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neurons
cells that transmit nerve impulses between parts of the nervous system 3 types: 1) sensory neurons 2) interneurons 3) motor neurons structure: has a cell body (where organelles & nuclei reside), dendrites (many short extensions that carry info TO a cell body), & an axon (nerve fiber; single long extension that carries impulses AWAY from the cell body) TERM 2
sensory neurons
DEFINITION 2 take nerve signals from a sensory receptor (special structure that detects changes in the environment) to the CNS structure: has a long axon covered by a myelin sheath that takes nerve impulses all the way from dendrites to the CNS TERM 3
interneuron
DEFINITION 3 -lies entirely within the CNS -can receive input from sensory neurons & also from other interneurons in the CNS - thereafter, they sum up all the info received from other neurons before they communicate with motor neurons structure: some have short axon that is not covered by a myelin sheath TERM 4
motor neuron
DEFINITION 4 takes nerve impulses away from the CNS to an effector (muscle fiber, organ, or gland) -effectors carry out our responses to environmental changes, whether these are external or internal structure: long axon covered by a myelin sheath TERM 5
central nervous system (CNS)
DEFINITION 5 consists of the brain and the spinal cord -works with the peripheral nervous system (PNS)
peripheral nervous system (PNS)
consists of the nerves TERM 7
Schwann cell
DEFINITION 7 cell that surrounds a fiber of a peripheral nerve & forms the myelin sheath in the PNS TERM 8
myelin sheath
DEFINITION 8 lipid; white, fatty material derived from the membrane of Schwann cells, that forms a covering for nerve fibers -acts to increase the speed of nerve impulse conduction, insulation, & regeneration in the PNS TERM 9
node of Ranvier
DEFINITION 9 gap in the myelin sheath around a nerve fiber TERM 10
how nerve impulses work
DEFINITION 10 2 components: 1) resting potential 2) action potential
synaptic cleft
a small gap between the sending neuron & the receiving neuron -transmission is accomplished across this gap by a neurotransmitter -Ex: ACh, dopamine, & serotonin TERM 17
How does the transmission across the
synapse occur?
DEFINITION 17 -nerve impulse reaches axon termial -synaptic vesicles fuse with the presynaptic membrane -neurotransmitters are released to diffuse across the synapse & bind with the postsynaptic membrane to inhibit or excite the neuron TERM 18
synaptic integration
DEFINITION 18 the summation of the inhibitory and excitatory signals by a neuron or by some part of the brain TERM 19
polarization
DEFINITION 19 the energy, called resting potential, exists because the cell membrane is POLARIZED: positively charged ions are stashed outside the cell, negatively charged ions inside TERM 20
neurotransmitter
DEFINITION 20 chemical stored at the ends of axons that is responsible for transmission across a synapse Examples: acetylcholine (ACh),norepinephrine (NE), dopamine, serotonin,glutamate, and GABA (gamma aminobutyric acid) -ACh & NE are active in both the CNS & PNS -in the PNS, they act at synapses called neuromuscular junctions -in the PNS, ACh excited skeletal muscle but inhibits cardiac muscle or glands -NE generally excites smooth muscle -in the CNS, NE is important to dreaming, waking, & mood -serotonin is invovled i
excitatory signals
an excitatory neurotransmitter produces an excitatory signal by opening sodium gates at a synapse -this drives the neuron closer to its threshold -if threshold is reached, an action potential is inevitable TERM 22
inhibitory signals
DEFINITION 22 an inhibitory signal drives the neuron farther from an action potential by opening the gates for potassium TERM 23
meninges(sing.: meninx)
DEFINITION 23 protective membranous coverings about the central nervous system (the spinal cord & the brain) TERM 24
gray matter
DEFINITION 24 nonmyelinated axons & cell bodies in the CNS TERM 25
white matter
DEFINITION 25 myelinated axons in the CNS
cerebrum
-also called the telencephalon -is the largest portion of the brain in humans -last center to receive sensory input & carry out integration before commanding voluntary motor responses - communicates with & coordinates the activities of the other parts of the brain -subparts: 1) cerebral hemispheres 2) cerebral cortex
- primary motor & sensory areas of the cortex 4) association areas 5) processing centers 6) central white matter TERM 32
cerebral hemispheres
DEFINITION 32 -one of the large, paired structures that together constitute the cerebrum of the brain -2 halves: left & right -a deep groove called the LONGITUDINAL FISSURE divides the left & right cerebral hemispheres TERM 33
corpus callosum
