Psy 387 Study Guide First Exam free essay sample

Genes- units of heredity that maintain their structural identify from one generation to another xi. Come in pairs because they are aligned along chromosomes xii. Gene is a portion of a chromosomes, which is composed of deoxyribonucleic acid xiii. A strand of DNA serves as a template for ribonucleic acid which is a single strand molecule xiv. Can be either homozygous ( identical pair of genes on the two chromosomes) or heterozygous (unmatched pair of genes) xv. Dominant – gene shows a strong effect in either the homozygous or heterozygous condition xvi. Recessive- gene shows its effect only in the homozygous condition j. Proteins xvii. Enzymes- biological catalyst that regulate chemical reactions in the body 4. Sex-Linked and Sex-limited Genes k. Sex-linked genes- genes located on sex chromosomes (usually X chromosomes) xviii. Male: XY Female: XX l. Autosomal genes- chromosomes that are not on sex chromosomes m. Sex-limited genes- which are present in both sexes (generally on autosomal genes) but active mainly in one sex xix. Ex- breast size in women 5. Heredity and environment n. To determine what kind of contributions heredity and environment has, researchers focus on comparing monozygotic (from one egg) twins and dizygotic (from two eggs) twins. o. Second kind of evidence is studies of adopted children to see if they relate to parents p. Third kind researchers find genes linked to a disorder q. Sometimes, environment might be based on genes due to the multiplier effect: if genetic or prenatal influences produce even a small increase in some activity the early tendency will change the environment in a way that magnifies that tendency Nerve Cells and Nerve Impulses Chap 2 . Anatomy of Neurons and Glia r. Neurons – Receive information and transmit it to other cells 7. The Structure of an Animal Cells s. Membrane- the surface of a cell, also called plasma membrane, is a structure that separated the inside of the cell form the outside environment t. All animal cells have (other than red blood cells) have nucleus the structure that contains the chromosome, mitochondrion the structure that performs metabolic activities, providing the energy that the cell requires for all other activities. Also has ribosomes- are the sites at which the cell synthesizes new protein molecules endoplasmic reticulum- a network of thin tubes that transport newly created proteins to other locations 8. The Structure of a Neuron u. Neurons are distinguished from other cells by their shape, the larger neurons have components: dendrites, soma (cell body) an axon and presynaptic terminals v. Motor Neuron- has its soma in the spinal cord. It receives excitation from other neurons through its dendrites and conducts impulses along its axon to a muscle w. Sensory neuron- is specialized at one end to be highly sensitive to a particular type of stimulation such as light sound or touch x. Dendrites- are branching fibers that get narrower near their ends 4. Receives information from other neurons 5. Dendritic spines – the short outgrowths that increase the surface area available for synapses y. Cell Body or Soma contains the nucleus, ribosomes, mitochondria, and other structures found in most cells z. Axon- is a thin fiber of constant diameter, in most case longer than the dendrites xx. Axon is the information sender of the neuron, converting an impulse toward other neurons or an organ or muscle xxi. Many vertebrate axons are covered with an myelin sheath- insulating material, with interruptions known as nodes of Ranvier xxii. An axon has man branches each of which swells at its tip forming a presynaptic terminal (end bulb or bouton) xxiii. Afferent axon brings information inside, efferent brings information out {. Interneuron or intrinsic neuron– if a cell’s dendrite and axon are entirely contained within a single structure 9. Glia |. Glia are the other major components of the nervous system, do not transmit information over long distance xxiv. Glia are smaller but also more numerous than neurons xxv. Astrocytes- wrap around the presynaptic terminals of a group of functionally related axons. They help synchronize the activity of the axons enabling them to send messages in waves they also help remove waste material created when neurons die and control the amount of blood flow to each brain area. Lastely they dilate blood vessels to bring more nutrient into that area 6. Blood brain barrier 7. Allows small uncharged molecules, including oxygen and carbon dioxide cross freely 8. Molecules that dissolve in the fats of the