Immune system Flashcards
(131 cards)
1
Q
What are the two branches of the immune system?
A
Innate and acquired.
Non specific and specific.
The innate system is in-built; the acquired mechanism involves the body’s ability to develop resistance to specific diseases after exposure.
The specific immune systems is known as acquired. Because acquired immunity is only obtained when an indivdual comes in contact with a certain pathogen and develops specific immunity to the pathogen.
Non specific is known as innate. It is unspecific. Refers to the basic resistance against disease.
2
Q
Is the innate response non specific or specific?
A
It is non specific.
This means that it recognises and responds to pathogens in a generic way.
It does not confer long lasting or protective immunity
3
Q
What are the characteristics of innate immunity?
A
1) Responses are broad spectrum
2) There is no memory or lasting protective immunity
3) The number of recognition molecules is limited so it is not always sufficient as a defence mechanism
4
Q
How long does the innate system take to destroy a pathogen?
A
minutes or hours
5
Q
When does the acquired immune system become involved?
A
Only when the innate defences are breached and not sufficient to overcome the invading pathogen.
6
Q
Are white blood cells or red blood cells most numerous?
A
Red blood cells.
7
Q
Which are larger- WBC or RBC?
A
White blood cells.
8
Q
How do WBC differ structurally to RBC?
A
They are larger and contain cytoplasm and a nucleus
9
Q
How are WBC classified?
A
granular or agranular.
When the cytoplasm contains many granules and their nuclei appear to have many lobes- classified as granular ( granulocytes)
Some Wbc do not have granular cytoplasm- therefore described as agranular.
10
Q
What cells are in the granulocyte family of WBC?
A
Neutrophils, eosinophils and basophils
11
Q
What cells are in the agranular family?
A
monocytes (macrophages) and the T and B lymphocytes
12
Q
Where are WBC ( agranular and granular) made?
A
All ( but not B and T lymphocytes) are made in the red bone marrow.
13
Q
Where are B and T lymphocytes made?
A
Formed in the lymphatic tissue from stem cells.
14
Q
What part of the immune system are lymphocytes part of?
A
Involved in cell-mediated and humoral immune responses of the acquired immune system.
15
Q
Where are antigens found?
A
On the surface of cells.
They are protein or glycoprotein molecules found on the surface membrane of cells.
It is the antigen on the cell surface that the body identifies as being foreign.
16
Q
What blood group is considered the universal receipient?
A
AB Rh+
These people have no antibodies and possess both A and B cells surface antigens and the Rhesus factor, therefore no blood type will trigger agglutination.
17
Q
Which blood group is considered to be a universal donor?
A
Blood group O Rh-
They have no cell surface antigens and no Rhesus factor on teh surface of their red blood cells.
18
Q
What is the first line of defence in any immune reponse?
A
Anatomical, mechanical and chemical barriers.
19
Q
What is an anatomical barrier?
A
The skin.
First line of defence against infection.
Other systems act to protect body openings such as the lungs, intestines and genitourinary tract from infection.
20
Q
How do the lungs provide an anatomical barrier?
A
couching and sneesing mechanially expel pathogens and other irritants from the respiratory tract.
Mucus secreted helps to prevent pathogens from further entering the body.
21
Q
Is inflammation a line of defence?
A
Yes. It is a first line of defence ( innate/ non specific) response.
22
Q
Give examples of chemical barriers?
A
salt, fatty acids and acidic environments within the GI tract, lysozyme in tears, the anti viral interferons, sweat and skin secretions and a system of proteins called the complement system.
23
Q
Which blood group can be transfused into a O Rh- patient
A
O Rh- only.
Their blood will posses both an antibody a and b.
Have no rhesus antibodies.
24
Q
Antibodies are formed from which white blood cell?
A
B lymphocytes.
25
What are two types of lymphocyte?
T and B lymphocytes.
The type of lymphocyte is determined by the location of cell maturation.
26
Where are lymphocytes formed?
All lymphocytes are formed from stem cells in either the thymus or lymphoid tissue?
B lymphocytes complete their development in the spleen or lymph nodes
Lymphocytes that mature in the thymus are known as T lymphocytes.
27
What are the four stages of the immune response?
1) Engulfing the pathogens by phagocytes. This makes the pathogen visible for targeting by the immune response.
2) This visibility allows T lymphocytes to bind to the foreign antigen.
3) Activated T cells release substances to activate B lymphocytes and stimulate the production of plasma cells and memory cells.
