Topic 11 Flashcards
What is an antigen?
Any foreign molecule that triggers an immune response
Is the antigen on the pathogen?
YES
What are the most common antigens?
Proteins and polysaccharides
What do the surface of our own cells contain?
Proteins and polypeptides
What does the immune system function based on?
Recognising the distinction between foreign and self antigens
What do antigens on red blood cells stimulate?
Antibody production in a person with a different blood group
What are blood groups based on?
Prescence of certain anitgens on RBCs
What are important in blood transfusions?
-ABO blood group and the Rhesus ( Rh) as mismatches can lead to an immune response
What happens when there is transfusion with the wrong blood type?
Aggultination
What is agglutination?
When the RBCs clump together
What happens after agglutination?
Hemolysis
What do beta cells produce?
Plasma and memory cells
Beta cells
- divide many times by mitosis to generate a clone of plasma cells that all produce the same anti body type
- these antibodies persist in the body for a few weeks and plasma cells are lost when infection is overcome
- small number of beta cells become memory cells and remain inactive unless reinfection occurs where they become active and respond rapidly
What is clonal selection?
Plasma cells that produce one specific antibody type
Immunity
- Due to persistance of memory cells that produce antibodies
- Develops when the immune system is challenged by a specific antigen and produces antibodies
What is secondary immune response?
When memory cells ensure that the 2nd time the antigen is encountered the body is ready to respond
Vaccines
-Contain a weakened version of the pathogen which stimulates a primary immune response so that if the micro-organism enters again it will be destroyed by the secondary immune response
Histamines
- secreted by mast cellls
- causes dilation of small blood vessels in the infected area causing them to become leaky which increases the flow of fluid containing immune components to the area
- causes allergic symptoms like rashes, nose itching, sneezing, anaphylaxis
What do anti-histamines do?
Decrease the allergic symptoms
Monoclonal antibodies
- produced by hybridoma cells ( the hybridoma divides and forms a clone where they are cultured in a fermenter and secrete monoclonal antibodies)
- can be used to test for Malaria, HIV and the creation of antibdies for injection into rabies victims
- many hybridomas are produced and they are tested to find the one that produces the required antibody
Pregnancy testing
-Use monoclonal antibodies to detect hCG which is produced by the embryo and later the placenta
What is hCG?
Human chorionic gonadotrophin
What can the immune system be described as?
Challenge and response
Specific immune response
- Macrophage ingests pathogen and displays antigens for it
- Helper T cells specific to the antigen are activated
- b cells specific to the antigen are activated by proteins from Helper T cells
- B cells divide repeatedly to produce plasma cells that secrete antibodies
- B cells also produce memory cells
- Antibodies produced by the plasma cells are specific to the antigen on the pathogen
plasma cells
- Secrete antibodies
- mature B lymphocytes
- their cytoplasm has a rough eR which modifies and transports network proteins
What is the role of antibodies?
To destroy pathogens
What are the 4 ways in which antibodies destroy pathogens?
- Agglutination ( pathogens stick together so they are prevented from entering cells and easier for phagocytes to ingest)
- Oponisation ( makes the pathogen more recognisable to phagocytes)
- Neutralisation ( prevent viruses from docking onto host cells and bind to toxins produced by pathogens preventing them from infecting susceptible cells)
- Complement system ( complement cascade activated )
Smallpox
- 1st infectious disease to have been eradicated by vaccines
- campaign was successful because only humans can catch it, symptoms emerge quickly allowing teams to ring vaccinate all the people who might have come in contact with the infected person, immunity is long lasting
Zoonosis
- diseases that can pass through the species barrier
- examples are the bubonic plague, lyme disease, bird flu
- there has been an increase in zoonotic diseases because increase in contact between humans and animals
Hybridoma cells
- tumour + plasma cell
- Antigen recognised by the antibody is injected into the mammal
- Mouse’s immune system makes plasma B cells
- 3.Plasma cells are removed from the spleen
- B cells are fused with the cancerous cells
- This forms a hybridoma
What is an exoskeleton?
