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220 Cards in this Set
- Front
- Back
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sensory neurons
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a nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system
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ganglia
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a cluster of nerve cell bodies in a centralized nervous system
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interneurons
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an association neuron; a nerve cell within the central nervous system that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output
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nerves
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a rope-like bundle of neuron fibers (axons) tightly wrapped in connective tissue
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motor neurons
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nerve cells that transmits signals from the brain or spinal cord to muscles or glands
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Central Nervous System
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brain and a longitudinal nerve cord
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peripheral nervous system
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neurons that carry information into and out of the CNS
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cell body
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the part of a neuron that houses the nucleus and most other organelles
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dendrites
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highly branched extensions that receive signals from other neurons
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axon
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an extension of a neuron that transmits signals to other cells. axons are much longer than dendrites, can be over 1 meter long
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axon hillock
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the cone-shaped region of an axon where it joins the cell body
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synapse
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the junction where one neuron communicates with with another cell across a narrow gap. Neurotransmitter molecules released by the neuron diffuse across the synapse, relaying messages to the other cell
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synaptic terminal
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a bulb at the end of an axon in which neurotransmitter molecules are stored and from which they are released
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neurotransmitters
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a molecules that is released from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to the postsynaptic cell, triggering a response
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presynaptic cell
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the transmitting neuron
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postsynaptic cell
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the neuron, muscle or gland cell that receives the signal from the neurotransmitter
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glia
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supporting cells, nourish neurons, insulate axons, regulate extracellular fluid
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membrane potential
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a voltage difference across the plasma membrane of cells
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resting potential
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the membrane potential of a resting neuron--one that is not sending signals
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ion channels
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pores formed by clusters of specialized proteins that span the membrane, allow ions to diffuse back and forth across membrane
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selective permeability
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only certain ions are allowed to pass.
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equilibrium potential
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the magnitude of the membrane voltage at equilibrium. the resting potential of a neuron is much closer to Ek than Ena
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gated ion channels
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ion channels that open and close in response to stimuli. this forms the basis of nearly all electrical signaling in the nervous system
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hyperpolarization
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the oppositte of depolarization. the inside of the membrane becomes more negative relative to the outside. reduces the chance that a neuron will transmit a nerve impulse
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depolarization
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a change in the cell's membrane potential such that the inside of the membrane is less negative to the outsde. For example, a neuron membrane is depolarized if stiumulus decreases its voltage of -70mV towards 0
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sodium-potassium pump
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a transport protein in the plasma membrane of animal cells that actively transports sodium of of the cell and potassium into the cell
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graded potentials
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when the change in membrane potential is based on the strength of the stimulus. they are not the actual nerve signals that travel along axons, but they have a major effect on the generation of nerve signals
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voltage-gate ion channels
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ion channels that open or close in response to a stimulus
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action potential
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a rapid change in the membrane potential of an excitable cell, caused by stimulus-triggered, selective opening and closing of voltage-sensitive gates in sodium and potassium ion channels
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threshold
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the potential that an excitable cell must reach for an action potential to be initiated
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resting state
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the gated Na+ and K+ channels are closed. ungated channels maintain resting potential
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rising phase of the action potential
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deplarization opens most sodium channels,while the potassium channels remain closed. Na+ infllux makes the inside of the membrane positive with respect to the outside
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falling phase of the action potential
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most sodium channels become inactivated, blocking Na+ inflow. Most potassium channels open, permitting K+ outflow, which makes the inside of the cell negative again
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undershoot
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the sodium channels close, but some potassium channels are still open. as these potassium channels close and the sodium channels become unblocked, the membrane returns to its resting state.
