Psychology 1000 Chapter 3

glial cells

provide structure to the nervous system, supportive role for neurons, provide insulation, transport nutrients and waste products, mediate the immune response

neurons

information processors, functional unit of the nervous system

semipermeable membrane

the outer surface of the neuron. allows smaller molecules and molecule without an electrical charge to pass through it

soma

cell body of the neuron

dendrites

extensions from the soma. they can accept neurotransmitters from other dendrites, which allows for information transmission

axon

major extension from the soma, transmits signals down its body to continue the transmission of information

terminal buttons

extensions from the opposite end of the axon. transmit signals by releasing neurotransmitters from synaptic vesicles

synaptic vesicles

the containers of neurotransmitters. live in the terminal buttons

neurotransmitters

chemical messengers

myelin sheath

a glial cell coating on the axon of a neuron. increases the speed at which the signal travels

nodes of ranvier

gaps in the myelin sheath. signals jump over the gaps

phenylketonuria (pku)

causes a reduction in myelin and abnormalities in white matter cortical and subcortical structures. associated with cognitive deficits, exaggerated reflexes, and seizures

multiple sclerosis (ms)

large scale loss of myelin sheath due to autoimmune dysfunction. results in interference in electrical signals, causing symptoms like dizziness, fatigue, loss of motor control, and sexual dysfunction

synaptic cleft

the space between the synaptic vesicles of one neuron and the dendrites of another. neurotransmitters are released here

receptors

proteins on the cell surface of the dendrite which allow neurotransmitters to bind with the cell

lock and key mechanism

neurotransmitters must be a certain shape and size to fit into the receptor and cause a signal

membrane potential

the fluid on the outside of the cell is a different electrical charge than the fluid inside of the cell

resting potential

\-70mV. the cell is held in a state of readiness (potential movement)

sodium-potassium pump

allows movement of sodium and potassium across the membrane (both in and out). ions in high concentrations move toward areas of low concentration

sodium

higher levels outside the cell

potassium

more concentrated inside the cell

electrochemical gradient

difference in charge, particularly in the Na/K pump. this is the reason that sodium is pushed into the cell in the sodium potassium pump.

threshold of excitation

the charge that the inside of a cell must gain in order to start an action potential

peak action potential

the highest influx of sodium at one time. sodium channels will now shut and the potassium gates will open

repolarization

cell becomes more negative as the sodium influx stops and potassium leaves

action potential

positive spike in the electric charge of a neuron. moves down the axon to be transmitted to other neurons

all-or-none phenomenon

a signal is either strong enough to reach the threshold of excitation, or not. there is no turning it off once it starts

reuptake

excess neurotransmitters in the synaptic cleft are reabsorbed by the original neuron

degradation

another way of clearing the synapse. an enzyme breaks down the neurotransmitters into its components so that it can no longer transmit a signal

postsynaptic neuron

the neuron receiving the signal (it is *after* the synapse)

presynaptic neuron

the neuron sending the signal (it is *before* the synapse)

psychotropic medications

treat psychiatric conditions by restoring neurotransmitter balance

acetylcholine

muscle action and memory. can increase arousal and cognition

beta-endorphin

pain and pleasure. can decrease anxiety and tension

(think beta makes it better)

dopamine

mood, sleep, and learning. can increase pleasure and suppress appetite

gamma-aminobutyric acid/GABA

brain function, sleep. can decrease anxiety and tension

glutamate

memory, learning. increases learning and memory

norepinephrine

heart, intestines, and alertness. can increase arousal and suppress appetite

serotonin

mood, sleep. can modulate mood and suppress appetite

agonists

medications that mimic the effect of neurotransmitters

antagonist

medications that block signals and normal activity of the neurotransmitter

parkinson’s disease

low levels of dopamine. would receive dopamine agonists

schizophrenia

overactive dopamine neurotransmission is associated with some symptoms. may be prescribed antagonists of dopamine

reuptake inhibitors

prevent unused neurotransmitters from being reabsorbed into the neuron. allows for neurotransmitters to be used for longer durations

SSRIs

selective serotonin reuptake inhibitors. used for depression to prolong the efficacy of serotonin

ex. prozac, paxil, zoloft

central nervous system

brain and spinal cord

peripheral nervous system

all nerves extending from the spinal cord

peripheral nervous system (subdivisions)

somatic and autonomic

somatic nervous system

conscious or voluntary activities. consists of motor neurons and sensory neurons. involved in relaying sensory and motor information to and from the CNS

efferent fibers

motor neurons. carry signals away from the central nervous system to the muscles

afferent fibers

sensory neurons. bring sensory information toward the central nervous system for interpreting

interneuron

located primarily in the central nervous system. responsible for communication among neurons. allows multiple sources of available information to combine into one coherent picture

autonomic nervous system

controls internal organs and glands - things outside of voluntary control. divided into sympathetic and parasympathetic

sympathetic nervous sytem

stress-related activities “fight or flight”

parasympathetic nervous system

“rest and digest” - associated with daily routines and day-to-day operations

homeostasis

state of balance. biological conditions are maintained at optimal levels

spinal cord

connects the brain to all of the peripheral nerves. allows the brain to act, and acts as a relay centre. responsible for reflexes

brain stem

basic processes of life are controlled here

reflexes

sensory information is dealt with immediately by the spinal cord.

