2.4 The Human Nervous System Flashcards

Vocabulary flashcards covering the components of the human nervous system, brain structures, types of neurons, neurotransmitters, and reflex actions based on the lecture transcript.

Central nervous system (CNS)

The component of the nervous system that contains the brain and spinal cord, responsible for receiving and processing information.

Peripheral nervous system (PNS)

The part of the nervous system containing the nerves that connect the central nervous system to the rest of the body.

Sensory neurons

Neurons that take messages from the sense organs and environment to the central nervous system.

Motor neurons

Neurons that relay messages away from the central nervous system to effectors such as muscles or glands.

Reticular formation

A network of neurons in the hindbrain and midbrain that regulates alertness, motivation, movement, and some body reflexes.

Medulla (brain stem)

Located between the spinal cord and cerebrum, it controls involuntary actions such as breathing, heartbeat, and blood pressure.

Cerebellum

Meaning 'little brain' in Latin, this structure takes up approximately $10\%$ of the brain's volume and is responsible for posture, coordination, and balance.

Cerebrum

The largest part of the brain, making up about $90\%$ of its volume, responsible for higher-order thinking, speech, and voluntary actions.

Corpus callosum

A linking bridge of nerve fibres through which the two cerebral hemispheres communicate with each other.

Somatic nervous system

A division of the peripheral nervous system that controls voluntary actions via the skeletal muscles.

Autonomic nervous system

A division of the peripheral nervous system that controls involuntary actions of internal organs and systems.

Sympathetic nervous system

A branch of the autonomic nervous system responsible for the 'flight or fight' response, such as increasing heart rate.

Parasympathetic nervous system

A branch of the autonomic nervous system that maintains homeostasis by having opposite effects to the sympathetic system, such as decreasing heart rate.

Dendrites

Highly sensitive branching extensions on the cell membrane of the cell body that possess receptors to receive messages.

Axon

A long structure of the neuron that carries electrical messages away from the cell body.

Myelin

A white insulating substance that covers the axon to help speed up the conduction of electrical impulses.

Interneurons

Also called connector neurons, these carry impulses through the central nervous system between sensory and motor neurons.

Synapse

The gap between neurons across which chemical messages are sent.

Neurotransmitters

Chemicals contained in tiny vesicles that are released into the synapse to bind to receptors on the next neuron.

Mirror neurons

A group of neurons that activate both when performing an action and when seeing others perform it, likely linked to empathy.

Serotonin

A neurotransmitter that acts like 'brakes' on emotions, producing a calming effect and regulating appetite and mood.

Noradrenaline

Also known as norepinephrine, it acts as an 'accelerator' to promote alertness, focus, and the formation of new memories.

Dopamine

A neurotransmitter important for healthy assertiveness and autonomic nervous system function; its synthesis is diminished in Parkinson's disease.

Reflex arc

A nerve pathway for quick, involuntary actions that travels only to and from the spinal cord, bypassing the brain.

Acetylcholinesterase

An enzyme that regulates nerves controlling muscle action; it is blocked by nerve gases such as tabun, sarin, and VX.