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refractory period
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the "downtime following an action potential when a second action potential cannot be initiated
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myelin sheath
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a layer of electrical insulation that surrounds vertebrate axons
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oligondendrocytes, schwann cells
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two types of glia that produce myelin sheaths. oligondendrocytes are in the CNS and shwann cells in the PNS
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nodes of Ranvier
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gap in the myelin sheath of certain axons where an action potential may be generated. In salatory conduction, an action potential is regenerated at each node, appearing to "jump" along the axon from node to node
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saltatory conduction
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rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of ranvier to another, skipping the myelin-sheathed regions of the membrane
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electrical synapses
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synapses that contain gap junctions and do allow electrical current to flow directly from one neuron to another. synchronize the activity of neurons responsible form rapid, unvartying behaviors
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chemical synpases
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makes up the majority of synapses. involves the release of a chemical neurotransmitter by the presynpatic neuron
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synaptic vesicles
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membranous sac containing neurotransmitter molecules at the tip of an axon
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synaptic cleft
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the narrow gap that separates the presynaptic neuron from the postsynaptic cell
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ligand-gated ion channel
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a protein pore in cellular membranes that opens or closes in response to a signaling chemical (its ligand) allowing or blocking the flow of specific ions
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excitatory postsynaptic potential
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an electrical charge (depolarization) in the membrane of a postsynaptic cell caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more likely for a postsynaptic cell to generate an action potential
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inhibitory postsynaptic potential (IPSP)
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an electrical change (usually hyperpolarization) in the membrane of a postsyptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more difficult for a postsynaptic neuron to generate an action potential
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temporal summation
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on some occasions, two EPSPs occur at a single synapse ini such rapid succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the arrival of the second EPSP. then, the EPSPs add together
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spatial summation
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EPSPs produced nearly simultaneousy by different synapses on the same postynaptic neuron add together
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acetylcholine
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one of the most common neurotransmitters, functions by binding to receptors and and altering the permeability of the postsynaptic membrane to specific ions, either depolarizing or hyperpolarizing the membrane
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biogenic amines
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neurtransmitters derived from amino acids
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serotonin
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a biogenic amine synthesized from tryptophan
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dopamine
epinephrine norepinephrine |
neurotransmitters that are catecholamines
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gamma-aminobutyric acid (GABA)
glutamate |
the two amino acids taht serve as teh major neurotransmitters in the vertebrate CNS.
GABA-the neurotransmitter at most inhibitory synapses in the brain, produces IPSPs by increasing the permeability of the postynaptic membrane to Cl- |
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neuropeptides
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relatively short chains of amino acids
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supstance P
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a key excitatory neurotransmitter that mediates our perception of pain
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endorphins
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a neurpeptide that functions as a natural anesthetic
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nerve net
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a web-like system of neurons, characteristic of radially symmetrical animals, such as hydra
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nerve
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a rope-like bundle of neuron fibers(axons) tightly wrapped in connective tissue
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reflexes
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the body's automated response to certain stimuli
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central canal
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the narrow cavity in the center of the spinal cord that is continuous with the fluid-filled ventricles of the brain
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cerebrospinal fluid
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blood-derived fluid that surrounds, protects against infections, nourishes, and cushions the brain and spinal cord
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gray matter
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consists of mainly neuron cell bodies, dendrites, unmyelinated axons
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white matter
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bundled axons that have myelin sheaths, which give the axons a white-ish appearance
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astrocyte
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a glial cell witih diverse functions, including providing structural support for neurons, regulating interstitial environment, facilitating synaptic transmission, assisting in regulating the blood supply to the brain
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blood-brain barrier
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a specialized capillary arrangement in the brain that restricts the passage of most substances into the brain, thereby preventing dramatic fluctuations in the brain's environment
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radial glia
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in an embryo, supporting cells that form tracks along which newly formed neurons migrate from the neural tube; can also act as stem cells that give rise to other glia cells and neurons