External skeletons that surrond and protect most of the body surface of animals like insects
Bones and exoskeletons
-Provide anchorage for muscles and act as levers
Levers
- Change the size and direction of forces
- Is an effort force
- A pivot point ( called a fulcrum)
- Resultant force
What 3 things determine the class of a liver?
-Fulcrum, effort force and resultant force
What are the features of a 1st class lever?
The fulcrum is between the effort and resultant force
What are the features of a 3rd class lever?
The fulcrum is at the body end and the effort force is between the fulcrum and resultant force
Antagonistic muscles
- Movement of the body requires antagonistic pairs
- when one contracts and the other relaxes
- produces opposite movement at a joint
Insect legs
- Antagonistic muscles
- PREPARE FOR JUMPING – flexor muscles contract bringing the tibia and the tarsus to resemble a Z and t, extensor relaxes
- The femur and tibia are brought together
- Extensor muscles then contract, the the flexor muscle relaxes and the tibia is pushed away from the femur DURING JUMPING
Skeletal muscle contraction
- Achieved by the sliding of actin and myosin filaments
- myson pulls the actin filament to the centre of the sacromere which shortens the sarcomere and muscle fibre length
- Myosin is able to do this because they have heads that bind to special sites on the actin creating cross bridges through which they can exert a force with energy from ATP
What are the features of a relaxed skeletal muscle fibre?
- LIght bands wider
- Sarcomere is longer
- Z line further apart
Ranges of movement
- Different joints allow different ranges of movement
- Joint structure and ligaments determine the movements possible
Knee joint
- HInge joint which allows flexion and extension
- greater range of movement when flexed
Hip joint
- Ball and socket joint
- Can rotate, flex, extend, move sideways and back
Striated muscle
- are multinucleate and contain specialised endoplasmic reticulum
- composed of muscle fibres
- each fibre is surronded by a sarcolemma
- the endoplasmic reticulum = sarcoplasmic reticiulum which wraps around the myofibril conveying the signal to contract to all parts at once and stores calcium
Myofibril
- in muscle fibres
- composed of alternating light and dark bands and a z line between 2 light bands
- made up of sarcomeres
Sarcomeres
- the part of the myofibril between one z line and the next
- light and dark bands are due to the thin actin filaments and thick myosin filaments
- Actin = attatched to a z line at one end
- Myosin = occupy the centre
Draw a sarcomere
Control of skeletal muscle contraction
- calcium ions, tropomyosin, troponin control action
- Muscle is relaxed – Tropomyosin blocks the actin binding sites, sarcoplasmic reticulum releases calcium ion, the ions bind to troponin which causes tropomyosin to move
- myosin heads then bind towards the centre moving the actin filaments
ATP hydrolysis
What are the two key functions that excretory functions perform?
- Removes nitrogenous wastes that may be toxic to the body in large concentrations
- Removes excess water to maintain a suitable osmolarity within the tissues and cells
How are nitrogenous wastes produced?
Breaking down amino acids and nucletodies
What do aquatic animals eliminate their nitrogenous waste as?
NH3 (ammonia)
What do mammals excrete their nitrogenous waste as?
Urea which is
Explain how the nephron changes the composition of blood.
higher nitrogen/urea as blood enters nephron/Bowman’s capsule than when it leaves the nephron (in the renal vein);
b. most small soluble molecules/glucose/nutrients/ions are removed from blood in Bowman’s capsule;
c. through ultrafiltration;
d. proteins / blood cells / large molecules remain in the blood;
e. as filtrate moves through the nephron (tubule), water is returned to the blood (by osmosis);
f. glucose/nutrients is returned to blood by active transport (and diffusion) / selective reabsorption;
g. in the proximal convoluted tubule;
h. urea / uric acid remain in the filtrate / removed from blood;
i. sodium is pumped into the medulla in the loop of Henlé;
j. water reabsorption is enhanced by a high sodium gradient (in the medulla);
k. permeability of the collecting duct membrane is regulated by hormones / ADH;
l. water concentration in urine is variable to maintain homeostasis in the blood;
m. more oxygen/less carbon dioxide in blood entering (kidney) than in blood leaving (kidney);
