Biology and Psychology

1. Biological psychology is the study of the role of physical and chemical factors in behavior and mental processes.



Example: Changes in brain biochemicals are associated with depression.



REMEMBER: Biological psychology is the study of the biological factors that influence psychological phenomena.


2. The nervous system is a complex combination of cells that has three basic functions: to receive information, to integrate it with previous information to generate choices and decisions, and to guide actions and output based on those decisions.



Example: When we stand at the curb of a busy street, our nervous system receives sensory information about oncoming traffic, makes a decision to cross the street at a particular moment, and controls the movement (output) of stepping off the curb and crossing the street.


3. Neurons are the cells that make up the nervous system. Neurons can communicate with one another by receiving and sending signals. Three structures allow neurons to communicate: synapses, "excitable" (electrically polarized) membranes, and long thin fibers that extend outward from the cell called axons and dendrites.



REMEMBER: A neuron is similar to a computer in that information comes in, is processed, and is sent out.


4. Axons usually carry signals from the neuronal cell body out to the synapse, where communication with other nerve cells takes place. Generally, each neuron has only one axon.



REMEMBER:Axons create action potentials. Most of the time, the action potential travels from the cell body to the end of the axon. (See Key Term 7)


5. Dendrites are branches of the neuron that usually receive signals from the axons of other neurons and carry those signals to the neuron's cell body. Each neuron can have many dendrites.



REMEMBER:Dendrites detect signals from other neurons.


6. Glial cells hold neurons in place and help to sustain them.



REMEMBER:Glial means "glue"; part of the glial cells' job is to "glue" neurons together.



Example: A glial cell may secrete chemicals to stabilize a neuron's environment or to help repair a damaged neuron.


7. Action potentials occur when the neuron becomes depolarized and sodium rushes into the axon. Opening one sodium gate causes the gate next to it to open, which causes the next one to open, and so forth, all the way down the length of the axon. Action potentials are all-or-nothing activities; the cell either fires at full strength or does not fire at all.



REMEMBER: Electrical potentials occur when there is a difference in charge between the outside and inside of the cell. When an active change occurs in the electrical potential such as depolarization, sodium rushes into the axon and makes the inside less negative, causing an action potential.


8. Myelin is a fatty substance that wraps around some axons. It speeds an action potential's travel down the length of the axon.



Example: When a stray object flies toward your face, the sensory nerves must quickly transmit this information to your brain, and the motor nerves must carry the signal to your muscles to move very rapidly. These sensory and motor nerves are covered with myelin.


9. A refractory period is a rest period between action potentials. Following one action potential, the axon must repolarize before another action potential can occur. The time required for the axon to repolarize is called a refractory period.



REMEMBER: An axon refrains from firing an action potential during a refractory period.
A synapse is the very small gap between the presynaptic cell sending a message and the postsynaptic cell receiving that message. Typically, the axon is the presynaptic cell and the dendrite is the postsynaptic cell. Neurotransmitters released from the presynaptic cell cross the synapse and fit snugly into the receptors on the postsynaptic cell.



REMEMBER:Pre means "before." The presynaptic cell comes before the synapse. Post means "after." The postsynaptic cell comes after the synapse.


10. Neurotransmitters are chemicals that carry a signal from the presynaptic cell across the synapse to the receptors on the postsynaptic cell.



REMEMBER:Neuro refers to neuron. Transmit means to send something across space. Neurotransmitters send the signal or message across the space of the synapse to the postsynaptic neuron.


11. Receptors, usually located on the dendrites of the postsynaptic cell, are stimulated when neurotransmitters fit into them, like a key fits a lock.



REMEMBER: A receptor is something that receives. Receptors receive neurotransmitters.
Postsynaptic potential occurs when the membrane potential of the postsynaptic cell is changed.


12. An excitatory postsynaptic potential (EPSP) causes the postsynaptic membrane to become depolarized, thus increasing the probability that a neuron will fire an action potential. The strength of an EPSP weakens as it travels down the dendrite.



REMEMBER: An excitatory postsynaptic potential excites the neuron that will cause it to fire. But also note that all the EPSPs and IPSPs that a dendrite receives combine to determine whether or not the axon of the postsynaptic cell will fire an action potential. If there are more EPSPs than IPSPs, the neuron will fire an action potential.


13. An inhibitory postsynaptic potential (IPSP) causes the postsynaptic membrane to become hyperpolarized, thus decreasing the chances a neuron will fire an action potential. The strength of an IPSP weakens as it travels down the dendrite.