4) Plasma cells produce many clones of the B cell which secrete antibodies specific to the forgein antigen. These antibodies help to clear the infection.
28
Compared to the primary immune response, a secondary response is described as being...
Faster and more intense.
29
What is the primary immune response?
When a forgein antigen enters the body for the first time it stimulates an immune response.
The primary response is normally slow
30
What happens during the primary reponse?
The body makes memory cells
31
What happens during the secondary immune response?
The body recognises the antigen and the response is much faster and more intense because memory cells exist.
Often in a secondary immune response, the body will have eradicated the pathogen before any symptoms develop.
32
What is one of the first reponses to infection or irritation?
Inflammation
| Generic non specific response to invading pathogens.
33
What are the characteristics of inflammation?
local accumlation of fluid, plasma proteins and white blood cells.
34
What initiates inflammation?
Physical injury, infection or a local immune response ( inflammation stimulated by chemical factors released from injured cells).
35
What purpose does inflammation have?
It establishes a physical barrier that prevents the spread of infection and promotes healing of damaged tissue following removal of pathogens.
36
What is the process of inflammation?
Chemical factors produced during inflammation sensitise pain receptors and cause vasodilation of the blood vessels at the scene.
Mast cells release histamine which causes itching and swelling.
37
What symptoms characterise the inflammatory response?
redness, heat, swelling, pain and possible loss of function of the organs or tissues involved.
38
Is inflammation a specific or generic reponse?
It is a generic response that is not specific to any invading pathogen.
39
How is inflammation initiated?
Through physical injury, infection or a local immune response and is stimulated by chemical factors released by injured cells.
It establishes a physical barrier preventing the spread of infection and promoting healing of damaged tissue following removal of pathogens.
40
What do the chemical factors produced during inflammation do?
They sensitise pain receptors and cause vasodilation of the blood vessels at the scene.
Mast cells release histamine which causes itching and swelling.
41
How does the antibody ( humoral) immune response work?
An invading antigen causes the B lymphocytes to divide and differentiate into either plasma or memory cells.
Each plasma cell secretes antibodies ( immunoglobulins) into the blood which can detect the antigen on the surface of a foreign invader.
Other activated B cells form memory cells. These can be activated later for rapid antibody production when the foreign antigen is detected again- this is the basis for long term immunity.
42
What is an antibody?
A specialised protein substance produced by the body in response to a foreign antigen.
43
How is artificial acquired immunity achieved?
Immunisation/ Vaccination.
44
How do vaccines acheive acquired immunity?
The substance stimulates the immune system to produce antibodies and memory cells to the antigen in the vaccine.
The vaccine stimulates a primary immune reponse- so that the body now has the memory cells required to initiate a future secondary immune response.
45
What is the response to a subsequent second infection of a recognised pathogen?
The body will launch a rapid, intense secondary response to the invading pathogen, hence the disease is not given the chance to fully develop. This is why people usually only contract chickenpox once in a lifetime.
46
What is the complement system?
A biochemical catalytic cascade that attacks the surfaces of foreign invading cells.
47
What does the complement system link?
The innate and acquired immune systems
48
How does the complement system link the innate and acquired immune system?
1) Enhancing antibody responses and immune memory
2) Lysing foreign cells
3) Removing antibody-antigen complexes and apoptotic cells
49
Why does the complement system have it's name?
It contains 20-25 different enzymes and is named because of its ability to enhance the antibodies' destruction of pathogens.
50
What is the alternative to active immunity?
Passive immunity
51
What is passive immunity
It is provided when the body is given antibodies rather than producing them itself
52
What are some examples of passive immunity?
1) A new-born baby has passive immunity to several diseases from antibodies passed from its mother via the placenta and breast milk.
2) Anti venom injection administered after certain snake bites
53
How long does passive immunity last?
Only for a few weeks or months, usually this is enough for a baby's immune system to develop.
The short term nature of passive immunity is also why babies are immunised against a number of diseases after the first few months of life- they need to develop their own antibodies.
54
What is agglutination?
When a person is transfused with non compatible blood, agglutination will occur.
This is triggered when an antibody and its specific antigen come together.
It causes the cells to clot, forming clumps of blood that can block small blood vessels and damage vital organs, such as heart or brain, which can be fatal.
55
What will happen if a A Rh+ patient is transfused with B Rh+ blood and why?
Agglutination
The A antigens on the surface of the type A blood react with 'a' antibodies made by type B blood.
56
What is rhesus factor ( Rh)?
