Final: Immunology: Animal Defense Systems Slides Flashcards
Immune system functions
- Protect against infection and microbes (invasion of pathogens)
- Destroy pathogens that do enter the body
How can pathogens enter the body?
Openings (nose, mouth, etc.) or if skin gets cut
What are pathogens and where are they found?
Unwanted material; found literally everywhere
What are types of pathogens (5)?
Parasites (multicellular worms), bacteria (prokaryotes), protists (unicellular), fungi, virus (nonliving)
Types of immune response
Nonspecific (general, first response) and specific (specific to one pathogen)
Barriers to infection (3)
Physical barriers, chemical barriers, reflexes (sneeze, cough, etc.)
Examples of physical barriers (3)
Skin (best example), fibrous layer of eyes, mucous membranes (of respiratory, digestive, urinary, reproductive systems, and of ears)
What makes skin a good physical barrier?
Outermost skin cells are essentially dead; they make so much keratin that they can’t function
Examples of chemical barriers (9)
Sebum, mucus, saliva, sweat, cilia, macrophages, lacrimal glands, wax, stomach acid
Sebum
Oily acidic substance released from sebaceous glands (skin); affects osmolarity of pathogens
Lysozymes
Enzymes secreted from the mucous membranes (found in tears, saliva, etc.)
Defensins
Peptides secreted from the mucous membranes (found in saliva, etc.)
Lymphoid tissue function
Clusters of organs that make immune cells (to be released to circulation) or are where immune cells are stationed
Examples of lymphoid tissues (7)
Adenoids, tonsils, thymus, lymph nodes, spleen, lymphatic vessels, bone marrow
What occurs in bone marrow?
Many types of immune cells grow, mature, and are released into the circulation
Immune cell function
Attack and destroy pathogens
Neutrophil function
Destroy pathogens through phagocytosis (most abundant phagocytic cells) and release cytokines, vasodilators, and chemotaxins
Cytokine function
Increase alertness, recruit other immune cells
Vasodilator function
Increase blood vessel diameter to make circulation easier (immune cells use blood vessels to travel)
Chemotaxin function
Direct immune cells to site of need
Difference between monocytes and macrophages
Monocytes when in circulation; macrophages are functional monocytes, once recruited and ready to attack
Macrophage functions (2)
-Engulf and digest pathogens (phagocytose/endocytose)
-Activate T cells (by releasing cytokines)
(do these simultaneously: attack while calling for backup)
Mast cell location
Throughout connective tissues (not in blood)
Mast cell function
Release histamine (type of signal cytokine) and other chemicals to recruit immune cells - not in direct contact with pathogens
B lymphocyte functions (2)
- Transform into plasma cells and release antibodies into circulation
- Form memory cells
How do antibodies help immune response?
Tag pathogens so other immune cells can destroy them
What are memory B cells?
Produce antibodies that remember specific pathogens for a faster, more efficient attack
Cytotoxic T cell functions
- Release perforin and granzymes directly into target cell
- Induce apoptosis by activating Fas receptor
Granzyme function
Digest or break down pathogen
General sequence of immune response (4 steps)
- Phagocytosis and recruitment
- Vasodilation and increase in permeability
- Phagocytic cells migration
- Tissue repair
What do injured cells release?
Chemotaxin (or chemoattractants), which attracts immune cells and tells them where to go
Why does swelling occur at site of injury?
Vasodilation means increased blood vessel permeability, so stuff normally supposed to be in blood vessel leaks to extracellular space
Which cells line blood vessels?
Endothelial cells
Effects of vasodilation (caused by histamine) (4)
- Increase in blood flow to infected areas
- Redness
- Increased protein delivery
- Edema (swelling)
Margination
Macrophages en route to injury site match receptors with endothelial cells (so they know where to exist blood vessel)
What are the receptors and attachment process for cytokines and phagocytic cells?
Cytokines signal endothelial cells to express selectin; phagocytic cells produce integrin (facilitates attachment)
Diapedesis
Phagocytic cells move from blood to infected area (attracted to specific injury site by chemotaxins)
Steps of phagocytosis
- Attachment (receptors match)
- Internalization (phagosome fuses with lysosome)
- Degradation in phagolysosome
- Exocytosis
- process of intracellular digestion/destruction
What is a phagolysosome?
Enzymes of lysosome fuse with phagosome
What is the process of attachment called in phagocytosis?
Opsonization (physical binding)
What is an example of extracellular destruction?
Membrane Attack Complex (MAC) - complement system
How does MAC work?
Series of proteins that embed themselves on pathogen membrane surface, triggering event cascade of protein activation that leads to insertion of pores in pathogen membrane - pathogen cell swells as water and salt enter, and lysis (bursting) occurs
