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82 Cards in this Set
- Front
- Back
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why are drugs considered to be psychoactive for the most part?
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they alter ongoing functions in the brain. they influence behavior and psychological processes.
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what is the optimal normal body temperature?
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98.6 degrees F (37 degrees C)
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what is the definition of homeostasis?
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General: staying the same
specific: maintenance of an environment of body functions within a certain range. |
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what are the 2 types of cells found throughout the nervous system?
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1. neurons, sometimes referred to as nerve cells
2. glia, also called glial cells |
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what are neurons responsible for?
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analyzing and transmitting information.
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how many neurons does the nervous system contain?
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more than 100 billion
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describe the function of the neurons membrane.
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each neuron is contained within a single membrane that seperates the inside of the neuron from the outside.
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what are the 4 parts of a neuron?
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1. cell body
2. dendrites 3. axon 4. axon terminals |
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what is the function of the cell body?
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it is the central region of a neuron, which is the control center.
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what are dendrites?
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branchlike structures that extend from the cell body & specialize in receiving signals from other neurons.
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what is an axon?
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a thin tube that extends from the cell body and specializes in transmitting signals to other neurons.
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what are axon terminals?
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the end region of the axon
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dendrites have receptors within their membranes. what are receptors?
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specialized structures that recognize and respond to specific chemical signals.
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where are neurotransmitters stored?
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in the axon terminals, in small, round packages known as synaptic vesicles.
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what percentage of the cells in the human brain are glia?
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90%
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what is the meaning of the Greek word glia?
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"glue"
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what are some functions of glia cells?
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1. provide firmness & structure to the brain
2. responsible for getting nutrients in the system 3. eliminating waste 4. forming myelin |
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what is myelin?
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It's a white fatty substance that is wrapped around the axons of some neurons to form a myelin sheath, which increases the information-processing speed of these neurons.
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what is the onset of the autoimmune disease multiple sclerosis caused by?
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a loss of myelin wrappings
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another important function of glia is to create the blood-brain barrier. what is the blood-brain barrier and its function?
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a barrier between the blood and the fluid that surrounds neurons. it is semipermeable. it protects the brain from potentially toxic chemicals circulating in the blood.
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for a drug to be psychoactive what must happen?
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It's molecules must be capable of passing through the blood-brain barrier.
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what is an essential process for neuronal communication?
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action potential. this electrical signal initiates a chain of events that allows one neuron to communicate with another through the release of neurotransmitters.
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what causes the action potential to occur?
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it occurs as a result of the opening of ion channels that allow electrically charged particles called ions to move inside of the cell. this change moves the cell's membrane away from its resting potential to a more positively charged voltage.
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what happens when the cell membrane is at rest?
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there is an uneven distribution of ions between the inside and the outside of the cell.
there are more potassium (K+) ions and negatively charged organic anions on the inside of the cell. there are more sodium (Na+) and (Cl-) ions on the outside of the cell. |
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what are the sources of the negative resting potential across the membrane?
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the uneven distribution of ions and opened (K+) channels. in this state, the neuron is hyperpolarized.
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what generates the action potential?
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a sequential opening and closing of ion channels in the neuron's membrane. as Na+ channels open, Na+ ions rapidly move across the membrane into the cell. as a result, the cell is depolarized. if the cell is depolarized to the threshold of excitation, an all-or-none potential will occur.
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More helpful info. Flip card.
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Action potential = all-or-none b/c once initiated it will travel to the axon terminal w/o reduction.
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more helpful info. flip card.
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During the action potential, additional Na+ channels open allowing the influx of even more Na+ ions. Near the peak of the action potential, more K+ channels now open, while Na+ channels close. The now positive internal state of the cell causes K+ ions to exit the cell, which causes the membrane potential to become even more negative than it is at rest. Once K+ certain channels close, the cell will return to its normal resting level.
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a figure of action potential. flip card.
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From left to right
BOX1: Open K+ channels create resting potential BOX 2: Na+ channels open, depolarizing the cell to threshold BOX 3: Additional voltage-gated Na+ channels open, causing rapid change of polarity--the action potential. BOX 4: Na+ channels are inactivated; gated K+ channels open, repolarizing and even hyperpolarizing the cell (undershoot phase) BOX 5: All gated channels close. The cell returns to its resting potential. |
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what are receptors?
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Recognition mechanisms that respond to specific chemical signals.
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what are neurotransmitters?
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Chemical messengers released from axon terminals.
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what are synaptic vesicles?
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Small bubbles of membrane that store neurotransmitters.
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what is myelin?
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A fatty white substance that is wrapped around portions of the axons.
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what is an autoimmune disease?
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A condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue.
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define multiple sclerosis
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An autoimmune illness caused by damage to the myelin sheath that wraps axons. A wide range of symptoms can accompany this disorder including muscle spasms, vision loss, severe pain, dizziness, fatigue, and intestinal problems.
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What is the blood-brain brain barrier?
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Structure that prevents many drugs from entering the brain.
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Define semipermeable
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Allowing some, but not all, chemicals to pass.
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What is neurotransmission?
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The process of transferring information from one neuron to another at a synapse.
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What is action potential?
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The electrical signal transmitted along the axon when a neuron fires.
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What are ion channels?
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when proteins in the cell membrane form pores that allow the passage of ions from one side of the membrane to the other.
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Define an ion.
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An atom or molecule that has a net electrical charge because of a difference in the number of electrons and protons.
