Immune System Flashcards
(55 cards)
1
Q
immune System consists of:
A
- cells: lymphocytes, antigen-presenting cells
- lymphatic tissue: diffuse and nodular
- lymphatic Organs: lmyph nodes, Spleen, Thymus
- lymphatic vessels
2
Q
Main functions of immune system
A
- production of immune cells
- Monitoring Body tissues
- reaction to harmful Antigens
- storage of blood and lymph
3
Q
Antigen (Ag)
A
- target for specific immune Response
- soluble substance or infectious organism
4
Q
Cellular (cell-mediated) immunity
A
- mediated by T lmyphocytes
- attack and destroy virus-infected host cells
- no antibodies released
5
Q
Humoral (antibody-mediated) immunity
A
- antibodies act directly on invading Agent
- antibodies produced by Plasma cells derived from B lymphocytes
6
Q
Functional classification of lmyphocytes
A
- B cells
- T cells
- NK cells
7
Q
Morphological classification of lymphocytes
A
small
medium
large
in circulating blood: majority are small
in tissues and Organs: medium and large
8
Q
T cells
A
- differentiate in Thymus
- 60-80% of circulating lymphocytes
subtypes: Helper T Cytotoxic T Regulatory T Gamma/Delta T
9
Q
Helper T cells
A
- secrete cytokines
- interact with cytotoxic T, NK and macrophages in cellular Response
- interact with B cells for initiating humoral response
10
Q
Cytotoxic T cells
A
- kill target cells
- release:
>perforins: create channels in cells Plasma membrane
>granzymes: into target cells, activate apoptosis
11
Q
Regulatory T cells
A
- can supress an immune Response to Antigen
12
Q
Gamma /Delta T cells
A
- develop in Thymus
- migrate to epithelial tissues (intraepithelial lymphocytes)
- first line of defense against invadors
- kill cells similar to CT cells
- do not recirculate!
13
Q
B cells
A
20-30%
- differentiate into Plasma cells
14
Q
Plasma cells
A
- large eccentric nucleus
- synthesize and secrete anitbodies –> immunoglobins
- immunoglobins M, A, D, E, G
- antibody binds to Antigen: antibody-Antigen complex
- eliminated by phagocytosis
15
Q
Natural Killer (NK) cells
A
5-10%
- recognize transformed cells (Virus or Tumor)
- similar mechanism as CT cells
16
Q
Antigen-presenting cells
A
- lymphocytes can only recognize Antigens broken down and presented by APCs
- Antigen –> 8 to 10 aa Peptides on APC cell Surface
- most APCs belong to MPS
17
Q
Mononuclear phagocytotic system
A
- derived from monocytes
macrophages in CT, lungs, Spleen
Kupffer cell, microglia, M cells
Langerhans cells, Dendritic cells
18
Q
Primary lymphatic organs
A
Bursa-equivalent Organs (for B cells)
- bone marrow
- gut-associated lymphatic tissue (GALT)
Thymus (for T cells)
19
Q
Secondary lymphatic organs
A
lymphatic nodules
lymph node
spleen
20
Q
Primary lymphatic Organs - what they do
A
- initial education Centers
- cells differentiate into immunicompetent cells
- –> can differentaite “self” vs “non-self”
- differentation is antigen-Independent
- lymphocytes then enter blood to populate secondary organs
21
Q
Secondary lymphatic Organs - what they do
A
- secondary education Centers
- immunocompetend lymphocytes differentiate into:
>immune effector cells
>Memory cells - These cells undergo antigen-dependent activation
22
Q
Primary immune respinse
A
- body’s first Encounter with an Antigen
- characterized by lag period of several days before Antigen is detected
23
Q
Secondary immune response
A
- more rapid and intense
- presence of Memory lymphocytes that are programmed to respond
24
Q
Bone marrow
A
YELLOW BONE MARROW:
- in adults
- consists of fat cells
- occupies diaphysis of Long bones
RED BONE MARROW:
- in adults: in flat bones and epiphyses of Long bones
- in new Born: all bone marrow is red
in extreme blood loss: yellow marrow can revert to red marrow
25
Red bone marrow
stroma: reticular cells and fibers with fat cells, fibrophages, macrophages…
parenchyma:
- blood cells in different stages arranged as Cords
- erythrocytes nest: near sinusoids
- granulocytes and lymphocytes: nest farther away from sinusoids
- Megakaryocytes: adjacent to sinusoidal wall
26
Gut-associated lymphatic tissue
lymphatic nodules of the distal gut
- submucosa of Ileum (Peyer's Patches)
- submucosa of appendix
27
Thymus main functions
T-cell initial education
| Population of secondary lymphatic organs
28
Organization of Young thymus
dense irregular CT capsule
trabeculae divide into irregularly shaped lobes
Stroma: Epithelioreticular cells (ERCs)
Parenchyma: T cells /thymocytes
29
Lobe of thymus
Cortex: a lot of lmyphocytes
