psychology praxis 5391

Neuron

Individual nerve cell responsible for transmitting information

Neuroanatomy

The study of parts of and functions of neurons

Dendrite

Root like parts of the cell that stretch from the cell body (soma) to make synaptic connections with other neurons

soma (cell body)

The body of a neuron that contains the nucleus and other parts of the cell needed to sustain life

Axon

Wirelike structures ending in the terminal buttons that extends away from the cell body.

Terminal buttons

Also called end buttons, terminal branches of axon, and synaptic knobs – the branched end of the axon that contains neurotransmitters

Neurotransmitters

Chemicals contained in terminal buttons that enable neurons to communicate. They fit into receptor sites on the dendrites of neurons.

Synapse

The space between the terminal buttons of one neuron and the dendrites of another.

The charge of a neuron at rest

Negative

Receptor sites

Areas on the surface of dendrites where neurotransmitters fit.

Threshold

The level of stimulation required to trigger an impulse.

Action potential

A neural impulse; And electric message firing down the axon of a neuron.

All or none principle

The law that the neuron fire is completely or not at all

Excitatory neurotransmitter

A chemical secreted that excites the next cell into firing.

Inhibitory neurotransmitter

A chemical secreted that inhibits the next cell from firing.

Acetylcholine

A neurotransmitter that triggers muscle contraction and affects learning and memory. Lack of it is associated with Alzheimer’s disease.

Dopamine

A neurotransmitter associated with movement and alertness. Lack Of it is associated with Parkinson’s disease; Over abundance is associated with schizophrenia

Endorphins

Natural, opiate-like neurotransmitters linked to pain control, and to pleasure. Associated with addictions.

Serotonin

A neurotransmitter that affects hunger, sleep, arousal, and mood. Lack of it is associated with clinical depression.

GABA

A major inhibitory neurotransmitter. Under supply linked to seizures, tremors, and insomnia.

Glutamate

A major excitatory neurotransmitter; Involved in memory. Associated with migraines and seizures.

Norepinephrine

A neurotransmitter involved in alertness and arousal. Associated with depression.

Types of neurons

Afferent (sensory), efferent (motor), and interneurons.

Afferent neurons

Take information from the senses to the brain

Efferent neurons

Take information from the brain to the rest of the body

Interneurons

When information reaches the brain, they take the messages and send them elsewhere in the brain or to efferent neurons.

Categories of the nervous system

Central and peripheral

Central nervous system (CNS)

The brain and spinal cord- All nerves our house within bone (skull and vertebrae).

Peripheral nervous system (PNS)

All nerves in the body that aren’t encased in bone; divided into two categories: Autonomic and sympathetic.

Autonomic nervous system

Part of the peripheral nervous system, that controls automatic functions of the body, i.e., our heart, lungs, internal organs, glands, etc.

Sympathetic nervous system

Part of the peripheral nervous system that mobilizes our body to respond to stress. Is both an accelerator (heart) and decelerator (digestion).

Parasympathetic nervous system

The brake pedal of the autonomic nervous system. It causes our body to slow down after a response to a stressful situation.

Lesioning

The removal or destruction of part of the brain.

Electroencephalogram (EEG)

Detect brain waves, used in sleep research.

Computerized axial tomography (CAT or CT) scan

A sophisticated x-ray. Creates a 3-D image of the brains structure, and only shows structure (Does not explain function).

Magnetic residence imaging (MRI)

Brain – imaging method that utilizes radio, magnetic waves, not x-rays. Better than CAT scans, but still doesn’t provide information on function.

Position emission tomography (PET)

Identify what areas of the brain are active during certain activities.

Functional MRI

Combines MRI and PET scans – shows details of the brain structure with information about blood flow in the brain.

Three major brain categories

Hindbrain, midbrain, forebrain

Hindbrain

Top part of the spinal cord, includes the medulla, ponds, and cerebellum

Medulla

Controls blood pressure, heart rate, breathing.

Pons

Facial expressions

Cerebellum

Means little brain; Coordinate some habitual muscle movement (ie tracking object with eyes, playing an instrument).

Midbrain

Located just above the spinal cord, but below forebrain. Coordinates movements with sensory information.

Reticular formation

Netlike collection of cells that control general body arousal, and the ability to focus attention.

