The Nervous System - Lecture Review

Flashcards covering the vocabulary and functional components of the human nervous system including the reflex arc, brain regions, meninges, and spinal cord anatomy.

Reflexes

Rapid, predictable, and involuntary responses to a stimulus.

Somatic reflexes

Reflexes that stimulate the skeletal muscles, such as pulling the hand away from a hot object.

Autonomic reflexes

Reflexes that regulate the activity of smooth muscles, the heart, and glands.

Sensory receptor

The element of a reflex arc that reacts to a stimulus.

Sensory neuron

A neuron that carries a message to the integration center.

Integration center ($CNS$)

The site that processes information and directs motor output within a reflex arc.

Motor neuron

A neuron that carries a message to an effector.

Effector organ

The muscle or gland to be stimulated in a reflex response.

Two-neuron reflex arc

The simplest type of reflex arc, such as the patellar (knee-jerk) reflex.

Three-neuron reflex arc

A reflex arc consisting of five elements (receptor, sensory neuron, interneuron, motor neuron, and effector), such as the flexor (withdrawal) reflex.

Gyri

Ridges on the surface of the cerebral hemispheres.

Sulci

Grooves on the surface of the cerebral hemispheres.

Fissures

Deep grooves that divide the cerebrum into lobes.

Cerebral cortex

The outer layer of gray matter in the cerebrum composed mostly of neuron cell bodies.

Basal nuclei

Subcortical motor centers or deep pockets of gray matter that help control skeletal muscle movements.

Primary somatic sensory area

An area located in the parietal lobe posterior to the central sulcus that receives impulses from the body’s sensory receptors for pain, temperature, and light touch.

Primary motor area

Located in the frontal lobe, it sends impulses to skeletal muscles via the corticospinal (pyramidal) tract.

Broca’s area

A specialized area involved in the ability to speak, usually located in the left hemisphere.

Corpus callosum

The structure that connects the two cerebral hemispheres.

Thalamus

The relay station for sensory impulses surrounding the third ventricle that transfers impulses to the correct part of the cortex.

Hypothalamus

Important autonomic nervous system center located under the thalamus that regulates body temperature, water balance, metabolism, and the pituitary gland.

Epithalamus

Forms the roof of the third ventricle and houses the pineal body and choroid plexus.

Pineal body

An endocrine gland housed within the epithalamus.

Choroid plexus

Capillaries in the ventricles of the brain that form cerebrospinal fluid ($CSF$).

Midbrain

Part of the brain stem containing the cerebral peduncles and the corpora quadrigemina, which are visual and auditory reflex centers.

Pons

The bulging center part of the brain stem composed mostly of fiber tracts and nuclei involved in breathing control.

Medulla oblongata

The lowest part of the brain stem containing control centers for heart rate, blood pressure, breathing, swallowing, and vomiting.

Reticular formation

A diffuse mass of gray matter along the brain stem involved in motor control of visceral organs.

Reticular activating system ($RAS$)

A functional system that plays a role in awake/sleep cycles, consciousness, and filtering incoming sensory information.

Cerebellum

The region with two hemispheres and convoluted surfaces that controls balance, equilibrium, and the coordination of skeletal muscle activity.

Dura mater

The tough, double-layered outermost layer of the meninges.

Arachnoid mater

The middle weblike layer of the meninges that has extensions spanning the subarachnoid space.

Pia mater

The internal layer of the meninges that clings to the surface of the brain.

Cerebrospinal fluid ($CSF$)

A watery cushion formed by the choroid plexus that circulates in the subarachnoid space, ventricles, and central canal.

Blood-brain barrier

A barrier including the least permeable capillaries that excludes metabolic wastes and most drugs while allowing water, glucose, and essential amino acids to pass.

Cauda equina

A collection of spinal nerves at the inferior end of the spinal cord, which ends around vertebra $L1$ or $L2$.

Dorsal (posterior) horns

Internal gray matter structures in the spinal cord that house interneurons and receive information from sensory neurons.

Anterior (ventral) horns

Internal gray matter structures in the spinal cord that house motor neurons of the somatic nervous system.