cell’s plasma membrane surrounding their capsid, which may contain embedded proteins for host cell attachment.
Enveloped viruses
157
# What is...
A protein coat surrounding the genetic material of a virus. It helps protect the viral genome and facilitates attachment to host cells.
Capsid
158
# What is...
An outer lipid bilayer surrounding some viruses, derived from the host cell's membrane, which may contain viral proteins that assist in infection.
Envelope
159
# What is...
A type of viral infection that results in the destruction (lysis) of the host cell, releasing new viral particles.
Lytic infection
160
# What is...
A process by which cells take in external substances, such as viruses, by engulfing them in a vesicle.
Endocytosis
161
# What is...
The process by which an enveloped virus merges its lipid envelope with the host cell membrane to gain entry into the cell.
Fusion
162
# What is...
The process by which viruses exit the host cell, often involving the budding off of new viral particles from the cell membrane.
Exocytosis
163
# What is...
The virus responsible for COVID-19, characterized as an enveloped virus with spike proteins that facilitate attachment and entry into host cells.
SARS-CoV-2
164
# What is...
Surface proteins on some viruses, such as SARS-CoV-2, that enable the virus to bind to specific receptors on the host cell, facilitating infection.
Spike proteins
165
# What is...
A type of viral infection where the virus is released slowly from the host cell without killing it, leading to a prolonged presence in the host.
Chronic or persistent infection
166
# What is...
A condition in which a virus remains dormant inside a host cell without replicating, potentially becoming reactivated later.
Latent state
167
# What is...
A carbohydrate derivative of glucose that forms a tough, protective shell around fungal cells, similar to the exoskeletons of insects and crustaceans.
Chitin
168
# What is...
Single-celled fungi that reproduce by budding. They are oval-shaped and can be found in various environments.
Yeast
169
# What is...
A form of asexual reproduction in yeast where a new cell develops from an outgrowth or bud on the parent cell.
Budding
170
# What is...
Multicellular fungi that form a network of cells known as mycelium. They often appear as fuzzy or thread-like structures and are commonly seen on spoiled food.
Molds
171
# What is...
A network of fungal cells that forms the vegetative part of a fungus, such as mold. It helps in nutrient absorption and growth.
Mycelium
172
# What is...
A type of fungal infection commonly known as athlete's foot, which affects the skin between the toes.
Tinea
173
# What is...
A fungal infection caused by Candida species, which can occur in areas such as the mouth (thrush) or other mucosal surfaces.
Candidiasis
174
# What is...
Individuals with weakened immune systems, such as those with HIV/AIDS, undergoing immunosuppressive treatments, or having chronic conditions like cancer or diabetes, who are more susceptible to severe fungal infections.
Immunocompromised
175
# What is...
A relationship between two organisms living together in close association. In the context of microbes and humans, it refers to how microbes interact with humans, either beneficially, neutrally, or harmfully.
Symbiosis
176
# What is...
Also known as resident flora, microbiota, or the microbiome. These are the microorganisms that regularly inhabit various parts of the human body and usually benefit the host by outcompeting harmful pathogens and assisting in various bodily functions.
Normal flora
177
# What is...
Microorganisms that temporarily inhabit the body but do not establish a permanent presence. They may be picked up from the environment and do not necessarily contribute to the body’s normal flora.
Transient microbes
178
# What is...
A type of symbiotic relationship where the microbe benefits from the interaction, while the host is unaffected (neither helped nor harmed).
Commensalism
179
# What is...
A symbiotic relationship where both the microbe and the host benefit from the interaction.
Mutualism
180
# What is...
A symbiotic relationship where the microbe benefits at the expense of the host, potentially causing harm or disease to the host.
Parasitism
181
# What is...
Refers to diseases that can be transmitted from one person to another. Infectious diseases are not always communicable, as some, like tooth decay, do not spread between individuals.
Communicable
182
# What is...
A type of bacteria found in the gastrointestinal tract and vagina. They metabolize glycogen to produce lactic acid, which maintains an acidic environment that inhibits the growth of harmful microbes.
Lactobacillus
183
# What is...
A bacterium commonly found in the large intestine. It helps with the metabolism of waste products and the production of essential vitamins, such as B-group vitamins and vitamin K, which are crucial for various bodily functions.
Escherichia coli (E. coli)
184
# What is...
A vitamin produced by intestinal bacteria, essential for normal blood clotting. Infants are often given a injection at birth to ensure proper clotting until their gut flora is established.
Vitamin K
185
# What is...
A fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine. It supports cell health and reduces the risk of colon cancer by enhancing blood flow and immune function.
Butyrate
186
# What is...
The body's initial, non-specific defense mechanisms that respond quickly to pathogens. It includes physical barriers like skin and mucous membranes, as well as various immune cells and proteins.
Innate immune defenses
187
# What is...
The part of the immune system that develops a specific response to pathogens and improves its response with each exposure. It involves specialized cells and antibodies.
Adaptive immune defenses
188
# What is...
An objective change in the body that can be observed or measured by a healthcare provider, such as a fever.
Sign
189
# What is...
A subjective experience reported by the patient, such as pain or fatigue, which cannot be directly measured but indicates an underlying condition.
