Chapter 22 The Lymphoid system and immunity Flashcards
What is nonspecific resistance (innate Immunity)
Present at birth and includes defense mechanisms that provide general protection invasion by a wide range of pathogens
What is immunity (adaptive immunity)
Involves activation of specific lymphocytes that combat a particular pathogen or other foreign substances
What is the lymphatic system?
Consists of several structures and organs that contain
1. lymphatic tissue
2. bone marrow
3. Lymph fluid that flows within lymphatic vessels
What is the functions of the lymphatic systems?
- Drain excess interstitial fluid
- transport dietary fats
- Carries out immune response
Lymphatic vessels begin as what?
Lymphatic capillaries, which are closed on one end
Lymphatic capillaries are located where?
Between cells of many tissues
Lymphatic capillaries merge to form what?
Lymphatic vessels, which have thin wall and many valves
From Lymphatic vessels, lymph passes through what?
Lymph nodes and then into lymph trunks
What does lymph trunk include?
- lumbar
- intestinal
- bronchomediastinal
- subclavian
- jugular trunks
Lymph trunks then merge to form what?
Either Thoracic ducts or the right lymphatic duct
What is the formation and flow of lymph?
- interstitial fluid
- lymph capillaries
- lymph vessels
- lymph trunks
- lymph ducts
- Subclavian veins
What happens at primary lymphatic organs
Immune cells become immunocompetent
What are some sites of primary lymphatic organs/ sites?
Red bone marrow and thymus
Secondary lymphatic organs and tissues include what?
- Lymph nodes
- Spleen
- lymphatic nodules
Lymphatic nodules are masses of lymphatic tissues that are what?
Surrounded by a capsule
Where are lymphatic nodules scattered?
Throughout the lamina propria of mucous membranes lining the
1. gastrointestinal
2. Urinary
3. Reproductive tracts
4. Respiratory airways
What are Mucosa- associated lymphatic tissue (MALT)
Lymphatic nodules found throughout the lamina propria of mucous membranes
What is innate immunity?
Wide variety of body responses that serve to protect us against invasion by a wide variety of pathogens and their toxins
What are the two lines of defense in innate immunity?
- Skin and mucous membranes
- Internal defenses
What are mechanical defenses?
- skin
- mucous membranes
- Tears
- Saliva
- Mucus
- Cilia
- epiglottis
- Urine flow
- Defecating
- Vomiting
What are chemical defenses?
- sebum
- lysozyme
- gastric juice
What are internal defenses?
- Antimicrobial proteins
- phagocytes
- Natural killer cells
- Inflammation
- Fever
What is the function of the epidermis of skin?
Forms physical barrier to entrance of microbes
What is the function mucous membranes in terms of defences?
Inhibit entrance of many microbes, but not as effective as intact skin
What is the function of mucus in terms of defense?
Traps microbes in respiratory treat and digestive canal
What is the defensive purpose of hair?
Filter out microbes and dust in nose
What is the defensive function of cilia?
Together with mucus, trap and remove microbes and dust from upper respiratory tract
What is the defensive function the lacrimal apparatus?
Tears dilute and wash away irritating substances and microbes
What is the defensive function of saliva?
Washes microbes from surfaces of teeth and mucous membranes of mouth
What is the defensive function of urine?
Washes microbes from urethra
What is the defensive function of defecation and vomiting?
Expel microbes from body
What is the defensive function of sebum?
Forms acidic film over skin surface that inhibits growth of many microbes
What is the defensive function of lysozyme?
Antimicrobial substances in
1. Perspiration
2. Tears
3. Saliva
4. Nasal secretion
What is the defensive function of gastric juice?
Destroys bacteria and most toxins in stomach
What is the defensive functions of vaginal secretions?
Slight acidity discourages bacterial growth; flush microbes out of vagina
What is the defensive functions of interferons?
Protect uninfected host cells from viral infection
What is the defensive function of the complement system?
- Causes cytolysis of microbes
- Promotes phagocytosis
- Contributes to inflammation
What is the defensive function of iron binding proteins?
Inhibit growth of certain bacteria by reducing amount of available iron
What is the defensive functions of antimicrobial proteins?
Have broad spectrum antimicrobial activities and attract dendritic cells and mast cells
What is the defensive functions of natural killer cells?
Kill infected target cells by releasing granules that contain perforin and granzymes; phagocytes then kill released microbes
What is the defensive functions of phagocytes?
Ingest foreign particulate matter
What is the defensive purpose of inflammation?
Confines and destroys microbes; initiates tissues repair
What is the defensive purpose of fevers?
- Intensifies effects of interferons
- Inhibits growth of some microbes
- Speeds up body reactions to aid repair
What is adaptive immunity?
The body’s ability to defend itself against invading agents?
Antigens are substances recognized as what?
Something foreign that provoke immune responses
Adaptive immunity has both specificity and memory and is divided into two types what are they?
- Cell mediated
- Antibody mediated
For an immune response to occur what must happen?
B cells and T cells must recognize that foreign antigen is present
What do B Cells do?
Recognize and bind to antigens in lymph, interstitial fluid, or blood plasma
What does T cells do?
Recognize fragments of antigenic proteins that are processed and presented in a certain way
What happens in antigen processing?
Antigenic proteins are broken down into peptide fragments that associate with MHC molecules
What is antigen presentation?
Two steps
1. Antigen processing
2. MHC complex is then inserted into the plasma membrane of body cell
In cell-mediated immunity what happens?
- Antigen is recognized and bound
- A small number of T cells proliferate and differentiate into a clone of effector cells
- The antigen is eliminated
In antibody- mediated immunity what happens?
- An antigen is recognized and bound
- Helper T cells costimulate the B cells so that B cells can proliferate and differentiate into a clone of effector cells that produce antibodies
- The antigen is eliminated
What is naturally acquired active immunity?
Following exposure to a microbe, antigen, recognition by B cells and T cells and costimulation lead to formation of antibody- secreting plasmacytes, cytotoxic T cells, and B and T memory cells
What is Naturally acquired passive immunity?
IgG antibodies are transferred from mother to fetus across placenta, or IgA antibodies are transferred from mother to baby in milk during breast feeding
What is artificially acquired active immunity?
Antigens introduced during vaccination stimulate cell mediated and antibodymediated immune responses, leading to production of memory cells. Antigens are pretreated to be immunogenic but not pathogenic (they will trigger an immune response but not cause significant illness)
What is artificially acquired passive immunity?
Intravenous injection of immunoglobulins (antibodies)