DEFINITION 33 bridge of nerves tract that connects the 2 cerebral hemispheres -the 2 cerebral hemispheres communicate via this TERM 34
sulci (sing.: sulcus)
DEFINITION 34 shallow grooves that divide each cerebral hemisphere into lobes: 1) frontal lobe 2) parietal lobe 3) occipital lobe & 4) temporal lobe TERM 35
frontal lobe
DEFINITION 35 most anterior lobe (directly behind the forehead) -controls movement & higher reasoning & smell sensation -smell sensations travel to the primary olfactory area found on the deep surface of this lobe
parietal lobe
posterior to the frontal lobe -somatic sensing is carried out by the nerves in this lobe -primary taste area accounts for taste sensations TERM 37
temporal lobe
DEFINITION 37 lies inferior to the frontal & parietal lobes (at the temple & the ear) -receives sound information through the nerves in this lobe; the primary auditory area in this lobe accepts info from our ears TERM 38
occipital lobe
DEFINITION 38 -posterior to the parietal lobe (at the rear of the head) -visual information is received by the primary visual cortex & processed in the lobe TERM 39
cerebral cortex
DEFINITION 39 a thin, highly convoluted outer layer of gray matter that covers the cerebral hemispheres -contains over 1 billion cell bodies & is the region of the brain that accounts for sensation, voluntary movement, & all the thought processes we associate with consciousness TERM 40
primary motor area (of the cerebral cortex)
DEFINITION 40 -the frontal lobe just anterior to (before) the central sulcus - voluntary commands to skeletal muscles begin here & each part of the body is controlled by a certain section -large areas of the cerebral cortex are devoted to controlling structures that carry out very fine, precise movements -muscles that control facial movements--swallowing, salivation, expression--take up an especially large portion of this area -hand movements require tremendous accuracy -these 2 structures command nearly 2/3 of this area
auditory association area
-in the temporal lobe -performs the same functions as the visual association area with regard to sounds TERM 47
processing centers
DEFINITION 47 -receive info from the other association areas & perform higher-level analytical functions -include: 1) prefrontal area
- Wernicke's area 3) Broca's area TERM 48
prefrontal area
DEFINITION 48 -an association area in the frontal lobe -receives info from the other association areas & uses this info to reason & plan our actions -integration in this area accounts for our most cherished human abilities -reasoning, critical thinking, & formulating appropriate behaviors are possible because of integration carried out in the prefrontal area TERM 49
unique ability of humans to speak is partially
dependent upon 2 processing centers found
only in the left cerebral cortex
DEFINITION 49
- Wernicke's area: located in the posterior part of the left temporal lobe -helps us understand both the written & spoken word & sends the info to Broca's area 2) Broca's area: located in the left frontal lobe; located just anterior to the portion of the primary motor area for speech musculature (lips, tongue, larynx, etc) -adds grammatical refinements & directs the primary motor area to stimulate the appropriate muscles for speaking & writing TERM 50
central white matter
DEFINITION 50 -much of the rest of the cerebrum is composed of this - myelination occurs & white matter develops as a child grows -progressive myelination enables the brain to grow in size & complexity
basal nuclei
nerve cells that integrate motor commands to ensure balance and coordination -Parkinson disease is believed to be caused by degeneration of specific neurons in the basal nuclei; Parkinson disease is the progressive deterioration of the CNS due to a deficiency in the neurotransmiter dopamine TERM 52
diencephalon
DEFINITION 52 portion of the brain in the region of the third ventricle that includes the thalamus & the hypothalamus TERM 53
hypothalamus
DEFINITION 53 -forms the floor of the third ventricle -an integrating center that helps maintain homeostasis -regulates hunger, sleep, thirst, body temperature, & water balance -controls the pituitary gland & thereby, serves as a link between the nervous system & endocrine systems TERM 54
thalamus
DEFINITION 54 -consists of 2 masses of gray matter located in the sides & roof of the third ventricle -is on the receiving end for all sensory input except the sense of smell -visual, auditory, & somatosensory info arrives here via the cranial nerves & tracts from the spinal cord - integrates this info & sends it on to the appropriate portions of the cerebrum -involved in arousal of the cerebrum & also participates in higher mental functions such as memory & emotions TERM 55
pineal gland
