the nervous system 🧠

CNS

Central Nervous System, which includes the brain and spinal cord.

PNS

Peripheral Nervous System, consisting of nerves outside the brain and spinal cord.

Sensory neurons

Also known as afferent neurons, they carry information to the CNS.

Motor neurons

Also known as efferent neurons, they carry commands away from the CNS to muscles or glands.

Voluntary actions

Actions that you consciously choose, like lifting your arm.

Involuntary actions

Actions that happen without conscious control, like your heart beating.

Reflex

A rapid, automatic response to a stimulus.

Cerebrum

Part of the brain responsible for thinking, memory, and voluntary movements.

Cerebellum

Part of the brain that helps with balance, coordination, and smooth movements.

Brainstem

Part of the brain that controls basic life functions such as breathing and heart rate.

Meninges

Three protective layers surrounding the brain and spinal cord.

Neurotransmitter

A chemical messenger that carries signals between nerve cells.

Acetylcholine (ACh)

A neurotransmitter that helps muscles contract and is important for learning and memory.

Dopamine

A neurotransmitter involved in motivation, reward, learning, and movement.

Serotonin

A neurotransmitter that helps regulate mood, sleep, and appetite.

Noradrenaline

A neurotransmitter that aids alertness, attention, and response to stress.

Adrenaline

A hormone that prepares the body for fight-or-flight by increasing heart rate.

Endocrine system

A group of glands that release hormones to control and coordinate body activities.

Hormone

A chemical messenger released by an endocrine gland that affects target cells.

Skeletal muscle

Muscle attached to bones, usually under voluntary control.

Cardiac muscle

Muscle found in the heart, involuntary in nature.

Smooth muscle

Muscle found in organs, involuntary and responsible for moving substances.

Flexion

A movement that decreases the angle at a joint.

Extension

A movement that increases the angle at a joint.

Abduction

A movement that moves a body part away from the midline of the body.

Adduction

A movement that moves a body part toward the midline of the body.

Dorsal root

Sensory nerve root that carries information toward the spinal cord.

Ventral root

Motor nerve root that carries commands away from the spinal cord.

Reflex arc

A pathway involved in a reflex, including receptor, sensory neuron, integration center, motor neuron, and effector.

Autonomic nervous system (ANS)

Controls automatic body functions without conscious thought, such as heart rate and digestion.

Sympathetic division

Part of the ANS that prepares the body for fight-or-flight responses.

Parasympathetic division

Part of the ANS that focuses on resting and digestion.

Frontal lobe

The part of the brain responsible for planning, thinking, and decision-making.

Parietal lobe

Processes touch, pressure, pain, and temperature.

Temporal lobe

Responsible for hearing, processing sounds, and memory.

Occipital lobe

Processes visual information.

Dendrites

Receive signals from other cells.

Cell body (soma)

Contains the nucleus and maintains the neuron's function.

Axon

Carries electrical impulses away from the cell body.

Myelin sheath

Insulates axons and helps impulses travel faster.

Axon terminals

Release neurotransmitters to communicate with the next cell.