Midterm 2.1 Flashcards
chp 3
types of neurotransmitters: Ach
involved in voluntary motor control
found in neurons of the brain and in synapses where axons connect to muscles and body organs, such as heart
activates muscle movement and contributes to regulation of attention, learning, sleeping, dreaming, memory
Alzheimer’s related to deterioration of ACh-producing neurons
types of neurotransmitters: dopamine
regulates motor behaviour, motivation, pleasure, emotional arousal
role in motivated behaviours
plays a role in drug addiction
high levels of dopamine in brain pathways linked to schizophrenia
low levels in other areas linked to Parkinson’s disease
types of neurotransmitters: glutamate
major excitatory NT in the brain (enhances transmissions of info between neurons)
GABA in contrast is the primary INHIBITORY NT in the brain (prevents firing of neurons)
too much glutamate or too little GABA can cause neurons to be overactive -> seizures
types of neurotransmitters: nerepinephrine and serotonin
both involved in mood and arousal
norepinephrine: involved in states of vigilance or heightened awareness of dangers in the environment
serotonin: involved in regulation of sleep and wakefulness, eating, aggressive behaviour
low levels of both associated in mood disorders (depression)
types of neurotransmitters: endorphines
chemicals that act within pain pathways and emotion centers of the brain
similar to morphine
endorphines are internally produced substances that dull experience of pain and elevating moods
runner’s high caused by release of endorphines in the brain
balance of NT
imbalance of NT can drastically affect behaviour
if the brain doesn’t produce enough serotonin, depression/anxiety
some people seek imbalances such as people who smoke, drink, take drugs, alter balance of NT in brain
ex. drug LSD is structurally simiar to serotonin, so it binds easily with serotonin receptors in the brain, producing similar effects
how drugs mimic NT
agonists: drugs that increase NT action
(clonidine)
antagonists: drugs that diminish NT action
(caffeine)
L-dopa used to treat Park (movement disorder), made known by Mihammad Ali and Michael J. Fox
Parkinson’s caused by loss of neurons that make NT dopamine by modifying L-dopa produced naturally in body
ingesting L-dopa as a drug elevates its concentration in the brain and spurs surviving neurons to produce more dopamine (it is a agonist for dopamine)
Amphetamine (illegal) stim release of norepinephrine and dopamine (mood control), and blocks reuptake (creates excess of NT that flood the synapse, activating receptors over and over), leads to euphoria, wakefulness, energy, increase heart rate
cocaine prevents reuptake of NT
opioids, derived naturally (morphine and heroin) or made synthetically (oxycodone hydrocodone, fentanyl)
act as agonists for endorphins, powerful feelings of calm and euphoria
prescribed for pain relief as they as highly effective antagonists that decrease release of NT involved in perception of pain, and diminish brainstem’s sensitivity to rising levels of CO2 in blood, which depresses breathing
in the case of an overdose, leads to asphyxiation and death
drugs with medical implications
naloxone can help with opioid overdose, it is an opioid but acts as an antagonist (bind to opioid receptors, blocking agonists like heroin and preventing their effects on neurons)
Prozac treats depression, neurotransmitter agonist, blocks reuptake of NT serotonin
selective serotonin reuptake inhibitors (SSRIs)
by blocking reuptake of serotonin, NT remains in synapse longer, produces greater activation of serotonin receptors
Propanolol, antagonist, beta blockers, obstruct receptor sites in heart for norepinephrine (increases heartbeat, because norepinephrine cannot bind to these receptors, heart rate slows sown
beta blockers are also prescribed to reduce the agitation, racing heart, and nervousness associated with stage fright
peripheral nervous system subdivisions
somatic NS: set of nerves that conveys information between skeletal muscles and CNS
autonomic NS: set of nerves that carries involuntary and automatic commands that control blood vessels, body organs, glands
- two subdivisions
sympathetic: challenge
parasympathetic: return to rest
CNS
connections between sensory inputs and motor neurons in SC mediate spinal reflexes, simple pathways in NS that rapidly generate muscle contractions
reflex arc: neural pathway that controls reflex actions
Divisions of the brain
hindbrain: SC is continuous with the hindbrain, an area of the brain that coordinates info coming into and out of SC
- controls basic functions of life: respiration, alertness, motor skills
- medulla: extension of SC into skull that coord heart rate circulation, respiration
- reticular formation: small cluster of neurons that regulate sleep, wakefulness, arousal. many general anesthetics work by reducing activity in the reticular formation, rendering the patient unconscious
- cerebellum: a large structure of the hindbrain that controls fine motor skills, fine-tuning of behaviour
- pons: structure that relays info from the cerebellum to rest of the brain
midbrain: on top of hindbrain, central location of NT involved in arousal, mood, motivation. you could survive if you only had hindbrain (take care of body functions) and midbrain (orientation to pleasurable or threatening stimuli)
- tectum: orients an organism in the environment, receives stimulus input and moves the organism in a coordinated way towards stimulus
- tegmentum: involved in movement and arousal, helps orient to sensory stimuli
forebrain: highest lvl of the brain, controls complex cognitive, emotional, sensory and motor functions
forebrain
- cerebral cortex: outermost layer of the brain, divided into two hemispheres
- subcortical structures: areas of the forebrain housed under the cerebral cortex near the center of the brain