When reticular formation doesn’t function:

People fall into a deep coma

Forebrain

Controls what we think of as thought and reason. Includes the Thelmas, Hypothalamus, amygdala, and hyppocampus.

Thalamus

The brains sensory switchboard, located on top of the brain stem; It direct messages to the Sensory receiving areas in the cortex, transmit replies to the cerebellum and medulla.

Hypothalamus

Small structure next to the Falma, direct metabolic functions, including body temperature, sexual arousal, hunger, thirst, and the endocrine system.

Amygdala

a limbic system structure involved in memory and emotion, particularly fear and aggression.

Hippocampus

In neural center located in the limbic system; Helps process explicit memories for storage

Cerebral cortex

Layer of densely packed neurons that create the gray wrinkled surface of the brain

Fissure

Wrinkles of the brain

Limbic system

A donut shaped system of neural structures at the border of the brain, stem and cerebral hemispheres; Associated with emotions, such as fear and aggression and such as those for food and sex. Includes the hippocampus, amygdala, and hypothalamus.

Contralateral Control

Each hemisphere of the brain controls the opposite side of the body.

Brain lateralization or hemispheric specialization

Specialization of function in each hemisphere

Corpus callosum

A broad band of nerve fibers joining the two hemispheres of the brain

Lobes of the cerebral cortex

Eight total, four on each hemisphere; temporal, parietal, occipital

Frontal lobe

Also called the prefrontal cortex, plays a critical role in thought processes

Broca’s area

Usually, in the left frontal lobe, it controls the muscles involved in producing speech

Wernicke’s area

In the temporal lobe, related to language comprehension (written or spoken)

Motor cortex

An area of the frontal lobe that controls voluntary movements

Parietal lobe

Contains the sensory cortex; Perceives incoming touch sensations from the rest of the body

Occipital lobe

Visual processing; Located at the back of the brain

Temporal lobe

Processes auditory information

Endocrine system

Network of glands that secrete hormones; Controlled by hypothalamus

Transduction

Signals transformed into neural impulses

Sensory adaptation

Decreasing responsiveness to stimuli due to constant stimulation

Sensory habituation

How much we focus on sensations determines our perception of them

Cocktail-party phenomenon

People tune in one message even while they filter out others nearby

Energy senses

Vision, hearing, touch

Chemical senses

Taste and smell

Visible light spectrum

The portion of the electromagnetic spectrum that is visible to the human eye; ROYGBIV

Cornea

Protective covering of the eye

Pupil

The adjustable opening in the center of the eye through which light enters

Iris

A ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Accommodation

The process by which the eyes lens changes shape to focus near or fire objects on the retina

Retina

A screen on the back of the eye that contains specialized neurons that are activated by different wavelengths of light

Cones and rods

Cone – color, bright lights

Rod – black and white, gray hues

20:1

Ratio of rods to cones

Fovea

The central focal point in the retina, around which the eyes cones cluster

Ganglion cells

Their axons form the optic nerve

Lateral geniculate nucleus (LGN)

Nucleus and thalamus that processes, most visual information from eye

Blindspot

The spot on the retina where the optic nerve leaves; No rods or cones are present

Optic chasm

The place nerves from both eyes joint and cross over within the brain

Trichromatic theory

theory or color vision that proposes three types of cones: red, blue, and green

Afterimage

A visual image that persists after a stimulus is removed

Opponent – process theory

Sensory receptors in the retina come in pairs; red – green, yellow – blue, and black – white. If one sensor is stimulated, its pair is inhibited from firing.

Soundwaves

Created by vibrations

Amplitude

Height of a wave, determines loudness of a sound, measured in decibels

Frequency

Length of a wave, determines pitch, measured in megahertz

Ear canal (auditory canal)

A tube running from the outer ear to the middle ear

Eardrum

A thin membrane that vibrates when sound waves reach it

Ossicles

Three Tiny bones in the middle ear (hammer, anvil, stirrup)

Oval window

Membrane at the entrance to the cochlea through which the ossicles transmit vibrations

Organ of Corti

Center part of the cochlea, neurons activated by the movement of hair cells

Place theory

In hearing, theory that the hair cells in the cochlea respond to different frequencies

Frequency theory

In Hearing, theory that hair cells fire at different rates in the cochlea

Conduction deafness

Occurs when something goes wrong with the system of conducting the sound to the cochlea

Nerve deafness

Occurs when the hair cells in the cochlea are damaged (by a loud noise)