Symptom
190
# What is...
An infection or disease that does not produce noticeable symptoms, often because the immune system has successfully contained the pathogen.
Subclinical disease
191
# What is...
The capacity of a microbe to cause disease. It measures how harmful the microbe is and affects the severity of the disease it can cause.
Virulence
192
# What is...
The minimum number of pathogens required to cause an infection. A lower infectious dose indicates higher virulence.
Infectious dose
193
# What is...
Microbes that cause disease in individuals with normal immune defenses. Examples include viruses like the measles virus and bacteria like Neisseria gonorrhoeae.
Conventional pathogens
194
# What is...
Microbes that usually do not cause disease in healthy individuals but can lead to infections when the host’s immune defenses are compromised or when they colonize an unusual body site.
Opportunistic pathogens
195
# What is...
A disruption in the normal balance of microbes, allowing opportunistic pathogens to overgrow. For instance, the reduction of Lactobacillus bacteria can lead to the overgrowth of Candida albicans.
Ecological imbalance
196
# What is...
When normal flora microbes move to a part of the body where they are not typically found, potentially causing infections. For example, E. coli from the large intestine causing a urinary tract infection.
Relocation
197
# What is...
When the immune system or physical barriers are weakened, making the host more susceptible to infections. Factors include preexisting conditions, age, and compromised immune systems.
Compromised host defenses
198
# What is...
A genus of fungus found in various environments, such as damp hay, which can cause respiratory infections in immunocompromised individuals.
Aspergillus
199
# What is...What is...
The initial reaction of the immune system to a pathogen, aimed at eliminating it and leading to recovery.
Primary immune response
200
# What is...
A faster and more effective immune response that occurs upon subsequent exposure to a pathogen, often preventing disease or reducing its severity.
Secondary immune response
201
# What is...
The site through which a pathogen enters the body. Different pathogens may have preferred entry points for effective infection.
Portal of Entry
202
# What is...
Physical barriers of the body that act as the first line of defense against pathogens. Pathogens may enter through openings in the skin or mucous membranes.
Skin and Mucous Membranes
203
# What is...
A sticky substance secreted by some bacteria that helps them adhere to body surfaces and can contribute to the formation of biofilms, such as dental plaque.
Glycocalyx
204
# What is...
The process by which viruses bind to specific molecules on the surface of target cells to facilitate infection.
Viral Attachment
205
# What is...
Microbes that obtain nutrients from extracellular fluids and do not need to enter host cells to cause disease.
Extracellular pathogens
206
# What is...
Microbes that obtain nutrients from within host cells, causing disease by infecting and replicating inside these cells.
Intracellular pathogens
207
# What is...
Traits or abilities of a pathogen that enable it to evade host defenses, cause damage, or persist within the host.
Virulence factors
208
# What is...
Physical and chemical defenses of the body, such as the skin and mucous membranes, that prevent microbial entry and infection.
Surface Barriers
209
# What is...
A mechanism by which pathogens alter their surface proteins to evade recognition by the immune system, leading to ongoing or repeated infections.
Antigenic Variation
210
# What is...
Direct damage caused by pathogens, particularly viruses, which leads to the death of host cells.
Cytopathic Effects
211
# What is...
Formation of excess fibrous connective tissue in response to chronic inflammation, leading to scarring and loss of function.
Fibrosis
212
# What is...
The route through which a pathogen exits the host's body to spread to new hosts, commonly through respiratory or digestive tracts.
Portal of Exit
213
# What is...
An infection characterized by a rapid onset of symptoms and a relatively short duration, typically resolved once the pathogen is eliminated.
Acute Infection
214
# What is...
An infection that begins acutely but persists over a long period, often with slow multiplication of the pathogen and progressive tissue damage.
Chronic Infection
215
# What is...
An infection where the pathogen remains dormant within the host after an initial acute phase, not causing symptoms or being transmissible until reactivation.
Latent Infection
216
# What is...
The phase of an infection characterized by mild or nonspecific symptoms that precede the onset of more severe symptoms.
Prodromal Period
217
# What is...
The phase of an infection marked by the peak of symptoms and tissue damage, defining the disease's impact on the host.
Disease Period
218
# What is...
The phase following the peak of an infection where symptoms decrease as the host's defenses overcome the pathogen.
Recovery Period
219
# What is...
A combination of antigens and antibodies that can deposit in tissues, activating complement proteins and attracting phagocytes.
Immune Complex
220
# What is...
Proteins in the blood that assist in the immune response by marking pathogens for destruction and attracting phagocytes.
Complement Proteins
221
# What is...
A condition where muscles become weak and limp due to the inability to contract, often caused by toxins affecting neuromuscular junctions.
Flaccid Paralysis
222
# What is...
Sustained muscle contractions due to a disruption in normal nervous system function, often caused by certain toxins.
Tetany
223
# What is...
A reactivation of the varicella-zoster virus that causes a painful rash, usually along the path of a spinal nerve.
Shingles
224
# What is...
A group of viruses that can cause latent infections and reactivate later, such as varicella-zoster virus which causes both chickenpox and shingles.
Herpes Viruses
225
What role do microbes play in our lives?