membrane also cross passively 9. For certain other essential chemicals the brain uses active transport, to bring in glucose, amino acids etc xxvi. Microglia- very small cells also remove waste material as well as viruses, fungi, and other microorganisms xxvii. Oligodendrocytes- build myelin sheath in the brain and spinal cord and schwann cells in the PNS xxviii. Radial Glia guide the migration of neurons and their axons and dendrites during embryonic development }. Nourishment Of Vertebrate Neurons xxix. Vertebrate neuron depends almost entirely on glucose, a simple sugar xxx. Glucose is practically the only nutrient that crosses the blood-brain barrier in adults xxxi. Thiamine- a chemical that is necessary for the use of glucose 10. The Nerve Impulse Module 2. 2 ~. The Resting Potential of the neuron xxxii. Electrical gradient- a difference in electrical charge between the inside and outside of the cell xxxiii. In the absence of any outside disturbance the cell membrane mains an polarization- meaning a difference in electrical charge between two locations xxxiv. Resting potential- the difference in voltage in a resting neuron, which is mainly the result of negatively charged proteins inside the cell . Forces acting on sodium and potassium ion xxxv. Sodium-potassium pump a protein complex repeatedly transports three sodium ions out of the cell while drawing two potassium ions into the cell. xxxvi. When the neuron is at rest, two forces act on sodium both tending to push it into the cell. 10. First consider the electrical gradient, sodium is positively charged and the inside of the cell is negatively charged. Opposite electrical charges attract so the electrical gradient tends to pull sodium into the cell. 11. Second consider the concentration gradient; the difference in distribution of ions across the membrane- sodium is more concentrated outside than inside so just by the laws of probability sodium is more likely to enter the cell than leave. . The Action Potential xxxvii. Hyperpolarization- which means increased polarization xxxviii. Depolarize- reduce its polarization toward zero xxxix. Threshold of excitation-a massive depolarization of the membrane. 12. Causes a rapid flow of ions across the membrane. xl. Action potential- a rapid depolarization and slight reversal of the usual polarization . The molecular basis of the action potential xli. The membrane proteins that control sodium entry are voltage-gated channels membrane channels whose permeability depends on the voltage difference across the membrane xlii. All-or-none law- amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it . The Refractory period xliii. Refractory period- immediately after an action potential , the cell resists the production of further action potentials 13. First part is called the absolute refractory period, where the membrane cannot produce an action potential regardless of the stimulation 14. The second part is the relative refractory period, a stronger than usually stimulus is necessary to initiate an action potential . Propagation of the action potential xliv. Action potential begins on the axon hillock, which is a swelling where the axon exits the soma xlv. Propagation of the action potential- describes the transmission of an action potential down an axon xlvi. Reviewing action potential 15. As a result of synaptic input, sodium channels open and depolarize the axon membrane to its threshold 16. Sodium ions rush in and depolarize the membrane even further 17. Positive charge flows down the axon and opens voltage-gated sodium channels at the next point 18. At the peak of the action potential, the sodium gates snap shut. They remain closed for the next millisecond or so, despite the depolarization of the membrane 19. Because the membrane is depolarized, voltage-gated potassium channels open 20. Potassium ions flow out of the axon, returning the membrane toward its original depolarization 21. After the membrane returns to its original level of polarization the voltage-dependent potassium channels close . The myelin Sheath and salutatory conduction xlvii. Myelin- an insulating material composed of fats and proteins xlviii. Myelinated axons- those covered with a myelin sheath is the same, found only in vertebrates xlix. Salutatory conduction- the jumping of action potentials from node to node l. Local neurons-neurons without axons exchange information with only their closest neighbors li. Graded potential- membrane potential that vary in magnitude without following the all-r –none law 11. Chapter 3: Synapses lii. in late 1800’s ramon y cajal found