Lymphatic System Flashcards
What is the functions of the Lymphatic System?
defend the body against disease
What are the lymphatic organs?
- Red Bone Marrow
- Thymus Gland
- Tonsils
- Spleen
- Lymph Vessels
- Lymph Nodes
What is the function of the lymphatic capillaries?
take up and return excess fluid to the bloodstream
What do lacteals do?
- recieve lipoproteins
- transport them to bloodstream
Spleen
- found in all vertebrates
- mechanical filtration of blood
Thymus
- active immune response through humoral and cell-mediated pathways
- develops T-lymphnodes from hematopoietic progenitor cells
- has 2 identical lobes
Appendix
- vestigal organ in humans
- found in digestive tract of most herbivores
- may carry and protect beneficial bacteria for the fuctions of the human colon
What is appendicitis?
- inflamation of the appendix
- may lead to appendix rupturing and even death if untreated
Lactile
absorbs dietary fats
Macrophage
- develop from…
- function
- description
- develop form monocytes
- attack foreign microbes by phagocytosis
- major component of the vertebrates lymphatic system
What are the two types of defense mechanisms?
- Non-specific defense mechanisms
- Specific defense mechanism
Describe the nonspecific defense mechanisms
First line of defense
- skin
- mucous membrane
- secretions of skin and mucous membranes
(physical barrier/defense)
Second line of defense
- phagocytic WBCs
- Antimicrobial proteins
- Inflammatory response
Describe the Specific defense mechanism
Third line of defense
- Lymphocytes
- Antibodies
What are the different human secretions?
Where do they come from?
- Sebaceous = ear
- Sweat = skin (sweat glands)
- Mucous = nose
- Saliva = mouth (salvatory glands)
- Tears = eye (tear ducts)
What is the function of human secretions?
How do they perform their function?
They prevent colonization by microbes
Some give the skin a pH of 3-5, acidic enough to kill microbes. Others inhibit with washing action.
What do human secretions contain to help them fight microbes?
What is their function?
antimicrobial proteins - lysosomes
digest cell walls of bacteria
What does the second line of defense mainly depend on? Describe it.
Phagocytosis
The engulfing of another substance (phagosome)
What are the different phagocytes?
- neutrophils - 60-70% of all WBCs
- monocytes - 5% of WBCs; more effective phagocyte
What does eosinophils defend against?
How does it accomplish this?
Eosinophils defend against large parasitic invaders
They position themselves to the outer wall of a parasite, then discharge destructive enzymes from cytoplasmic granules
What do Natural Killer (NK) cells attack?
How do they attack?
NK cells don’t attack microorganisms but destroy virus-infected body cells and potentially cancerous abnormal body cells
They attack on the cell’s membrane causing them to lyse
What is one way microbes have developed to evade the second line of defense?
outer capsules
Myobacterium tuberculosis, are readily engulfed but are resistant to lysosomal destruction, and can even reproduce inside the macrophage
What triggers an inflammatory response in the body?
- damage to tissue by physical injury
- entry of microorganisms
Outline the inflammatory response of the body
Release of histamine
- by injured tissue cells and mast cells
- causes capillaries to dilate and increase blood flow
Phagocytize pathogens and Release of cytokines
- by macrophages and dendritic cells
- stimulate inflammatory response
- cytokines calls other cells to come
Monocytes become macrophages
- squeeze through capilliary wall (with neutrophils) and phagocytize pathogens
Blood clotting
- walls of capillary and prevents blood loss
What is responsible for allergies?
It is released by what?
histamine
released by basophils and mast cells
What is discharged by leukocytes and damaged tissue cells?
It is responsible for what?
prostaglandins
responsible for increased blood flow to site of injury
Cytokines are secreted by what?
What do they do?
Secreted by blood vessel endothelial cells and monocytes
- attract phagocytes to the area
- induce the production of toxic forms of O2 in phagocyte lysosomes
- induce the release of histamine from basophils
Fever, another systemic response to infection, can be triggered by what?
toxins from pathogens or by pyrogens
How does a fever contribute to defense?
Inhibits growth of some microbes
facilitates phagocytosis
speeds up tissue repair
What is the compliment system?
- complimented by antibodies
- carry out steps that lead to lysis of microbes
- some complement components work with chemokines (aka cytokines) to attract phagocytes to infection site
What are interferons?