An antigen that may be present on the surface of blood cells.
57
What does Rh+ mean?
It means that they have the ability to manufacture the Rh antigen
85% of world's population have this.
58
What does Rh- mean?
It means they don't have the ability to manufacture the Rh antigen?
Their immune system will manufacture antibodies against the Rh antigen when they encounter it.
59
Why is the Rh factor important during pregnancy?
A mother who is Rh- but carrying a foetus Rh+ may become sensitised to the rhesus antigen and generate anti-rhesus antibodies.
This can threaten a SUBSEQUENT pregnancy with a RH+ foetus.
60
Group A blood group:
cell surface antigen present?
Antibodies in plasma?
Safe donors?
GROUP A
Cell surface antigen present:
Antibodies in plasma: anti B
Safe donors: A and O
61
Group B blood group:
cell surface antigen present?
Antibodies in plasma?
Safe donors?
Cell surface antigen: B
Antibodies in plasma: anti A
Safe donors: B and O
62
Group AB blood group:
cell surface antigen present?
Antibodies in plasma?
Safe donors?
Cell surface antigen: A and B
Antibodies: None
Safe donors: A, B, AB and O ( ALL)
UNIVERSAL RECEIPIENT
63
Group O blood group?
cell surface antigen present?
Antibodies in plasma?
Safe donors?
Cell surface antigen: None
Antibodies in plasma: anti-a and anti-b
Safe donors: O only
UNIVERSAL DONOR ( NO ANTIGENS)
64
What are the two broad categories of immunity?
Non specific ( innate) and specific ( acquired)
65
What are the three parts of innate immunity?
1) Mechanical and anatomical barriers ( surface membranes, cilia, reflexes ( e.g coughing and sneezing), fever
2) Chemical ( Acidic environments, salt, fatty acids, lysozyme in tears, interferons, tumor necrosis factor, complement enzymes, transferrins)
3) Defence cells ( neutrophils, monocytes and macrophages and NK ( natural killer) cells)
66
What are the WBC involved in innate ( non specific) immunity?
Neutrophils
Monocytes and macrophages
Natural Killer ( NK) cells
SECOND LINE OF DEFENCE
67
What are the two branches of acquired ( specific) immunity?
1) Cell mediated immunity
| 2) Humoral immunity
68
What is the main WBC involved in cell mediated immunity?
T lymphocytes
69
What are T Lymphocytes?
Mature in thymus gland
| recognise antigens
70
In cell mediated immunity- what do T Lymphocytes do?
Differentiate into:
1) T helper
2) T memory
3) Cytotoxic (killer) t cells
4) Suppressor T cells
71
What do T helper cells do?
Differentiation of T lymphocytes in cell mediated, specific immunity process
FUNCTION: stimulate B cells and cytotoxic T cells
72
What to T memory cells do?
Differentiation of T lymphocytes during cell mediated, acquired immunity.
FUNCTION: Stimulate B cells and cytotoxic T cells ( during secondary infection- (secondary response)
73
What do cytotoxic ( killer) T cells do?
Differentiated of T lymphocytes during cell mediated (acquired) immunity
FUNCTION: Cause abnormal cells to burst
74
What do suppressor T cells do?
Differentiation of T lymphocytes during cell mediated, acquired immunity
FUNCTION: Swtich off immune responses
75
What is the first line of defence?
Mechanical and chemical defences
76
What is the second line of defence?
Defence cells in innate, non specific response:
Neutrophils
Monocytes ( macrophages)
NK cells
77
What is the third line of defence?
Specific, acquired immunity
Includes cell mediated and humoral immunity
78
What is the primary WBC involved in humoral immunity?
B lymphocytes
Mature in bone marrow
Moves into spleen and lymph nodes
Recognise antigens
79
What are the main cell differentiations in humoral immunity?
1) Plasma cells ( differentiated B lymphocytes)
2) B-memory ( differentiated B lymphocytes)
FUNCTION: Make antibodies
80
What does excessive oedema impair?
The ability of the cells to make exchanges with the interstitial fluid and ultimately the blood.
81
Is the lymphatic system a one way system?
Yes
82
Describe lymphatic capillary valves? ( note not the valves in lymphatic vessels)
the edges of endothelial cells forming their walls loosely overlap one another, forming flaplike mini valves.
These act as one way swinging doors.
These flaps are anchored by fine collagen structures.
They open when the fluid pressure is higher in the interstitial space, allowing fluid to enter the lymphatic capillary.