Microbes influence our health by having both beneficial and harmful effects. They are crucial for understanding infection processes and disease prevention in clinical settings.
226
What are microbes?
Microbes are microscopic organisms, including bacteria, fungi, and viruses, that can only be seen with a microscope.
227
What percentage of Earth's biomass is made up of microbes?
Microbes make up 90% of the Earth's biomass.
228
What types of organisms are included in the term "microbes"?
Microbes include bacteria, fungi, protozoa, algae, and viruses.
229
Why are viruses not considered living organisms when outside a host?
Viruses lack the components necessary for cell function and independent metabolism.
230
What distinguishes eukaryotic cells from prokaryotic cells?
Eukaryotic cells have membrane-bound organelles and a nucleus, while prokaryotic cells do not.
231
Which cells are considered prokaryotic?
All bacteria are prokaryotic cells.
232
What is the size range of typical bacteria?
Bacteria range from 1 to 5 micrometers in diameter.
233
How do viruses compare in size to bacteria?
Viruses are much smaller than bacteria, falling in the nanometer range and requiring an electron microscope to be seen.
234
What system is used to name microbes?
The binomial nomenclature system, which includes a genus name and a species name.
235
What is the scientific name for "golden staph"?
The scientific name is Staphylococcus aureus.
236
What shape is indicated by the term "bacilli"?
"Bacilli" refers to rod-shaped bacteria.
237
What does the term "cocci" describe?
"Cocci" describes spherical bacteria.
238
How do bacteria obtain nutrients?
Bacteria release enzymes to digest organic material extracellularly and then absorb the nutrients in dissolved form.
239
What is the cell envelope of a bacterium composed of?
The cell envelope includes the cell membrane (phospholipid bilayer) and, in many cases, a cell wall made of peptidoglycan.
240
Why are antibiotics like penicillin effective against bacteria?
Penicillin targets peptidoglycan in the bacterial cell wall, disrupting cell wall formation and leading to bacterial death.
241
What is the function of a bacterial capsule?
A capsule helps bacteria adhere to hosts and can be sticky or slippery.
242
What is the role of pili in bacteria?
Pili are used for the exchange of genetic material between bacteria.
243
What is the function of a bacterial flagellum?
A flagellum aids in locomotion and can function as a receptor for detecting external chemicals or temperature changes.
244
Where is bacterial genetic material located?
The genetic material is located in the nucleoid, a region containing a single circular chromosome.
245
What is the process of bacterial reproduction called?
Bacterial reproduction is called binary fission.
246
How quickly can E. coli reproduce under optimal conditions?
E. coli can divide every 20 minutes under optimal conditions.
247
What are viruses made of?
Viruses are packets of genetic material, either DNA or RNA, surrounded by a protein coat called a capsid.
248
What distinguishes a naked virus from an enveloped virus?
A naked virus has only a protein capsid surrounding its genetic material, while an enveloped virus has an additional outer phospholipid bilayer derived from the host cell's plasma membrane.
249
Why are viruses considered obligate parasites?
Viruses are obligate parasites because they must infect a host cell to reproduce, as they lack the necessary machinery to reproduce on their own.
250
How do naked viruses typically enter a host cell?
Naked viruses usually enter a host cell via endocytosis.
251
How do enveloped viruses typically enter a host cell?
Enveloped viruses can fuse their envelope with the host cell membrane to enter more easily.
252
What is a lytic infection?
A lytic infection is one where the virus attaches to the host cell, enters, uses the host's machinery to replicate, and eventually causes the cell to lyse and die, releasing new viral particles.
253
What is an example of a virus that causes a lytic infection?
SARS-CoV-2, which causes COVID-19, is an example of a virus that causes a lytic infection.
254
How does SARS-CoV-2 facilitate its entry into host cells?
SARS-CoV-2 uses spike proteins on its envelope to bind to receptors on epithelial cells, facilitating fusion with the host cell membrane.
255
What happens during the maturation of enveloped viruses?
Enveloped viruses assemble their nucleic acids and capsid proteins inside the host cell, then bud off from the host cell membrane, taking part of the plasma membrane with them to form their envelope.
256
What are the four possible outcomes of a viral infection?
Lytic infection
Chronic or persistent infection
Latent infection
Transformation of host cells into tumor cells
257
What is a chronic or persistent viral infection?
A chronic or persistent infection occurs when the virus is released slowly from the host cell without killing it, and the infection can last for months, years, or even a lifetime.
258
What characterizes a latent viral infection?
In a latent infection, the virus remains dormant inside the host cell without replicating or causing damage, and it can be reactivated later to cause a lytic infection.
259
What is an example of a virus that can transform normal cells into tumor cells?
Papillomavirus is an example that can cause benign tumors like skin warts or malignant tumors like cervical cancer.
260
What is the primary component of a fungal cell wall?
The primary component of a fungal cell wall is chitin.
261
How do yeast cells reproduce?
Yeast cells reproduce by budding.
262
What are molds, and how do they differ from yeast?
Molds are multicellular fungi that form a network of cells called mycelium, whereas yeast are single-celled fungi.
263
What types of infections can fungi cause?
Fungi can cause superficial infections like athlete’s foot and thrush, as well as more serious infections in immunocompromised individuals.