a narrow gap separating one neuron from another. liii. In 1906 charles scrot Sherrington physiologically demonstrated that communications between one neuron and the next differs from communications along a single axon 22. Che inferred a specialized gap between neurons and introduced the term synapse . Properties of synapses liv. Reflexes- automatic muscular responses to stimuli 23. the circuit from sensory neuron to muscle response is called a reflex arc 24. Sherrington observed several properties – a. Reflexes are slower than conduction along an axon b. Several weak stimuli presented at slightly different times or slightly different locations produce a stronger reflex than a single stimulus does c. When one set of muscles becomes excited a different set become relaxed . Temporal Summation lv. Sherrington found that repeated stimuli within a brief time have a cumulative effect, called temporal summation lvi. Sherrington surmised that a s ingle pinch produced a synaptic transmission less than the threshold for the postsynaptic neuron- the cell that receives the message (the cell that delivers the synaptic transmission is the pre-synaptic neuron) lvii. Unlike action potentials which are always depolarization’s, graded potential’s may be either depolarization (excitatory) or hyperpolarization’s (inhibitory) a graded depolarization is known as an excitatory postsynaptic potential (EPSP) 25. EPSP occurs when sodium ions enter the cell 26. If an EPSP does not cause the cell to reach its threshold the depolarization decays quickly . Spatial Summation lviii. Spatial summation- synaptic inputs from separate locations combine their effects on neurons . Inhibitory Synapses lix. Temporary hyperpolarization of a membrane called an inhibitory postsynaptic potential or IPSP resembles an EPSP 27. Occurs when synaptic inputs selectively opens the gates for potassium ions to leave the cell carrying a positive charge with them or for chloride ions to enter the cell carrying a negative charge 12. Chemical Events at the Synapse Module 3. 2 lx. Synapses rely on chemical processes, which are much faster and more versatile. . The Sequence of Chemical Events at a synapse lxi. Events in Order 28. The neuron synthesizes chemicals that server as neurotransmitters. It synthesizes the smaller neurotransmitters in the axon terminals and neuropeptides in the cell body. 29. The neuron transports the neuropeptides that were formed in the cell body to the axon terminals or to the dendrites (Neuropeptides are released from multiple sites in the cell) 30. Action potential travels down the axon. At the presynaptic terminal, an action potential enables calcium to enter the cell. Calcium releases neurotransmitters rom the terminals and into the synaptic cleft (the space between the presynaptic and post synaptic neurons 31. The released molecules diffuse across the cleft, attach to receptors and alter activity of the postsynaptic neuron 32. The neurotransmitter molecules separate from their receptors. Depending on the neurotransmitter, it may be converted to into inactive chemicals 33. The neurotransmitter molecules may be taken back into the presynaptic neuron for recycling or may diffuse away. In some cases, empty vesicles are returned to the cell body 34. Some postsynaptic cells send reverse messages to control the further release of neurotransmitter by presynaptic cells. . Types of neurotransmitters lxii. Neurotransmitter- at a synapse one neuron releases these chemicals that affect a second neuron 35. Amino acids- acids containing an amine group (NH2) 36. Neuropeptide- chains of amino acids 37. Acetylcholine-a chemical similar to an amino acid except the NH2 group has been replaced by an N(CH3)3) group 38. Monoamines- neurotransmitter containing one amine group (NH2) formed by a metabolic change in certain amino acids 39. Purines- a category of chemicals including adenosine and several of its derivatives 40. Gases- nitric oxide and possibly others lxiii. Nitric Oxide- a gas released by many small molecules 41. Increases blow flow to an area . Activation of Receptor of the Postsynaptic Cell lxiv. Ionotropic Effects- when the neurotransmitter binds to a receptor on a the membrane it opens the channels for some kind of ion 42. Begin quickly and last only about 20 ms lxv. Metabotropic effects- slower and longer lasting than inotropic effects 43. Take 30 ms or more to come into play, than last seconds minutes or longer lxvi. Neuromodulator- several properties that neuropeptides that set them apart from other transmitters . Inactivation and reuptake of Neurotransmitters lxvii. Acetylcholinesterase- the enzyme that breaks down acetylcholine after it activates a receptor. xviii. Reuptake-the presynaptic neuron that takes up most of the released neurotransmitter molecules intact and reuses them 44. Occurs because of the special membrane proteins called transporters lxix. COMT- breaks down the excess dopamine into inactive chemicals that cannot stimulate the dopamine receptors lxx. Autoreceptors- receptors that detect the amount of transmitter released and inhibit further synthesis an d release after it researches a certain level. 