Psych unit 3

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 fire again.

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)