(03) Immune System II

Question 1

(LYMPH NODES)

lymphatic tissue (lymphatic nodules plus diffuse lymphatic tissue)

1. with or without a capsule?
2. What is the function?

Answer 1

1. with a capsule
2. filters lymph that drains from a region, allowing it to encounter and mount a response to foreign antigens

Question 2

(Structure of Lymph Nodes)

1. this encapsulated bean shaped organ is divided into and outer what and and an innter what?
2. What is the regions where arteries, veins and efferent lymphatics enter or leave the node?

Answer 2

1. outer cortex, inner medulla
2. the indented (hilar) region

Question 3

(Capsule of Lymph Node)

1. what kind of tissue?
2. What kinds of extensions and into what?

Answer 3

1. dense irregular c. tissue
2. trabecular extensions into the parenchyma

Question 4

(Cortex of Lymph Nodes)

• Outer Cortex with what containing what? surrounded by what?
• Paracortex (inner or deep cortex) - what kind of tissue containing what?

Answer 4

1. primary and secondary (activated) nodules containing B-cells; diffuse lymphatic tissue
2. diffuse lymphatic tissue; numerous T-cells

Question 5

(Medulla of the Lymph Nodes - less organized than cortex)

1. What are cord-like aggregates of small lymphocytes, macrophages and plasma cells?
2. Separated from each other by what?
3. In what animal dot the cortex and medulla have a reversed arrangement?

Answer 5

1. medullary cords
2. medullary (lymph) sinuses
3. THE PIG

Question 6

What is the only organ with afferent lymphatics?

Answer 6

• the lymph node

Question 7

(Lymph Circulation in a Lymph Node)

Give me the order (5 of them starting with afferent lymphatic vessels)

Question 8

(Lymph Nodes)

1. With the medulla, lymph percolates into the what through gaps in the what? What does this give the parenchymal cells access to?
2. What can be done with the foreign antigens?
3. eg - are macrophages positioned close to the medullary (lymph) sinuses in abundance? What do they do?

Answer 8

1. the parenchyma through gaps in the sinus walls; all the antigens, particles and cels that are within the lymphatic circulation
2. can be captured, presented and/or reacted to by various immune cells
3. yes; help clear the lymph of undesireable cells, microorganisms, and other particulate matter (innate immune response) or process antigens for presentation to lymphocytes (adaptive immune response)

Question 9

(LYMPH NODE)

1. Note: Activation of B-cells (in response to an infection) will result in what?
2. In this process the lymphatic nodules (B-cell regions) become larger or smaller? What happens as a consequence of this?

Answer 9

1. proliferation/differentiation into plasma cells.
2. larger; increase in size (ie swollen glands)

Question 10

(Vascular Circulation in a Lymph Node)

1. Arteries entering lymph node ( _____ region) follow what? looping through what region as capillaries?
2. Post-capillary venules (aka ?) are positioned where? serve as a site of what?

Answer 10

1. hilar; connective tissue trabeculae; the cortical region
2. high endothelial venules (HEV); at the paracortical (deep cortex) region; a site of transendothelial migration of lymphocytes out of the blood into the lymph node parenchyma

Question 11

(Normal and High Endothelial Venules in Cross Section)

learn this

Answer 11

do it

Question 12

1. Do mucosal associated lymphatic tissues and lymph nodes both commonly have HEVs?
2. What is theis a place for?
3. In lymph nodes, lymphocytes will home (via what?) to these HEV (what region?). What occurs within this region?

Answer 12

1. yes
2. lymphocytes can exit the blood (passing between venule’s plump endothelial cells) and gain access to lymphatic organ.
3. chemotactic chemokines; paracortical region; region where cellular interactions (antigen presenting cells or T helper cells) may result in activation of T or B cells

Question 13

LOOK AT THE PICTURES

Question 14

SPLEEN - lymphatic nodules plus diffuse lympatic tissue as a fuctional component of this organ!

1. Function of the spleen (four things - 1 in fetus)?

Answer 14

1. filters the blood; can store blood; erythropoeisis (in fetus); responds immunologically to antigens in the blood

Question 15

(Regarding the functions of the spleen)

(Filters the blood)

1. what macrophages phagocytize here?

(Store Blood)

2. serve as what in several species?
3. especially important in what species?

(and then the other two - have nothing to add here)

Answer 15

1. old RBC, lymphocytes, platelets, and blood borne foreign particulate matter
2. automatic transfusion bank
3. horse, dog, and pig

Question 16

(Structure of the SPLLENNN)

1. Capsule and trabecular extensions = ?
2. Contractile properties of this region helps do what?
3. What is the region for exit/entrance of nerves and vessels (including efferent lymphatics) at the medial aspect of the spleen?
4. Parenchyma (splenic pulp) - consists of what two kinds of pulp? names based on what?

