L/R Hemispheres & Parts of the Brain

neurons, nervous systems, neurotransmitters, hormones

Reflex Arc

Neural pathway that controls a reflex

Sensory/afferent neurons

carry sensory information from the external environment to the CNS

Motor/efferent neurons

Transmit signals from the CNS to muscles

Interneurons

Connect sensory neurons to motor neurons in the CNS

Central Nervous System 

Consists of the brain and spinal cord 

Peripheral Nervous System

Consists of sensory and motor pathways

Motor Pathways

Broken into Somatic (voluntary) nervous system and Autonomic (involuntary) nervous system

Autonomic (involuntary) nervous system

Broken into sympathetic and parasympathetic division

Gila

Provide structural support and insulation; 1 to 5 trillion

Neurons

Receive and transmit information; 100 billion with 100-500 trillion synaptic connections

Critical Period

specific developmental window during which neurons are highly sensitive to environmental stimuli 

Synaptic Pruning

Unnecessary connections between neurons are eliminated in the brain for efficiency

Parts of Neuron

Dendrite, Cell body/soma, Axon, Myelin sheath, Axton terminals/terminal buttons, Synapse/synaptic cleft 

Nerve Impluse

Electrochemical reaction (researched by Hodgkin & Huxley) where (+) Na and K ions and (-) Cl ions flow back and forth across cell membrane but does not cross at the same time

Resting Potential (Neuron firing)

Stable, negative charge where the cell is inactive (polarized)

Action Potential (Neuron firing)

Brief shift in the neuron’s electrical shift that travels down the axon (like spark on gunpowder)

Neuron Firing

When stimulated, channels in its cell membrane open and allow (+) ions in

All-Or-None-Law

A neuron either fires or it doesn't (like a gun); all action potentials are the same size; Neurons convey messages about the strength of the stimulus by varying the rate (volley principle) at which they fire (a stronger stimulus will cause a more rapid volley of impulses

Absolute Refractory Period 

Minimum time which another impulse can not occur (about 1-2 milliseconds) 

Post-synaptic potential (lock and key - neurotransmitters)

Not like action potentials, they are graded and increase/decrease the probability of a neural impulse being fired

What two types of messages can be sent?

Inhibitory and excitatory

Agonist

A chemical that mimics the actions of a neurotransmitter

Antagonist

A chemical that blocks the action of a natural neurotransmitter by occupying receptor sites

Acetylcholine (ACh)  

Muscle movement 

Dopamine (DA) 

Voluntary muscle movement, pleasurable emotions - cocaine elevates activity of DA synapse (reward center)

Low levels: parkinson’s disease

High levels: schizophrenia

GABA

Inhibitory transmitters - inhibition in the CNS; valium, anti-anxiety drugs, and alcohol are agonists to 

Low levels: anxiety disorders 

Endorphins 

Pain relief and some pleasurable emotions; opiate drugs (morphine and heroin) agonists 

Too much: reduce pain sensitivity 

Too low: increased pain 

Serotonin

Regulation of sleep, wakefulness, eating, and aggressive behavior

Low levels: may contribute to depression and OCD 

High levels: hallucinations (LSD antagonist to Serotonin)

Norepinephrine

Contributes to mood and arousal

High levels: agitated anxiety

Low levels: depression

Glutamate

Learning and memory; mood regulation

High levels: migraines, seizures

Low levels: fatigue, trouble learning

Substance P

Regulation of pain

High levels: chronic pain and inflammation 

Low levels: reduced pain 

Adrenaline

Affect the body’s reaction to stress (automatic to NS)

Leptin

Hormone produced by fat cells that signal the hypothalamus in the brain about the body’s fat levels

High levels: indicate the body has enough stored energy and suppresses hunger (vice versa) 

Ghrelin

Hormone produced by the stomach that stimulates hunger

Left Hemisphere

Controls the right side of the body, language: written and spoken, simple math, logical and analytical

Right Hemisphere

Controls the left side of the body, nonverbal expression - body language/facial expression, spatial skills, and holistic thinking 

Hemispheric Dominance

Difference between males and female = hormones; myths about dominance = left/right handedness and intelligence

Split-brain research

Roger Sperry cut the corpus collosum of epileptic patients

Electroencephalograph (EEG)

Monitors the electrical activity of the brain, brainwaves; used in clinical diagnosis of various neurological disorders

Brain Imaging (MRI) 

Person’s head is surrounded by a magnetic field, and the brain is exposed to radio waves, which causes hydrogen atoms in the brain to release energy

Brain Imaging (fMRI) 

Like MRI but measures the movement of blood molecules (an index of neural activity); provides both functional and structural information in the same image

Lesioning

Destroying a piece of the brain; insert an electrode into a brain structure and pass a high electric current to burn tissue

ESB (electrical stimulation of the brain)

Sending an electric current into a brain structure to activate it