PSIO Exam 3 Flashcards
Lymphatic System Functions
- drain excess interstitial fluid
- transport dietary lipids
- carry out immune responses
Primary Lymphatic Organs
- red bone marrow
- thymus
Secondary Lymphatic Organs and Tissues
- lymph nodes
- spleen
- lymphatic nodules/follicles
Lymphatic Vessels
- drain excess ISF and return it to the blood stream
- originate in “close ended” lymph capillaries, which lie adjacent to blood capillaries in the tissue space
Lymphatic Capillaries
- slightly larger than blood capillaries
- have one way valves
Lymph Nodes
found at irregular intervals along the lymph vessels
Non-Specific Resistance
the body’s lines of defense against invasion by pathogen (ie. bacteria, viruses, fungi, and environmental hazards)
Non-Specific defenses include:
- physical barriers (first line of defense)
- fever
- inflammation
- cells and chemicals
Physical Barriers to pathogenic invasion
- skin
- mucus membranes
- hairs and cilia
- acid
- tears
Skin as a Physical Barrier
sebaceous glands, sudoriferous glands (sweat glands), and lysosome
Mucus Membranes as a Physical Barrier
mucus is secreted by specialized epithelial cells called goblet cells
Hairs and Cilia as a Physical Barrier
mucus-coated hairs, cilia on specialized epithelial cells that line trachea
Acid as a Physical Barrier
the pH of the stomach is about 2.0
Tears as a Physical Barrier
also contain lysosome
Fever
- abnormally high body temperature in response to invading microorganisms
- the body’s thermostat is reset upwards in response to PYROGENS (chemicals secreted by leukocytes and macrophages exposed to bacteria and other foreign substances)
- high fever is dangerous because it can denature enzymes
How can moderate fever be beneficial
- the liver and spleen sequester iron and zinc (needed by microorganisms). The combination of raised fever and lowered iron inhibits bacterial growth.
- an increase in the metabolic rate, which speeds up the repair of tissues
- triggers production of interferons
Inflammation
The inflammatory response is triggered whenever body tissues are injured
- prevents the spread of damaging agents to nearby tissues
- disposes of cell debris and pathogens
- sets the stage for repair processes
4 Cardinal Signs
- redness
- heat
- swelling
- pain
Cells and Chemicals White Blood Cell Types
- eosinophils
- basophils
- neutrophils
- lymphocytes
- monocytes
Cells and Chemicals White Blood Cells Function
WBCs enhance the innate defenses by:
- attacking microorganisms directly
- hindering the ability of microorganisms to move, grow, reproduce, etc.
Cells: Neutrophil Function
- Fastest responders to bacteria
- Direct actions against bacteria
- release lysosomes to digest bacterial cell walls
- release defense proteins that act like antibiotics and form pores in bacterial cell membranes, destroying them
- release strong oxidants (e.g. H2O2) that destroy bacteria
Cells: Basophil Function
Exit capillaries at sites of inflammation and play a role in allergic reactions
-release heparin, histamine, and serotonin which heighten the inflammatory response and can often contribute to hypersensitivity (allergic) reactions
Cells: Eosinophils Function
- respond to and attack parasitic worms
- enter ISF and releases histaminase (slows down inflammation caused by basophils)
- able to phagocytize antibody-antigen complexes
Cells: Lymphocyte Function
- Most types involved in adaptive immunity
- B lymphocytes
- T lymphocytes - Natural killer (NK) cells are involved in innate immunity
- attack many different microbes directly
- attack spontaneously arising tumor cells
Cells: Monocyte Function
Arrive later to sites of infection, but arrive in much larger numbers
- destroy microbes and clean up dead tissue following an infection
- become wandering macrophages in ISF
Cells and Chemicals: Natural Killer (NK) Cells
- NK cells are a specialized class of T-lymphocytes which perform generalized functions
- kill tumor cells
- kill some virus infected cells - NK cells kill via CYTOLYSIS
- secrete a chemical known as perforin, which perforates the cell membrane - Reduces NK cell counts can be associated with HIV/AIDS
Cells and Chemicals: Antimicrobial Proteins
- Like WBCs, antimicrobial proteins enhance innate defenses
- Specifically, antimicrobial proteins:
- (also) attack microorganisms directly
- hinder the ability of some microorganisms to reproduce - The two most important types of antimicrobial proteins are:
- interferons
- complement proteins
Antimicrobial Proteins- Interferons
- interferons are proteins that are produced by virus-infected body cells, T lymphocytes, natural killer cells and macrophages
- interferons and other chemical messengers that alter cellular activities are called cytokines
- the action of interferons is non-specific, meaning that they work effectively against a large number of virus types
The Complement System
- refers to over 30 specific proteins that “complement” or enhance the action of antibodies
- complement proteins attach to antibody-antigen complexes
- the end result of attachment is the formation of membrane attack complex (MAC) which punches holes in bacterial cell membranes (attraction of phagocytes, stimulation of phagocytosis, and inflammation are also the result of complement activation)
C3 can be activated via:
- classical pathway
- alternative pathway
- lectin pathway
Innate Immunity (non-specific resistance to disease)
Lines of defense against invasion of pathogens:
- physical barriers
- fever
- inflammation
- cells and chemicals
Adaptive Immunity
- Body’s ability to recognize and defeat a specific invading agents such as bacteria, viruses and foreign tissues
- Distinguished from innate immunity by two properties
1. Specificity for particular foreign molecules (foreign antigens) and tolerance for self proteins
2. Memory of previously-encountered foreign antigens so that the 2nd exposure prompts a more rapid and vigorous response
Molecular Information in Residual Bodies:
- things present in extracellular fluid
2. if what was destroyed is something truly foreign
Peptide fragments >8 amino-acids in length
human and bacterial protein sequences can be distinguished from each other
MHC Proteins
- immune system’s ID and anti-privacy/surveillance system
- display information in the form of peptides (pieces of protein) to the immune system
Function of MHC Class II Proteins
- present small fragments of protein called processed antigen to the cells of the immune system
- presented antigen is from protein components of materials engulfed and digested by phagocytes (MHC II displays extracellular antigen)
Helper T cells
have T cell receptors whose job it is to interact with MHC II- presented antigen
Random Sampling (every nucleated cell randomly samples the proteins in its cytoplasm and does the following)
- digests the protein into small peptide fragments of 8-15 amino acids in length
- displays those fragments on MHC I
- as if to say “here is a sample of what proteins I am making”
> 8 amino-acids in length
human and bacterial protein sequences can be distinguished from each other
Function of MHC I proteins
- present small fragments of protein called “processed antigens” to the cells of the immune system
- presented antigen is from randomly-sampled proteins inside of cells (MHC I displays intracellular antigen)
Cytotoxic T cells
have T cell receptors whose job it is to interact with MHC presented antigen