DEFINITION 55 -located in the diencephalon -secretes the hormone melatonin -some researchers believe melatonin can help alleviate jet lag or insomnia; the hormone may also regulate the onset of puberty
reticular formation
-complex network of nuclei (masses of gray matter) & fibers that extend the length of the brain stem -a major component of the reticular activating system (RAS) -the RAS receives sensory signals & sends them to higher centers -motor signals received by the RAS are sent to spinal cord -RAS arouses the cerebrum via the thalamus & causes a person to be alert -if you want to awaken the RAS, surprise it with sudden stimuli, such as an alarm clock ringing, smelling salts, or splashing cold water on your face -RAS TERM 62
limbic system
DEFINITION 62 -association of various brain centers, including the amygdala & hippocampus -governs learning (higher mental functions) & memory & primitive emotions,such as pleasure, fear, & happiness TERM 63
amygdala
DEFINITION 63 -portion of the limbic system that functions to add emotional overtones to memories & also creates the sensation of fear -uses past knowledge fed to it by association areas to assess a current situation -if necessary, it can trigger the fight-or-flight reaction - the frontal cortex can override the limbic system & cause us to rethink the situation & prevent us from acting out strong reactions TERM 64
hippocampus
DEFINITION 64 -portion of the limbic system where memories are stored - also plays a crucial role in learning-->acts as info gateway during the learning process -determines what info is to be encoded & stored by other regions of the brain TERM 65
higher mental functions
DEFINITION 65 -the limbic system indicates the cortical areas may work with lower centers to produce: 1) memory 2) learning
memory
the ability to hold a thought in mind or to recall events from the past, ranging from a word we only learned yesterday to an early emotional experience that has shaped our lives TERM 67
learning
DEFINITION 67 takes place when we retain & use past memories TERM 68
types of memory
DEFINITION 68
- short-term memory 2) long-term memory 3) semantic memory 4) episodic memory 5) skill memory TERM 69
short-term memory
DEFINITION 69 retention of info for only a few minutes, such as remembering a telephone number TERM 70
long-term memory
DEFINITION 70 retention of info that lasts longer than a few minutes
Alzheimer's disease
brain disorder characterized by a general loss of mental abilities TERM 77
cranial nerves
DEFINITION 77 -nerves that arise from the brain -referred to by roman numerals - humans have 12 pairs -some are sensory nerves that contain only sensory fibers -some are motor nerves that contain only motor fibers -others are mixed nerves that contain both sensroy & motor fibers -largely connected to the head, neck, & facial regionsof body -however, the vagus nerve (X) has branches not only to the pharynx & larynx, but also to most of the internal organs -the vagus arises from the brain stem, specifically the medulla oblo TERM 78
spinal nerves
DEFINITION 78 -nerves that arise from the spinal cord -emerge from either side of the spinal cord -there are 31 pairs spinal nerves -the roots of a spinal nerve physically separate axons of sensory neurons from the axons of motor neurons, forming an arrangement resembling a letter Y -the posterior root of a spinal nerve contains sensory fibers that direct sensory receptor info inward (toward the spinal cord) - the cell body of a sensory neuron is in a posterior-root ganglion (also called a DORSAL-ROOT GANGLION) -the anter TERM 79
somatic system
DEFINITION 79 -the portion of the PNS containing motor neurons that control skeletal muscles, the skin, & tendons -somatic system sensory nerves take sensory info from external sensory receptors to the CNS -motor commands leaving the CNS travel to skeletal muscles via somatic motor nerves -not all somatic motor actions are voluntary -some actions are automatic -REFLEXES TERM 80
reflex
DEFINITION 80 automatic, involuntary response of an organism to a stimulus
autonomic system
-branch of the PNS that has control over the internal organs - consists of the sympathetic & parasympathetic systems -activation of these 2 systems generally causes opposite reactions -although their functions are different, the 2 divisions share some features:
- function automatically & usually in an involuntary manner 2) they innervate all internal organs 3) they use 2 neurons & one ganglion for each impulse -the first nerve has a cell body within the CNS & a preganglionic fiber that enters the ganglion - TERM 82
sympathetic division
