Immunology 2 Flashcards
What is immunolgy?
The study of an organism’s defense system
What is the immune system composed of?
Organs (spleen)
Cells (T-cells)
Molecules (antibodies)
What are 4 microbes?
Viruses
bacteria
Fungi
Protozoa
What are the 5 organs of the immune system?
Tonsils
Thymus
Spleen
Bone marrow
Lymph nodes
What is a primary lymphoid organ?
Production of white blood cells
What is a secondary lymphoid organ?
Sites where immune responses are initiated
Describe the spleen in terms of the secondary lymphoid organs
Site of initiation for immune responses against blood-borne diseases
Describe bone marrow in terms of the primary lymphoid organs
Source of stem cells that develop into innate and adaptive immune responses
Describe the thymus in terms of primary lymphoid organs
School for T cells to learn not to react to the wrong cells
Describe the lymph nodes in terms of secondary lymphoid organs
Located along lymphatic vessels
Drains lymph fluid and filters from blood and tissues
Site of initiation of immune Reponses
What is the epidermis comprised of?
Dead cells, keratin, and phagocytic immune cells
What is the dermis comprised of?
Thick layer of connective tissue, collagen, blood vessels
What layer of the skin are the dendritic cells located?
Dermis
What is the purpose of a lysozyme?
Breaks down bacterial cells walls on the skin
Describe the skin’s chemical defense system
Pores which secrete:
- Lysozymes
- Sebum (low pH)
- Salt (hypertonic)
Where are the mucosal membranes?
Ocular (eye)
Respiratory (throat/lungs)
Oral (stomach)
Urogenital/rectal
What is a mucosal membrane?
Live layer of mucus producing cells
Describe the process of the mucociliary escalator
Dust and other particles get stuck on the mucus. Cilia move the mucus up the pharynx.
What are the chemical defenses of the mucosal surfaces?
Stomach
Gall Bladder
Intestine
Mucus
Defensins
Lysozymes
What is the function of the stomach as a chemical defense of mucosal surfaces?
Low pH
What is the function of the gall bladder as a chemical defense of mucosal surfaces?
Bile
What is the function of the intestine as a chemical defense of mucosal surfaces?
Digestive enzymes
What is the function of the lysozymes as a chemical defense of mucosal surfaces?
Tears, urine
Which has more layers, skin or the mucous membranes?
Skin
Are the cells of the mucous membranes loosely packed?
No
Is sebum present in mucous membranes?
No
Is cilia present in skin?
No
What are the two surface barriers of the immune system?
Skin and mucous membranes
What is the difference between innate and adaptive immunity?
Innate immunity is rapid, and because it is already in place, has limited specificities and no specific memory.
Adaptive immunity is variable, and is highly specific, it can ‘learn’ and therefore has a long-term memory
What parts of the immune system are part of the innate immunity?
Surface barriers
Internal defences
What are the internal defences?
Phagocytes
Natural Killer Cells
Inflammation
Antimicrobial properties
Fever
What parts of the immune system are part of the adaptive immunity?
Humoral Immunity
Cellular Immunity
What are the humoral immunities?
B cells
What are the cellular immunities?
T cells
What is blood composed of?
Plasma and Cells
What is plasma composed of?
Proteins
Other solutes
Water
What are the formed elements of blood?
Platelets
White blood cells
Red blood cells
What are the two types of blood cells derived from hematopoietic stem cells?
Myeloid
Lymphoid
Red blood cells are what kind of cell?
Myeloid
B and T cells are examples of what kind of cell?
Lymphoid
White blood cells
Granulocytes, monocytes, dendritic cells, and platelets are all types of what cell?
Myeloid
White blood cells (except platelets)
What is the purpose of a granulocyte in the blood?
Circulate in the blood and can move into tissue during inflammation
What is the function of a neutrophil
Highly phagocytic, numbers increase with infection
What is the purpose of granulocytes in tissue?
Mast cells
Line mucosal surfaces
Releases granules that attract white blood cells to areas of tissue damage
Are fast acting
What is the purpose of monocytes?
When they are present in the blood, they have low phagocytosis
When they enter tissues, they become highly phagotic macrophages
What is the purpose of a macrophage?
They are either sessile or migratory
- Phagocytosis
- Release of chemical messages
- Share info about microbes to T cells
What is the purpose of a dendritic cell in immune responses?
Links Innate and adaptive immune responses.
Phagocytic
Trigger adaptive immune responses
How do the cells of the immune system move around the body?
Carried in the blood and lymph, allowing them to leave and enter tissues.
Lymph in tissues collects and drains into lymph nodes
What is a PAMP?
Pathogen-associated molecular patterns.
Building blocks
What are the common building blocks of viruses?
Nucleic acids: ssRNA and dsDNA
What are the common building blocks of a bacteria cell wall?
Lipopolysaccharides (LPS)
Endotoxins
Lipoteichoic acid
What are the common building blocks of a bacteria flagellum?
Flagellin
What are the common building blocks of Bacterium nucleic acid?
Unmethylated CpG DNA
Describe pattern recognition receptors in a phagocytic cell
Receptors can either be on the outside or inside of a cell.
On the outside, they work to recognise bacterium and viruses on the cell membrane.
Within the cell, the phagolysosomes break down the bacteria and viruses into nucleic acids to recognise them.
All information is then sent to the nucleus of the cell
What is the purpose of fever/pyrexia?
Inhibits bacterial replication
Some features of the immune system work better at higher temperatures
What is the first step of the inflammatory response?
Chemical signals are released from resident cells to attract more cells to the injury site
What is the process of neutrophils in an inflammatory response?
Enter blood from bone marrow and cling to the capillary wall. They are then attracted to the site of the injury by the chemical trail.
What do the chemical signals from resident cells do during the inflammatory response?
Dilate blood vessels and make capillaries leakier, allowing neutrophils to get out.
True or false:
Myeloid cells are NOT phagocytic?
False
Describe the 5 stages of phagocytosis
Phagocyte recognises pathogen by adhering to it
Phagocytes form around the pathogen and forms a pseudopod, engulfing the particle and forming a phagosome.
Lysosomes fuse with the phagocytic cell.
Toxic compounds in the lysosome break down the pathogens.
Exocytosis sometimes removes the indigestable parts.
What happens when a lysosome and phagosome join?
A phagolysosome is formed because phagosomes do not have the right environment to break down and kill the pathogen or debris
Describe the killing and digestion of phagocytosed microbes
There is a low pH
Reactive hydrogen and nitric oxide intermediates
Enzymes
What are the 3 enzymes that break down pathogens in phagolysosomes?
Proteases
Lipases
Nucleases
Describe what happens during the complement cascade
A series of proteins that act in a sequence, allowing pathogens to be labelled and broken down
What are the 3 stages of the complement cascade?
Label pathogens
Recruit phagocytes
Destroy pathogens
Describe the process of opsonisation in the complement cascade
Pathogens are labelled so that they can bind to phagocytic cells and be uptaken during phagocytosis. This can either be through an antibody or a complement fragment of C3b.