Psy 2012 Module 3

Dendrites

• receiving antennas

• branched, tree-like extensions

• receiving end of a neuron

• attached directly to cell body (soma)

Cell Body

keeps cell alive/running

Axon

• electrical wire sends electrical signal down the line

Presynaptic terminals

• located at tip of axon

• look like dendrites

• sends neurotransmitters (chemical messengers)

Myelin sheath

fatty coding covers most of axon

Node of ranvier

• gaps in the myelin sheath

• speed up electrical signal

How an action potential is generated in the neuron

• Na at rest is more positive outside than inside

• sodium and potassium ions positively charged

1. charge increases as SODIUM ENTERS

2. charge on inside becomes more positive then the outside

3. charge reached THRESHOLD OF EXCITATION to fire

4. REFRACTORY PERIOD: charge decreases as potassium ions exit to reset

Saltatory Conduction

rapid jumping of an action potential down myelinated axon from one gap to the next

• regeneration of the action potential at each point is inefficient

• one generation of action potential is not possible without regeneration

Synapse

gaps between neurons

Presynaptic neuron

before/left side of synapse

• sending

Postsynaptic neuron

after/right side of synapse

• receiving

Neurotransmitters

chemical messengers

• released by neurons and glial cells

  • More localized, released into synapse 

  • More direct, quicker

Excitatory neurotransmitters

want presynapsis to fire

• open so sodium comes in

Inhibitory neurotransmitters

want presynapsis not to fire

• shut out sodium

Dopamine

• excitatory

• rewarding

• linked to schizophrenia

• parkinson: insufficient dopamine ; tourettes: excess dopamine

Serotonin

• inhibitory

• relaxation, sleep

Acetylocholin

• excitatory

• cognitive processes

• learning, memory, attention

GABA

• inhibitory

• makes you feel relaxed

• xanax helps it

Glutamen

excitatory

Lock and Key Mechanism

Transmitter must have specific shape to fit receptor sites

• drugs can have same shape and similar effects

Hormones

chemical messengers

• typically released by glands into blood stream

• slower, longer lasting effects

Neurotransmitters

• chemical messengers

• released by neurons and glial cells

• released into synapse, more localized

• more direct, quicker

The Crash

• stimulant wears off and you feel depressed

• makes you want to take more of the drug

• caused by exhausting neurotransmitter supply

• adrenal, caffeine, cocaine, nicotine, MDMA

Function of Opiates

• relieve pain

• can make you feel euphoric

Endorphins

neurotransmitter or hormone

• body’s natural pain reliever

• natural opiates

  • internal morphine

*narcan bumps out opioid drug and blocks site*

Hallucinogens

• cause hallucination: false sensation or perception

  • visual, auditory, taste, touch, etc.

  • also caused by lack of sleep, schizophrenia, dementia, dehydration

  • ex. LSD, salvia, psilocybin

Alcohol

depresses the part of the brain that blocks bad behavior

• inhibitory

• works with GABA

• decreases/blocks glutamate (excitatory)

Effects of Marijuana

• increased appetite and reduced nausea

• pain relief, reduced anxiety

• paranoia

• could cause hallucinations

• slows down perception of time

• reduced seizures

• heightened senses

What neurotransmitter do all drugs enhance?

dopamine

What is the problem with doing research on the effects of illegal drugs?

• might test another mammals

• using lab rats may not be representative of humans

• hard to find participants

• if other drugs are being used, you don’t know what’s causing what

• drug may not be pure

Tolerance

the body gets used to the effect of a drug

Withdrawal

when a person stops taking a drug and their body feels uncomfortable

• may cause hospitalization or even death

Cerebral Cortex

brain shell

Which side of the body is controlled by which side of the brain

• right side of body → left side of brain

• left side of body → right side of brain

What are the sulky/fissures?

the wrinkles of the brain

• shrink size of brain to fit in skull

• more surface area = more neurons and more mental processing power

• deeper than gyri

What are the gyri?

bumps/hills in the brain

Differences between male and female brains on average:

• same surface area

• men have larger brains

• women have more compact brains

Broca’s aphasia

• damage to area in frontal lobe

• trouble speaking fluidly but can understand

• usually on left side of brain

Wernicke’s aphasia

• damage to area in temporal lobe

• trouble comprehending and don’t make sense when they talk

Strokes

starvation of blood to a part of the brain

• likely the cause of aphasia’s

Ischemia

blockage of artery to the brain

• blood clot

• plaque build up

• more common (85% of strokes)