83
FACT
Proteins, and even larger particles such as cell debris, bacteria and viruses are normally prevented from entering blood capillaries, but they enter the lymphatic capillaries easily, particularly in inflamed areas.
84
What is the problem with bacteria, viruses and cancer cells being able to enter the lymphatics?
They can then use these to travel throughout the body.
This dilemma is partly resolved by the fact WBC can also travel in lymph and lymph is filtered in lymph nodes.
85
Describe the sequence of lymph transport?
Transported from the lymph capillaries through successively larger lymphatic vessels, referred to as lymphatic collecting vessels.
It's finally returned to the venous system through two large ducts in the thoracic region.
86
What does the right thoracic duct drain?
Lymph from right side of the head and thorax (25%)
87
What does the left thoracic duct drain?
Receives lymph from all of body ( other than right side of head and thorax) 75%
88
Where do both lymphatic ducts empty?
Into the subclavian vein on their own side of the body
89
What are some mechanisms that aid the return of lymph to the heart?
1) The milking action of skeletal muscles
2) pressure changes in the thorax during breathing
3) smooth muscle in the walls of larger lymphatics contract rhythmically
4)
90
Describe some features of lymph vessels?
Thin walled
Low pressure
Larger ones have valves
91
Where are lymph nodes?
Clustered along the lymphatic vessels
92
Where are large clusters of lymph nodes found?
Inguinal
Axillary
Cervical regions
93
What two main immune cells are found in lymph nodes?
Macrophages ( engulf and destroy bacteria, viruses and other foreign substances)
Collections of lymphocytes
94
Why do swollen lymph nodes happen?
They swell as the result of the trapping function of the nodes
95
Describe the structure of lymph nodes?
Vary in size and shape
Most are kidney shaped
1 cm long and buried in the connective tissue that surrounds them.
Each node is surrounded by a fibrous capsule from which connective tissue strands ( called trabeculae) extend inward to divide the node into a number of compartments
Internal framework is a network of soft reticular connective tissue. These provide a place for lymphocytes to sit as they monitor the lymphatic system.
The outer part of the node- cortex. Contains collections of lymphocytes ( mostly B lymphocytes).
T lymphocytes- the rest of the cortical cells are in transit. They circulate continously between the blood, lymph, nodes and lymphatic stream ( perform a surveillance role).
Phagocytic macrophages are round in the central medulla of the lymph node.
96
Describe the production of lymphocytes?
They are produced in the red bone marrow.
Then they migrate to the lymph nodes and other lymphoid organs, where they reproduce further.
97
How does lymph enter a lymph node?
It enters the convex side of a lymph node through afferent lymphatic vessels.
It then flows through a number of sinuses that meander through the lymph node.
It then exits from the node at its indented region ( the hilum) via efferent lymphatic vessel.
98
Why is the flow of lymph through a lymph node very slow?
Because there are fewer efferent vessels draining the node than afferent vessels feeding it.
This allows time for the lymphocytes and macrophages to perform their functions.
99
What is happening if the lymph nodes remain swollen or enlarge over a period of time?
They are likely to contain cancer cells.
100
What are the names of the lymphoid organs?
```
Spleen
Thymus
Tonsils
Peyer's patches
Appendix
```
As well as bits of lymphoid tissue scattered in epithelial and connective tissues.
101
What is the structure of most lymphoid organs?
An abundance of reticular connective tissue and lymphocytes
102
How do the lymphoid organs and nodes differ in function?
Only the lymph nodes filter lymph
103
What is the function of the spleen?
The spleen filters and cleanses blood of bacteria, viruses and other debris.
It provides a site for lymphocyte proliferation and surveillance.
Destroys worn out red blood cells and returns some of their breakdown products to the liver.
Stores platelets and acts as a blood reservoir ( like the liver)
104
Where is the spleen?
Left side of abdominal cavity
| curls around the anterolateral aspect of the stomach
105
What is the most important function of the spleen?
Destroy worn out red blood cells and return some of their breakdown products to the liver.
E.G iron is used again to make hb, the rest of the hb molecule is secreted in bile.
106
What do the spleen and liver do during haemorrhage?
Contract and empty their blood into circulation to help bring the blood volume back to it's normal level.
107
How does the function of the spleen differ in foetuses compared to adults?
Foetuses- spleen serves a haemopoietic function ( i.e makes blood cells)
In adults- the spleen only produces lymphocytes
108
Where is the thymus found?
Found in the anterior mediastinum, overlying the heart.
109
What are tonsils?
