Immune - 2nd line defense Flashcards
(108 cards)
1
Q
What is the second line of defence in the immune system?
A
Includes responses when pathogens penetrate the physical and chemical barriers of the skin and mucous membranes
Key components include injury, complement system, phagocytes, natural killer cells, inflammation, cytokines, and fever.
2
Q
What components are part of the second line of defence?
A
- Complement system
- Transferrins
- Phagocytes
- Natural killer cells
- Inflammation - non-specific
- Cytokines (I.e. interferons)
- Fever - non-specific
3
Q
What is the function of the complement system?
A
A defensive system made of over 30 proteins produced by the liver.
It creates an immune cascade - a cascade of immune events that lead to inflammation, phagocytosis and cytolysis.
The most common mechanism it is activated is via the CLASSICAL PATHWAY
4
Q
What are transferrins?
A
Iron-binding proteins mostly found in blood that prevent certain bacteria from stealing iron
They latch onto iron to prevent certain bacteria from utilizing it for energy.
5
Q
What role do phagocytes play in the immune system?
A
White blood cells that engulf and digest pathogens
They are crucial for the body’s defence against infections.
6
Q
What do natural killer (NK) cells release to destroy infected cells?
A
Release PERFORIN, which creates holes in the membranes of foreign cells
This leads to cell rupture and death.
7
Q
What are cytokines?
A
Small protein hormones (chemical messengers) secreted by leukocytes that attract other immune cells to the site of infection
Examples include interferons, interleukins, tumour necrosis factor (TNF)
8
Q
True or False: Inflammation is a specific response to pathogens.
A
False
Inflammation is a non-specific response that occurs during infection. The response to different insults is the same (non-specific).
9
Q
What is the purpose of fever in the immune response?
A
To create an environment less favorable for pathogens
Fever is a systemic response that can inhibit the growth of bacteria.
10
Q
Fill in the blank: The process by which phagocytes engulf pathogens is called _______.
A
phagocytosis
11
Q
How do transferrins affect bacterial growth?
A
They inhibit the growth of certain bacteria by reducing the amount of available iron for bacterial growth.
12
Q
Why is iron important for bacteria?
A
Bacteria could use the iron available for their growth.
13
Q
What is the structure of hemoglobin in adults?
A
Each Hb molecule contains four polypeptide chains (two alpha and two beta).
Each polypeptide chain contains a haem group that contains iron.
14
Q
Fill in the blank: Bacteria love _______ for their growth.
A
Iron
15
Q
What does ‘trans-‘ signify in the term transferrins?
A
It signifies ‘across’.
16
Q
How are complement proteins identified?
A
By a letter (mostly C) with a number, e.g., C3
17
Q
What happens to complement proteins before they become active?
A
They are inactive and only become active when split by enzymes into active fragments
18
Q
What type of reaction do activated complement proteins undergo?
A
They act in a cascade (amplified) - the classical pathway whereby antigen-antibody complexes are formed is the most common mechanism through which complement is activated.
19
Q
What is the result of antigen-antibody complexes depositing in the glomerulus?
A
It creates an immune response, causing damage and inflammation - glomerulonephritis
20
Q
True or False: Complement proteins are active at all times.
A
False
21
Q
What is the primary function of complement proteins?
A
Destroy microbes by promoting phagocytosis, contributing to inflammation, and causing cytolysis.
Complement proteins play a crucial role in the immune response.
22
Q
What process promotes the attachment of a phagocyte to a microbe?
A
Opsonisation.
This process involves the coating of the microbe by the fragment C3b.
23
Q
What do the fragments C3a and C5a do in the complement system?
A
Bind to mast cells and cause them to release histamine.
This contributes to inflammation.
24
Q
What is cytolysis?
A
The breakdown or bursting of cells.
In the context of the complement system, it refers to the destruction of microbes.
25
What are the complement proteins designated as?
C1-C9.
## Footnote
These proteins are part of the complement system.
26
What do C5-9 proteins do in the complement system?
Bind together to create a pore in the foreign cell membrane, leading to cytolysis.
## Footnote
This pore formation causes the target cell to burst.
27
Fill in the blank: The fragment C3b coats a microbe in a process called _______.
Opsonisation.
## Footnote
Opsonisation enhances phagocytosis of the coated microbe.
28
True or False: C3a and C5a are involved in promoting phagocytosis.
False.
## Footnote
C3a and C5a primarily contribute to inflammation.
29
What are cytokines?