13. Synapse, Drugs, and Addiction Modules 3. 3 . Types of Mechanisms lxxi. Antagonist- a drug that blocks the effects of a neurotransmitter lxxii. Agonist- a drug that increases or mimics the effect of a neurotransmitter lxxiii. Drugs 45. If it has an affinity for a receptor if it Binds to it. 46. A drug’s efficacy is its tendency to activate the receptor lxxiv. 1. Name and briefly describe the five major philosophical approaches to the mind-body problem as described in lecture. The five major philosophical approaches to the mind-body problem are interactionism, psychophysical parallelism, epiphenomenalism, materialism, and subjective idealism (or mentalism). Interactionism is a dualistic position which posits that mind and body interact with each other. Psychophysical parallelism is a dualistic position which maintains that mind and body are separate entities that operate simultaneously, but independently from one another. Epiphenomenalism is a dualistic position which states that mind is a by-product of brain activity. Materialism is a monistic position which posits that everything can be explained in physical terms, so mind is brain activity. Subjective idealism, or mentalism, states that only mind exists, all matter is simply a figment of the imagination. 2. Briefly describe (as presented in lecture) how genetic material is expressed, using the following terms: DNA, mRNA, tRNA, ribosomes, and proteins. The genetic material, DNA, is transcribed by mRNA which transports the information from the nucleus to the cytoplasm, where it is translated into proteins by means of tRNA transferring amino acids to the ribosomes in the sequence dictated by the codons on the mRNA. 1. Briefly describe (as presented in lecture) the major functions of each of the following glial cells: oligodendrocytes, Schwann cells, astrocytes, microglia, and radial glia. Oligodendrocytes function to mylenate axons in the central nervous system, while Schwann cell mylenate axons in the peripheral nervous system. Astrocytes provide nutritive and functional support for neurons. Microglia work to remove waste material around neurons. Radial glia function as guides for migrating neurons. 2. Describe the five phases of an action potential (as described in lecture). During the first phase, a depolarizing signal reaches threshold and opens the voltage-gated sodium channels. During the second phase, the influx of sodium ions causes a peak depolarization until sodium channels become refractory. During the third phase, potassium rushes out of the open potassium channels, causing re-polarization. During the fourth phase, there is an overshoot of potassium efflux and the potassium channels close, while the sodium channels reset. During the fifth stage, the excess potassium dissipates and the membrane is restored to its initial resting potential. . Name and briefly describe the five steps in synaptic transmission as presented in lecture. The first step in synaptic transmission is the influx of calcium at the axon terminals. This leads to the second step, whereby the calcium triggers the migration and fusing of synaptic vesicles with the presynaptic membrane. During the third step, the neurotransmitters from the vesicles are released into the synaptic c left, a process called exocytosis. Binding of the neurotransmitters onto receptors on the post-synaptic membrane constitutes the fourth step of synaptic transmission. The fifth step is the deactivation of the transmitter by degradation or reuptake. 2. Name and briefly describe (as presented in lecture) five ways in which drugs often interfere with synaptic transmission. The first way a drug can affect synaptic transmission is by altering the synthesis or transport of neurotransmitters. A second way is by interfering with the storage or release of transmitters. A third way is by modifying the binding of transmitters on the postsynaptic membrane. A fourth way is by binding to autoreceptors. Finally, a drug can affect the breakdown or re-uptake of a neurotransmitter.