PSIO202 Exam 2 Lecture 15-16 Flashcards
What are the functions of the lymphatic system?
returns excess ISF to the circulation, immune response/protect body from infection, and transport dietary fats and vitamins
What are the two ducts in the lymphatic system, and what do they drain?
thoracic duct - drains left side up upper body and all of lower body
right lymphatic duct - drains right side of upper body
What are the key features of lymphatic capillaries?
close ended, one way valves, larger than blood capillaries, and have lymph nodes at regular intervals
Lymphatic tissues create a dense 3D meshwork of…
reticular connective tissue
What occupies the spaces in the meshwork of lymphatic tissue?
lymphocytes and phagocytes
What are the primary/generative lymphatic tissues?
red bone marrow and the thymus
What are the secondary lymphatic tissues?
lymph nodes, spleen, mucosal associated lymphoid tissue (peyer’s patches, appendix, tonsils), and cutaneous associated lymphoid tissue
What cells are produced from lymphoid stem cells?
T lymphoblasts, B lymphoblasts, and NK lymphoblasts
What leukocytes are produced from myeloid stem cells?
eosinophilic myeloblasts, basophilic myeloblasts, and CFU-GM which creates myeloblasts and monoblasts
What cells come from myeloblasts?
neutrophils
What cells come from monoblasts?
monocytes and macrophages
What are leukocytosis and leukopenia? What are the causes of each?
leukocytosis - high WBC count secondary to infection, strenuous exercise, anesthesia, or surgery
leukopenia - low WBC count secondary to radiation, septic shock, or chemotherapy
What are cytokines? How are they produced, and why? What are two types?
local hormones of bone marrow
produced by marrow cells to stimulate proliferation of other marrow cells
colony-stimulating factors (CSF) and interleukins
Do WBC’s have a nucleus? Do they have hemoglobin?
they all have a nucleus, not no hemoglobin
What are the granulocytes and agranulocyte leukocytes?
granular: neutrophils, eosinophils, and basophils
agranular: monocytes and lymphocytes
What is the percentage of WBC that are circulating in the blood at any given time?
2%
How many RBC vs WBC in the blood?
1 WBC for every 700 RBC
Since very few WBC are in the blood, where are the rest?
lymphatic fluid, lymphatic tissue of the skin, lungs, lymph nodes, and spleen
What do neutrophils do?
fast response to bacteria
-release defensin, creates holes in bacterial cell walls
-release lysozymes, which destroy bacteria
-release strong oxidants, which destroy bacteria
What do eosinophils do?
leave the capillaries to enter tissue fluid
-release histaminase, which breaks down histamine and calms the response of basophils
-attack parasitic worms
-phagocytose antibody-antigen complexes
What do basophils do?
- inflammatory and allergic reactions
- leave capillaries and enter connective tissue as mast cells
- release heparin, histamine, and serotonin: heighten inflammatory response, increase blood flow, and create allergic reactions
What do B cells do?
antibody-mediated immunity,
stay in lymphatic tissue,
destroy bacteria and their toxins,
turn into plasma cells which produce antibodies that enter the lymphatic fluid
What do T cells do?
cell mediated immunity,
go out into tissues,
attack viruses, fungi, transplanted organs, cancer cells, and some bacteria
What do natural killer cells do?
directly attack and destroy many kinds of microbes and some tumor cells
Where are B and T cells matured?
B cells - bone marrow
T cells - thymus
Where do most lymphocytes reside?
spleen and lymph nodes
Where do B and T cells act? (in lymphatic tissue, blood, etc.)
Something ends up in the blood in each case - what?
B cells remain in the lymphatic tissue and release antibodies in to the blood
T cells leave the lymphatic tissue and enter the blood to migrate to distant sites
What do monocytes do?
arrive in large numbers at sites of infection (slower, but more of them)
become wandering macrophages once they leave the capillaries
destroy microbes and clean up dead tissue following an infection
When do monocytes become macrophages?
when they leave the capillaries
What does a differential WBC count do?
detect changes in numbers of circulating WBC (percent of each type)
What are normal WBC counts?