Why are they useful?
interferons are proteins secreted by virus-infected cells, which signal nearby cells to produce chemicals inhibiting viral reproduction.
Make the host cells more resistant to viruses, thus limiting cell-to-cell spread of viruses
What does the third line of defense rely on?
lymphocytes
What are the two types of lymphocytes? Differentiate each.
B lymphocytes
- develop from Bone Marrow
- has 2 antigen-binding sites
- respond to extracellular infection
T lymphocytes
- develop from Thymus
- has 1 antigen-binding site
- respond to intracellular infection (destroy host cell)**
What elicits a specific response by lymphocytes?
a foreign molecule called an antigen
describe antigens
- made of protein
- target of antibodies (WBCs), from B lymphocytes
Describe Immunoglobins (Igs)
- it is an antibody found in plasma cells
- attach to a specific antigen’s epitope via lock and key
- epitope - antigen’s binding site
What are antigen receptors on a B cell?
- transmembrane versions of antibodies
- aka membrane antibodies/immunoglobins
- allows B cells to recognize the antigen
How do antigen receptors on a T cell differ from those on a B cell?
they are structurally related, but never produced in secreted form
What allows the immune system to respond to millions of antigens, and thus, millions of potential pathogens?
The high variety of B and T cells in the body
each with a very particular and specific antigen receptor
Outline clonal expansion
- Antigen molecules pair up with antigen receptors
- Differentiation into effector cells and memory cells
Differentiate effector cells and memory cells
Effector cells
- eliminate antigen by…
- secreting antibodies
- signal other cells to secrete antibodies
Memory cells
- remember antigen for future recognition (immunity)
What are the benefits of attaching antibodies?
Expound on each.
Neutralization
- block viral binding site = neutralizing it
Opsonization
- cooperation of 2nd & 3rd line of defense
- helps macrophage
Compliment Activation
- attachment of antibodies
- leading to lysis
What is the primary immune response?
- first encounter with the pathogen
- B cells generate effector B cells (plasma cells)
- T cells generate effector T cells
Explain Vaccination
- introducing the pathogen sequence
- same sequence w/ lesser effects
- sequence will trigger primary immune response
- Memory Cells will grant host future immunity
What is the secondary immune response?
second exposure to a previously encountered antigen
Differentiate the primary and secondary immune responses
Primary immune response
- initial exposure
Secondary immune response
- second exposure
- faster effects
- produce more lymphocytes
- prolonged effects
- more effective
When B and T cells are maturing in the bone marrow and thymus, their antigen receptors are tested for what?
Describe it
potential self-reactivity
if they’re able to distinguish self (host cells) from nonself (foreign cells)
T cells interact with what molecules to determine if it is a host cell or not?
Major histocompatibility complex (MHC)
What are the two main classes of MHC molecules to mark the cell as self?
Class I
- found in almost all nucleated cells
Class II
- only in macrophages, B cells, activated T cells and inside the thymus
What are the two main types of T cells?
What MHC molecule do they respond to?
How do they respond?
CD8 Cytotoxic T cells (Tc)
- Class I
- killing infected host cells
CD4 Helper T cells (TH)
- Class II
- send out chemical signals to call other cell types to fight pathogen
What are the 5 Classes of Immunoglobulins?
- IgM
- IgG
- IgA
- IgD
- IgE
Describe IgM
- biggest Ig (pentamer)
- first to be produced and respond
- very effective
- promotes neutralization and cross-linking of antigens
Describe IgG
- most abundant in blood
- “swiss knife”
- most prevalent & effective
- only during secondary immune response
- promotes neutralization, oponization and cross-linking of antigens
- only Ig that can cross placenta
Describe IgA
- 2nd most prevalent
- found in all mucosal surfaces (secretions)
- localized defense by neutralization and cross-linking of antigens
Describe IgD
- on surface of B cells before antigen exposure
- acts as antigen receptors
Describe IgE
- present in blood at low concentrations
- causes allergic reactions
- triggers release of histamine from basophils and mast cells
Explain Blood Transfusions
What is Rhesus factor?
Another blood-typing system using Rh+ or Rh-
What is known as the hemolytic disease of the newborn?
Expound.
Erythroblastosis fetalis
- newborn has Rh+ and mother is Rh-
- mother’s immune response identifies baby as foreign
- First baby is safe because still in primary response (IgM can’t cross placenta)
- Succeeding babies die because already in secondary response (IgG can cross placenta and kill baby)
