A substance secreted into the bloodstream by an endocrine gland or other tissue (or organ) to regulate processes in distant target organs and tissues.

An endocrine gland next to the kidney which secretes hormones that regulate metabolism, blood pressure, immune system, and response to stress as well as other essential functions.

A gland that lies at the base of the brain that monitors and regulates numerous bodily functions through the hormones it secretes.

A small, important area at the center of the brain that produces hormones. It primarily controls the autonomic functions of the body and integrates appropriate autonomic responses to difference stimuli.

An endocrine gland forming a shield-like structure on the front and sides of the throat. It plays a role in metabolism, growth, and the development of the human body.

A small endocrine gland found near the thyroid gland that regulates calcium levels in the bloodstream.

A small, cone shape gland located in the center of the brain which receives information about the state of the environment and convey this information in order to secrete melatonin.

Located behind the stomach, inside the abdomen, this gland secretes pancreatic juice and regulates blood sugar.

The female reproductive organ, which produces ova and sex hormones, and controls menstruation and pregnancy.

The principle male reproductive organ, which produces sperm and testosterone, which in turn, regulates sex drive, muscle mass, strength, fat distribution, and the production of red blood cells.

A system of interconnected neurons, nerves, tracts, and associated tissues that transmit signals between the brain and the rest of the body, including internal organs.

Consisting of the brain and spinal cord, this term is one of two different parts of the Nervous System. This is the body's central processing center.

Residing outside the brain and spinal cord, this type of Nervous System can be separated into two parts and is primarily an extension of its other half, helping its partner relay information between the brain and the rest of the body.

The portion of the Peripheral Nervous System that controls voluntary movements and communication to and from the sense organs- they are controlled, they are not automatic.

This Nervous System controls involuntary functions or items that happen automatically with our bodies- breathing, eating, digestion, heartbeat. It can be separated into two different sections.

Broken off from the Autonomic Nervous System, this system physically arouses the body, preparing it act/react in stressful situations, expending energy. It initiates the fight or flight response.

This system calms the body, conserving its energy and maintaining homeostasis. It is the second half of the Autonomic Nervous System.

A neuron that receives information from the environment via specialized receptor cells and transmits this information-in the form of nerve impulses- through synapses with other neurons to the Central Nervous System. They are located just outside of the spinal cord.

These neurons are located in the cerebral cortex and brainstem to the spinal cord. They transmit impulses out of the Central Nervous system to the Peripheral Nervous System and muscles.

The only neurons in the Central Nervous System, these neurons act as messenger between sensory and motor neurons.

A region of specialized membrane on the surface of a neuron that contains receptor molecules that receive and react with particular messenger molecules (e.g. neurotransmitters).

A branching, threadlike extension of the sell body that increases the receptive surface of a neuron. They receive incoming messages from other neurons.

The cell body of a neuron that houses the nucleus and decides whether or not the send the message through the axon body.

The long, thin, hollow, cylindrical extension of a neuron that normally carries a nerve impulse way from the cell body

The insulating layer around many axons that increases the speed of nerve impulses.

Space in between the Myelin Sheath.

The end of an axon branch from which an impulse is transmitted through a discharge of a neurotransmitter across the synapse to a neighboring neuron.

A fluid-filled, saclike structure, that contains neurotransmitter molecules.

Open space between two neurons; the space in which neurotransmitters cross.

Any of a large number of chemicals that can be released by neurons to mediate the transmission of nerve signals across synapses. There are two different kinds.

A membrane that allows some, but not all, to pass through.

Nonneural tissue in the nervous system that provides structural, nutritional, and other kinds of support to the neurons.

A type of nonneural cell that forms the myelin sheath around the axon body.

At resting potential, when sodium is on the outside of the neuron and potassium is on the inside. At this state, the neuron is at homeostasis.

When the neuron transmits a message, Sodium ions come in and neutralize the axon body.

the electrical pulse or "message" that travels the length of the axon;

the change in electric potential that propagates along the axon of a neuron during he transmission of a nerve impulse. It is marked by rapid depolarization of the cell's plasma membrane.

The change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential.

When a neuron is not firing and has a negative charge with mostly potassium ions inside and mostly sodium ions outside of the axon. This means the neurons are polarized.

The process by which neurotransmitter molecules that have been released at a synapse are reabsorbed by the presynaptic neuron that first released them.

A period of inactivity after a neuron has undergone excitation. As the cell is repolarized, it will not response to ay stimulus.

Th principle that the amplitude of the action potential in a neuron is independent of the magnitude of the stimulus. Thus, all stimuli above the neuron's threshold trigger action potentials of identical magnitude.

The minimum intensity of a stimulus that is necessary to evoke a response.

A drug or other chemical agent that produces an effect by binding to a particular receptor.

A drug or other chemical agent that inhibits the action of another substance. They block neurotransmitter activity.

Neurotransmitters that exert a faciliatory effect on postsynaptic neurons, resulting in a greater likelihood of action potential.

Neurotransmitters that hyperpolarize postsynaptic neurons- thereby making the intracellular space more negative, and hence, requiring a greater positive charge to overcome- resulting in a smaller likelihood of an action potential.

A major, predominantly excitatory neurotransmitter both in the Central and Peripheral Nervous Systems. In the CNS, it plays an important role in memory formation and learning and is implicated in Alzheimer's disease. In the PNS, it mediates skeletal, cardiac, and smooth muscle contraction.

Both a neurotransmitter and a hormone, this substance plays an important role in our body's "fight or flight" response. It increases heart rate and force of heart contractions, among other things.

Acting as both a neurotransmitter and a hormone, this substance is a chemical made by some nerve cells in the adrenal gland. Together with its partner, it regulates heart rate and blood flow.

A major excitatory neurotransmitter involved in cognitive, motor, and sensory functions.

A neurotransmitter that has an important role in more behavior and is implicated in numerous mental conditions and emotional states.

A neurotransmitter that has roles in emotional processing, mood, appetite, sexual desire and performance, sleep, pain processing, hallucinations, and reflex regulation.

A major inhibitory neurotransmitter that is linked to epileptic seizures, tremors, and insomnia.