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cranial nerves
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connect the brain with locations mostly in organs of the head and upper body
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spinal nerves
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run between the spinal cord and parts of the body below the head
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motor system
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consists of neurons that carry signals to skeletal muscles, mainly in response to external stimuli. subject to conscious control
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autonomic nervous system
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reguolates internal environment by controlling smooth and cardiac muscles and the organs of the digestive, cardiovascular, excretory, and endocrine systems
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sympatic division (nervous s ystem)
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corresponds to arousal and energy generation, prepares body for action, "fight or flight" response
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parasympatic division
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promotes calming and a return to self-maitenance functions "rest and digest"
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enteric division
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PNS. consists of networks of neurons in the digestive tract, pancreas, and gallbladder. control secretion, smooth muscles that produce peristalsis
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hormone
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a molecule that is secreted into the extracellular fluid, circulates through the blood or hemolymph, and communicates regulatory messages throughout the body
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nervous system
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a network of specialized cells-neurons-that transmit signals along dedicated pathways
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endocrine system
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chemical signals by horomones
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endocrine glands
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a ductless gland that secretes hormones directly into the interstitial fluid, from which they diffuse into the bloodstream
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exocrine gland
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have ducts that secrete substances onto body surfaces/body cavities
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local regulators
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secreted molecules that act over short distances and reach their target cells solely by diffusion
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paracrine signaling
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secreted molecules diffuse locally and trigger a response in neighboring cells
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autocrine signaling
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secreted molecules diffuse locally and trigger a respons in the cells that secrete them
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synaptic signaling
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neurotransmitters diffuse across synapses and trigger responses in cells of target tissues( neurons, muscles, or glands)
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neuroendocrine signaling
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neurohorones diffuse into the bloodstream and trigger resonsees in target cells anwhere in the body
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endocrine signaling
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secreted molecules diffuse into the bloodstream and trigger responses in target cells anywhere in the body
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neurotransmitter
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a molecule that is released from the synaptic terminal of a neuron at a chemical synapse, diffuses acros the synaptic cleft, and binds to the postsynaptic cell, triggering a response
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neurohormone
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a molecule that is secreted by a neuron, travels in body fluids, and acts on specific target cells to change their functioning
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neurosecretory cells
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specialized neurons typically found in the brain that secrete molecules that diffuse from nerve cell endings into the bloodstream
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pheromones
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chemicals released into external environment. mark trails leading to food, define territory, ward off predators, attract potential mates
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signal-transduction
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the series of changes in cellular proteins that converts the extracellular signal to a specific cellular response
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epinephrine
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catecholamine hormone that mediates the "fight or flight" response to short-term stress. also known as adrenaline
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cytokine
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any group of proteins secreted by a number of cell typ0es, including macrophages and helper T cells, that regulate the function of lymphocytes and other cells of the immune system
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prostaglandins
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one of a group of modified fatty acids secreted by virtually all tissues and performing a wide variety of functions as local regulators
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negative feedback
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a loop in which the response reduces the initial stimulus
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insulin
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hormone secreted by pancreatic beta cells, lowers blood glucose levels promotes uptake of glucose by most body cells and synthesis/storage of glycogen in the liver, also stimulates protein and fat synthesis
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glucagon
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promotes release of glucose into the blood when glucose drops below set point
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islets of langerhans
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clusters of endocrine cells, each islet has alpha cells that make glucagon and beta cells tha tmake insulin
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diabetes mellitus
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caused by a defficiency of insulin or a decreased resonse to insulin in target tissues. blood glucose levels rise but cells can't take up enough to make metabolic needs
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ecdysone
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promotes each successive molt and metamorphasis of caterpiller
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juvenille hormone
