WEEK 2 (PART 2) Flashcards
1
Q
What are tonsils?
A
Masses of lymphoid tissue that protect against pathogens entering the body.
2
Q
Where are tonsils located?
A
Form a broken ring around the opening of the throat at the back of the mouth.
3
Q
What are the different types of tonsils?
A
Palatine, tubal, pharyngeal (adenoids), and lingual.
4
Q
Why are tonsils prone to infection?
A
Their location exposes them frequently to external antigens.
5
Q
What is the name of a tonsil infection?
A
Tonsillitis
6
Q
What is the thymus?
A
A central organ of the lymphatic system.
7
Q
Where is the thymus located?
A
In the mediastinum, behind the sternum and under the thyroid gland.
8
Q
What is the size of the thymus throughout life?
A
Largest in infancy (70g), shrinks in puberty (30g), remains around 3g in old age.
9
Q
What is the main function of the thymus?
A
Enables immature lymphocytes to develop into T cells.
10
Q
What hormones does the thymus produce?
A
Thymosin (peptide) and Thymopoietin (protein), both involved in immune cell development.
11
Q
Where is the spleen located?
A
Left upper abdomen, under the diaphragm, behind the stomach.
12
Q
What is the shape and size of the spleen?
A
Ovoid, about the size of a fist.
13
Q
What happens to the spleen during infection?
A
Hypertrophies (increases in size) due to immune cell division.
14
Q
What are the main functions of the spleen?
A
Defense, tissue repair, hematopoiesis, red & platelet destruction, blood reservoir.
15
Q
How does the spleen defend against pathogens?
A
Macrophages in the spleen ingest and destroy microorganisms from the blood.
16
Q
How does the spleen aid in tissue repair?
A
Monocytes from the spleen migrate to injured tissue to assist in healing.
17
Q
What is hematopoiesis?
A
The process of blood cell formation. (Spleen helps differentiate monocytes and lymphocytes)
18
Q
What is the role of the spleen in red blood cell destruction?
A
Macrophages remove worn-out red blood cells and salvage iron for reuse.
19
Q
How does the spleen act as a blood reservoir?
A
Stores about 350ml of blood that can be released back into circulation during blood loss.
20
Q
Where is bone marrow located?
A
Inside the hollow spaces of bones like the femur.
21
Q
What is the main function of bone marrow?
A
Houses hematopoietic cells that give rise to all blood cells.
22
Q
What are hematopoietic cells?
A
Stem cells that can differentiate into various types of blood cells.
23
Q
What types of immune cells develop in bone marrow?
A
Immature B and T cells.
24
Q
Where do immature B and T cells go after bone marrow?
A
They migrate to other lymphoid organs to mature into fully functional immune cells.
25
What are lymph nodes?
Bean-shaped organs distributed throughout the body, connected by lymphatic vessels.
26
What is the function of lymph nodes?
Filter lymph fluid and present antigens to T and B cells.
27
How does lymph enter and exit lymph nodes?
Enters through afferent vessels, flows through sinuses, exits through efferent vessels.
28
What cells are found in lymph nodes?
T and B cells, which can identify foreign particles in the lymph fluid.
29
What is MALT?
Mucosa-associated lymphoid tissue, found in mucous membranes throughout the body.
30
Where is MALT located?
Digestive, urinary, respiratory, and reproductive tracts.
31
How is MALT similar to lymph nodes?
Both filter fluids and contain immune cells (T and B cells).
32
How is MALT different from lymph nodes?
MALT has a closer connection to the external environment (e.g., gut lumen).
33
What is the lymphatic system?
A network of vessels that drains fluid, macromolecules, and immune cells from tissues.
34
What is the main function of the lymphatic system?
To return excess fluid and waste products to the bloodstream.
35
How does the lymphatic system collect fluid?
Lymphatic vessels begin blindly in tissues and collect fluid as it travels towards the bloodstream.
36
How does lymph fluid return to the bloodstream?
The right lymphatic duct drains lymph from the upper right body to the right subclavian vein. The thoracic duct drains lymph from the rest of the body to the left subclavian vein.
37
What helps move lymph fluid?
Skeletal muscle pump, respiratory pump, and one-way valves in the lymphatic vessels.
