(02) Immune System

Question 1

Immune system protects against what two things?

Answer 1

1. foreign invaders (bacteria and viruses)
2. altered self (cancer cells)

Question 2

1. response when body reacts non-specifically and rapidly
2. specifically but more slowly

Answer 2

1. innate immunity (macrophages, granulocytes, etc.)
2. acquired or adaptive immunity (lymphocytes)

Question 3

Immune system consists of what three things?

Answer 3

1. lymphatic system and blood vessels for transport individual immune cells throughout body
2. immune cells
3. immune system organs (bone marrow, thymus, lymph nodes, spleen)

and

diffuse lymphatic tissue (lymphocytes, other immune cells associated with mucosal tissues and skin)

Question 4

(Lymphatic System)

1. Lymphatics drain off what?
2. What is their route?
3. How fast is the flow? What does it depend on?

Answer 4

1. excess tissue fluids and cells
2. “blind-ended” lymphatic capillaries within connective tissue converge –> lymphatic vessels –> thoracic duct –> brachiocephalic vein
3. slow; surrounding structures (skeletal muscle) compressing lymphatic walls

Question 5

(Lymphatic capillaries)

1. Is endothelium of basal lamina continuous or discontinous?
2. What does this make it?
3. Allowing what to get through into lumen?

Answer 5

1. discontinuous
2. very permeable
3. proteins and lipids

Question 6

(Lymph Vessels)

1. as lymph vessel size increase so does what?
2. What do larger lymph vessels have more of in their wall?
3. Do they have valves?

Answer 6

1. the thickness of the wall
2. more c.t. and maybe more smooth muscle
3. yes

Question 7

(Immune cells)

1. Derivates of how many bone marrow progenitor cells?
2. What ones are derivatives of the common myeloid progenitor cells?

Important to what kind of response?

3. What are derivatives of the common lymphoid progenitor?
4. What are these cells important for?
5. What is derived from common lymphoid progenitor but belongs to innate immune response?

Answer 7

1. two
2. macrophages, granulocytes, mast cells, and dendritic cells

innate immune response

3. lymphocytes
4. the adaptive immune response
5. NK cells (not specific, destroy abnormal cells)

Question 8

(Immune System Organs and Diffuse Lymphatic Tissues)

1. What are sites where lymphocytes develop?
2. What are sites where they encounter/respond to antigens?

3.

Answer 8

1. primary immune organs

2. secondary immune organs

Question 9

(Characteristics of Immune System Organs and Diffuse Lymphatic Tissues)

1. many or few lymphocytes?
2. Have reticular connective tissue - consists of what?
3. Is reticular connective tissue the most supportive connective tissue of lymphatic organs?
4. Except not in what organ? What is the “special” supportive cell there?

Answer 9

1. many
2. reticular cells and their associated reticulr fibers (type II I collagen)
3. yes
4. Thymus; epithelial reticular cell

Question 10

1. What are the primary (central) immune organs and what happens at each?

Answer 10

1.

1. Bone Marrow - where B lymphocytes (b-cells) mature
2. Thymus - where T lymphocytes (T-cells mature)
3. Peyer’s Patches - +/- site of B-cell maturation

Question 11

1. What are the three Secondary (peripheral) immune tissues/organs

Answer 11

1. diffuse lymphatic tissue, lymph nodes, and spleen

Question 12

1. What happens in the bone marrow?
2. [Function] What kind of organ is it? What does it produce? What have hemopoietic capabilites prenatally?)
3. Contains what kind of cell? Gives rise to which two cells?

Answer 12

1. B-cell development/maturation
2. postnatal hemopoietic (bloodmaking) organ; white and red blood cells; yolk sac, liver, spleen
3. hematopoietic stem cell; common myeloid progenitor & common lymphoid progenitor

Question 13

(Bone Marrow)

1. Occupies the inner cavity of what?
2. Parenchyma (functional part of an organ) contains what two nests and what two cell types?

Answer 13

1. bones
2. red blood (erythroid) cell nests, white blood (granulocytic) cell nests, lymphocytes and platelets

Question 14

(Two types of bone marrow)

(Red)

1. actively producing what?
2. is it well vascularized?
3. located where?

(Yellow)

1. actively producing what?
2. What cell type is prominent?
3. What type can convert to the other if there is a need of more RBCs? What kinds of animals would need to do this?

Answer 14

(Red)

1. blood cells
2. yes
3. cancellous region of long bones

(Yellow)

1. trick question bitch - low production of white blood cells
2. adipose cells
3. yellow to red; severley anemic animals

Question 15

(Bone Marrow)

1. stroma and vasculature consist of what? What surrounds the sinuses and parenchymal cells?