264
Which organization has prioritized fungal pathogens and why?
The World Health Organization (WHO) has prioritized fungal pathogens due to their increasing incidence and the limited treatment options available.
265
What are the three types of relationships between humans and microbes?
Commensalism
Mutualism
Parasitism
266
What is commensalism?
In commensalism, the microbe benefits from the relationship without affecting the host.
267
What is mutualism?
In mutualism, both the microbe and the host benefit from the relationship.
268
What is parasitism?
In parasitism, the microbe benefits at the expense of the host, potentially causing harm.
269
What does the term "normal flora" refer to?
Normal flora refers to the variety of microbes that establish a population on body surfaces, such as the skin and gastrointestinal tract.
270
How are microbes colonized on the body?
Microbes colonize the body surfaces by establishing a population and growing there after birth, coming from sources like the maternal vagina, diet, and the environment.
271
Where are normal flora typically found on the skin?
Normal flora are usually found in warm, moist areas of the skin, such as the groin and armpits.
272
What role do commercial deodorants play in managing body odor?
Deodorants work by inhibiting microbial metabolic activity or by keeping the skin dry to prevent microbial growth and body odor.
273
How does the digestive tract support microbial growth?
The digestive tract is warm, moist, and filled with food sources, making it an ideal environment for microbes.
274
What is the microbial density like in the mouth compared to the stomach and intestines?
The mouth has about 100 billion bacteria per gram of wet tissue, the stomach has fewer microbes due to low pH, and the number of microbes increases in the small and large intestines.
275
What are some benefits of microbes in the large intestine?
Microbes in the large intestine help digest certain fibers, produce vitamins B and K, and create fatty acids that are used for energy.
276
Why are the bronchi and lungs relatively free of microbes?
The bronchi and lungs are relatively free of microbes due to the mucociliary escalator and the presence of macrophages.
277
Are the upper regions of the urinary tract sterile?
Yes, the upper regions of the urinary tract, including the kidneys, ureters, and bladder, are typically sterile.
278
What types of microbes are found in the urethra?
The urethra, which connects the bladder to the outside, can contain microbes in both males and females, but the number is low due to the flushing action of urine.
279
Where are microbes found in the reproductive tracts?
In females, microbes are commonly found in the vagina, while the ovaries and higher areas of the reproductive tract are sterile. In males, the urethra contains some microbes.
280
What is the proportion of microbial cells to human cells on our body surfaces?
There are about 10 times as many microbial cells on our body surfaces as there are human cells.
281
How do normal flora maintain ecological balance with the host?
Normal flora live, reproduce, and feed in place on body surfaces, maintaining a stable ecosystem with relatively constant numbers and types of microbes.
282
How can the composition of normal flora change over time?
The composition can change due to factors like the emergence of a baby’s teeth creating a new ecological niche.
283
What is commensalism in the context of normal flora?
In commensalism, one partner benefits (the microbe) while the other (the host) remains unaffected.
284
How does mutualism benefit both the normal flora and the host?
In mutualism, both the microbe and the host benefit, such as when normal flora prevent pathogens from colonizing or produce beneficial compounds like vitamins.
285
How does Lactobacillus bacteria benefit the host in the vagina?
Lactobacillus bacteria metabolize glycogen into lactic acid, which helps maintain an acidic environment and prevents overgrowth of harmful microbes.
286
What is the role of E. coli in the large intestine?
E. coli helps metabolize waste products and produce essential vitamins like B-group vitamins and vitamin K.
287
Why are babies given a vitamin K injection at birth?
Babies are given vitamin K injections because their gut flora are not fully developed yet to produce sufficient vitamin K for normal blood clotting.
288
What is butyrate and why is it important?
Butyrate is a fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine and helps reduce the risk of colon cancer.
289
What is parasitism in relation to microbes?
Parasitism is a relationship where one partner (the parasite) benefits at the expense of the host, causing tissue damage and activating host defenses.
290
What type of pathogens are also considered parasites?
Pathogens that cause infectious diseases and use the host as a resource for growth are also considered parasites.
291
What must a microbe do to establish an infection?
It must attach to a body surface, colonize that surface by multiplying while avoiding host defenses, and then invade deeper tissues.
292
What is the difference between a sign and a symptom of disease?
A sign is an objective change that can be observed or measured, such as a fever, while a symptom is subjective and relates to the patient's experience, like a headache.
293
What is the primary cause of tissue damage in infectious disease?
Tissue damage is primarily due to the activities of the pathogen, although host defenses may also contribute.
294
What happens during a primary immune response?
The primary immune response is triggered by an infection, aiming to combat the pathogen and lead to recovery.
295
What is asymptomatic disease?
Asymptomatic disease occurs when an infection is present but shows no symptoms.
296
What is subclinical disease?
Subclinical disease refers to an infection with very minor symptoms.
297
What factors influence whether an infectious disease occurs and is transmitted?
Three factors include the pathogen's pathogenicity, the host's susceptibility, and the environment's suitability for the microbe's survival and transmission.
298
What is virulence?
Virulence is a measure of how harmful a microbe is, with more virulent microbes causing more severe disease.
299
What is an infectious dose?