REMEMBER: An inhibitory postsynaptic potential inhibits or prevents the neuron from firing. But also note that all the EPSPs and IPSPs that a dendrite receives combine to determine whether or not the axon of the postsynaptic cell will fire an action potential. If there are more IPSPs than EPSPs, the neuron will not fire an action potential.


14. Neural networks are organized groups of interconnected neurons in the brain and spinal cord. These networks communicate with one another and are parts of larger network systems.


15. Sensory systems, which include vision, hearing, touch, taste, and smell, provide us with input about the environment.


Example: When you walk into a friend's house for a dinner party, your nose provides information about the food she or he has prepared.


16. Motor systems influence muscles and other organs to respond to the environment in some way.


Example: After you have smelled the food prepared for the dinner party and have decided that you want to eat it, your motor system allows you to walk to the table, sit down, and manipulate the fork, knife, and spoon.



17. The peripheral nervous system is the major division of the nervous system that is not encased in bone. It has two major subdivisions, the somatic and autonomic nervous systems.


REMEMBER:Peri means "around." The peripheral nervous system is located around the center of your body.

18. The central nervous system (CNS) is the major division of the nervous system that is encased in bone and includes the brain and spinal cord. Its primary function is to process the information provided by the sensory systems and to decide on appropriate courses of action for the motor system.


REMEMBER: The brain and spinal cord are centrally located. Your spinal cord is in the center of your torso; the brain is centered over your shoulders. Therefore, the brain and spinal cord make up the central nervous system.

19. The somatic nervous system, which is part of the peripheral nervous system, transmits information from the senses to the CNS and carries signals from the CNS to the muscles that move the skeleton.


Example: When you dance, the somatic nervous system transmits the sound of the music to your brain and carries the signals from your brain to the muscles that move your arms and legs.


REMEMBER:Soma means "body." The somatic nervous system is involved with taking sensory information from the body parts, such as the ears, and sending signals back to the body, such as movement instructions to coordinate dance steps.

20. The autonomic nervous system, which is part of the peripheral nervous system, carries messages back and forth between the CNS and the organs and glands.


Example: While you dance, your peripheral nervous system may alter the expansion of your lungs so that you can inhale more oxygen. Also, your heartbeat increases so that more blood reaches your muscles.


REMEMBER: The autonomic nervous system regulates the automatic functions of your body, such as breathing and blood pressure. You do not normally think about these functions.
Nuclei are collections of cell bodies.


REMEMBER: If you think of the CNS as a map of Boston, nuclei would represent "neighborhoods" on the map.

21. Fiber tracts or pathways are collections of axons that travel together in bundles, interconnecting nuclei.


REMEMBER: Again, if you think of the CNS as a map of Boston, fiber tracts would represent the large "superhighways" on the map.

22. The spinal cord, part of the central nervous system, receives signals from the somatic system in the periphery, such as vision, and relays them to the brain via fiber tracts within the spinal cord. The brain then relays signals to the muscles via fiber tracts in the spinal cord.


Example: The sensory information from feeling the fur on a kitten travels through the spinal cord's fiber tracts on its way to the brain. When your brain makes the decision to pick up the kitten, it sends signals through the fiber tracts in the spinal cord on the way to the muscles in your hands and arms.

23 Reflexes are quick, involuntary responses to incoming sensory information (along afferent neurons). The reflexive movement exits the nervous system and contacts the muscles along efferent (or motor) neurons.


Example: If you accidentally step on a pin embedded in your carpet, a withdrawal reflex occurs.


24. The afferent sensory neurons will take the information from your foot to the spinal cord, and the efferent motor neurons will send the signal back to the foot to make it withdraw from the floor.

25. The hindbrain, a major subdivision of the brain, includes the medulla, reticular formation, and cerebellum. The hindbrain, an extension of the spinal cord, is housed in the skull and involved in controlling vital functions. The medulla is located in the hindbrain. It helps to regulate blood pressure, heart rate, and breathing. (see The Hindbrain)


Example: A person with damage to her medulla would most likely need artificial life support to maintain breathing and perhaps would not survive the injury.

26. The reticular formation is not a well-defined area of brain tissue but a collection of nuclei and fibers that form a network of cells throughout the hindbrain and midbrain. The reticular formation is involved in arousal and attention.


REMEMBER:Reticular means "net-like." The cells of the reticular formation are not arranged in any distinct structure but, rather, thread throughout the hindbrain.

27. The locus coeruleus is a small group of cells that may be involved in the state of vigilance. Activity in the reticular formation stimulates the locus coeruleus.


Example: The numerous branches of axons from the locus coeruleus contact other cells, perhaps causing a state of attention or change in mood.

