Study Lower Structures

Brainstem

Brainstem

The oldest part of the brain responsible for automatic survival functions, located where the spinal cord swells and the brain begins.

Medulla

The base of the brainstem that controls life-supporting functions like heartbeat and breathing; damage can lead to death.

Reticular Formation

A nerve network extending up and down the spinal cord into the brain that controls an organism’s level of alertness; damage can cause a coma.

Thalamus

The brain's sensory switchboard that directs messages to sensory receiving areas in the cortex; located atop the brainstem.

Cerebellum

Latin for "little brain," located in the rear of the brain; helps coordinate voluntary movements and balance.

Limbic System

A ring of structures around the thalamus that helps regulate memory, aggression, fear, hunger, and thirst; includes the hypothalamus, hippocampus, and amygdala.

Hypothalamus

Located directly under the front of the thalamus; regulates eating, drinking, body temperature, and fight or flight reactions to stress.

Hippocampus

Wraps around the back of the thalamus; plays a role in processing new memories for permanent storage.

Amygdala

Two almond-shaped structures that control emotional responses such as fear and anger.

Central Nervous System (CNS)

Comprises the brain and spinal cord; the brain is the location of most information processing.

Peripheral Nervous System (PNS)

The sensory and motor nerves that connect the CNS to the rest of the body; subdivided into somatic and autonomic nervous systems.

Somatic Nervous System

The division of the PNS that controls the body’s skeletal muscles and contains motor nerves for voluntary muscles. “Waving to someone”

Autonomic Nervous System

The division of the PNS that controls the glands and muscles of internal organs; monitors autonomic functions. “Breathing, Blood Pressure”

Sympathetic Nervous System

The part of the autonomic nervous system that arouses the body to deal with perceived threats; responsible for the fight or flight response.

Parasympathetic Nervous System

The part of the autonomic nervous system that calms the body and brings it back to a relaxed state.

Endocrine System

One of the body’s two communication systems; a set of glands that produce hormones, which are chemical messengers that circulate in the blood

Hormone

Chemical messengers produced by endocrine glands and circulated in the blood; slower communication system with longer-lasting effects.

Pituitary Gland

The “master gland” of the endocrine system that controls other endocrine glands; located at the base of the brain.

Thyroid Gland

An endocrine gland that helps regulate the energy level in the body; located in the neck.

Adrenal Gland

Endocrine glands that help to arouse the body in times of stress; located above the kidneys and release epinephrine and norepinephrine.

Pancreatic Gland

Regulates the level of blood sugar in the blood.

Sex Glands

Ovaries (females) and testes (males) that influence emotion and physical development; produce testosterone and estrogen.

Nervous System

The electrochemical communication system of the body that sends messages from the brain to the body for movement.

Neuron

The basic building block of the nervous system; performs tasks of receiving, carrying, and passing information.

Action Potential

A brief electrical charge that travels down the axon of a neuron; considered an "on" condition of the neuron.

Refractory Period

The "recharging phase" when a neuron cannot generate another action potential after firing.

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 that a neuron fires at the same intensity each time; action potentials are of the same strength.

Synapse

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

Neurotransmitters

Chemical messengers that travel across the synapse from one neuron to the next; influence whether the second neuron will generate an action potential.

Excitatory Effect

A neurotransmitter effect that makes it more likely for the receiving neuron to generate an action potential.

Inhibitory Effect

A neurotransmitter effect that makes it less likely for the receiving neuron to generate an action potential.

Receptor Cells

Specialized cells in the sensory systems that convert other forms of energy into action potentials for processing by the nervous system.

Sensory Nerves

Nerves that carry information to the central nervous system, connecting sense organs to the brain and spinal cord.

Interneurons

Nerve cells in the brain and spinal cord responsible for processing information related to sensory input and motor output.