Topic 6.3/11.1 Flashcards
Pathogen
Microbes that cause disease
List the primary defence of the body
Skin and mucous membranes
Outline how the skin acts as a barrier to infection
- Tough layer and provides a physical barrier against the entry of pathogens
- Protection against physical and chemical damage
- Sebaceous glands secrete sebum that maintains skin moisture and lowers skin pH (inhibits the growht of bacteria and fungi)
Outline how the mucous membranes act as a barrier to infection
- Secrete a sticky solution of glycoproteins
- Pathogens and harmful particles are trapped in it (swallowed or expelled)
- Antiseptive properties because of the anti-bacterial enzyme lysozyme
Outline the benefits of blood clots
- Seals up the wound and prevents further loss of blood and blood pressure
- Prevents entry of pathogens until new tissue has grown to heal the cut
Outline reasons for a reaction mechanism to regulate blood clotting
- Clots can cause blockages if they occur inside blood vessels
- Should only occur when the skin is cut and the blood vessel is severed
Platelets
- Cellular fragments that circulate in the blood
- Release clotting factors
Outline the process of blood clotting
- Platelets aggregate at the site of injury, forming a temporary plug
- Release clotting factors that trigger off the production of thrombin (enzyme) - Thrombin converts soluble protein fibrinogen into insoluble fibrin
- Fibrin forms a mesh in cuts that traps more platelets and blood cells
- The clot is initially a gel, but dries and forms a hard scab when exposed to air
Coronary thrombosis
- Formation of blood clots in the coronary arteries
- Block suupply of oxygen and nutrient
- Can be fatal unless resolves naturally or through medical intervention
Outline how atherosclerosis cause occlusion in the coronary arteries
- Atheroma develops
- The endothelium of the arteries tends to become damaged and roughened (especially by deposition of calcium salts)
- Atheroma sometimes rupture and cuase a lesion
- Increases the risk of coronary thrombosis
List the factors of increased risk of coronary thrombosis and heart attack
- Smoking
- High blood cholesterol concentration
- High blood pressure
- Diabetes
- Obesity
- Lack of exercise
Describe how phagocytes provide non-specific immunity to diseases
- Squeeze out through pores in the walls of capillaries and move to sites of infection
- Engulf pathogens by endocytosis
- Digest pathogens with enzymes from lysosomes
- Dead phagocytes form pus
Antigen
- Chemicals that induce an immune response inside the body
- Proteins (glycoproteins or other macromolecules) on the surface of the cell membrane of the pathogen that are recognized by a specific antibody
Antibodies
- Protein molecules produced by B-lymphocytes
- Recognize and bind to the antigens on the foreign pathogens
- Each antibody is specific to each type of antigen
State the substance that stimulate a specific immune response
Antigen
Why does it take time for the body to fight off a disease (specific immunity)
- Initially there are few lymphocytes that target the specific antigen
- They produce few antibodies and cannot control a pathogen
- Antigens on the pathogen sticulate cell division of the specific lymphocytes and produce enough antibodies to ctonrol th epathogen and clear the infection
Describe the structure of antibodies
- Two functional regions
- Hypervariable region that binds to a specific antigen
- Another region that helps the body to fight the pathogen in several ways
Memory cells
- Some lymphocytes produced during an infection are not active plasma cells
- Become dormant until the body encounters the same pathogen again
- Then they replicate rapidly
Descibe why the immune response is faster for a second response than first response
- Memory cells can quickly replicate and produce enough antibodies to target the pathogen
Antibiotic
- Chemical that inhibits that growth of microorganisms
- Most ar antibacterial
- Blockprocesses that occur in prokaryotes but not in eukaryotes
- Used to kill bacteria inside the body wihtout causing harm to human cells
What processes in bacteria are targeted by antibiotics
- Bacterial DNA replication
- Transcription
- Translation
- Ribosome function
- Cell wall formation
State the type of cells that human immunodeficiency virus target
Helper T-cell
Outline the consequence of human immunodeficiency virus
- Progressive loss of capacity to produce antibodies
HIV positive
- Early stage of infection
- Immune system makes antibodies against HIV and can be detected
Retrovirus
- Virus that has inheritary information stored in RNA
- Use reverse transcriptase to make DNA copies of its genes once it has entered a host cell
Describe three ways that HIV can transmit from person to person
- Sexual intercouse, during which abrasions to the mucous membranes of the penis and vagina can cause minor bleeding
- Transfusion of infected blood, or blood products such as Factor VIII
- Sharing of hypodermic needles by intravenous drug users
Who discovered penicillin
Alexander Fleming
Who tested penicillin on bacterial infections in mice
- Howard Florey
- Ernst Chain
Outline Florey and Chain’s experiment on mice
- Four infected mice were given injections with penicillin
- All of the untreated mice were dead by the four were healthy
Outline the purpose of molecules on the surface of cells
- Usually polysaccharides (antigens) and proteins/polypeptides (on our body cells)
- Recognize the distinction between antigens and body cells
Antigen H