• helped by a blood thinner or Sten

Hemorrhage

leaking of blood in the brain

• too much blood in one area

• blood doesn’t get to where it needs to

  • neurons die

• increased pressure in the brain

• head trauma, hypertension (high BP), bleeding disorders

• emergency surgery stops the bleeding

Symptoms of Strokes

• paralysis of one side of body

• pain such as severe headache

• numbness

• speech issues

• confusion, trouble with perception

• depend on where it’s happening in the brain

Ventricles

4 cavities in the brain

• largest 2: lateral

• 3rd and 4th: smaller, skinner

  • in the middle

• filled with cerebral spinal fluid

  • produced in lateral ventricles and flows into meninges

Meninges

three protective layers

• found in:

1. between skull & brain: keeps brain afloat and cushions brain

2. between spine and spinal cord

• dura mater: toughest, closest to bone

• arachnoid: thin, looks like spider web

• CFS between arachnoid and Pia mater

• pia mater: soft, clear, closer to brain/spinal cord

Neuroplasticity

• brain is flexible/malleable

• allows learning, adapting, surviving, and repairing brain damage

• adding/subtracting connections

Neural Connections

brain keeps and grows best working connections and discards others

• born with the most amount of connections in brain

  • prepares for any environment/situation possible

  • helps with language

• loses connections to declutter

• occurs throughout life but mostly in infancy

Neurogenesis

creation of new neurons

• occurs on:

  • hippocampus; structure involved in creating new memories

  • on tongue and in nose

• occurs throughout life but best at infancy

  • when you learn language

Divisions in the Nervous System

Central Nervous System

• brain

• spinal cord

Peripheral Nervous System

• somatic nervous system

• autonomic nervous system

  • sympathetic nervous system

  • parasympathetic nervous system

Spinal Cord 2 R’s

function of spinal cord

• reflex: automatic movement

  • information reaches spinal cord and reacts

  • shortcut, doesn’t reach brain

• relays: information to/from the brain

  • sensory ascends to brain

  • motor descends from brain

Somatic Nervous System

• voluntary body movement

Autonomic Nervous System

• involuntary movement

• ex. heart beating, internal organs

• sympathetic and parasympathetic

Sympathetic Nervous System

• arousal/stimulation

  • excitement, anxiety, adrenaline, etc.

• body is getting ready for action

Parasympathetic

• rest and digest

Neurons

• main communicators

• larger

• fewer

• distant communication

Glial Cells

• support neurons

• smaller

• more abundant

• local communication

Similarities between neurons and glial

• cells in nervous system

• communication

• have different subtypes

Phrenology

the idea that you could feel bumps on the skull and determine different functions of different parts of the brain

What was wrong with phrenology?

the bumps and crevices in the brain mean nothing about characteristics or functions of the brain

Frontal Lobe

• largest, the front

• the thinking part of the brain

• decision making, judgment, actions/behavior, planning

• personality, emotion, aspects of memory

• all the senses send information here

Occipital Lobe

• smallest, in the back

• vision

Parietal Lobe

• top middle of brain

• primary somatosensory cortex

• touch/feel information

• identify where something is

Temporal Lobe

• near the temples, bottom middle

• first place we process smell and hearing

• advanced visual processing

Corpus Callosum

highway of myelinated axons that connect the left and right hemisphere

Gray Matter

made of cell bodies and dendrites

• outer part / on the side

White Matter

made of myelin sheath

• white because it’s covered in fat

• inner part

Medulla

governs breathing and reflexes

• important in keeping you alive

• digestion, heart rate, breathing

Pons

bridge that exchanges information from one side of body to other side of brain and from lower to upper areas

• governs sleep and arousal

Cerebellum

rounded structure involved in motor coordination

• little brain

• more neurons than the rest of the brain

• movement, coordination, balance

Thalamus

relays/sorts information between higher and lower brain centers

• in the middle

Hypothalamus

controls the release of hormones

• involved in endocrine system

• Fight, Flight, Food, Fornication

• plays role in emotion, stress, hunger, thirst, temperature regulation, motivation

• below thalamus

• works with pituitary

  • below hypothalamus

Amygdala

involved in fear and discrimination of objects necessary for organisms survival

• emotions of aggression, fear, anxiety

• we have one on each side

Hippocampus

structure involved in creating new memories

• one on each side of the brain

• looks like seahorse when cut