paralysis

an injury to the spinal cord causes every segment lower than the injury to lose function

hindbrain

medulla, pons, cerebellum

medulla oblongata

controls automatic processes - breathing, blood pressure, heart rate

pons

literally “bridge”. connects the hindbrain to the rest of the brain. involved in regulating brain activity during sleep

cerebellum

receives messages from muscles, tendons, joints, and structures in the ear. controls balance, coordination, movement, and fine motor skills. involved in procedural memory

midbrain

reticular formation, substantia nigra, ventral tegmental area

reticular formation

centred in the midbrain but extends the full length of the brain. sleep/wake cycle, arousal, alertness, and motor activity.

substantia nigra and ventral tegmental area

produce dopamine, critical for movement. degradation of this area would result in parkinson’s disease. also involved in mood, reward, and addiction

forebrain

cerebral cortex, thalamus, hypothalamus, pituitary gland, and limbic system

cerebral cortex

outer surface of the brain. uneven, contain gyri and sulci. has 2 hemispheres. associated with higher level processes (consciousness, thought, emotion, reasoning, language, memory)

gyri

raised areas on the cerebral cortex

sulci

grooves in the cerebral cortex

longitudinal fissure

deep sulcus that splits the brain is 2 halves

frontal lobe

from the front of the brain to the central sulcus. involved in reasoning, motor control, emotion, and language. contains motor cortex, prefrontal cortex, and broca’s area

motor cortex

located in the frontal lobe. involved in planning and coordinating movement

prefrontal cortex

higher level cognitive functioning, located in frontal lobe

broca’s area

language production (writing and speaking), located in frontal lobe

parietal lobe

immediately behind the frontal lobe/ processes information from the senses. contains the somatosensory cortex

somatosensory cortex

located in the parietal lobe. processes touch, temperature, and pain. organized so that structures that are near each other in the body are adjacent in the cortex

temporal lobe

located on either side of the head by the temples. associated with hearing, memory, emotion, and some aspects of language. contains the auditory cortex and wernicke’s area

auditory cortex

located in the temporal lobe. processes auditory information

wernicke’s area

located in the temporal lobe. involved in speech comprehension

occipital lobe

very back of the brain. contains primary visual cortex which processes visual information. organized retinotopically

retinotopic

there is a close relationship between the position of an object in the visual field and how it is projected in the occipital lobe

thalamus

sensory relay area. all senses except smell are routed through the thalamus before being directed to other areas for processing

limbic system

emotion and memory. smell is routed through here first. made up of three structures: hippocampus, amygdala, and hypothalamus

hippocampus

essential for learning and memory

amygdala

involved in emotion and associating emotions with memories

hypothalamus

regulates a number of homeostatic processes (temperature, appetite, BP). also communicates with endocrine system in the regulation of sexual motivation and behaviour

lateralization

specialization of function within the brain. occurs in each hemisphere. the left half of the brain controls the right side of the body, and the right side of the brain controls the left side of the body

right hemisphere

pitch perception, arousal, negative emotions

left hemisphere

forms associations in memory, selective attention, positive emotions

corpus callosum

neural fibers that connect the two hemispheres. allows information being processed on one side of the brain to be communicated to the other side

neuroplasticity

brain’s ability to create new neural pathways following an experience or injury, helps adapt the brain

brain imaging

visualizations of the brain

radiation imaging

CT, PET,

computerized tomography (CT)

takes a number of x-rays of a particular section of the body. x-rays pass through tissues with different densities at different rates. the computer constructs an overall image from the images.

often used to diagnose a tumour or brain atrophy

positron emission tomography (PET)

creates pictures of the active/living brain. patient is typically injected with a mildly radioactive substance (but can also drink it). once this gets to the bloodstream, the amount of the liquid in any given part of the brain can be monitored

the computer monitors the activity and creates a map of the active brain

magnetic field imaging

MRI, fMRI

magnetic resonance imaging

person is placed in a machine creating a strong magnetic field. when the magnetic field is turned off, the atoms return to their original position and emit electromagnetic signals. tissues of different densities give off different signals. the computer monitors these symbols and displays them

functional magnetic resonance imaging

same principles as MRI, but can show changes in the brain over time by tracking blood flow and oxygen levels