Answer 16

1. dense connective tissue contating smooth muscle (or myofibroblasts)
2. help discharge stored RBCs into systemic ciruclation at times of need (muscular exertion - esp horse)
3. the hilus
4. red and white pulp; gross color

Question 17

1. Which pulp is the lymphatic tissue of the spleen?
2. Comprised primarily of? also has?
3. What are the two components?
4. Splenic nodules = ?
5. periarterial lymphatic sheaths = ?

Answer 17

1. the white pulp
2. lymphocytes; plasma cells and macrophages
3. splenic nodules (lymph nodules) and periarterial lymphatic sheaths (PALS) (diffuse lympathic tissue)
4. B-cells
5. T-cells (as name suggests these lymphocytes surround a vessel - it actually is the size of an arteriole)

Question 18

1. What pulp is the spleen’s “blood filter”?
2. Filled with what and occupies what space?
3. What are the components (2 of them)?
4. What do the splenic cords consist of?

Answer 18

1. red pulp
2. Filled with RBC and occupies all spaces by white pulp or connective tissue trabeculae
3. Splenic sinuses/venules; splenic cords
4. reticular fibers, reticular cells, macrophages, lymphocytes and other leukocytes

Question 19

(Spleen)

1. What zone is between the red and white pulp?
2. What are prominent in this area?
3. Antigens of blood origin trapped in this zone are transported by macrophages to what areas? What does this facilitate?

Answer 19

1. the marginal zone
2. B-cells, macrophages, and terminal capillaries from both pulp areas
3. the T-cell rich areas; oppurtunities for immune responses by lymphocytes and dendritic cells

Question 20

(Spleen)

1. What is the function called where te spleen is able to bite off sections of the red blood cells passing through that are marked by the immune system? What can the spleen remove from the circulating RBC by doing this? Are full RBC sometimes removed to prevent spread of parasites? Is this always a good thing?
2. In what disease does the spleen remove so many RBC portions that the infection is difficult to detect?
3. What else can happen to patient?

Answer 20

1. pitting; RBC parasites; yes; no can get out of hand
2. Feline Infectious Anemia
3. They can become anemic (from spleen removing RBC)

Question 21

Give me the order of blood flow through the spleen (starting with splenic artery)

Answer 21

splenic artery –> trabecular artery –> artery of the white pulp –> artery of the red pulp (aka pulp arteriole) –> sheathed/terminal capillary –> splenic venules/sinuses –> trabecular vein –> splenic vein

Question 22

(Spleen)

1. what is found in the PALS (t lymphocytes) and in the splenic nodules (B lymphocytes)?
2. What are sheathed/terminal capillaries?

Answer 22

1. white pulp
2. capillaries sheathed by macrophages

Question 23

(Theories related to the junction of the sheathed capillary and the splenic sinus/venule)

1. capillaries open directly into splenic venules/sinuses
2. capillaries open into the spaces between the reticular cells of the red pulp, blood enters the splenic sinuses thorugh slits in their walls
3. both situations exist depending on the physiological state of the animal (contracted vs relaxed spleen)

Answer 23

1. closed theory
2. open theory
3. combined theory

Question 24

(Clinical Note - occasionally a mass may be found on the spleen)

1. What kinds of tumors can these be?
2. Another name for benign tumors?
3. . What malignant tumors grow from the red pulp? from white pulp?
4. In dogs most splenic masses are what?
5. In cat they are usually what?

Answer 24

1. benign tumors or malignant tumors
2. hemangiomas
3. hemangiosarcomas; masT-cell tumors and lymphosarcoma
4. hemangiomas or hemangiosarcomas
5. mast cell tumors or lymphosarcomas

Question 25

(Immune/Nervous System/Endocrine Interaction)

1. are these system tightly linked?
2. do they communicate with one another?
3. What are three means of communication between the brain and immune system?

Answer 25

1. yes
2. yes
3. hypthalamic/pituitary/adrenal (HPA) axis; sympathetic and peripheral nervous system; vagus nerve and cytokine feedback to the brain

Question 26

(Immune Effects on the Nervous System & Endocrine Systems)

1. The immune system can affect th nervous system through the release of what?

(Examples)

2. potentially resulting in an alteration of cognitive processes, central neurotransmission and the function of the peripheral nervous system (eg… culminating in what?)
3. What can activate the hypothalamus-pituitary-adrenal axis? induce what? What may this be due to?

Answer 26

1. cytokines
2. depressive affect on social behavior (amygdala) or the feeling of nausea (activation of hypothalamus-pituitary-adrenal axis)
3. Pro-inflammatory cytokines (eg IL-1b, TNFa); sickness behavior (weakness, malaise, listlessness…) during the acute phase response; IL-1b binding to vagal fibers, increasing nerve discharge

Question 27

(Nervous System Effects on the Immune System)

• accumulating evidence points to the sympathetic (norepinephrine) innervation of primary and secondary lymphatic organs as an important communcation between the nervous and immune systems.
  1. Activation of these sympathetic fibers causes what?

(Influence of neuroendocrine hormones on the immune system)

Both what and what depress immune function?

Answer 27

1. suppression of the immune system
2. ACTH and adrenal corticosteroids