Topic 11 - Animal Physiology Flashcards
antigen
any substance that is recognized as “not-self” by the body
how do white blood cells distinguish between self and not-self?
- all body cells have the same genetic info and a common set of plasma membrane proteins
- any cells with those membrane proteins are “self” and any without those proteins are “not-self”
B lymphocyte
- plasma cells capable of synthesizing specific antibodies to bind to specific antigens
problem with using only B lymphocytes as immune defense
- B lymphocytes are few in number (just 1% of cells in the bloodstream)
- thus cellular communication methods are necessary to lead to the cloning of the appropriate B lymphocyte cell
polyclonal response
i. e. primary immune response
1. A macrophage (large phagocyte) encounters an antigen found on a pathogen
2. The macrophage engulfs the pathogen via phagocytosis and partially digests it
3. Molecular pieces of the pathogen are displayed on the cell membrane of the macrophage (antigen presentation)
4. Helper T cells (leucocytes) recognize the antigen and activate the relevant B lymphocyte
5. Upon activation, the lymphocyte begins a series of cell divisions (cell cloning)
types of cloned B cells
- plasma cells: immediately secretes antibodies to help fight off the primary infection
- memory cells: long-lived, doesn’t secrete antibodies, but retains information on the antigen to be used on secondary infection
true immunity
- occurs after the steps of the primary response
- as memory cells are long-lived, they can respond to a secondary infection more quickly and effectively
antibodies
- Y-shaped protein molecules
- produced by lymphocytes in response to a specific pathogen
- the main difference between each antibody lies in the 2 amino acids at the end of each Y fork
- they’re used to bind to a specific antigen and are identical to each other
ways antibodies help the immune system
- binds to pathogen and marks it for destruction
- binding pathogens together (agglutination) to help phagocytic cells locate them
how does a vaccine confer immunity without resulting in symptoms?
- vaccines are composed of the chemical components of a pathogen after the disease-causing abilities have been removed
- however, leucocytes still recognize the antigen as not-self
- so the primary immune response still takes place
how can diseases cross from one species of host to another?
- a protein to protein match must occur for a virus to recognize another species’ cell as a host cell
- this normally happens if the two species are in close contact for extended periods (i.e. long enough for viral mutations to occur)
why is the primary immune response also called a “polyclonal response”?
- a virus’ capsid (protein coat) is made up of multiple types of protein
- so it’s typically recognized as more than one antigen
- each of the protein types stimulate an immune response, so more than one B lymphocyte will undergo clonal selection
- once a polyclonal response occurs, it’s difficult to separate the different kinds of antibodies produced
monoclonal antibodies
antibodies of the same type (“pure”)
how are monoclonal antibodies produced?
- An antigen is injected into an animal
- The animal is given time to undergo a primary immune response
- After some time the animal’s spleen is harvested to obtain blood cells
- B leucocytes are isolated and grown together with myeloma cells under proper conditions, resulting in their fusion to form hybridoma cells (retains their function but with extended lifespan)
- The entire mix is transferred to an environment only the hybridoma cells can survive; each hybridoma cell is then isolated to be cultured in separate containers
- Each container is given the ELISA (enzyme-linked immunosorbent array) test to test for a specific protein – this test identifies which containers hold a pure colony of B cells that produce the specific antibody desired
example of monoclonal antibody usage
- pregnancy testing
- the hormone human chorionic gonadotropin (HCG) is only produced by the embryo
- so it can only be found in the bloodstream of pregnant women (and even then only in small amounts)
- hybridoma cells can be formed that produce antibodies specific to HCG
- those anti-HCG antibodies can be chemically bonded to an enzyme that catalyses a color change when the antibody encounters HCG
allergic response
- immune response occurring when leucocytes encounter a non-pathogenic substance (allergen)
- the primary immune response to allergens involve the synthesis of the antibody IgE
- IgE binds to mast cells (type of WBC)
- when the allergens are encountered a second time, IgE antibodies bind to the allergen
- this causes the mast cell to release large quantities of histamine, which causes allergy symptoms
function of skeleton
- support
- attachment points for muscles
- individual bones and segments also act as levers to maximize efficiency of movement
- for animals with exoskeletons, this leads to incredible strength/agility
antagonistic pairs
- a muscle can only contract to cause movement
- muscles work in pairs so that two opposite actions can occur
synovial joints
bone-to-bone joints
- with a capsule-like space containing a lubricant called synovial fluid
- the ends of the bones in the capsule are cushioned with cartilage to cushion bone-to-bone contact
parts of the human elbow
- cartilage
- synovial fluid
- joint capsule
- tendons
- ligaments
- biceps muscle
- triceps muscle
- humerus
- radius
- ulna
parts of the human elbow: cartilage
- reduces friction
- absorbs compression
parts of the human elbow: synovial fluid
- lubricates to reduce friction
- provides nutrients to cartilage cells
parts of the human elbow: joint capsule
- encloses the synovial cavity
- unites the connecting bones
parts of the human elbow: tendons
attaches muscle to bone
parts of the human elbow: ligaments
connects bone to bone
parts of the human elbow: biceps muscle
contracts to cause flexion (bending)
parts of the human elbow: triceps muscle
contracts to cause extension (straightening)
parts of the human elbow: humerus
acts as lever to allow anchorage of elbow muscles
parts of the human elbow: radius
acts as lever for biceps
parts of the human elbow: ulna
acts as lever for triceps
types of muscle tissue
- smooth muscle
- cardiac muscle
- striated (skeletal) muscle
components of muscle tissue
- thousands of muscle cells (muscle fibres)
- surrounding connective tissues, blood cells, and nerves
components of muscle fibre
- sarcolemma
- sarcoplasm
- multiple nuclei just within sarcolemma
- myofibrils
sarcolemma
- plasma membrane of muscle fibre
- contains multiple invaginations called transverse tubules (T tubules)
sarcoplasm
- cytoplasm of muscle fibre
- contains large numbers of organelles that store glycogen as an energy reserve
- also contains myoglobin
myoglobin
- similar to haemoglobin
- acts as an emergency store of oxygen
- only used when muscle tissue is very heavily used and the normal supply becomes limited
myofibrils
- tubules running parallel to each other in muscle fibre
- spaces in between them are packed with mitochondria
sarcomeres
- contractile units
- found in myofibrils
- contains actin and myosin
- repeating sarcomeres are the reason why striated muscles have a banded pattern
how do muscle fibres work?
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