The infectious dose is the minimum number of pathogens required to cause disease.
300
Name a highly virulent pathogen and its impact.
Smallpox has killed approximately 300 million people in the 20th century alone.
301
How can preexisting poor health affect susceptibility to infection?
Conditions like malnutrition or diabetes can impair immune function and increase the risk of infection.
302
How does immune status affect susceptibility to infection?
Vaccination status and treatments that compromise immune defenses can significantly affect susceptibility.
303
Why are extremities of age a risk factor for infection?
Young babies have immature immune systems, and the elderly may have waning immune defenses, both affecting their ability to combat pathogens.
304
What role do environmental conditions play in infection risk?
Environmental conditions affect individual health, the reservoir of infection, and how easily pathogens are transmitted, influencing the likelihood of infection.
305
What are conventional pathogens?
Conventional pathogens are microbes that cause disease in individuals with normal defenses, such as the measles virus and Neisseria bacteria.
306
What are opportunistic pathogens?
Opportunistic pathogens are microbes that usually do not cause disease in healthy individuals but can do so under certain conditions.
307
What is an example of an opportunistic infection caused by ecological imbalance?
Candidiasis or thrush caused by Candida albicans overgrowing when normal flora like Lactobacillus are reduced.
308
How can relocation of normal flora lead to opportunistic infection?
Normal flora can cause infections if they move to areas of the body where they are normally excluded, such as E. coli causing a urinary tract infection.
309
What is an example of an opportunistic infection due to compromised host defenses?
Pneumonia caused by Streptococcus bacteria in individuals with impaired mucociliary escalator function or severe immunocompromised patients, like those with AIDS.
310
What is an opportunistic infection?
An opportunistic infection is caused by microbes that typically have low pathogenicity but can cause disease in individuals with reduced immune defenses.
311
Give an example of a fungus that can cause opportunistic infections in compromised individuals.
Aspergillus, a common fungus found in damp hay and straw, can lead to chronic respiratory infections in compromised individuals.
312
What are the two possible outcomes when a microbe attaches to the body?
The microbe may be quickly dislodged, resulting in a transient association.
The microbe may multiply and colonize the body surface.
313
What happens when a microbe establishes a stable relationship with the host?
It can become part of the normal flora, where the relationship is commensal or mutualistic, and the host is not harmed or may benefit.
314
What is the difference between an asymptomatic and a subclinical infection?
An asymptomatic infection has no symptoms or tissue damage, while a subclinical infection has minor symptoms and tissue damage.
315
List the steps involved in an infectious disease.
Entry
Multiplication
Damage
Exit
Evade Host Defenses
316
What is the portal of entry for most pathogens?
The portal of entry is the site where a pathogen enters the body, such as the respiratory tract or gastrointestinal tract.
317
How can pathogens enter the body through the skin?
Pathogens can enter through openings like hair follicles or sweat glands, or through compromised skin due to injury or puncture.
318
What is the role of adhesions in pathogen attachment?
Adhesions are surface molecules that help pathogens bind to receptors on target cells.
319
What is glycocalyx and how does it assist bacteria?
Glycocalyx is a sticky substance secreted by some bacteria that cements them to body surfaces, forming biofilms like dental plaque.
320
Give an example of a pathogen that adheres to specific surface molecules on target cells.
HIV adheres to CD4 and CCR5 molecules on helper T cells and macrophages.
321
Why do pathogens need to multiply to a critical population size?
To cause disease, pathogens need to reach a critical population size during the incubation period to overcome host defenses and spread throughout the body.
322
What distinguishes extracellular pathogens from intracellular pathogens?
Extracellular pathogens obtain nutrients from extracellular fluids, while intracellular pathogens obtain nutrients from inside host cells.
323
How do some pathogens overcome host defenses?
By penetrating barriers, avoiding or inactivating host defenses, or producing virulence factors.
324
What is the role of collagenase produced by Streptococcus bacteria?
Collagenase breaks down collagen in the skin, allowing bacteria to invade deeper tissues.
325
How does Bordetella pertussis contribute to disease development?
It secretes toxins that inactivate the mucociliary escalator, allowing the bacteria to reach deeper lung tissue.
326
How do some bacteria resist phagocytes?
By having slippery capsules or glycocalyx that prevent phagocytes from adhering and engulfing them, or by producing leukocidins that kill phagocytes.
327
What is the function of IgA proteases produced by some pathogens?
IgA proteases destroy IgA antibodies, preventing them from neutralizing microbes and allowing infection to occur.
328
What is antigenic variation and how does it affect pathogen recognition?
Antigenic variation is the process by which pathogens alter their surface molecules, making them unrecognizable to previously generated antibodies and evading immune responses.
329
Why can people get COVID-19 multiple times?
Due to antigenic variation in the spike protein of coronaviruses, antibodies from a primary infection may not effectively block subsequent infections.
330
How do mutations in the spike protein of coronaviruses affect vaccine effectiveness?
Mutations can impact how the virus binds to and enters cells, potentially reducing the effectiveness of vaccines and treatments.
331
What type of damage can pathogens cause directly?
Pathogens can cause damage directly through the secretion of enzymes or toxins, killing host cells, or consuming host resources.
