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61 Cards in this Set
- Front
- Back
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what is the structure of a neuron and its components, the dendrites and axon
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specialized for transmitting signals from one location in body to another - cell body includes two structures
- dendrites - axons |
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what is the structure of a dendrite
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receives signal - conveys to rest of neuron
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what is the structure of an axon
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conduct message toward tip
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what is the function of sensory neurons
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communicate information from receptors to CNS
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what is the function of the interneurons
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integrate sensory and motor output - connect only with other neurons
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what is the function of motor neurons
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convey information from CNS to effector cells
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what is the function of supporting cells
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provide support for nerves
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- interprets information from stimulation of sensory receptors and associates with appropriate responses by body
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Central Nervous System (CNS)
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- communicates sensory and motor signals between CNS and rest of body
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Peripheral Nervous System (PNS)
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- membrane potential of nonconducting excitable cell - normally negative
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Resting potential
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- rapid change in membrane potential of excitable cell - caused by opening and closing of sodium and potassium ion gates in membrane - causes changes in concentrations inside and outside of cell
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Action potential
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Potassium ions (+ charge) higher inside cell
Proteins & amino acids (- charge) normally higher inside cell In nonconducting nerve cell, charge at rest negative (-70mV) |
resting potential
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Protein “gates” in membrane
Pump sodium ions out of cell and potassium ions into cell (against concentration gradient) - requires energy Maintains negative charge on inner surface of membrane (resting potential) |
sodium potassium pump
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what are the phases of action potential
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-depolarizing
- repolarizing - undershooting |
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- sodium gates open - influx of sodium ions causes positive charge to develop on inner side of membrane
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Depolarizing phase
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potassium gates open - outflux of potassium ions causes negative charge to develop on inner side of membrane
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Repolarizing phase -
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- continuing outflux of potassium accentuates negative charge
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Undershoot
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what is the refractory period
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at initial site prevents “backward” movement of impulse
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Presynaptic cell receives impulse - causes calcium to enter nerve cell
Synaptic vesicles containing neurotransmitter fuse with membrane - neurotransmitter released into synapse Neurotransmitter binds to receptor(s) in postsynaptic cell - causes response Neurotransmitter degraded rapidly |
transmission between cells chemical synapses
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What is an electrical synapse and what role do gap junctions play in the transmission of nerve impulses between such cells
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Gap junctions between cells allow ion currents of action potential to flow between neurons
Action potential spreads directly from presynaptic cell to postsynaptic cell |
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- gates allow Na+ to enter & K+ to exit - neurotransmitter depolarizes membrane
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Excitatory postsynaptic potential
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- gates allow Cl- to enter & K+ to exit- neurotransmitter hyperpolarizes membrane
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Inhibitory postsynaptic potential
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- chemical transmissions close together in time
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Temporal summation
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- transmissions close together in space
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Spatial summation
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- transmissions close together in space
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Spatial summation
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one of most common in vertebrates and invertebrates - degraded by cholinesterase
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Acetylcholine
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what are the bodies nospecific defenses
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- skin and mucous membrane
- phagocytic cells, antimicrobial proteins and the inflammatory response |
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first line of defense - represent barriers to infection - secretions may contain antimicrobial proteins (e.g., lysozyme)
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skin and mucous membrane
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- second line of defense - nonspecific - affect wide range of pathogens
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Phagocytic cells, antimicrobial proteins and inflammatory response
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what are the different trypes of phagocytic cells
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- neutrophils
- monocytes - eosinophils - Natural killer cells |
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- constitute 60-70% of all white blood cells - attracted by chemical signals - life span short - tend to self-destruct after phagocytosis
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Neutrophils
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- circulate for a few hours, then develop into large macrophages (“big eaters) - enter tissues
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Monocytes
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- defense against larger invaders - e.g., parasitic worms
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Eosinophils
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- do not attack microorganisms directly - attack membrane of virus-infected or abnormal cells - cause lysis
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Natural Killer (NK) Cells
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Provides highly-specific defense(s) against foreign molecules (antigens)
Components provide immediate defense against invaders and confer long-term immunity to certain pathogens Involves activities of several types of lymphocytes (white blood cells) |
Body’s third line of defense
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what is an antigen
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foreign molecule or abnormal cell
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do particular pathogens or toxins have only one antigen or many?