Answer 15

1. reticular connective tissue; reticular fiber and reticular cells

Question 16

(Bone Marrow)

1. “nutrient” artery penetrates what?, branches within what?, and terminates as what?
2. Newly formed blood cells can enter the vasculature system after what three things happen?
3. Conversely, contraction of the perivascular reticular cells restricts access to what? Thereby doing what?

Answer 16

1. bone cortex, bone marrow cavities, thin walled sinuses with a discontiuous basal lamina
3. retraction of surrounding reticular cells
4. depolymerization of basal lamina
5. creation of transient pore in the endothelial cell
6. the sinus basal lamina; reduces the number of cells that can enter into circulation

Question 17

(Bone Marrow)

1. Venules extend from what? Coalesce into what? which penetrates what to exit what?

Answer 17

1. sinusoids, one main “central” vein, penetrates the bone cortices to exit the marrow cavity

Question 18

(Thymus)

1. what happens here?
2. Embryoligaclly originates as what of what?
3. IMPORTANTLY, these epithelial cells of the pouch form what cells than constitute what?

Answer 18

1. T-cell maturation
2. epithelial (endoderm) outgrowth of the third pharyngeal pouch
3. epithelial reticular cells (ERCs) that constitute the thymic stroma

Question 19

(Thymus)

1. Lymphocyte progenitors migrate from the bone marrow to populate what?
2. After maturation/differentiation within the thymus, what are released into the circulation?

Answer 19

1. the thymus
2. T lymphocytes (T-cells, thymocytes)

Question 20

(Structure of Thymus)

1. Bi-lobed thymus covered by what? thin connective tissue septa (trabeculae) divides it into what?
2. Each lobule has a “cap” of what surrounding a more centrally located what?
3. Do medullary regions of neighboring lobules often remain connected?

Answer 20

1. a thin capsule; lobules
2. “cap” of cotrical tissue surrounding a more centrally located medulla

Question 21

(Structure of Thymus Cont)

1. Parenchyma is mainly what?
2. What are T-cells like in the cortex?
3. in the medulla?

(other cells types are present; macrophages, dendritic cells, and plasma cells)

Answer 21

1. mainly T-cells
2. small with dense nucleus
3. larger with euchromatic nuclei

Question 22

(Structure of Thymus cont)

1. Stoma: epithelial reticular cells (ERCs) connected to each other how? to form what?
2. How many types of ERCs? which are in cortex? in the medulla?

Answer 22

1. by desmosomes or occluding junctions; form a net of supportive cells thoughout the thymus
2. six; 1-3; 4-6

Question 23

(Type 1 ERC)

1. unite with each other via what?
2. interposed between what?
3. What do they create? Isolating what from what? Forming an important part of the what barrier?

Answer 23

1. occluding junctions
2. cortex and the connective tissue
3. a barrier; developing cortical T cells from connective tissue and body fluids; the blood thymic barrier

Question 24

(Type 4 ERCS)

1. For a histologically distinct structure called the what?
2. This thing is a concentrically arranged mass of flattened Type IV ERCs that may actually show evidence of what? why might this be predictable? It is thought that this mass of cells produces what to assist with what?

Answer 24

1. Thymic (Hassal’s) corpuscle
2. keratinization; cell origin is oropharyngeal epithelium; interleukins that assist with differentiation and education of T-cells.

Question 25

1. The thymus protects developing lymphocytes from random antigen exposure (eg. from the blood) by creating what? 2. Composed of what three things? 3. Capillary Wall - ie endothelium of the capillary wall... What type is it? impermeable to macromolecules? What are two other things that are part of the cell wall? 4. Macrophages in Perivascular Space... available to do what? 5. Type I ERCS... united to each other by what? their associated basal lamina form what?

Answer 25

1. BLOOD-THYMUS BARRIER 2. capillary wall, macrophages in perivascular space, type I ERCS 3. Continuous type with occluding junctions; approx?; basal lamina and pericytes 4. phagocytize any antigen that might escape from the capillary 5. occluding juctions; the last component of the barrier

Question 26

(Blood thymus barrier) 1. Provides an isolated region (the _cortex_) for the presentation of what by what? 2. Only T-cells with recognition to what and what survive? 3. These "postitive selected cells" move into what? In here the cells undergo what? what does this mean? 4. What is the resultant cell after this process? where can move to what (via what) for distribution through what? 5. What promote factors (interleukins) that promote this process of T cell education?

Answer 26

1. of antigens by type II and III ERCS 2. self-MHC and self- or foreign- antigens survive (only cells that might be of use toward antigen recognition surface) 3. the medulla; negative selection; cells recognizing self-MHC are eliminated (ie only cells that react with nonself antigens survive) 4. a single-positive (CD8 or CD4) naive lymphocyte; move into the blood (via postcapillary venule) for distribution throughout body 5. ERCs

Question 27

(Thymic Vasculature) (Blood flow) (Order) 1. enters via what? 2. travels within trabeculae to what? 3. flows through what (where there is a what)? 4. toward what region? 5. exits via what? - vessels can also shunt through what without entering what?