332
How do toxins produced by pathogens cause harm?
Toxins can kill phagocytes, induce high fevers, affect the cardiovascular system leading to shock, or cause diarrhea. They can sometimes be a major factor in the host's death.
333
What is an example of a toxin that affects the nervous system?
Tetanus toxin affects the central nervous system, causing sustained muscle contractions and potentially leading to respiratory failure.
334
What does botulinum toxin do to the neuromuscular junction?
Botulinum toxin blocks the release of acetylcholine at the neuromuscular junction, causing flaccid paralysis.
335
What are cytopathic effects?
Cytopathic effects refer to direct damage caused by a pathogen, leading to the death of host cells.
336
Which virus is known for causing poliomyelitis and its associated effects?
Poliovirus causes poliomyelitis, leading to damage in corticospinal pathways and resulting in flaccid paralysis of the limbs.
337
How do bacteria obtain essential nutrients from host cells?
Some bacteria, like those needing iron stored in the liver, kill host cells to access the nutrients they need.
338
What is a cytotoxin and how does it affect host cells?
A cytotoxin damages cell membranes or other critical cellular components, leading to the destruction of host cells.
339
What role does inflammation play in tissue damage?
Inflammation can cause swelling, which might compress and abrade tissues, and potentially lead to severe conditions like airway obstruction or brain herniation.
340
How can extracellular release of digestive enzymes cause tissue damage?
Immune complexes or large parasites might lead to the release of enzymes from phagocytes, which can damage surrounding tissues.
341
What is an example of a condition resulting from chronic inflammation leading to scarring?
Pelvic inflammatory disease caused by long-term infection can lead to scarring in the reproductive organs and potentially result in infertility.
342
How do pathogens typically exit the body to spread to new hosts?
Pathogens often exit through the respiratory or digestive tracts, for example, via coughing or diarrhea.
343
What are the four phases of an acute infection?
The four phases are the incubation period, the prodromal period, the disease period, and the recovery period.
344
What happens during the incubation period of an infection?
The incubation period is the time between exposure to the pathogen and the onset of symptoms, influenced by factors such as pathogen virulence and host resistance.
345
What characterizes the prodromal period?
The prodromal period is marked by mild or nonspecific symptoms such as headache or fatigue, with the pathogen continuing to multiply.
346
During which phase of an infection are specific signs and symptoms most prominent?
The disease period is when specific signs and symptoms of the disease are most prominent.
347
What occurs during the recovery period of an infection?
During the recovery period, the number of pathogens decreases, signs and symptoms reduce, and eventually, the pathogen may no longer be detectable.
348
Can a patient transmit a pathogen during the incubation period?
Yes, a patient can transmit the pathogen during the incubation period, even before symptoms appear.
349
What is the initial phase of a chronic infection like?
A chronic infection begins with an acute symptomatic disease, but the pathogen is not completely eliminated and continues to multiply slowly.
350
How does a chronic infection differ from an acute infection in terms of pathogen multiplication?
In a chronic infection, the pathogen continues to multiply slowly over time, whereas in an acute infection, the pathogen typically causes rapid and severe symptoms but is usually eliminated quickly.
351
What happens to the pathogen numbers in a chronic infection over time?
The pathogen numbers slowly increase over time, and there may be subsequent acute periods where symptoms reappear.
352
Can a host with a chronic infection still transmit the pathogen?
Yes, even if the host appears healthy, they can still transmit the pathogen because the pathogen continues to multiply, albeit slowly.
353
Give an example of a chronic infection and its potential long-term effects.
Hepatitis B is a chronic infection that can lead to liver damage, scar tissue formation, liver failure, and potentially liver cancer.
354
How do latent infections begin and what happens to the pathogen after the initial acute phase?
Latent infections start with an acute symptomatic disease, but the pathogen becomes dormant after the initial phase, hiding within body cells and not multiplying.
355
What is the state of the pathogen during the latent period of an infection?
During the latent period, the pathogen remains dormant, does not multiply, and cannot be transmitted. The host remains asymptomatic.
356
How does reactivation of a latent infection differ from the initial infection?
Reactivation leads to a new episode of acute disease, and the symptoms may differ from those of the initial infection.
357
What is a classic example of a latent infection and how does it manifest later?
Herpes viruses are a classic example. Chickenpox caused by varicella-zoster virus can later reactivate as shingles, presenting with a rash following the distribution of a spinal nerve.
358
What is the duration and characteristic of an acute infection?
Acute infections are short-term with present symptoms and generally result in rapid recovery. The pathogen is transmissible as long as it is multiplying.
359
How does a chronic infection typically progress after the initial acute phase?
A chronic infection progresses with the pathogen continuing to multiply slowly, causing progressive tissue damage, and may lead to periodic acute episodes.
360
Can a latent infection ever become transmissible again?
Yes, when a latent infection reactivates, the pathogen can begin multiplying again and may become transmissible.
361
Provide an example of an acute infection and its duration.
Influenza virus is an example of an acute infection, which is typically short-term with rapid onset and recovery.
362
What is the primary difference between chronic and latent infections in terms of pathogen activity?