Small masses of lymphoid tissue deep to the mucosa surrounding the pharynx.
110
Where are Peyer's patches found?
In the wall of the distal small intestine
Peyer's patches and the appendix are in the ideal position to capture and destroy harmful bacteria and therefore prevent them from penetrating the intestinal wall.
111
What does MALT consist of?
Mucosa Associated Lymphoid Tissue
Peyer's patches
the appendix
The tonsils
112
What is the function of MALT?
To protect the upper respiratory and digestive tracts from the constant attacks of foreign matter entering those cavities
113
Which are the most important of the immune cells?
Lymphocytes
Dendritic cells
Macrophages
114
In which part of the immune system do macrophages play a role?
The innate and adaptive mechanisms
115
What is the innate defense system also known as?
Non specific
Responds immediately to protect the body from all foreign substances, what ever they are.
116
What does our innate defences include?
```
Anatomical barriers ( e.g intact skin, mucous membranes)
Chemical barriers ( e.g lysozyme, inflammatory response)
```
117
What is the adaptive defence system also known as?
Specific, acquired defence system
Mounts an attack against a PARTICULAR forgein susbtance.
118
The immune system protects us from bacteria, viruses, transplated organs and grafts and...
cancer cells.
119
What is immunity?
The highly specific resistance to a disease
120
What are the two lines of defence for non specific innate system?
1) First line of defence
Skin
Mucous membranes
Secretions of skin and mucous membranes
```
2) Second line of defence
Phagocytic cells
NK cells
Anti microbial proteins
The inflammatory response
Fever
```
121
What is the specific/ adaptive defence mechanism also known as?
Third line of defence
122
What is involved in the third line of defence?
Lymphocytes
Antibodies
Macrophages and other antigen presenting cells
123
What are the features of innate ( non specific) body defences? FIRST LINE
Intact skin ( epidermis) ( mechanical barrier)
- Acid mantle ( acidic ph to skin- inhibits bacterial growth and contains bacterial killing chemicals)
- keratin ( provides resistance to acids, alkalis and bacterial enzymes)
Intact mucous membranes ( mechanical barrier)
- mucous ( traps in respiratory and digestive tracts)
- nasal hairs ( traps_
- cilia ( propels mucus in lower respiratory tracts)
- gastric juice ( HCL and protein digesting enzymes)
- Acid mantle of vagine ( inhibits growth of bacteria and fungi in female reproductive tract)
- Lacrimal secretion ( tears), saliva ( continously lubricate and cleanse and contains lysozyme)
124
What are the features of the second line of defence ( Innate, non specific)
Cellular and Chemical defences
Phagocytes ( engulf and destroy pathogens)
NK cells ( Promote cell lysis by direct cell attack against virus infected or cancerous body cells- do not depend on specific antigen recognition)
Inflammatory response- ( prevents spread of injurious agents to adjacent tissues, disposes of pathogens and dead tissue cells, promotes tissue repair, releases chemical mediators that attract phagocytes)
Antimicrobial chemicals ( complement, interferons, fluids with acid pH)
Fever- systemic response triggered by pyrogens. High body temp inhibits multiplation of bacteria and enhances body repair processes.
125
What are the names and functions of some of the antimicrobial chemicals released during the second line of defence of the innate, non specific immune response
Complement- groups of plasma proteins that lyses microorganisms, enhances phagocytosis by opsonisation and intensifies inflammatory response.
Interferons- proteins released by virus-infected cells that protect uninfected tissue cells from viral takeover. Mobilise immune system.
Fluids with acid Ph- inhibits bacterial growth. Urine cleanses the lower urinary tract as it flushes from the body.
126
What do mucous membranes lie?
All body cavities open to the exterior
127
When do internal innate mechanisms come into play?
When the surface (anatomical) barriers are breached
128
Where are NK cells?
They roam the body in blood and lymph.
They are a unique group of aggressive lymphocytes.
129
How do NK cells work?
They can act spontaneously against any target by recognising certain targets on the intruder's surface, as well as it's lack of certain self cell surface molecules.
They are NOT phagocytic.
They attack the target cell's membrane and release lytic chemicals called perforin and granzymes which degrade target cell contents.
They also release powerful inflammatory chemicals.
130
What is the inflammatory response?
Part of second line of defence of innate, non specific immune response.
It is triggered whenever the body tissues are injured.
131
What are the four most common indicators of acute inflammation? ( The cardinal signs)
redness
heat
pain
swelling ( oedema)
