Nervous System 🧠💗

A complete set of vocabulary flashcards covering the divisions of the nervous system, neuron types, action potential phases, brain regions, and the reflex arc.

Central Nervous System (CNS)

The control center of the body, made up of only the brain and spinal cord, which processes information and coordinates responses through effectors.

Peripheral Nervous System (PNS)

The communication network made up of sensory organs, effectors (muscles, glands), and nerves that relay signals between the CNS and the rest of the body.

Sensory Input

The function of sensory neurons to receive signals from sensory receptors and relay them toward the brain.

Integration

The process performed by interneurons to interpret sensory information and determine an appropriate response.

Motor Output

The function where motor neurons deliver messages from the brain to muscles and glands to produce a response.

Afferent Division

Also known as the sensory division, it consists of nerves that relay signals to the brain; these signals 'arrive' at the CNS.

Efferent Division

Also known as the motor division, it consists of nerves that send messages from the brain to muscles and glands; signals 'exit' the CNS.

Autonomic Nervous System

A division of the PNS that controls involuntary functions through motor neurons leading to smooth muscle, cardiac muscle, and glands.

Somatic Nervous System

A division of the PNS responsible for voluntary movements by sending motor neurons from the brain to skeletal muscles.

Sympathetic Nervous System

The division responsible for the 'fight or flight' response, increasing heart rate, blood pressure, and glucose release while slowing digestion.

Parasympathetic Nervous System

The division responsible for the 'rest and digest' response, returning the body to normal by decreasing heart rate and increasing digestion.

Sensory Neurons

Also known as afferent neurons, they transmit impulses from sensory receptors toward the CNS.

Interneurons

Also known as association neurons, they are located between sensory and motor neurons to interpret information.

Motor Neurons

Also known as efferent neurons, they transmit impulses from the CNS to effectors like muscles and glands.

Resting Potential

The state of a non-transmitting neuron where the outside is positively charged and the inside is negatively charged at $-70\,mV$.

Threshold

The level of stimulus required to trigger a nerve impulse, often initiated by mechanical, chemical, or electrical stimuli.

Depolarization

The phase of an action potential where voltage-gated $Na^+$ channels open, allowing $Na^+$ ions to rush into the cell, making the inside positive at $+35\,mV$.

Repolarization

The phase where $Na^+$ channels close and $K^+$ channels open, allowing $K^+$ to rush out and returning the internal charge toward $-70\,mV$.

Hyperpolarization

A state where $K^+$ channels stay open too long, causing the potential to drop to $-75\,mV$, during which the neuron is briefly refractory.

Myelinated Neuron

A neuron where the nerve impulse jumps from node to node (saltatory conduction), achieving speeds of up to $150\,m/s$.

Unmyelinated Neuron

A neuron where the nerve impulse moves down the entire length of the axon via continuous conduction, meeting higher resistance.

Brain Stem

The region connecting the spinal cord to the brain, consisting of the pons, midbrain, and medulla oblongata; it controls vital involuntary functions.

Cerebellum

The region located below the cerebrum responsible for coordinating all motor activity.

Diencephalon

Found above the brainstem, it serves as the primary processing center for sensory information and homeostasis regulation.

Thalamus

The part of the diencephalon that directs sensory information.

Hypothalamus

The part of the diencephalon responsible for maintaining homeostasis.

Pineal Gland

A gland in the diencephalon that produces melatonin to regulate sleep.

Cerebrum

The largest part of the brain responsible for perception, reasoning, and memory.

Frontal Lobe

The front portion of each cerebral hemisphere responsible for deliberate movements and conscious thoughts.

Parietal Lobe

The lobe located behind the frontal lobe and separated by the central sulcus; it is responsible for sensory processing.

Temporal Lobe

The lobe found below the frontal lobe and separated by the lateral sulcus; it is responsible for hearing.

Occipital Lobe

The back portion of each cerebral hemisphere responsible for vision.

Reflex Arc

The five-step order of a response: sensory receptor, sensory neuron, interneuron, motor neuron, and effector.

Gray Matter

Consists of neuron cell bodies and synapses; it is responsible for processing information and control.

White Matter

Consists of myelin and tracts; its main job is to interpret and transmit information throughout the nervous system.