Chronic infections involve ongoing pathogen multiplication and tissue damage, while latent infections involve a dormant pathogen that does not multiply or cause damage during the latent period.
363
How does the transmissibility of a chronic infection compare to that of a latent infection?
A chronic infection remains transmissible as the pathogen continues to multiply, while a latent infection is not transmissible during the dormant phase but can become transmissible if reactivated.
364
Which of the following is a major structural feature of bacteria?
a) Nucleus
b) Cell wall
c) Chloroplast
d) Mitochondria
b) Cell wall
365
What structure is unique to fungi compared to bacteria and viruses?
a) Capsule
b) Cell membrane
c) Chitin cell wall
d) RNA genome
c) Chitin cell wall
366
Which of the following is a characteristic of viruses?
a) Cellular structure
b) Ability to reproduce independently
c) DNA or RNA genome
d) Cell wall
c) DNA or RNA genome
367
Which type of microbe is characterized by having a chitinous cell wall and is eukaryotic?
a) Bacteria
b) Virus
c) Fungi
d) Protozoa
c) Fungi
368
What is one of the three main types of microbes humans interact with?
a) Bacteria
b) Rocks
c) Plants
d) Metals
a) Bacteria
369
Which relationship describes a microbe that benefits at the expense of the host?
a) Mutualism
b) Commensalism
c) Parasitism
d) Synergism
c) Parasitism
370
Which term describes a pathogen that only causes disease when the host's defenses are compromised?
a) Conventional pathogen
b) Opportunistic pathogen
c) Primary pathogen
d) Secondary pathogen
b) Opportunistic pathogen
371
What is a key factor that determines whether an infection will occur?
a) Pathogen's color
b) Pathogen's resistance to sunlight
c) Host’s immune status
d) Host's dietary habits
c) Host’s immune status
372
Which of the following is a step in the infectious disease process?
a) Symptom resolution
b) Pathogen exit
c) Pathogen replication
d) None of the above
c) Pathogen replication
373
What is the first step in the infectious disease process?
a) Infection
b) Incubation
c) Exposure
d) Recovery
c) Exposure
374
During which phase of an acute infection do symptoms become most severe?
a) Incubation period
b) Prodromal period
c) Disease period
d) Recovery period
c) Disease period
375
Which type of infection is characterized by an initial acute disease followed by a long-term, slowly progressing infection?
a) Acute infection
b) Chronic infection
c) Latent infection
d) Subclinical infection
b) Chronic infection
376
What happens during the latent period of an infection?
a) The pathogen multiplies rapidly
b) The pathogen is dormant and not multiplying
c) Symptoms are severe and pronounced
d) The host's immune system is compromised
b) The pathogen is dormant and not multiplying
377
What is a common outcome of a chronic infection?
a) Rapid recovery
b) Persistent mild symptoms
c) Sudden severe symptoms
d) Immediate resolution
b) Persistent mild symptoms
378
In which type of infection does the pathogen remain dormant within body cells for years before reactivation?
a) Acute infection
b) Chronic infection
c) Latent infection
d) Secondary infection
c) Latent infection
379
Which example represents a latent infection?
a) Influenza
b) Chickenpox leading to shingles
c) Hepatitis B
d) Tuberculosis
b) Chickenpox leading to shingles
380
What is the main feature of an acute infection?
a) Long-term persistence with progressive damage
b) Periodic reactivation of symptoms
c) Short-term illness with rapid onset and recovery
d) Persistent mild symptoms over many years
c) Short-term illness with rapid onset and recovery
381
Which of the following infections is classified as chronic?
a) Common cold
b) Measles
c) Hepatitis C
d) Herpes simplex
c) Hepatitis C
382
What phase follows the initial acute symptoms in a chronic infection?
a) Immediate recovery
b) Latent phase
c) Gradual resolution
d) Long-term persistence
d) Long-term persistence
383
During which phase of an acute infection are pathogens actively multiplying and causing significant damage?
a) Incubation period
b) Prodromal period
c) Disease period
d) Recovery period
c) Disease period
384
What are the 3 types of relationship that exist between humans and microbes?
Commensal
Mutualistic
Parasitic
385
What 3 conditions determine if an infection will occur?
1. Susceptibility of the host
2. Virulence of the pathogen
3. How conducive the environment is to infection
386
What are the 4 stages of an acute infection?
Incubation
Prodromal
Disease
Recovery
387
List 3 types of infection.
Acute
Chronic
Latent
388
Where are the normal flora found?
Skin - mainly in warmer, damper areas
Digestive tract - mouth - lots! Throughout tract but few in stomach (low pH)
Respiratory tract - upper tract only - due to mucociliary escalator
Urinary tract - Lower tract only (urethra)
Reproductive tract - lower tract only (urethra and vagina)
389
2. Summarise the benefits both humans and the normal flora receive from our symbiotic relationship.
Normal flora receive:
* Living space
* Nutrition
Human hosts benefit from:
* Presence of normal flora prevents pathogens from colonising body surfaces
* Products of normal flora can make the body surface inhospitable to pathogens, e.g. acidic environment produced by Lactobaccillus in the vagina
* Normal flora may produce useful molecules, e.g. vitamins B and K, butyrate
390
3. Identify three (3) ways the body’s normal flora can cause an opportunistic infection and disease, and give an example of each.
