dendrites
-input fibers that carry electrical signals into a neuron from connected cells.
soma (cell body)
-control center of neuron
-integrates inputs from all dendrites
-determines whether neuron should fire or not
axon
-output fiber carries electrical signal from a neuron to a neighboring cell.
-neurons have one each
-larger than dendrites
-divide into branches at end called terminals
myelin sheath
-a layer of fatty tissue that covers around the axon
-enables greater transmission speed of neural impulses as impulses jump from node to node
-composed of glial cells (glove), support, nourish, protect neurons.
synapse
-the junction between the axon tip and the dendrite of the receiving neuron.
-called the synaptic gap or cleft as well
resting state
-a neuron has a slightly negative charge
-negative ions mostly inside cell, positive ones outside.
level of excitation
-level of stimulation needed for electrochemical communication to occur.
action potential
-brief charge that travels down the axon as it becomes depolarized.
-travels down to terminal where it causes neuro transmitters that bind to specific receptor sites on receiving neurons to fire.
refractory phase
-return to state of resting slightly negative charge (polarization)
-no amount of stimulation can cause the neurons to fire again in this stage.
-absolute refractory phase is followed by relative refractory phase in which neuron needs more stimulation to
excitatory neurotransmitter
-excite the cell into firing
inhibitory neurotransmitter
-inhibit the nerve cell from firing
serotonin
-regulates mood, eating, sleeping, and arousal
-prozac and ecstasy work by boosting its effects
dopamine
-regulates movement and posture
-particularly in basal ganglia
-lack= Parkinson's or catatonic
-overabundance, associated with Tourrete's and schizophrenia
acetylcholine
-regulates cognitive functioning and memory
-Alzheimer's associated with loss of it in neurons that connect with hippocampus
-nicotine is an agonist (mimics it), thats why cigarettes boost arousal and concentration
norepinephrine (noradrenalin)
-regulates alertness and wakefulness
-too much=mania, too little=depression
-puts the body on "red alert" during stressful or exciting situations
-coke and amphetamines boost levels
gaba
(agamma amniobutyric acid)
-inhibits the action of target cells
-low levels: implicated in anxiety and epilepsy
-alcohol and barbiturates raise levels
endorphins
-"morphine within"
-natural opiate-like neurotransmitter linked to pain control and pleasure
-exercise linked to raising endorphin level
glutamate
-most abundant excitatory n.t.
-plays significant role in learning and memory
afferent neurons (sensory neurons)
-takes info from senses to brain
interneuron
-once info reaches brain, it takes message and sends it along
efferent neurons (motor neurons)
-takes instructions back to muscles
Central Nervous System (CNS)
-made up of two major components: brain and spine
-receives, processes, interprets, and stores incoming sensory info.
-sends out messages for muscles, glands, and internal organs.
Peripheral Nervous System (PNS)
-consists of nerves/tissue outside brain and spinal cord
-two categories: somatic and autonomic nervous systems.
somatic
(skeletal)
-consists of nerves that are connected to sensory receptors and to skeletal muscles that permit voluntary action
-muscles, joints, skin
-associated with all body movement
autonomic
-controls autonomic functions of the body
- controls fight or flight response
Autonomic: sympathetic
-mobilizes body to respond to stress
-accelerates some functions (heart, b.p.) but conserves resources (digestion slows)
Autonomic: parasympathetic
-responsible for slowing down body after stress response
Wilder Penfield
-stimulated brain with electrical probes while patients underwent surgery for epilepsy
-created maps of sensory and motor cortices
localization
-major parts of brain perform different (though sometimes overlapping) tasks
plasticity
-in cases of injury certain structures can take on new tasks
hindbrain
-consists of structures in the top part of the spinal cord
-controls basic biological functions that keep us alive
-primitive part of brain
medulla oblongata
(hindbrain)
-regulates heart rate, b.p., breathing, etc.
pons
(hindbrain)
-connects the hindbrain with the mid and fore brains.
-involved in control of facial expressions
cerebellum
(hindbrain) "little brain"
-coordinates voluntary movement and balance
-damaged in people with autism
midbrain
-located just above the spinal cord, and hindbrain, below forebrain
-small in humans
-coordinates simple movements with sensory info.
-contains reticual formation: nerve network in brain stem
-plays role in controlling arousal
-if damaged, coma results
basal ganglia
(midbrain)
-body movements and speech
-overactive: Tourrette's, under-active= Parkinson's
nucleus acumbens
(midbrain)
-plays central role in rewards, laughter, sexuality, etc.
-high concentration of serotonin and dopamine pathways
thalamus
(forebrain)
-located on top of brain stem
-responsible for receiving sensory signals and sending them to appropriate ares in the forebrain.
-all senses except smell
hypothalamus
(forebrain)
-small structure below thalamus
-controls metabolic functions: body temp., hunger, thirst, endocrine system, libido
amygdala
(forebrain)
-almond shaped near the front of brain
-involved in the arousal and regulation of emotion and initial reaction to sensory info
hippocampus
(forebrain)
-involved in storage of new info, memories
limbic system
-made up of thalamus, hypothalamus, amygdala, and hippocampus
-deals with emotions and memory
cerebral cortex/cerebrum
-grey, wrinkled surface that is densely packed with neurons
-located in upper forebrain
-connections between neurons grow as we learn and develop
-surface is wrinkled to increase surface area (convolutions)
left hemisphere
-logic and reasoning (detail oriented)
-number manipulation, arithmetic
-language (grammar skills)
-right handed touch, movement.
right hemisphere
-spatial construction, non-verbal imagery
-face recognition
-more "big picture" oriented (initiative)
frontal lobe
-large area, 1/2 of brain
-goal oriented behavior, future planning
-believed responsible for abstract thought and emotional control
-contains Broca's area: controls muscles involved in speech
-thin,vertical strip at back of cortex, motor cortex: sends sig
parietal lobe
-located behind frontal lobe
-contains somato-sensory cortex: thin, vertical strip, receives incoming touch sensations
-both the motor and somato-sensory cortices are organized similarly: top receives sensations from bottom of body; and vice-versa.
-invol
occipital lobe
-located at the very back of brain, farthest from eyes
-however, one major function is to interpret messages from eyes into visual cortex.
-impulses from right half of each retina are processed in the visual cortex of the left side, and vice-versa.
temporal lobe
-processes sound sensed by ears
-sound waves processed, turned into neural impulses and interpreted in auditory cortex.
endocrine system
-system of glands that secrete hormones that affect many different biological functions in body
-controlled by hypothalamus
adrenal gland
-produces adrenaline
melatonin
-regulates biological rhythm, i.e. sleep
-controlled by pineal gland
-inhibited by light, increased by dark
monozygotic
-identical twins
dizygotic
-fraternal twins
Thomas Bouchard
-studied 100 identical twins, who were raised separately.