38
What is the role of lymph nodes in the lymphatic system?
Filter lymph fluid and house immune cells that identify foreign particles.
39
How many main mechanisms does the immune system have?
Two: Innate (non-specific) and Adaptive (specific) responses.
40
What is the role of the innate immune system?
First line of defense, providing general protection against invaders.
41
What is the role of the adaptive immune system?
Targeted defense against specific pathogens.
42
How can the innate immune system be further categorized?
External barriers (skin, mucous membranes) and internal defenses (phagocytes, inflammation).
43
How does the adaptive immune system differ from the innate system?
It is specific to a particular pathogen and develops memory for future encounters.
44
What is the innate immune system?
The body's first line of defense, present at birth and doesn't require specific training.
45
What are the characteristics of the innate immune response?
Fast response, non-specific (same response to different invaders).
46
What are the mechanisms of the innate immune response?
Physical & biochemical barriers (skin & membranes), phagocytosis, innate immune system cells, inflammation, interferons, and the complement system.
47
Give some examples of innate immune system cells.
Phagocytes, natural killer cells, mast cells, eosinophils.
48
What are physical barriers of the innate immune system?
Skin and mucous membranes that prevent pathogen invasion.
49
How does skin act as a physical barrier?
Layers of densely packed cells block pathogens.
50
How do mucous membranes act as physical barriers?
Goblet cells secrete mucus to trap pathogens, and cilia move mucus for removal.
51
Where is mucus produced and moved in the respiratory system?
Goblet cells secrete mucus, and cilia move it towards the pharynx.
52
What are chemical barriers of the innate immune system?
Substances produced by the body to inhibit or destroy pathogens.
53
Give some examples of chemical barriers.
Sebum, mucus, enzymes (in tears), stomach acid (HCl), saliva, perspiration, and urine.
54
How does mucus act as a chemical barrier?
Traps pathogens due to its viscosity, allowing for removal.
55
How does stomach acid act as a chemical barrier?
Destroys ingested pathogens.
56
How does commensal flora protect against pathogens?
Healthy bacteria compete with harmful bacteria for space and resources.
57
What is a phagocyte?
A white blood cell that engulfs and destroys pathogens through phagocytosis.
58
What is phagocytosis?
A process where a phagocyte engulfs a foreign particle (pathogen) and destroys it with enzymes.
59
How does phagocytosis work?
Phagocyte detects pathogen, engulfs it in a vesicle, fuses with lysosomes for digestion.
60
What are some examples of phagocytes?
Macrophages (also antigen-presenting cells).
61
What are granulocytes?
A type of innate immune cell that contains granules with chemicals to destroy pathogens.
62
What are some types of granulocytes?
Neutrophils, mast cells, basophils, eosinophils.
63
How do neutrophils work?
Engulf and destroy pathogens.
64
How do mast cells work?
Secrete enzymes to degrade pathogens.
65
What is the role of eosinophils and basophils?
Play a role in allergic response and inflammation.
66
What are natural killer (NK) cells?
Innate immune system cells that target virus-infected or cancerous cells.
67
How do NK cells recognize target cells?
They detect changes in the major histocompatibility complex (MHC) class I molecules on cell surfaces.
68
How do NK cells destroy target cells?
They release perforin, a protein that triggers apoptosis (programmed cell death) in the target cell.
69
What is a limitation of NK cells?
Not all viruses and cancers can be detected by NK cells, especially if they don't alter surface molecules or avoid detection.
70
What are interferons?
Signaling proteins released by virus-infected cells or phagocytes.
71
What is the function of interferons?
Induce antiviral proteins in healthy cells to prevent viral replication, and activate immune cells (NK cells and macrophages).
72
How do interferons work?
Bind to receptors on healthy cells, triggering antiviral protein production.
73
What are the three types of interferons and their functions?
Interferon alpha: activates NK cells. Interferon beta: slows inflammation. Interferon gamma: activates macrophages.
74
What is the complement system?
A protein-based innate immune system response.
75
How does the complement system work?
Complement proteins are activated by pathogens, leading to: Membrane attack complex formation (lysis of pathogen cells) -> Enhanced phagocytosis of pathogens. -> Histamine release (increased inflammation).
76
How are complement pathways activated?
