1.2, 1.3a Vocab

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 spinal cord

Peripheral nervous system (PNS)

The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

Nerves

Bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory organs

Sensory (afferent) neurons

Neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord

Motor (efferent) neurons

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

Interneurons

Neurons within the brain and spinal cord; they communicate internally and process information between the sensory input and motor outputs

Somatic nervous system

The division of the peripheral nervous system that controls the body’s skeletal muscles

Automatic nervous system (ANS)

The part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic dickinson arouses; ifs parasympathetic division calms

Sympathetic nervous system

The division of the autonomic nervous system that arouses the body, mobilizing it’s energy

Parasympathetic nervous system

The division of the autonomic nervous system that clams the body, conserving evergy

Reflex

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

Neuron

A nerve cell; The basic building block of the nervous system

Cell body

The part of the neuron that contains the nucleus; The cells life-support center

Debtrites

A neurons often bushy, branching extensions that create and integrate messages, conducting impulses toward the cell body

Axon

The segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

Myelin sheath

A fatty tissue layer segmentally encasing the axons of some neurons; It enables vastly greater transition speed as neural impulses hop from one node to the next

Glial cells

Cells in the nervous system that support, nourish, and protect neurons; They may also play a role in learning, thinking and memory

Action potential

A neural impulse; A brief electrical charge that travels down the axon

Threshold

The level of stimulation required to trigger a neural impulse

Refractory period

In neural processing, a brief resting pause that occurs after a neuron has fired; Subsequent action potentials cannot occur until the axon returns to its resting state

All-or-none response

A neurons reaction of either firing (with a full-strength response) or not firing

Synapse

The junction between the scot tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.

Neurotransmitters

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

Reputake

A neurotransmitters reabsorption by the sending neuron

Endorphins

“Morphine within”; natural, opioid-like neurotransmitters linked to main control and pleasure

Agonist

A molecule that increases a neurotransmitter’s action

Antagonist

A molecule that inhibits or blocks a neurotransmitter’s action

Endocrine system

The body’s “slow” chemical communication system; A set of glands and fat tissue that secrete hormones into the bloodstream

Hormones

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