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Define resting potential
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The voltage maintained by a cell when it is not generating action potentials. The resting potential of neurons is about - 65 mV
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Define hyperpolarized
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When the membrane potential is more negative.
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Define depolarized
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When the membrane potential is less negative.
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What nerve cells are referred to as a somatic system?
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The nerve cells that are on the "front lines", interacting with the external environment.
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What is the responsibility of the nerves in the somatic system?
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These peripheral nerves carry sensory information into the central nervous system and carry motor (movement) information back out. The cranial nerves that relate to vision, hearing, taste, smell, chewing, and movement of the tongue and face are included, as are spinal nerves carrying information from the skin and joints and controlling movement of the arms and legs.
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Does the somatic nervous system serve for voluntary actions or involuntary actions?
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Voluntary actions
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What is the relationship between acetylcholine and your muscles?
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It is the neurotransmitter at neuromuscular junctions in the somatic system. It acts on receptors that excite the muscle.
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What does ANS stand for and what is its function?
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Autonomic nervous system; monitors and controls our body's internal environment. Regulates the visceral, or involuntary, functions of the body, such as heart rate and blood pressure.
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What does acetylcholine inhibit?
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Heart muscle contraction
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What are the two branches of the autonomic nervous system.
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Sympathetic and parasympathetic
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What is one difference between the sympathetic and parasympathetic nervous systems?
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In the parasympathetic nervous system acetylcholine is the neurotransmitter at the end organ.
In the sympathetic branch norepinephrine is the neurotransmitter at the end organ. |
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Define acetylcholine
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Neurotransmitter found in the parasympathetic branch in the cerebral cortex.
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Define autonomic
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The part of the nervous system that controls "involuntary" functions, such as heart rate.
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Define sympathetic
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The branch of the autonomic system involved in flight or fight reactions
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Define parasympathetic
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The branch of the autonomic system that stimulates digestion, slows the heart, and have other effects associated with a relaxed physiological state.
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Define norepinephrine
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Neurotransmitters that may be important for regulating waking and appetite.
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The sympathetic system is interconnected, so it tends to act more as a unit. What functions does the sympathetic system control all together?
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To open the bronchi, reduce blood supply to the skin increase the heart rate, and reduce stomach motility. This has been called the fight or flight response.
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How do amphetamines stimulate the functions of the sympathetic nervous system?
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They have a chemical structure that resembles norepinephrine
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What are sympathomimetic drugs?
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Drugs that activate the sympathetic branch
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What does the central nervous system consist of?
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The brain and spinal cord. These two structures form a central mass of nervous tissue, with sensory nerves coming in and motor nerves going out. This is where most of the integration of information, learning and memory, and coordination of activities occur.
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more helpful info. Flip card.
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cells in the nucleus accumbens receive input from dopamine fibers that arise in the ventral tegmental area in the midbrain to form the mesolimbic dopamine pathway.
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what do we know about the mesolimbic dopamine pathway?
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overactivation of dopamine neurons in this pathway produces hallucinations, which are attenuated by dopamine-blocking drugs.
pathway has been proposed to mediate some types of psychotic behavior such as those seen in schizophrenia. |
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picture of the Mesolimbic & Nigrostriatal Dopamine Pathways
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what forms the Nigrostriatal Dopamine Pathway of the midbrain?
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cells from the substantia nigra course together past the hypothalamus, and terminate in the striatum to form this pathway.
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what can cause Parkinson's disease?
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a substantial loss of cells in the Nigrostriatal Dopamine Pathway. the disease can be defined as a dopamine-deficiency disorder.
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what is the treatment for Parkinson's disease?
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L-dopa is the precursor of dopamine. dopamine itself is not administered as a treatment because it does not readily cross the blood-brain barrier.
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what can be a cause or reason for having Alzheimer's disease?
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low levels of acetylcholine
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what is the nucleus accumbens?
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a collection of neurons in the forebrain that plays an important role in reward and emotional reactions to events.
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what is dopamine?
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neurotransmitter found in the basal ganglia and other regions
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what is the ventral tegmental area?
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a group of dopamine-containing neurons located in the midbrain whose axons project to the forebrain, especially the nucleus accumbens and cortex.
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what are the mesolimbic dopamine pathway?
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one of two major dopamine pathways; may be involved in psychotic reactions and in drug reward.
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what is schizophrenia?
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a mental disorder characterized by chronic psychosis.
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what is the nigrostriatal dopamine pathway?
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one of two major dopamine pathways; damaged in Parkinson's disease.
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what is the substantia nigra?
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a dopamine-rich midbrain structure that projects to the striatum.
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what is the hypothalamus?
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a structure found near the bottom of the forebrain. it participates in the regulation of hunger, thirst, sexual behavior, and aggression.
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what is the striatum?
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a term used to describe the caudate nucleus and putamen. located in the forebrain, it is involved in the initiation of body movements and procedural memory.
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what is Parkinson's disease?
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a movement disorder involving damage to and/or loss of dopamine neurons along the Nigrostriatal Dopamine Pathway. major symptoms include tremors, rigidity of the limbs, postural instability, and difficulty initiating movements
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what are precursors?
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chemicals that are acted on by enzymes to form neurotransmitters.
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what is the nucleus basalis?
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a group of neurons of the basal forebrain that send projections throughout the cortex
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what is the cerebral cortex?
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the outermost layer of the brain.
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what is Alzheimer's disease?
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a progressive brain disease that destroys memory and thinking skills.
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