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a hormone in anthropods that maintains the larval (juvenille) charachteristics
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pituitary gland
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and endocrine gland at the base of the hypothalamus, has posterior and anterior regions
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posterior pituitary
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an extension of the hypothalamus composed of nervous tissue that secretes oxytocin and antidiuretic hormone made in the hypothalamus. its a temporary storing site for these hormones
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anterior pituitary
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a portion of the pituitary that develops from nonneural tissue, consists of endocrine cells that synthesize and secrete several tropic and nontropic hormones
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oxytocin
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regulates milk release during nursing. mediated by a simple neurohormone pathway
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positive feedback
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reinforces a stimulus, leading to an even greater response
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antidiuretic hormone
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regulates blood osmolarity and kidney function. increases water retention in kidneys, thereby decreasing urine volume
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tropic hormone
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a hormone that regulates the function of endocrine cells or glands
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FSH, LH, ACTH
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act primary or exclusively as tropic hormones. FSH and LH stimulate the activities of the gonads, and the testes/ovaries. ACTH (adrenocorticotropic hormone) stimulates the production and secretion of steroid hormones by the adrenal cortex
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Prolactin (PRL)
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non-tropic. has diverse effects among vertebrate species. stimulates mammary gland growth/milk synthesis in mammals, regulates fat metabolism and reproduction in birds, delays metamorphosis in amphibians, regulates salt and water balance in freshwater fishes. suggests that this is an ancient hormone with functions that have diversified over time
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melanocyte-stimulating hormone (MSH)
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regulates the activity of pigment-containing cells in the skin of some amphibians. in mammals, acts on neurons in the brain, inhibiting hunger
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growth hormone
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stimulates growth both through tropic and non-tropic events
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thyroid gland
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an endocrine gland, locatedon the ventral surface of the trachea, that secretes two iodine-containing hormones, triodothronine (T3) and thyroxine(T4) as well as calcitonin
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parathyroid gland
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any of four small endocrine glands, embedded in the surface of the thyroid gland, that secrete parathyroid hormones (PTH) and play a major role in Ca2+ regulation. when Ca2+ falls below a set point it sectetes PTH
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parathyroid hormone (PTH)
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raises the level of blood Ca2+. in bone, causes the mineralized matrix to decompose and release Ca2+ into the blood. in kidneys, it stimulates reabsorbtion of Ca2+ through the renal tubules
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calcitonin
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a hormone that inhibits bone resorptino and enhances Ca2+ release into the kidney. contributes to calcium homeostasis
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adrenal glands
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one of the two endocrine glands located adjacent to the kidneys in mammals. each adrenal gland has two portions, adrenal cortex and adrenal medulla. each is a fused endocrine and neuroendocrine gland
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adrenal cortex
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responds to endocrine signals.the outer portion of the adrenal glands. consists of "true" endocrine cells.cells respond to ACTH by secreting steroid hormones that help maintain homeostasis during long-term stress
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adrenal medulla
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responds to neural signals. secrete epinephrine and nor-epinephrine in response to nervous inputs triggered by short-term stress. cells are derived from neural tissue during embryonic development
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catecholamines
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a class of amine hormones synthesized from the amino acid tyrosine.epinephrine and norepinephrine are examples
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norepinephrine
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similar to epinephrine, secreted in resonse to stress, increases amount of chemical energy available for immediae use. both epinephrine and norepinephrine increase rate of glycogen breakdown by liver and skeletal muscles to increase body fuel
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corticosteroids
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any steroid hormone produced and secreted by the adrenal cortex
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thyroid gland
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an endocrine gland, locatedon the ventral surface of the trachea, that secretes two iodine-containing hormones, triodothronine (T3) and thyroxine(T4) as well as calcitonin
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parathyroid gland
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any of four small endocrine glands, embedded in the surface of the thyroid gland, that secrete parathyroid hormones (PTH) and play a major role in Ca2+ regulation. when Ca2+ falls below a set point it sectetes PTH
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parathyroid hormone (PTH)
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raises the level of blood Ca2+. in bone, causes the mineralized matrix to decompose and release Ca2+ into the blood. in kidneys, it stimulates reabsorbtion of Ca2+ through the renal tubules
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calcitonin
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a hormone that inhibits bone resorptino and enhances Ca2+ release into the kidney. contributes to calcium homeostasis
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adrenal glands
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one of the two endocrine glands located adjacent to the kidneys in mammals. each adrenal gland has two portions, adrenal cortex and adrenal medulla. each is a fused endocrine and neuroendocrine gland
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adrenal cortex