1. Ecological balance us upset – allowing an overgrowth of a species normally present in small numbers e.g. Candida albicans in the vagina causing candidiasis (thrush)
2. Normal flora relocated to body areas they are normally excluded from e.g. E. coli from the large intestine moves into the urethra causing a UTI
3. Host defences (innate and/or adaptive) are compromised e.g. immunodeficiency disease (HIV), immunosuppression (chemotherapy)
391
4. Fiona McDonald is a 70-year old woman who had a fall and fractured the neck of her right femur. During her recovery, she has an in-dwelling urinary catheter. If all of the appropriate nursing procedures are followed, will there be an infection risk associated with this line? Explain your answer.
Yes, there will be a risk of infection
The urinary catheter compromises the first line of defence (physical barriers)
* provides a portal of entry
* allows normal flora to penetrate deeper tissues from which they are normally excluded
392
5. Successful infection of a host requires that the pathogen is able to enter the host, attach to the appropriate target tissue and evade host defences long enough to multiple and spread within the body.
a. Identify two (2) strategies that a pathogen might use to attach to target surfaces or cells.
Adhesins → molecules that attach to body surfaces/target cells
Sticky capsule (glycocalyx) → stick to body surfaces
Receptors → pathogen can bind specific surface molecules on target cell membranes, e.g. HIV, influenza
393
What strategies to overcome innate defences do pathogen use to avoid physical barriers?
* Enzymes that break down surface barriers/connective tissue
* Toxins that inactivate the mucociliary escalator
394
What strategies to overcome innate defences do pathogen use to resist phagocytes?
* Slippery capsule
* Toxins that kill phagocytes
* Enzymes that inactivate lysosomal enzymes
395
What strategies to overcome adaptive defences do pathogen use to degrade antibodies?
Enzymes that destroy IgA antibodies in mucus
396
What strategies to overcome adaptive defences do pathogen use to avoid recognition?
Antigenic variation - Variation of surface proteins to prevent recognition by memory lymphocytes and circumvent secondary immune responses
397
c. Host tissue damage is the result of the activities of both the pathogen and the host’s defences. List three (3) ways in which the process of inflammation (a host innate defence) can cause tissue damage to the host.
Swelling→ tissue compression/abrasion
Extracellular release of digestive enzymes → damages surrounding tissues
Fibrosis → loss of tissue function
398
Describe the pathogen activity during the incubation period
colonises body surface
infects host
begins multiplying
some evade host defences
399
Describe the pathogen activity during the prodromal period
more evade host defences
multiplying
causing tissue damage
400
Describe the pathogen activity during the disease period
multiplying (greatest numbers)
causing tissue damage (maximal damage)
many evade host defences
401
Describe the host activity/experience during the prodromal period
non-specific symptoms, e.g. headaches, malaise
innate defences active, adaptive defences developing
402
Describe the pathogen activity during the recovery period
overcome by host defences
numbers decreasing
403
Describe the host activity/experience during the incubation period
no signs or symptoms
innate defences active, adaptive defences developing
404
What is the host doing at the point marked “*” and why is this important?
Host defences are overcoming the pathogen thus pathogen numbers start to decrease.
If this does not occur the pathogen will continue to multiply, leading to severe tissue damage and potentially death.
404
Describe the host activity/experience during the disease period
specific signs and symptoms, e.g. measles rash
innate and adaptive defences active
404
Describe the host activity/experience during the recovery period
defences overcome pathogen
signs and symptoms subside
recovery
405
What is the time frame of an acute infection?
Short term
406
What is the time frame of an chronic infection?
Long term to lifelong
407
Describe the disease characteristics in a acute infection
Acute, symptomatic followed by recovery
407
What is the time frame of an latent infection?
Lifelong
408
Describe the disease characteristics in a chronic infection
Acute, symptomatic followed by apparent recovery
409
Describe the disease characteristics in a latent infection
Acute, symptomatic followed by apparent recovery, reactivation at later time(s)
410
Describe what happens to the pathogen in an acute infection
Cleared
411
Describe what happens to the pathogen in an chronic infection
Persists, multiplies slowly
412
Describe what happens to the pathogen in an latent infection
Persists inside host cells, does not multiply between reactivations
413
Describe the damage to the host in an acute infection
Only during acute infection
414
Describe the damage to the host in an chronic infection
Continual
415
Describe the damage to the host in an latent infection
Only during initial acute infection or when reactivation
416
When can transmission occur in an acute infection?
During any stage, when pathogen is multiplying
417
When can transmission occur in an chronic infection?
At any time (pathogen always multiplying, host is a carrier)
418
When can transmission occur in an latent infection?
During initial acute infection and reactivation (when pathogen multiplying and host symptomatic)
419
Provide an example of an acute infection
Influenza, rhinovirus
420
Provide an example of an chronic infection
Hepatitis B or C, HIV
421
Provide an example of an latent infection
Herpes virus, HIV
422
Identify which type of infection is represented by this graph
Latent
423
Identify which type of infection is represented by this graph
Chronic (persistent)
424
Identify which type of infection is represented by this graph
Acute