thalamus: relays and filters info from senses and transmits info to cerebral cortex, receives inputs from all major senses except smell (direct connections to cerebral cortex), acts as computer server in nerworked system, taking in multiple inputs and relaying them to variety of lcoations, actively filters sensory info, closes pahways of incoming sensations during sleep
three components of limbic system: where subcortical structures meet the cerebral cortex
- hypotha: located below thalamus, regulates body temperature, hunger, thirst, sexual behaviour, lesions result in overeating in some areas of hypothal, to other areas cause no desire for food, produce hissing and biting, release of hormones during sex
- hippocamp: critical for creating new memories and integrating them into a network of knowledge so that they can be stored indefinitely in other parts of the cerebral cortex, damage cause easy distractions
- amygdala: located at tip of each horn of the hippocampus, plays a central role in many emotional processes, particularly the formation of emotional memories, attaches significance to previously neutral evens that are associated with fear, punishment, reward
basal ganglia: set of subcortical structutres that directs intentional movements and plays a role in reward processing, reveive input from cerebral cortex and sen outputs to motor centers in brainstem, one part of basal ganglia, the striatum, has an important role in the control of posture and movement. park damages parts of the midbrain that normally supply the striatum with dopamine, undersupply of dopamine impairs function of striatum, which leads to visible tremors of park, part of striatum called nucleus accumbens has been linked to various kinds of rewards including social rewards such as approval
pituitary gland (part of endocrine system: a network of glans that produce and secrete into the bloodstream hormones, which influence a wide vaierty of basic funcitons)
- orchestrates the endocrine system
- master gland of hromone producing system, which releases homrones that direct the function of many other glands in the body
examples
hypothalamus sends hormonal signals to pituitary gland, which sends hormonal signals to other glands to control stress, digestive activities and reproductive processes
ex. sense threat, sensory neurons send signals to the hypothalamus, which stimulates release of adrenocorticotropic hormone (ACTH) from pituirary gland
ACTH stimulates adrenal glands to release hormones that activate the SNS (threat)
cerebral cortex: highest level of the brain
sits over brain like mushroom cap
raise parts called gyri
fissures called sulci
functions of CC understood at 3 levels: separation of cortex into two hemispheres, functions of each hemisphere, role of specific cortical areas
two symmetrical hemispheres, but each hemisphere controls functions of the opposite side of the body (contralateral control)
right cerebral hemisphere perceives stimuli from and controls movements on the left side of the body
cerebral hemispheres connected to each other by commissures (axon bundles), largest in the corpus callosum: connects large areas of the cerebral cortex on each side of the brain and supports communication of info across the hemispheres
occipital lobe: visual info
sensory receptors in the eyes send info to thalamus, sends info to occipital lobe, and simple features of stimulis are extracted such as location and orientation of object’s edges
other 3 lobes process info from multiple modalities
parietal lobe, processing info about touch, contains the somatosensory cortex, represents skin areas on the contralateral surface of the body
The somatosneosy cortex can be illustrrated as a distorted figure called a homunculus, body parts are rendered according to how much of the somatosensory crtex is devoted to them, in front of somatosensory cortex Iin frontal lobe) is motor cortex: initiates voluntary movement and sens messages to the basal ganglis, cerebellum, and SC
temperal lobe for hearing and language. the auditory cortex is analgous to somatosensory cortex in parietal lobe and primary visual areas of the occipital lobe. receives sensory info from ears based on frequenceis of sound, seoncadry areas of temporal lob then process info to meaningful units, such as speech and words, also houses ares that interpret meaning of visual stimuli and help us recognize common objects int he environment
frontal lobe: specialized ares for movement, abstract thinking, planning, memory, judgement, containes motor cortex, coordinates movement of muscle gorups throughout the boy,
organization within specific lobes
third level of organization, involves the representation of info within specific lobes in the cortex
association areas are composed of neurons that help provide sense and meaning to info registered in the cortex
ex) neurons in the primary visual cortex are highly specialized, some detect features of the environment that are in horizontal orientation, others detect movement, and still others process info about human versus nonhuman forms
association areas interpret the info extracted by the primary areas (shape, motion) to make sense of what’s being perceived
association areas stitch together the threads of info in the various parts of the cortex to produce a meaningful understanding of what’s being reigstered in the brain
- discovery of the mirror-neuron system: active when an animal performs a behaviour, such as reaching for or manipulating an object, and are also activated when another animal observes the animal performing the same behaviour.
mirror neurons in fronta lobe and parietal lobe
neurons in association areas are usually less specialized and more flexible than neurons in the primary areas, can be shaped by learning and experience to do their job more effectively
Brain Plasticity
sensory cortices are not fixed: they can adapt to changes in sensory inputs, a quality called plasicity (ability to be molded)