28. The cerebellum is located in the hindbrain. It controls fine motor coordination.


Example: Performing brain surgery requires delicate precision of movement so as to avoid damaging fragile tissue. A surgeon's cerebellum would be very active during an operation.

29. The midbrain, which includes the striatum and the substantia nigra, is located between the hindbrain and the forebrain. Sensory information is integrated in the midbrain to produce the smooth initiation of movement.

30. The substantia nigra is part of the midbrain and assists in the smooth initiation of movement.


Example: Phil, a person with damage to his substantia nigra, is unable to reach out his arm to shake hands with a neighbor.

31. The striatum is part of the cerebrum and interacts with the substantia nigra to control the smooth initiation of movement.


32. The forebrain, which is composed of the diencephalon and the cerebrum, is the most highly developed brain structure. It is responsible for the most complex aspects of behavior and mental processes.


Example: Many years ago a surgical procedure called lobotomy was used to treat several types of mental disorders. The surgery involved destroying large parts of the forebrain. Patients on whom this surgery was performed were often unable to perform complex cognitive tasks afterward.

33. The thalamus is located in the forebrain. This region processes and relays sensory information on its way to higher centers of the brain.


Example: Jane has damage to her thalamus. She has normal processing of visual images with her eyes, but is unable to send that information on to be acted upon further by the brain. In fact, Jane reports being totally unable to see.

34. The hypothalamus is located in the forebrain. It regulates hunger, thirst, and sex drives, and is involved in emotion.


Example: Destroying certain parts of the hypothalamus causes an animal to cease eating and drinking. It will eventually die if not force-fed.

35. The suprachiasmatic nuclei, part of the hypothalamus, determines our biological rhythms, acting much like an internal alarm clock.


Example: Bob is used to getting up at 10:00 a.m. and working until about 2:00 a.m. Bob's suprachiasmatic nuclei have probably influenced him to be a "night person."

36. The amygdala, part of the limbic system, plays an important role in combining the features of stimuli from two sensory modalities.

Example: When you eat ice cream, your amygdala is involved in your perception that the ice cream is both cold and sweet.

37. The hippocampus, also part of the limbic system, is involved in learning and storing new pieces of information or new memories.


Example: Going to class every day would be a waste of time if your hippocampus was damaged. Although you'd be able to understand everything the instructor said, you wouldn't be able to form a memory for the new information.

38. The limbic system is contained in several brain areas and is involved in emotion, memory, and some thought processes. Severe degeneration of limbic system structures is found in Alzheimer's patients.


Example: Grace has Alzheimer's disease, which causes not only memory lapses, but also emotional outbursts in which she falsely claims family members have taken advantage of her.

39. The cerebral hemispheres constitute the outermost part of the cerebrum. Each hemisphere makes up one half of the top of the brain. To understand how the cerebrum is split into hemispheres, do the following: place your finger right between your eyes, lift it straight over your forehead, and trace an imaginary part in the middle of your hair to the back of your head. The line that you have just traced is the dividing line of the two cerebral hemispheres.


REMEMBER:Hemi means "half." Cerebral hemisphere refers to half of the cerebrum, which is round like a sphere.

40. The cerebral cortex, the outer surface of the cerebral hemispheres, is divided into four lobes: frontal, parietal, occipital, and temporal. The cortex is also divided into three functional areas: the sensory cortex, the motor cortex, and the association cortex.

41. The sensory cortex, located in the parietal, occipital, and temporal lobes, receives information from different senses, including touch, vision, and hearing.


Example: If you were to take a walk on the beach, your sensory cortex would be receiving various types of information in your lobes: occipital (the color of the water); parietal (the sandy feeling on your skin and the salt water on your face); and temporal (the sound of the surf).

42. The motor cortex, located in the frontal lobe, controls all voluntary movement.


Example: During that walk on the beach, your motor cortex would be sending information to your muscles to help you walk in the sand in a particular direction.


43. The association cortex pertains to all lobes of the cortex. These regions of cortex receive information from more than one sense or combine sensory and motor information. These are the areas that perform such complex cognitive tasks as associating words with images and other abstract thinking.

REMEMBER: Think of the association cortex as forming an association between many types of sensory and motor information.

44. The corpus callosum connects the two cerebral hemispheres. Without the corpus callosum, the two hemispheres could not communicate regarding their respective activities.

REMEMBER: Corpus callosum begins with two c's. The corpus callosum connects the cerebral hemispheres.

45. A lateralized task is one that is performed more efficiently by one hemisphere than by the other. The left hemisphere is better at logical reasoning and language skills, while the right hemisphere is superior in musical and artistic abilities and spatial reasoning.

Example: When Lynne reads, her left hemisphere is more activated than her right.

