Psych Unit 2 Section 1

Nervous System

The body’s speedy electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous system

Central Nervous System

The brain and the spinal cord

Peripheral Nervous System

Connects CNS to the limbs and organs, essentially serving as a communication relay going back and forth between the brain and the extremities.

Somatic Nervous System

The division of the PNS that controls the body’s skeletal muscles. Also known as the skeletal nervous system.

Autonomic Nervous System

The part of the PNS that controls the glands and the muscles of the internal organs. Controls the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System

The division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations. “Fight or flight”

Parasympathetic Nervous System

The division of the autonomic nervous system that calms the body, conserving its energy. “Rest and digest”

Reflex

A Simple, automatic response to a sensory stimulus, such as the knee-jerk response

Neuron

a nerve cell; the basic building block of the nervous system.

Sensory Neurons

Neurons that carry incoming information from the sensory receptors to the brain and spinal cord.

Interneurons

Neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and the motor outputs.

Motor Neurons

Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.

Soma

The neurons life support center that also produces neurotransmitters

Dendrite

The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.

Axon

The extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons, muscles, or glands.

Myelin Sheath

A layer of fatty tissue that covers the axon which aids in the speed of neural impulses; the thicker the myelin sheath, the faster the impulse. If the myelin sheath degenerates, it could lead to multiple sclerosis (communication to muscles slows, with eventual loss of muscle control).

Nodes of Ranvier

Spaces between the myelin.

Excitatory

Accelerates neurons firing speed

Inhibitory

Slows neurons firing speed

Threshold

The level of stimulation required to trigger a neural impulse.

Synapse

The junction between the terminal branch of the synaptic gap

Synaptic gap / cleft

The tiny gap at the synapse in which neurotransmitters cross.

Neurotransmitters

Chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

Endorphins

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

Endocrine System

The body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

Adrenal Glands

A pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine/adrenaline and norepinephrine/noradrenaline) that help arouse the body in times of stress.

Pituitary Gland

Master endocrine gland located in the limbic system