Small protein hormones that act as chemical messengers used to communicate between different cell types
## Footnote
Cytokines stimulate or inhibit normal cell functions and are secreted by leukocytes.
30
What is the role of interleukins?
Act as mediators between leukocytes, mostly produced by T-helper cells
## Footnote
Interleukins facilitate communication in the immune system.
31
What is the function of interferons?
To interfere with viral replication by diffusing to uninfected neighbouring cells and introducing anti-viral proteins
## Footnote
Interferons help protect cells from viral infections.
Viruses can only cause disease IF they can replicate within body cells
32
What does Tumour Necrosis Factor (TNF) promote?
Accumulation of neutrophils and macrophages and causes cell death
## Footnote
TNF is important in inflammation and immune responses.
33
Fill in the blank: Cytokines are secreted by _______.
leukocytes
34
How do interleukins communicate with the brain?
Released by macrophages into the blood and signal the hypothalamus
(Interleukin 1 - is to increase body temperature - induce a fever)
## Footnote
This can lead to fever as part of the immune response.
35
What do interferons tell surrounding cells to do?
Stop dividing
## Footnote
This is because viruses can only replicate inside host cells.
36
True or False: Viruses can replicate on their own.
False
## Footnote
Viruses cannot copy themselves and require a host cell for replication.
37
How do interferons function in the body?
They diffuse to uninfected neighboring cells and induce synthesis of anti-viral proteins.
38
True or False: Interferons stop a virus from attaching to and penetrating a host cell.
False.
39
What is necessary for viruses to cause disease?
They must replicate within body cells.
40
What happens when interferons attach to special receptors?
They activate genes in nearby healthy cells to stop dividing.
41
What is the role of interferons in relation to viral nucleic acid?
They block viral nucleic acid.
42
What attracts phagocytic cells to sites of inflammation?
Chemotaxis
## Footnote
Chemotaxis is the process by which cells move towards chemical signals in response to inflammation.
43
What are the two major types of phagocytes?
* Macrophages (monocytes in blood)
* Neutrophils
## Footnote
These cells migrate to infected areas to perform phagocytosis.
44
What do monocytes become when they migrate to the site of infection?
Wandering macrophages
## Footnote
Monocytes enlarge and differentiate into wandering macrophages at the infection site.
45
What are fixed macrophages?
Macrophages that stand guard in specific tissues
## Footnote
Fixed macrophages remain in certain tissues, while wandering macrophages migrate to infection sites.
46
Are phagocytes selective in their targets?
No, they are non-selective
## Footnote
Phagocytes engulf and digest various foreign materials without selectivity.
47
What role do macrophages have in the immune system?
They are antigen presenting cells
## Footnote
Macrophages display fragments of digested pathogens on their cell membranes to activate T lymphocytes.
48
What do phagocytes use to digest foreign cells?
Lysosomes with digestive enzymes
## Footnote
Lysosomes contain enzymes that break down engulfed pathogens.
49
What happens to the fragments of digested pathogens?
They are displayed on the phagocyte's cell membrane
## Footnote
This process allows T-helper cells to recognize and respond to the antigens.
50
What is the function of T lymphocytes in relation to macrophages?
They learn about infections from macrophages' antigen presentations
## Footnote
T cells become informed about pathogens through the fragments presented by macrophages.
51
True or False: B cells are also antigen presenting cells.
True
## Footnote
B cells can present antigens to T cells, similar to macrophages.
52
What is the process by which monocytes migrate to the site of infection and enlarge?
Phagocytosis
## Footnote
Phagocytosis is a key immune response where cells engulf and digest pathogens.
53
What type of macrophages migrate to sites of infection?
Wandering macrophages
## Footnote
Wandering macrophages are derived from monocytes that enlarge upon migration.
54
What are fixed macrophages?
Fixed macrophages remain in one location and continuously monitor for pathogens.
55
What are the types of fixed macrophages found in specific tissues? List them.
* Histiocytes (connective tissue macrophages)
* Kupffer cells (liver)
* Alveolar macrophages (lungs)
* Microglia (nervous tissue)
* Langerhans cells (skin)
* Tissue macrophages (spleen, bone marrow, lymph nodes)
## Footnote
Each type of fixed macrophage has a specialized role in immune defense.
56
What is the function of Kupffer cells?
Break down microbes in the liver
## Footnote
Kupffer cells play a critical role in filtering blood and removing pathogens.
57
True or False: Alveolar macrophages are found in the lungs.
True
## Footnote
Alveolar macrophages help in clearing pathogens and debris from the alveoli.
