PSYCH 104: Chapter 3a

neurons

specialized cells that make up nervous system

cell body

contains nucleus aka soma

dendrites

branches // receive signals

axon

conduct electrical impulses

axon terminals

send signal to other cells

glial cells

hold neuron in place // make nutrients

neuron function 1

generate electricity - create nerve impulses

neuron function 2

release chemicals // communicate with other cells

neural impulse

aka action potential

resting potential

V= -70mV

action potential definition

depolarized // V= +40mV

how does action potential happen

Na⁺ channels open and Na+ enter

depolarized meaning

becomes less negative

How does restoring resting potential happen

Na⁺ channels close and K⁺ channels open

hyperpolarization

becomes more negative

absolute refractory period

cell will NOT fire again // limits how often impulses occur

the all or none law

action happens occur at max intensity OR not at all

stronger neural signal =

creates more action potential

stronger action potential

myelin sheath

made from glial cells // insulation = faster

nodes of ranvier

absence of myelin sheath // signals can “skip”

synapse

communicates across gaps // synaptic cleft

neurotransmitter

chemical substance that carries messages

synapse step 1

synthesis of neurotransmitters

synapse step 2

storage // held in synaptic vessels until needed

synapse step 3

released into synaptic space

synapse step 4

binding // attach to receptor sites

synapse step 5

deactivation // stop neurotransmitter signals

excitatory neurotransmitter

increase resting potential by depolarizing

inhibitory neurotransmitter

decrease resting potential by hyper polarization

glutamate

excitatory: learning and memory (controls behaviour)

acetylcholine

excitatory: muscle movement and memory

GABA

inhibitory: anxiety and motor control (controls behaviour)

Serotonin

inhibitory: mood, eating, and sleep

endorphins (adrenaline)

inhibitory: controls sensitivity to pain

norepinephrine

excitatory and inhibitory: wakefulness and memory (learning)

dopamine

excitatory and inhibitory: voluntary movement and pleasure (motivation)

sensory neurons

carry input from sense organs to spinal cord and brain // PNS → CNS

motor neurons

transmit impulses from brain and spinal cord to muscles and organs // CNS → PNS

interneurons

receives information and relays it to the CNS

Peripheral nervous system

Somatic and Autonomic

somatic nervous system

sensory and motor neurons // voluntary movements and sense

autonomic nervous system

involuntary movement and functions

where does sympathetic and parasympathetic belong to

autonomic nervous system

somatic nervous system

sympathetic nervous system

fight or flight

parasympathetic nervous system

rest and digest

Central Nervous System (CNS)

Spinal cord and brain

Spinal cord

Connects parts of PNS with brain

Spinal reflexes

Stimulus- response sequence // no brain involvement

Forebrain

Highly developed, numerous functions

Midbrain

Reflexes and voluntary movements

Hindbrain

Vital functions and coordinating movements

Parts of Forebrain (aka cerebrum)

• cerebral cortex

• Basal ganglia

• Limbic system

• Thalamus

• Hypothalamus

Cerebral cortex

outer layer of hemispheres (occipital, temporal, frontal, and parietal) // involved in thinking

Basal Ganglia

Collections of neurons needed for motor function

Hippocampus (limbic system)

Memory

Amygdala (limbic system)

Emotional response

Nucleus accumbens (limbic system)

Reward center

Thalmus

Relays sensory information

Hypothalamus

Regulate basic biological drives // homeostasis

Parts of Midbrain

• Reticular formation

• Superior colliculi

• Inferior colliculi

Reticular formation

Regulates consciousness

Superior colliculi

Involved in vision

Inferior colliculi

Involved in hearing

Parts of Hindbrain (aka brainstem)

• Medulla

• Pons

• cerebellum

medulla

controls automatic life-sustaining functions (ie breathing, digestion, heart)

pons

relay station for signals // regulate sleep and controls muscle/ glands in face

cerebellum

controls procedural memory (ie motor skills)

motor cortex

controls voluntary movements

Where is motor cortex located

Frontal lobe

somatic sensory cortex

receives input (sensations)

Where is somatic sensory cortex located

Parietal lobe

primary auditory cortex

temporal lobe of both hemispheres

Where is primary auditory cortex located

Temporal lobe

primary visual cortex

occipital lobe of both hemispheres

Where is primary visual cortex located

Occipital lobe

wernicke’s areas (speech)

language comprehension

Where is wernicke’s area located

Left side of temporal lobe

Broch’s area

speech production/ formation

Where is Broca’s area located

Left side of frontal lobe

Association cortex

all the other lobes of cerebral cortex

Right hemisphere

creativity - controls left side of body

Left hemisphere

analytical thinking- controls right side of body

corpus callous

bridges the hemispheres together

frontal lobe

personality and motor

parietal lobe

sensation

temporal lobe

hearing

occipital lobe

vision

EEG

measures changes in brain activity with electrodes

EEG’s are

cheap and quick

CT

takes horizontal pictures of the brain with x-rays

CT’s are

cheap and quick

PET

measure brain activity with radioactive liquid

PET’s are

cheap and quick

MRI

take a high quality picture of the brain with magnets

MRI’s are

expensive

fMRI

measure change in activity thorough O₂ levels

fMRI’s are

expensive

DTI

uses an MRI to build a picture