Module 5: The Nervous System and Endocrine System

Nervous System

the electrochemical communication system of the body

neuron

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

dendrite

branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Axon

The extension of a neuron through which neural impulses are sent

axon terminal

the end point of a neuron where neurotransmitters are stored & released to neighboring neurons

action potential

a neural impulse; a brief electrical charge that travels down the axon of a neuron

Refractory Period

The “recharging phase” during which a neuron, after firing, cannot generate another action potential

resting potential

the state of a neuron when it is at rest and capable of generating an action potential

all-or-none principle

the principle stating that if a neuron fires, then it always fires at the same intensity; all action potentials have the same strength

synapse

the tiny, fluid-filled gap between the axon terminal of one neuron and the dendrite of another

neurotransmitter

a chemical messenger that travels across the synapse from one neuron to the next and influences whether a neuron will generate an action potential

Excitatory Effect

a neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential, or fire

Inhibitory Effect

A neurotransmitter effect that makes it less likely that a receiving neuron will

generate an action potential, or fire

receptor cells

Specialized cells in every sensory system of the body that can turn other kinds of energy into action potentials (neural impulses) that the brain can process; also known as "sensory neurons"

sensory nerves

Nerves that carry information from the sense receptors to the spinal cord and brain.

Interneurons

nerve cells in the brain and spinal cord responsible for processing information

Motor Nerves

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

central nervous system (CNS)

the brain and spinal cord

peripheral nervous system (PNS)

the sensory and motor nerves that connect the brain and the spinal cord to the rest of the body

somatic nervous system

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

autonomic nervous system

The division of the peripheral nervous system that controls the glands and muscles of the internal organs; its subdivisions are the sympathetic (arousing) division and the parasympathetic (calming) division

sympathetic division

The part of the autonomic nervous system that arouses the body to deal with perceived threats.

parasympathetic division

the part of the autonomic nervous system that calms the body

endocrine system

one of the body's two communication systems; a set of glands that produce hormones, chemical messengers that circulate in the blood

hormone

a chemical messenger produced by the endocrine glands and circulated in the blood

pituitary gland

the endocrine system's master gland; in conjunction with an adjacent brain area, controls the other endocrine glands

Hypothalamus

The brain region controlling the pituitary gland

Thyroid gland

produces hormones that regulate metabolism, body heat, and bone growth

Adrenal glands

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

Pancreatic Gland

The endocrine gland which regulates the level of sugar in the blood

Sex Glands

Ovaries (females) and testes (males) are the glands that influence emotion and physical development