46. Synaptic plasticity is the brain's ability to strengthen neural connections at synapses and to establish new synapses.

Example: New synapses are formed in your brain when you learn new material.

47. A neurotransmitter system is a set of neurons that communicates with the same neurotransmitter. A neurotransmitter system may control an aspect of behavior such as memory.

(Example: The symptoms Grace experiences from Alzheimer's disease occur due to its effects on her acetylcholine neurotransmitter system.

48. Acetylcholine, the neurotransmitter found in the cholinergic system, is used by neurons in the peripheral and central nervous systems. It assists in the contraction of muscles and the formation of new memories.

Example: Grace's memory lapses are linked to a loss of cholinergic neurons in areas of her brain that store memories.

49. The neurotransmitter norepinephrine is used in the adrenergic system. It is involved in arousal, learning, and moods.

Example: Miguel's sympathetic nervous system has activated the fight-or-flight response by releasing norepinephrine to allow him to jump out of the way of an inexperienced cyclist.

50. Serotonin is a neurotransmitter that regulates sleep, moods, and appetite.

Example: Joyce finished a high-carbohydrate meal of macaroni and cheese; therefore, her desire for carbohydrates is being reduced by the release of serotonin.

51. The neurotransmitter dopamine is used in the substantia nigra and striatum to control movement. Dopaminergic neurons also play a role in the experience of pleasure.

Example: Nelson has Parkinson's disease, which is associated with a deterioration of dopamine cells. Nelson finds it increasingly difficult to move from a sitting to a standing position and is discouraged by his increasingly noticeable hand tremors.

52. GABA is an inhibitory neurotransmitter that is involved in a variety of behaviors and mental processes. Malfunctioning GABA systems are associated with severe anxiety, Huntington's disease, and epilepsy.

Example: Huntington's disease has reduced the number of GABA-containing neurons in Victoria's striatum. Because her dopamine system is no longer inhibited by GABA, Victoria experiences uncontrollable movements of her arms and legs.

53. Glutamate is an excitatory neurotransmitter that helps signals cross the synapse more efficiently.

Example: Craig believes he will one day be able to show evidence of learning through the tracking of glutamate's effects on synaptic connections.

54. Endorphins are naturally occurring opiate-like neurotransmitters that modify pain signals being sent to the brain such that perceived pain is reduced.

Example: "Runner's high," or the absence of pain and the euphoric feeling that many runners report after covering long distances, may be caused by the release of endorphins.

55. The endocrine system is made up of cells that can communicate with one another. A wide variety of behaviors and mental processes are influenced by this system. Hormones, traveling via the bloodstream, affect coordinated systems of target tissues and organs by producing such responses as the fight-or-flight syndrome.

56. Glands, the structures that make up the endocrine system, secrete hormones.

Example: The pituitary, adrenals, testes, ovaries, pancreas, and thyroid are all glands of the endocrine system.

57. Hormones are chemicals that, when released by the glands of the endocrine system, travel via the bloodstream and communicate with other cells, thus influencing behavior and mental processes.

Example: A woman's menstrual cycle is governed by the timed release of several different hormones from the pituitary and ovary glands.

58. The fight-or-flight syndrome, caused by the release of hormones, is a coordinated set of responses to danger that prepares the organism for action. The heart beats faster, the liver releases glucose to be used as energy, and the organism is placed in a state of high arousal. In short, the organism is prepared to stay and fight or to flee very quickly.

Example: Any scary experience will induce the fight-or-flight syndrome. Hearing strange noises at night, giving your first speech in college, or almost being hit by a car can be very frightening. If you have been in any of these situations, you may recall how your heart suddenly thudded.

59. Negative feedback systems are designed to monitor and adjust the level of activity in your physiological systems.

Example: Think of the hormones that are released from pituitary glands.

Negative feedback systems provide a way for your body to maintain the correct amount of pituitary hormone in your system--not too much and not too little. Your pituitary releases hormone X. Certain levels of circulating hormone X cause chemical Y to be secreted from another place in your body. Your pituitary can "read" the level of chemical Y in the bloodstream. When the Y level gets too high, the pituitary stops releasing hormone X.

REMEMBER:Negative feedback means providing feedback to a system and saying "No more--Stop!" to that activity (for example, releasing hormones).

60. The immune system monitors the internal state of the body, detects foreign and harmful substances, and eliminates them. Example: A virus will be surrounded by immune system cells and destroyed if the system is working properly.

61. Autoimmune disorders are diseases in which the body literally attacks itself and kills normal cells.

REMEMBER:Auto means "self" (think of autobiography). In an autoimmune disorder the immune system attacks the "self."