58
Fill in the blank: _______ are macrophages found in the nervous tissue.
Microglia
## Footnote
Microglia are essential for immune defense in the central nervous system.
59
What are Langerhans cells?
Macrophages found in the skin
## Footnote
Langerhans cells play a role in skin immunity and antigen presentation.
60
What is the role of tissue macrophages?
Monitor and respond to pathogens in spleen, bone marrow, and lymph nodes
## Footnote
Tissue macrophages are crucial for initiating immune responses in lymphoid organs.
61
What is the first stage of phagocytosis?
Chemotaxis
## Footnote
Chemotaxis involves the release of chemicals that attract phagocytes to the site of infection.
62
What is the second stage of phagocytosis?
Adherence
## Footnote
Adherence refers to the attachment of the phagocyte to the target pathogen, often aided by complement proteins.
63
What occurs during the third stage of phagocytosis?
Ingestion
## Footnote
Ingestion involves the cell membrane extending projections that engulf the microbe.
64
What is formed when the ingested structure merges with lysosomes?
Phagolysosome
## Footnote
The phagolysosome is where the digestion of the pathogen occurs.
65
What enzymes are involved in the digestion of pathogens during phagocytosis?
Lysozymes and digestive enzymes
## Footnote
Lysozymes are a type of enzyme found in lysosomes that help break down the ingested material.
66
What is the final stage of phagocytosis?
Excretion
## Footnote
Excretion is the process where indigestible material is expelled from the phagocyte.
67
True or False: Pathogens can be resistant to phagocytosis.
True
## Footnote
Some pathogens, such as tuberculosis, have developed mechanisms to evade phagocytosis.
68
What percentage of lymphocytes do Natural Killer (NK) cells account for?
5-10%
## Footnote
NK cells are a type of non-specific lymphocyte involved in the immune response.
69
Where are Natural Killer (NK) cells present in the body?
Blood, lymph nodes, spleen, and bone marrow
## Footnote
These locations are critical for their role in immune surveillance.
70
What types of cells do NK cells attack?
Anything they do not recognise, including abnormal body cells like cancerous cells
## Footnote
NK cells identify targets based on abnormal cell membrane proteins.
71
What protein do NK cells release to attack target cells?
Perforin
## Footnote
Perforin is crucial for the cytolytic action of NK cells.
72
What is the function of perforin when released by NK cells?
Inserts into the cell membrane and creates a channel for tissue fluid to flow into the cell
## Footnote
This process leads to cytolysis, or cell rupture.
73
Fill in the blank: NK cells are a type of _______ lymphocyte.
non-specific
## Footnote
This characteristic allows them to respond to a wide range of threats.
74
What is inflammation?
Inflammation is a non-specific defensive response to tissue damage.
## Footnote
Inflammation can occur due to various factors such as pathogens, abrasions, chemicals, cell distortion or disturbance, and extreme temperatures.
75
What does it mean that inflammation is non-specific?
It means the response to different insults is the same.
## Footnote
This indicates that the body reacts similarly regardless of the type of damage or threat.
76
What are the cardinal signs of inflammation?
* Redness
* Heat
* Pain
* Swelling
* Loss of Function
## Footnote
These signs are used to identify and diagnose inflammation in affected tissues.
77
What is one consequence of inflammation in Crohn's disease mentioned in the text?
Loss of function of intestinal lining.
## Footnote
This can lead to difficulties in nutrient absorption and overall health.
78
Fill in the blank: Inflammation can be caused by _______.
[pathogens, abrasions, chemicals, cell distortion or disturbance, extreme temperatures]
79
What are the three basic stages of inflammation?
1. Vasodilation and increased permeability
2. Emigration of phagocytes
3. Tissue repair
## Footnote
These stages are crucial for the inflammatory response and healing process.
80
What occurs during vasodilation in the inflammation process?
Increased blood flow to the area, bringing oxygen, nutrients, immune cells, and substances for repair, while removing toxins and dead cells.
## Footnote
Vasodilation contributes to redness, swelling, and heat in the affected area.
81
What is the effect of increased permeability during inflammation?
Permits movement of immune cells, antibodies, and clotting factors into the tissue.
## Footnote
This process is essential for immune response and repair.
82
What creates pain?
Pain results from injury to neurons, and toxic chemicals released by microbes.
83
What is the role of phagocytes in the second stage of inflammation?
Phagocytes migrate to the site of injury via chemotaxis, sticking to the endothelium and squeezing through the vessel wall.
## Footnote
This process is known as leukocytosis.
84
What happens to monocytes during inflammation?