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they have numerous amounts
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what are the basic types of lymphocytes
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- b cells
- cytotoxic t cells - helper t cells |
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- develop in bone marrow - when activated, secrete antibodies - humoral response
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B Cells
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- develop in thymus -when activated, attacks and destroys infected body cells - cell-mediated response
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Cytotoxic T Cells
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- responds to antigen - when activated, mediates both branches of immune system
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Helper T Cells
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what happens when an antigen is is exposed to a new antigen
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Initial exposure to antigen “selects” lymphocyte with appropriate receptor
Selected B or T cell proliferates - produces clones of effector cells (for immediate defense) and memory cells (for long-term immunity) - “clonal selection” - clones highly specific for that particular antigen Humoral (antibody-mediated) response - involves secretion of antibodies by activated B cells - marks foreign molecules or abnormal cells for destruction Cell-mediated response - activated Cytotoxic T cells become active killers - destroy infected or abnormal cells Both branches mediated by Helper T cells |
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what is the difference between primary and secondary responses
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Primary immune response - occurs following initial exposure to particular antigen - generates clones of effector cells and memory cells - specific to that particular antigen
Secondary immune response - occurs following subsequent exposure to antigen - response more pronounced - longer duration |
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- occurs following subsequent exposure to antigen - response more pronounced - longer duration
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Secondary immune response
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- occurs following initial exposure to particular antigen - generates clones of effector cells and memory cells - specific to that particular antigen
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Primary immune response
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how do self tolerance by lymphocytes develop
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While developing in bone marrow (B cells) or thymus (T cells), receptors tested for potential self-reactivity - receptors reactive against native molecules rendered nonfunctional or destroyed by programmed cell death (apoptosis)
Receptors interact with major histocompatability complex (MHC) molecules - cell surface markers involved in antigen presentation Failure of self-tolerance results in autoimmune disorders |
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how do molecules of the major histocompatibility complex present particles of antigen to T cells
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MHC molecule cradles fragment of antigen and presents it to T cell
Each antigen-MHC complex forms unique complex that is recognized by specific antigen receptors on certain T cells Receptors of Cytotoxic T cells bind to Class I MHC molecules - receptors of Helper T cells bind to Class II MHC |
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what is the general term for the type of diseases that develop when the immune system loses its self tolerance
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autoimmune disease
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- hypersensitive responses to certain antigens - in extreme cases, may lead to anaphylactic shock
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Allergies
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- humoral and/or cell-mediated response adversely affected and/or disfunctional - HIV and AIDS
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Immunodeficiency diseases
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what is the purpose of immunizations
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Organism innoculated with dead or weakened microbes - unable to cause disease - acts as antigen - triggers immune response (humoral and cell-mediated)
Memory cells & antibodies confer long-term immunity to pathogen |
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Potassium ions (+ charge) higher inside cell
Proteins & amino acids (- charge) normally higher inside cell In nonconducting nerve cell, charge at rest negative (-70mV) |
resting potential
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Protein “gates” in membrane
Pump sodium ions out of cell and potassium ions into cell (against concentration gradient) - requires energy Maintains negative charge on inner surface of membrane (resting potential) |
sodium potassium pump
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Presynaptic cell receives impulse - causes calcium to enter nerve cell
Synaptic vesicles containing neurotransmitter fuse with membrane - neurotransmitter released into synapse Neurotransmitter binds to receptor(s) in postsynaptic cell - causes response Neurotransmitter degraded rapidly |
transmission between cells electrical synapses
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receives impulse - causes calcium to enter nerve cell
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presynaptic cell
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- causes response
Neurotransmitter degraded rapidly |
postsynaptic cell
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allow ion currents of action potential to flow between neurons
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gap junctions
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- gates allow Na+ to enter & K+ to exit - neurotransmitter depolarizes membrane
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Excitatory postsynaptic potential
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- gates allow Cl- to enter & K+ to exit- neurotransmitter hyperpolarizes membrane
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Inhibitory postsynaptic potential
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one of most common in vertebrates and invertebrates - degraded by cholinesterase
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Ach
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distinguishing characteristics of animals and occur in a variety of forms
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nervous systems
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