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responds to endocrine signals.the outer portion of the adrenal glands. consists of "true" endocrine cells.cells respond to ACTH by secreting steroid hormones that help maintain homeostasis during long-term stress
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adrenal medulla
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responds to neural signals. secrete epinephrine and nor-epinephrine in response to nervous inputs triggered by short-term stress. cells are derived from neural tissue during embryonic development
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catecholamines
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a class of amine hormones synthesized from the amino acid tyrosine.epinephrine and norepinephrine are examples
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norepinephrine
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similar to epinephrine, secreted in resonse to stress, increases amount of chemical energy available for immediae use. both epinephrine and norepinephrine increase rate of glycogen breakdown by liver and skeletal muscles to increase body fuel
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corticosteroids
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any steroid hormone produced and secreted by the adrenal cortex
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myofibril
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muscle fibers contain bundles of theses arranged longitudinally. consists of think filaments and thick filaments
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thin filaments
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two strands of actin and two strands of a regulatory protein coiled around one anothers
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thick filaments
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staggered arrays of myosin molecules
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striated muscle
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skeletal muscle, arranged in a pattern of light and dark bands. has repeating units called sarcomeres
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sarcomere
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the basic contractile unit of the muscle. borders are lined up in adjacent myofibrils and contribute to striations. thin filaments are attached at the Z lines and project toward center of sarcomere, thick filaments are attached at M lines and centered at sarcomere
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sliding-filament model
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neither the thin or thick filaments contract, they just slide past each other longitudinally, increasing the overlap of the filaments
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tropomyosin
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the regulatory protein that blocks the myosin-binding sites on actin molecules
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troponin complex
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the regulatory proteins that control the position of tropomyosin on the thin filament
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transverse tubule
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and infolding of the plasma membrane of skeletal muscles
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sarcoplasmic reticulum
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a specialized endoplasmic reticulum. spread of the action potential along the t tubules triggers changes in the SR, opening Ca2+ channels. calcium ions stored in the SR flow through the channels into the cytosol and bind to the troponin complex, initiating contraction of the muscle fiber
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motor unit
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consists of a single motor neuron and all the muscle fibers it controls
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recruitment
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the process of progressively increasing the tension of a muscle by activating more and more of the motor neurons controlling the muscle
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tetanus
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when the rate of stimulation is so high that the muscle fiber cannot relax at all between stimuli, the twitches fuse into one, smooth contraction
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myoglobin
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an oxygen-storing protein found in oxidative fibers. it binds oxygen more tightly than hemoglobin, so it can extract oxygen from the blood
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oxidative fibers
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rely mostly on aerobic respiration. have many mitochondria, a rich blood supply, a lot of myoglobin.
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glycolytic fibers
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rely primarily on glycolysis. have a larger diameter nd less myoglobin than oxidative fibers. fatigue faster.
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fast-twitch fiber
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develop tension much faster. used for brief, rapid, powerful contractions. myosin heads hydrolize faster. can be oxidative or glycolytic. glycolitic ones can be converted to oxidative, so they they fatigue more slowly
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slow twitch fibers
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has less sarcoplasmic reticulum and pumps Ca2+ slower. can last longer. always oxidative.
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cardiac muscle
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have ion channels that cause rhythmic depolarization, triggering action potentials without input from the nervous system. have intercarlated discs
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intercarlated discs
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where the plasma membranes of adjacen cardiac muscle cells interlock. gap junctions provide direct coupling between cells
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smooth muscle
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found mainly in the walls of hollow organs. thick filaments are scattered, thin are attached to structures called dense bodies, less myosin, myosin is not associated with specific actin strands. no troponin complex or T tubules. Ca2+ enters mainly through plasma membrane during action potentials.
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hydrostatic skeleton
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consists of fluid held under pressure in a closed body compartment. main type of skeleton in most cnidarians, flatworms, nematodes, annelids.
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exoskeleton
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hard encasement deposited on an animal's surface
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endoskeleton
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hard supporting elements, such as bones, buried within soft tissues of an animal
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locomotion
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active travel from place to place
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lymphatic system
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a system of vessels and nodes, separate from the circulatory system, that returns fluids, proteins and cells to the blood.