N- 60-70%
L- 20-25%
M- 3-8%
E- 2-4%
B- <1%
What causes a change in the count for each leukocyte type?
N- bacterial infection
L- viral infection
M- fungal/viral infection
E- parasite or allergy
B- hypothyroid or allergy
Describe the process of emigration
WBCs roll along the endothelium.
integrins on WBC stick to the selectins on the endothelial cells
chemokines stimulate the affinity of integrins for selectins
What are the steps of phagocytosis?
chemotaxis, adherence, and destruction
What occurs in the chemotaxis step of phagocytosis?
chemokines that are released from the pathogen/infected cell attract phagocytic cells
What occurs in the adherence step of phagocytosis?
- phagocytes fuse to the pathogen’s membrane
- pseudopodia wrap around it, ingesting the pathogen to form a phagosome (the pathogen inside the WBC)
What occurs in the destruction step of phagocytosis?
- phagosome fuses with a lysosome to create a phago-lysosome
- lysosomal enzymes destroy the membrane of the pathogen
- fragments of the dead pathogens are encapsulated in a residual body or removed from the cell by exocytosis
What types of leukocytes primarily perform phagocytosis?
neutrophils and monocytes
What are the two main types of immunity?
innate (non specific) and aquired (adaptive, or specific)
What are the innate defenses?
physical barriers, fever, inflammatory response, and antimicrobial substances/cells that can kill (interferons, phagocytes, complement proteins, and natural killer cells)
What are the physical barriers of innate immunity?
skin, mucus membranes, hair, acid, and tears
How do tears contribute to innate immunity?
they contain lysozymes
What aspects of the skin make it a good physical barrier for innate immunity?
sebaceous glands, sudoriferous glands, and lysozymes
What causes an increase in body temperature (fever)?
pyrogens, which are secreted by phagocytes when exposed to bacteria and other foreign substances
In what ways can a moderate fever be beneficial?
liver and spleen sequester iron and zinc, trigger production of interferons, bacterial enzymes stop functioning, and increased metabolic rate helps inflammatory response
What are four signs of inflammation?
redness, heat, swelling, and pain
What does inflammatory response do for innate immunity?
prevent spread of damaging agents, promote disposal of debris and pathogens, set the stage for repair
What are the phases of phagocytic mobilization of inflammatory response?
- leukocytosis- cytokines released by injured cells trigger neutrophils to be released
- margination- neutrophils cling to the walls of capillaries in the injured area
- diapedesis- neutrophils squeeze through the capillary walls and begin phagocytosis
- chemotaxis- chemokines attract neutrophils to the site
How do antimicrobial substances enhance innate defenses (generally)?
attacking microorganisms directly, and hindering microorganisms ability to reproduce
What are interferons produced by?
natural killer cells, macrophages, T lymphocytes, and virus infected body cells
What do interferons do?
they warn adjacent cells and alter cellular activities
Why are interferons non-specific?
they act on a large number of viruses, not a specific virus
How do interferons work?
infected cell produces interferons, those interferons bond to a nearby cell’s interferon receptor, turns on the gene for antiviral protection which blocks viral reproduction.
What is a complement system?
11 specific proteins that complement the action of antibodies
What do complement proteins do?
They attach to antobody-antigen complexes, providing a second line of defense against an invasion by pathogens
What is the end result of a complement protein?
formation of a membrane attack complex (MAC) that attracts phagocytes, stimulates phagocytosis and inflammation
What is opsonizing?
coating with C3b that can create strong bonds with the pseudopodia
Describe the process of the complement system.
circulating proteins are activated by antigens
they self assemble to become a membrane attack complex
MAC forms a pore where ISF can pour in and rupture the microbe (cytolysis)
C3a and C5a degranulate the mast cell, releasing histamine and causing the capillaries to become more leaky.
Increased permeability allows more phagocytes to exit the blood vessel and engulf the microbes. microbes are also opsonized by C3b so pseudopodia can more strongly attach.
What percent of the lymphocytes are natural killer cells?
5-10%
How do natural killer cells function?
Kill tumor cells and some viruses via cytolysis.
They secrete perforin and granzymes which perforates the cell membrane and activate an apoptotic pathway within the target cell.