Medulla: fewer lympocytes
30
Developmental Sources of thymus
Stroma: endoderm (Invagination of Epithelium f 3rd pahyngeal pouch)
Capsule and trabeculae: mesenchyme
31
Epithelioreticular cells (ERC)
Functions:
- Framework for developing T cells
- blood-thymus barrier
- substances for education of cells
- form thymic corpuscle
32
Bloor-Thymus barrier
Endothelium of capillary wall
Perivascular connective tissue
Epithelioreticular cell layer
33
T cell "initial education"
Enter MEDULLA via postcapillary venules
into CORTEX for positive selection
---> Cells that recognize self/non-self pass
into MEDULLA for negative selection
---> Cells that recognize SELF antigents are eliminated
34
Thymic (Hassall's) corpuscle
- In Medulla of older Thymus
- produce Interleukins --> influence Differentiation of T cells
- concentrically arranged ERCs
- in Center: keratinization or calcification
35
Thymic involution
- at puberty
- T cells leave the Thymus to populate secondary lymphatic Organs
- Thymus Skinks and fills with Hassall's corpuscle and fat cells
36
MALT
mucosa-associated lymphatic Organs
accumulations of lymphatic tissue without capsule
GALT is part of MALT
consists of intraepithelial lypmocytes (Gamma /Delta T)
37
Diffuse lymphatic tissue
diffuse Aggregation of lymphocytes in LAMINA PROPRIA of:
- GI
- Respiratory
- Urogenital
38
Lymphatic nodules
- oval Aggregation of lymphocytes in
LAMINA PROPRIA or SUBMUCOSA
composed of T and B cells, antogen presenting cells
Primary vs secondary nodules
39
Primary nodules
- lmyphocytes are not activated
| - no germinal centers
40
Secondary nodules
- germinal Centers
- when B cells are presented with Antigen, reveice T cell help
- B-cells --> lmyphoblasts --> Plasma cells and Memory cells (this happens in germinal Centers)
41
Tonsils (MALT of Pharynx)
form waldeyer's tonsillar ring
pharyngeal tonsils
Tubal tonsils (around Openings of Eustachian tubes)
---> These two have Respiratory Epithelium
Palatine tonsils
Lingual tonsils
---> These two have stratified squamous epithelium
42
Structure of the tonsils
- Epithelium Dips into Underlying CT to form crypts
| - wall of crypts contains intraepithelial lmyphocytes, diffuse lymphatic tissue and lymphatic nodules
43
Lymph nodes
- conctentrated in Axilla, groin, mesenteries
- encapsulated
- Filtration and contact with Antigen
- Environment for secondary education
44
Lymph node structure
capusle: dense CT
Stroma: reticular CT
Parenchyma: immune cells
Cortex (B cells in Primary and secondary nodules)
Paracortex (T cells)
Medulla (B cells and medullary Cords and sinuses)
look at Picture!!!!!!
45
Lmyphatic circulation of lymph node
1. afferent lmyphatic vessels
2. subcapsular Sinus
3. trabecular Sinus
4. medullary Sinus
5. efferent lymphatic vessels
in sinuses: lmyph with macrophages and reticular cells
46
Blood circulation in lmyph node
```
artery in Hilum
arterioles in paracortex
capillary beds in Cortex
high endothelial postcapillary venules in paracortex
hilar vein
```
47
High endothelial postcapillary venules
- cuboidal endothelial cells
- important in circulating and concentrating lymph
- site of Exit of lymphocytes (90%)
48
Spleen organization
- capsule (dense CT and myocytes)
stroma: reticular CT
Parenchyma: blood cells
White Pulp vs red Pulp
look at Picture!!!!!!
49
Main functions of spleen
immune functions:
- filters and Monitors blood
- Environment for secondary education
Hematopoietic function:
- Formation of blood cells in fetal life
- removal of RBCs and platelets
- Retrieval of ion
Storage of blood
50
Splenic circulation
open circulation in humans:
1. Splenic artery
2. Trabevular arteries
3. Penicillar arterioles
4. Red Pulp
5. Spleic Cords
6. Splenic sinuses
7. Pulp venules
8. Trabecular vein
9. Splenic vein
```
closed circulation in animals
…
Penicillar arterioles
capillaries
splenic sinuses
...
```
51
White Pulp of spleen
lmyphatic Aggregation around central arteries
- periarterial lmyphoid sheaths (PALS, mostly T cells)
- lmyph nodules (mostly B cells)
52
Splenic follicle
Periarterial Zone: around central artery, T cells
Germinal Center (B cells)
Mantle Zone (around germinal Center) T and B cells
Marginal Zone (around follicle) T and B cells
53
Red Pulp of spleen
splenic Cords
| splenic sinuses
54
Splenic cords
Contain blood cells: RBCs , neutrophils, pletelets, macrophages
Reticular Framework supports the Cords
Cords are between sinusoids
55
Splenic sinuses
Endothelial cells
Discontinuous b.n.
Reticular fibers around sinuses