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lymph
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the fluid in the lymphatic system
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lymph nodes
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an organ located along a lymph vessel. filter lymph and contain cells that attack viruses and bacteria
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pathogens
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infectious agents that cause disease
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innate immunity
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active immediately upon infection, same whether or not the pathogen has been encountered previously. barrier defenses: skin, mucous membranes, secretions. internal defenses: phagocytic cells, antimicrobial proteins, inflammatory response, natural killer cellss
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acquired immunity
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recognition of traits specific to particular pathogens, using a vast array of receptors. slower response. humoral response: antibodies defend against infection in body fluids. cell mediated response: cytotoxic lymphocytes defend against infection in body cells
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lysozyme
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an enzyme that destroys bacterial cell walls
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phagocytosis
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the ingestion and digestion of bacteria and other foreign substances
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Toll-like receptor (TLR)
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a membrane receptor on a phagocytic white blood cell that recognies fragments of molecules common to a set of pathogens.
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neurophils
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the most abundant phagocytic cells. signals from infected tissues attract neutrophils, which engulf and destroy microbes
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macrophages
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"big eater", very effective phagocytic cells. can move.
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eosinophils
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a phagocyte. low phagocytic activity but are important in defending against multicellular invaders, such as parasite worms. rather than engulfing them, they postition themselves against parasite's body and discharge destructive enzymes that damage invader
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dendritic cells
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a phagocyte. populate tissues that are in contact with the environment. mainly stimulate development of acquired immunity against microbes they encounter
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interferons
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proteins that provide innate defense against viral infections. virus-infected body cells secrete these and induce nearby uninfected cells to produce substances that inhibit viral reproduction. limit cell-to-cell spread
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complement system
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consists of roughly 30 proteins in blood plasma that function together to fight infections.amplify inflammatory response, enhance phagocytosis, directly lyse extracellular pathogens
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inflammatory response
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innate immune defense triggered by physical injury, release of substances that promote swelling, enhance infiltration of white blood cells, aid in tissue repair and destruction of invading pathogens
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histamine
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an important inflammatory signaling molecule
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mast cells
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connective tissues cells that store chemicals in granules for secretion. produces histamine and other molecules that trigger inflmammation in response to infection and allergic reactions
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pyrogens
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can reset body's thermostat to a higher temperature, inducing fever
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septic shock
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overwhelming systemic inflammatory response. high fever, low blood flow/blood pressure.
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natural killer cells
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a type of white blood cell that can kill tumor cells and virus-infected cells as parte of innate immunity
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lymphocyte
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a type of white blood cell that mediates acquired immunity. two main classes are B and T cells
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thymus
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a small organ in the throacic cavity where maturation of T cells is completed
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T cells
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class of lymphocytes that mature in the thymus. includes effector cells for the cell-mediated immune response and helper cells for both innate and acquired immune response
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B cells
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lymphocytes that mature in the bone marrow, become effector cells for humoral immune response
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immunological memory
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an enhanced response to a foreign molecule encountered previously
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cytokines
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proteins secreted by phagocytic cells that help recruit and activate lymphocytes
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antigen
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any foreign molecule that is specifically recognized by lymphocytes and elicits a response
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antigen receptors
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embedded in the plasma membranes of B and T cells. each one has about 100,000 on its surface.
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antibody, immunoglobulin
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proteins secreted by B cells that binds to a particular antigen. a soluble form of the antigen receptor. y-shaped. have same organization as B cells but lack the transmembrand region and cytoplasmic tail. antibodies are secreted rather than membrane-bound.
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epitope
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also called antigenic determinant. a small, accessible portion of an antigen that antigen receptors and antibodies recgnize. all of the antigen receptors on a single lymphocyte are identical and recognize the same epitope
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B cell receptor
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y-shaped molecule consisting of four polypeptide chains: two identical heavy chains and two identical light chains, with disulfide bridges linking them.
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constanc (C) region
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where amino acid sequences are mostly the same among the receptors of different B cells. includes the cyoplasmic tail and transmembrane region of the heavy chain and all of the disulfide bridges.