Monocytes quickly follow neutrophils and transform into wandering macrophages.
## Footnote
Macrophages play a critical role in engulfing pathogens and dead cells.
85
What accumulates as dead phagocytes during inflammation?
Pus.
## Footnote
Pus is a thick fluid that can form at sites of infection.
86
What is the final stage of inflammation?
Tissue repair.
## Footnote
This stage involves the healing and regeneration of damaged tissues.
87
What is chemotaxis in the context of inflammation?
Chemical attraction. The migration of cells towards the site of injury in response to chemical signals.
## Footnote
Chemotaxis is essential for the recruitment of immune cells.
88
Fill in the blank: The accumulation of dead phagocytes is known as _______.
pus.
## Footnote
Pus is a common sign of infection.
89
What are the chemical mediators involved in inflammation?
Histamine, Leukotrienes, Kinins, Prostaglandins
## Footnote
These mediators coordinate the inflammatory response.
90
What is the role of Histamine in inflammation?
Causes vasodilation and increased permeability
## Footnote
Released by mast cells and basophils.
91
What do Leukotrienes do during inflammation?
Attract phagocytes and increase vessel permeability
## Footnote
Released by mast cells and basophils.
92
What are Kinins and their effects?
Kinins are chemical mediators for inflammation that induce vasodilation and increased permeability; attract phagocytes and induce pain
## Footnote
Kinins are PROTEINS involved in the inflammatory response.
93
What is the function of Prostaglandins in inflammation?
Enhance effects of histamine and kinins, intensifying pain
## Footnote
Prostaglandins are LIPIDS released by damaged cells.
94
What are the harmful effects of inflammation?
* Swelling
* Pain
* Adhesions and scar tissue
* Atherosclerosis
## Footnote
Swelling can be dangerous if in the cranium due to limited space.
Pain can become chronic
95
What benefits does inflammation provide?
* Promotes phagocytosis (via chemotaxis - chemical attraction)
* Promotes immune response
* Dilutes toxins
* Fibrin formation
## Footnote
Fibrin formation isolates affected areas and helps bind wound edges.
Immune response - vasodilation & increased permeability
96
What is the impact of increased temperature during inflammation?
Promotes activity of immune cells - enhances immune response
* Makes interferons more effective
* Inhibits growth of some microbes
* Speeds up the reactions that aid repair
## Footnote
Macrophage - Cytokines - Interleukin 1 (protein messenger to hypothalamus) - Fever
97
What is a potential consequence of chronic inflammation?
Chronic pain
## Footnote
Chronic inflammation can lead to long-term discomfort.
98
What is Atherosclerosis in relation to inflammation?
Inflammation plays a significant role in the development of atherosclerosis.
The endothelium needs to be damaged in order for inflammation to occur, thus kicking off the atherosclerosis process.
99
Fill in the blank: Inflammation promotes _______ which helps to isolate the affected area.
Fibrin formation
100
True or False: Inflammation only has harmful effects.
False
## Footnote
beneficial roles include: promoting phagocytosis, immune response, diluting toxins and fibrin formation.
101
What is the outcome of inflammation when the cause is successfully overcome?
Complete restoration
## Footnote
This indicates that the body's healing process has returned to normal without lasting damage.
102
What happens if the injury-causing agent persists?
Chronic inflammation - which can cause chronic pain
## Footnote
Chronic pain is often a result of ongoing inflammatory processes.
103
Which cells become prevalent during chronic inflammation?
Macrophages, plasma cells (anti-body producers), and lymphocytes
## Footnote
These immune cells contribute to the prolonged inflammatory response.
104
What is a granuloma?
Cellular attempt to contain a foreign body.
Characterized by aggregation of macrophages surrounded by lymphocytes.
## Footnote
Granulomas are often seen in infections like tuberculosis.
105
What is fibrosis?
Scar tissue formation due to the secretion of collagen by fibroblasts
## Footnote
Fibrosis typically occurs as a result of chronic inflammation and serves no function.
106
What is a non-specific fever?
An abnormally high body temperature
## Footnote
Fever is a common response to infection and inflammation.
107
What triggers the reset of the hypothalamus thermostat during a fever?
Bacterial toxins and fever-causing cytokines from macrophages
## Footnote
Interleukin-1 is the key cytokine that induces fever.
108
How does elevated body temperature enhance the immune response?
* Makes interferons more effective,
* Inhibits growth of some microbes,
* Speeds up repair reactions
## Footnote
These effects contribute to the overall efficiency of the immune system.