Answer 27

1. capsule 2. corticomeduallary region 3. cortex (a BTB) 4. medullary region 5. trabecular then capsular veins - the medullary cavity, the cortex

Question 28

1. thymus is fully functional from when until when? 2. what happens then (3 things)?

Answer 28

1. birth until puberty 2. 1. reduction in size 2. reduction in function 3. replacement of thymic lymphatic tissue by adipose tissue (ie thymic involution)

Question 29

(Secondary Lymphatic Organs) 1. Mature naive lymphocytes leave what, enter what, and then go where? 2. Where may lymphocytes first encounter antigen (and become activated)?

Answer 29

1. leave primary lymphatic organs (bone marrow and thymus), enter blood vessels or lymph, go to secondary lymphatic organs 2. secondary lymphatic organs

Question 30

(Characteristics of Secondary Lymphatic Organs) 1. Consist of lymphatic nodules (follicles) that consist of what (4 things)? 2. Activated B-cells undergo mitosis and differentiation within nodules to form what? 3. These activated nodules (aka what?) will what kind of staining center? due to what? 4. What is the paler center called?

Answer 30

1. stromal network or reticular cells, reticular fibers, dendritic cells, and tightly packed **B-cells** 2. plasma cells 3. secondary nodules; lighter staining; larger sized lymphocytes that are undergoing transformation 4. a germinal center

Question 31

(Characteristics of secondary lymphoid organs) 1. What does diffuse extranodular lymphatic tissue (adjacent to the nodules) contain (3 things)?

Answer 31

1. contains dense accumulations of small T-cells, macrophages, and some lymphoblasts

Question 32

(Lymphatic Tissues - lymphatic tissues nodules plus diffuse lymphatic tissue) 1. with or without a capsule?

Answer 32

1. without

Question 33

(Lymphatic Tissues) 1. ______ is lympatic nodules and associated diffuse lymphatic tissue found deep to mucous membranes. (Note: mucus membranes (aka mucosa) is the epithelium with underlying connective tissue that is lining cavities which connect to the outside eg, gut, respiratory tract and genitourinary tract. The epithelium varies depending on location)

Answer 33

1. Mucosal Associated Lymphatic Tissue (MALT)

Question 34

(Examples of MALT with regional name) 1. What are solitary and aggregated lymphatic nodules associated with the gut? 2. Especially rich in what? 3. Responsible for what? 4. What are prominent aggregates of lymphatic nodules in the small intestine called? (Increased prominence of MALT is seen in response to infection)

Answer 34

1. Gut-associated lymphatic tissue (GALT) 2. B-cells 3. localized to immunity to pathogens (bacteria, viruses, and parasites) 4. Peyer's Patches

Question 35

(in figure 8 note the dense accumulation of small lymphocytes (darker region labeled "mantle") associated with lymphatic nodules and overlying "dome." 1. The epithelium covering "dome" is modifed - lacks what? but has what special cell? that can do what? 2. The activated lymphocytes then migrate where to do what? 3. What else may also contain M cells?

Answer 35

1. goblet cells (no mucous secretion); the **M (microfold) cell;** able to capture surface antigens (endocytosis) and pass them on to lymphocytes that reside within invaginations of the M cells (transcytosis) 2. other immune tissues to initate the immune response. 3. the epithelium covering other mucosal associated lymphatic tissues

Question 36

(Clinical Note: Johne's Disease in Cattle) 1. When calves ingest what bacteria? it invades the last part of the small intestine and is taken up by what? 2. The bacteria is subsequently engulfed by what? are they able to kill this bacteria? 3. The bacteria replicates, ultimately causing what? 4. The ileum becomes thickened by granulomatous inflammation, and a condition known as what occurs? 5. Can this cause death?

Answer 36

1. mycobacterium paratuberculosis; M cells associated with Peyer's patches 2. macrophages, no 3. inflammation thatn impairs intenstinal function and causes diarrhea. 4. protein-losing enteropathy (protein absorption is impaired and excess protein is lost in the feces) 5. death

Question 37

1. What is the unencapsulated lymphatic tissue positioned at the entrance of the oropharynx and nasopharynx? 2. What is it doing? 3. Epithelium may be infiltrated with what? (Examples) (aka name that tonsil) 4. the covering epithelium if pseudostratified columnar 5. the covering is stratified squamous

Answer 37

1. Tonsils 2. guarding and responding to entry of infections/toxins. 3. lymphocytes, neutrophils, and macrophages 4. **pharyngeal tonsil** (aka nasopharyngeal tonsil) 5. **palatine tonsil** (oropharyngeal tonsil)