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variable (V) region
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where the amino acid sequence varies extensively from one B cell to another. together, parts of a heavy-chain V region and a light chain V region form an asymmetrical binding site for an antigen
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T cell receptor
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the antigen receptor on T cells. membrane-bound molecule consisting of one alpha and one beta chain linked by a disulfide bride and containing one antigen-binding site
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major histocompatibility complex (MHC)
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a family of genes that encode a large set of cell-surface proteins that function in antigen presentation. foreign MHC molecules on transplanted tissue can trigger T cell responses that may lead to rejection of the transplant
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antigen presentation
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the process by which an MHC molecule binds to a fragment of an intracellular protein antigen and carries it to the cell surface, where it is displayed and can be recognized by a T cell
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class I MHC molecule
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a type of MHC molecule found on the surface of nearly all nucleated cells and that functions in identification of infected cells by cytotoxic T cells
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class II MCH molecule
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a type of MHC molecule restricted to a few specialized immune cell types (dendritic cells, macrophages,and B cells) that serve as antigen-presenting cells
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cytotoxic T cell
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a type of lymphocyte that, when activated, kills infected cells as well as certain cancer cells and transplanted cells
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antigen-presenting cell
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a cell that upon ingesting pathogens or internalizing pathogen proteins generates peptide fragments that are bound by class II MHC molecules and subsequently displayed on the cell surface to T cells. macrophages, dendritic cells, and B cells are theprimary antigen-presenting cells
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helper T cell
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a type of cell that, when activated, secretes cytokines that promote the resonse of B cells (humoral response) and cytotoxic T cells (cell-mediated response) to antigens
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effector cells
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activateed B cells or T cells divide many times, forming these cells which are short lived and attach the antigen and any pathogens producing that antigen
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memory cell
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produced by activated B or T cells, bear receptors for an antigen. are long-lived and active in the secondary immune response
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clonal selection
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the presentation of an antigen to specific receptors on a lymphocye leads to repeated rounds of cell division. the result is a clonal population of thousands of cells, all specific for that antigen
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primary immune response
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the production of effector cells from a clone of lymphocytes during the first exposure to an antigen
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plasma cells
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antibody-secreting effector B cells generated by other B cells during primary immune response
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secondary immune response
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used if individual has been exposed to antigen before. relies on the memory of T and B memory cells generated following initial exposure
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humoral immune response
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the branch of acquired immunity that involves the activation of B cells and leads to the production of antibodies, which defend against bacteria and viruses in body fluids
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cell-mediated immune response
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the branch of acquired immunity that involves activation of cytotoxic T cells, which defend against infected cells
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CD4
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a surface protein, present on most helper T cells, that binds to class I MHC molecules, enhancing the interaction between the T cell and a target cell. helps keep them joined
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CD8
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a surface protein, present on most cytotoxic T cells, that binds to class I MHC molecules, enhancing the interaction between the T cell and target cell. helps keep them joined
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polyclonal
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antibodies that are products of many different clones of B cells, each specific for a different epitope
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monoclonal antibodies
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any of a preparation of antibodies that have been prduced by a single clone of cultured cells and thus are all specific for the same epitope. useful for tagging specific molecules
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neutralization
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one way in which the binding of antibodies to antigens interferes w/ pathogen function. antibodies bind to surface proteins of a virus/bacterium, thereby blocking the pathogen's ability to infect a host cell.
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opsonization
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when the antibodies bound to antigens present a recognized structure for macrophages and therefore increase phagocytosis
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membrane attack complex
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binding of antigen-antibody complexes on a microbe or foreign cell to one of the complement proteins triggers a cascade in which each protein of a complement system activates the next. forms a pore in the membrane of the foreign cell. ions and water rush into the cell, causing it to swell and lyse.
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active immunity
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when clones of memory cells form in response to infection
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passive immunity
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when the antibodies of a pregnant women cross the placenta to her fetus. transferred antibodies guard against microbes that have never infected the fetus. they go away when the fetus is born.
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immunization, vaccination
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artificially-induced active immunity
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allergens
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exaggerated responses to certain antigens
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autoimmune disease
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when the immune system turns against particular molecules of the body
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immunodefficiency
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a disorder in which the ability of an immune system to protect against pathogens is defective or absent
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AIDS
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an acquired immunodeficiency caused by a virus
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latency
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when viruses remain in a host without activating immune defences, they are dormant
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