Human Nervous System Lecture Notes

Vocabulary flashcards covering key terms from the Human Nervous System lecture.

Nervous system

Network of billions of neurons that provides the fastest communication in the body, senses internal and external changes, and regulates muscles and glands.

Neuron (Nerve cell)

Basic structural and functional unit of the nervous system; specialized cell that conducts nerve impulses.

Cyton (Cell body)

Part of a neuron containing the nucleus and cytoplasm (lacking a centrosome) that supplies energy and metabolic support to the cell.

Soma

Another name for the neuron’s cell body (cyton).

Axon

Long fiber that carries outgoing nerve impulses away from the neuron’s cell body.

Myelin sheath

Fatty insulating layer surrounding many axons, providing protection and speeding up impulse transmission.

Nodes of Ranvier

Regularly spaced gaps in the myelin sheath where the axonal membrane is exposed.

Dendrites

Branched extensions of a neuron that receive incoming impulses and convey them toward the cell body.

Schwann cell

Cell that produces the myelin sheath around axons in the peripheral nervous system.

Nerve

Thin threadlike bundle of nerve fibers that runs throughout the body.

Nerve impulse

Wave of electrical disturbance that travels along a nerve fiber; also called a nerve signal.

Sensory nerve

Nerve that carries impulses from sense organs to the brain and spinal cord.

Motor nerve

Nerve that carries impulses from the brain or spinal cord to muscles and glands.

Mixed nerve (Interneuron)

Nerve within the brain or spinal cord that connects sensory and motor neurons to facilitate communication.

Synapse

Junction between two neurons where nerve impulses are transmitted.

Synaptic cleft

Tiny gap between two neurons at a synapse.

Neurotransmitter

Chemical messenger released from a neuron’s terminal knob that carries a signal across the synaptic cleft.

Acetylcholine

Example of a neurotransmitter mentioned in the lecture.

Central Nervous System (CNS)

Division of the nervous system consisting of the brain and spinal cord; processes incoming signals and dictates responses.

Peripheral Nervous System (PNS)

Division consisting of nerves entering and leaving the CNS (cranial and spinal nerves).

Cranial nerves

Nerves that enter or leave the brain.

Spinal nerves

Nerves that enter or leave the spinal cord.

Meninges

Protective membranes surrounding the brain and spinal cord.

Meningitis

Inflammation of the meninges.

Gray matter

CNS tissue composed mainly of neuron cell bodies; inner in the brain and outer in the spinal cord according to the lecture.

White matter

CNS tissue composed mainly of axons; outer in the brain and inner in the spinal cord according to the lecture.

Brain

Organ protected by the skull and subdivided into forebrain, midbrain, and hindbrain.

Spinal cord

Column of nerve tissue extending from the medulla oblongata through the vertebral column; communication link and reflex center.

Forebrain

Anterior brain region consisting of the cerebrum, thalamus, and hypothalamus.

Cerebrum

Largest part of the brain with two hemispheres linked by the corpus callosum; seat of intelligence, memory, consciousness, and language.

Corpus callosum

Bundle of white matter connecting the two cerebral hemispheres.

Thalamus

Structure at the base of the forebrain that connects different parts of the brain and relays information.

Hypothalamus

Region beneath the thalamus that regulates internal environment, controlling blood pressure, heart rate, temperature, thirst, hunger, and emotions.

Midbrain

Brain region above the pons that controls eye movement and skeletal muscles.

Hindbrain

Posterior brain region composed of the cerebellum, medulla oblongata, and pons.

Cerebellum

Hindbrain structure behind the cerebrum that coordinates muscles and maintains balance.

Medulla oblongata

Base of the brainstem connecting the brain with the spinal cord; controls involuntary actions such as heartbeat and breathing.

Pons

Brainstem structure in front of the medulla that carries impulses between cerebellar hemispheres and aids coordination.

Reflex

Quick automatic action mediated by the spinal cord in response to a stimulus.

Stimulus

Any agent or environmental change that brings about a change in the activity of an organism.