By surface receptors on the pathogen.
77
What is inflammation?
The body's response to tissue damage, helping to counteract the damage.
78
What triggers inflammation?
Tissue damage, irritation, chemicals, pathogens, extreme temperatures.
79
What happens during cell damage in inflammation?
Cell contents are released, activating mast cells to release chemicals.
80
What are the two phases of inflammation?
Vascular phase (redness, swelling, pain) and cellular phase (phagocyte activation).
81
How does histamine cause redness and pain during inflammation?
Histamine increases blood flow (redness) and stimulates nerves (pain).
82
What is the role of fever in inflammation?
Fever inhibits pathogen growth and enhances some immune defenses.
83
How is fever triggered?
Pyrogens (bacterial proteins or damaged cell products) stimulate the hypothalamus to raise body temperature.
84
What is the adaptive immune system?
Highly specific defense system that recognizes and targets specific pathogens.
85
How does the adaptive immune system work?
Relies on lymphocytes (B and T cells) that recognize antigens (parts of pathogens).
86
What are the main organs involved in the adaptive immune system?
Bone marrow (where B and T cells form) and thymus (where T cells mature).
87
What are B cells and their functions?
Formed in bone marrow, differentiate into: Plasma cells: Produce antibodies to inactivate antigens.
Memory B cells: Remember antigens for faster response upon re-exposure.
88
What are T cells and their functions?
Formed in bone marrow, mature in thymus, differentiate into: Helper T cells: Help other immune cells (B cells) function more effectively. Cytotoxic T cells: Kill infected cells (cell-mediated immunity). Regulatory T cells: Control the activity of other lymphocytes. Memory T cells: Remember antigens for faster response upon re-exposure.
89
What are the two main types of adaptive immune responses?
Cell-mediated and antibody-mediated responses.
90
What are the key features of the adaptive immune system?
Specificity, versatility, and immunological memory.
91
How do T cells recognize antigens?
Through antigen presentation by MHC molecules or CD markers on antigen-presenting cells (APCs).
92
What happens after a T cell recognizes an antigen?
The T cell divides and produces clones to fight the pathogen.
93
How do cytotoxic T cells kill infected cells?
They secrete toxins (perforins or lymphotoxin) to destroy the target cell.
94
How do helper T cells help other immune cells?
They secrete cytokines that activate other immune cells (like B cells).
95
How does antibody-mediated immunity work?
B cells detect antigens and produce specific antibodies that bind to them.
96
What is the analogy for antigen-antibody binding?
Lock and key - each antibody is specific to its antigen.
97
What happens after a B cell recognizes an antigen?
The B cell divides into: Plasma cells: Produce large amounts of antibodies.
Memory B cells: Remember the antigen for faster response upon re-exposure.
98
How do antibodies help fight pathogens?
By: Neutralization: Blocking the active part of the pathogen. Agglutination: Clumping antigens for easier destruction by phagocytes and the complement system.
99
What are the two types of immunity?
Innate (non-specific) and adaptive (specific).
100
How can immunity be developed?
Actively (by the body's response) or passively (through antibodies from another source).
101
How can active and passive immunity be acquired?
Naturally (through exposure) or artificially (through vaccination).
102
What is passive immunity from a mother to child called?
Colostral immunity.
103
What are three ways the immune system balance can be disrupted?
Hypersensitivity, autoimmunity, and immunodeficiency.
104
What is hypersensitivity?
Delayed reaction to an antigen exposure.
105
What is autoimmunity?
Antibodies attack the body's own tissues.
106
What is immunodeficiency?
Weakened immune system leading to higher infection risk.
107
How does the immune system change with age?
It becomes less effective at fighting infections and cancer.
108
How does this reduced effectiveness make older adults more susceptible?
* Increased risk of infections (e.g., respiratory infections). * Higher chance of developing cancer. * Weaker response to vaccines. * More likely to develop inflammatory diseases (e.g., osteoarthritis).
109
What is unique about a fetus' immune system?
It needs to tolerate the mother's antigens (alloantigens).
110
How does a newborn's immune system develop?
By learning to recognize and respond to new antigens from the environment.
111
How does a child's immune system continue to develop?
Through exposure to antigens via: * Vaccination * Contact with other people (potentially infected)