- Basic antigen sequence on all three allels of blood types (A, B, O)
- Modified by the addition of molecules in different blood types (galactose for antigen B and N-acetylalactosamine for antigen A)
Describe the consequence of receiving the wrong type of blood
- Immune response, agglutination (clumping)
- Hemolysis where red blood cells are destroyed and blood may coagulate in the vessel
Macrophages
- Ingest pathogens
- Display antigens in the plasma membrane
Describe the role of helper T cells in the immune response
- Helper T cells have an abtibody-like receptor protein in their plasma membrane
- Bind to antigens displayed by the macrophages
- Only a few helper T cells have receptor proteins that fit the antigen
- Once binded, the helper T cells are activated by the macrophage
- The activated helper T cells bind to B cells and activate them (by binding and releasing a signalling protein)
Plasma cells
- Mature B lymphocytes
- Produce and secrete large number of antibodies during an immune response
What cell structure does plasma cells have in abundance and why
- rough endoplasmic reticulum (rER)
- Manufactures, modifies, and transports protein (antibodies)
Clonal selection
- Generation of large numbers of plasma cells that produce one specific antibody type
State five ways how antibodies aid in the destruction of pathogens
- Opsonization
- Neutralization of viruses and bacteria
- Neutralization of toxins
- Activation of complement
- Agglutination
Opsonization
- Antibodies make a pathogen more recognizable to phagocytes
- Once bound, they can link the pathogen to phagocytes
Neutralization of viruses and bacteria
Antibodies can prevent viruses from docking to host cells so that they cannot enter the cells
Neutralization of toxins
- Antibodies can bind to the toxins produced by pathogens
- Prevent them from affecting susceptible cells
Activation of complement
- The complement system is a collection of proteins which ultimately lead to the perforation of the membranes of pathogens
- Antibodies bound to the surface of a pathogen activate a complement cascade
- Allow water and ions to enter into the pathogen, causing it to lyse
Agglutination
- Antibodies can cause sticking together of pathogens
- Prevent from entering cells
- Easier for phagocytes to ingest
- The large allutinated mass can be filtered by the lymphatic system and then phagocytized
Outline what immunity is depended on
- Persistence of memory cells (allow production of antibodies)
- Presence of antibodies that recognize antigens
Annotate and explain the graph
- the primary immune response is launched the first time the pathogen infects the body
- the secondary immune response is launched the second time the pathogen infects the body
- memory cells ensure that the second time the pathogen is encountered, the body is ready to respond rapidly by producing more antibodies at a faster rate
Vaccine
- Contain antigens that trigger immunity but do not cause the disease
- Live attenuated (weakened) version of the pathogen
Outline how vaccination works
- Ingject a weakened or dead pathogen
- Stimulates a primary immune response
- If the actual microorganism enters the body, it will be destroyed quickly in a secondary immune response
State the first infectious disease that have been eradicated by vaccination
Smallpox
Outline the three reasons for the successful eradication of smallpox
- Only humans can catch and transmit the disease
- Symptoms emerge quickly and are readily visible
- Immunity to smallpox is long-lasting
Epidemiology
Study of distribution, patterns, and causes of disease in a population
Give an example of species-specific disease
- Syphilis, polio and measles are specific to humans
Give an example of cross specifies disease
- Avian flu, swine flu, zoonosis, bubonic plague
Mast cells
Immune cells found in connective tissue that secrete histamine in response to infection
Histamine
- Released by mast cells and basophils (that circulate in the blood)
- Causes the dilation of the small blood vessels in the infected area
- Increases the flow of fluid containing immune components to the infected area, leading to specific and non-specific immune responses
- Contributes to a number of symptoms of allergic reactions
What causes allergic symptoms
Histamine
What are some allergic symptoms
- Itching
- Inflammation
- Fluid build-up
- Sneezing
- Mucus secretion
- Rashes
- Dangerous swelling (leading to anaphylaxis)
Monoclonal antibodies
- Highly specific, purified antibodies that are produced by a clone of cells
- Recognize only one antigen
Hybridoma cell
Fusion of a tumour cell with an antibody-producing plasma cell
Describe the produce of producing monoclonal antibodies
- Antigen recognized by the antibody is injected into a mammal
- The immune system of the mammal makes plasma B cells producing specific antibody
- Plasma cells are removed and fused with cancer cells
Why are cancer cells used in the production of antibodies
Reproduce rapidly
Name some diagnostic tests that use monoclonal antibodies
- HIV antibodies
- Heart attack
- Pregnancy test
Describe how preganacy test strip works
- Immobilized antibodies to hCG (point C)
- Free antibodies to hCG attached to a dye (point B)
- Immobilized antibodies that bind to the dye-bearing antibodies (point D)
- Urine applied to the ened of the strip washes antibodies down the strip
human chorionic gonadotrophin (hCG)
- Uniquely produced during pregnancy by the developing embryo and later the placenta
- The urine of a pregnant woman contains detectable levels of hCG