DEFINITION 82 -the part of the autonomic system that usually promotes activities associated with emergency (fight-or-flight) situations -uses norepinephrine as a neurotransmitter -most preganglionic fibers of this arise from the middle, or thoracolumbar, portion of the spinal cord -they terminate almost immediately in ganglia that lie near the spinal cord -in this division, the preganglionic fiber is short, but the postganglionic fiber that contacts an organ is long TERM 83
fight-or-flight
DEFINITION 83 -sympathetic division of the autonomic system is important in this -accelerates heartbeat & dilates the bronchi--active mucles need a ready supply of glucose & oxygen -sympathetic neurons inhibit the digestive organs, as well as the kidneys & urinary bladder -the activities of these organs (digestion, defaction, & urination) are not immediately necessary if you're under attack -the neurotransmitter relased by the postganglionic axon is primarily norepinephrine (NE) TERM 84
parasympathetic division
DEFINITION 84 -part of the autonomic system that is active under normal conditions -uses acetylcholine (ACh) as a neurotransmitter - includes a few cranial nerves as well as the fibers that arise from the sacral (bottom) portion of the spinal cord -this division is often referred to as the craniosacral portion of the autonomic system - the preganglionic fier is long, & the postganglionic fiber is short b/c the ganglia lie near or within the organ -this division, sometimes called the "housekeeper division", promotes all int TERM 85
drug therapy & drug
abuse
DEFINITION 85 -neurological drugs promote, prevent, or mimic the action of a particular neurotransmitter -dependency occurs when the body compensates for the presence of neurological drugs - DRUG ABUSE: physical and/or psychological dependence on a drug, which assumes an "essential" biochemical role in the body following habituation & tolerance
marijuana
-tetrahydrocannabinol (THC) -psychoactive -mimics the actions of the neurotransmitter anandamide -mild euphoria occurs, along with alterations in vision & judgement -distortions of space & time can also occur in occasional ussers -in heavy users, hallucinations, anxiety, depression, rapid flow of ideas, body image distortions, paranoia, & psychotic symptoms can result TERM 92
sensory receptors
DEFINITION 92 dendrites specialized to detect certain types of stimuli TERM 93
exteroceptors
DEFINITION 93 sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision, hearing, & equilibrium TERM 94
interoceptors
DEFINITION 94 -receive stimuli from inside the body -include pressoreceptors (sometimes referred to as baroreceptors) that respond to changed in blood pressure -osmoreceptors to monitor the body's water-salt balance TERM 95
chemoreceptor
DEFINITION 95 -sensory receptor sensitive to chemical stimuli--for example, receptors for taste & smell -is an interoceptor that monitors the pH of the blood -they are located in the carotid arteries & aorta -if the pH lowers, the breathing rate increases -as more carbon dioxide is exhaled, the blood pH rises -a type of chemoreceptor = pain receptor
pain receptor (nociceptor)
-sensory receptor that is sensitive to chemicals released by damaged tissues or excess stimuli of heat or pressure - protective b/c they alert us to possible danger -Ex.: without the pain of appendicitis, we might never seek medical help needed to avoid a ruptured appendix TERM 97
photoreceptor
DEFINITION 97 -sensory receptor in the retina that responds to light stimuli/energy -provide us with a sense of vision -stimulation of the photoreceptors known as rod cells results in black-and- white vision -stimulation of the photoreceptors known as cone cells results in color vision TERM 98
mechanoreceptor
DEFINITION 98 -sensory receptor that responds to mechanical stimuli, such as that from pressure, sound waves, & gravity -when we hear, airborne sound waves are converted to fluid-borne pressure waves that can be detected by mechanoreceptors in the inner ear - mechanoreceptors are responding to fluid-borne pressure waves when we detect changes in gravity & motion, helping us keep our balance -these receptors are in the vestibule & semicircular canals of the inner ear, respectively -the sense of touch depends on pressure re TERM 99
thermoreceptor
DEFINITION 99 -sensory receptor that is sensitive to changes in temperature -located in the hypothalmus & the skin -those that respond when temperatures rise are called warm receptors, & those that respond when temperatures lower are called cold receptors TERM 100
sensation/How does sensation occur?
DEFINITION 100 -conscious awareness of a stimulus due to nerve impulses sent to the brain from a sensory receptor by way of sensory neurons -sensory receptors respond to environmental stimuli by generating nerve signals -sensation occurs when nerve signals reach the cerebral cortex
