Nervous System Study Guide - Biology 275

Meninges

Meninges

Three connective tissue layers that separate and support the soft tissue of the brain from the bones of the cranium.

Dura Mater

Outer, dense irregular connective tissue covering of the brain that forms two fused layers and contains dural venous sinuses.

Arachnoid Mater

Delicate web of collagen and elastic fibers that lies external to the pia mater and contains the subarachnoid space.

Pia Mater

Innermost layer of the cranial meninges, a thin layer of areolar connective tissue that covers small blood vessels and helps with CSF formation.

Ventricles

Cavities within the brain that are derived from the neural canal and contain cerebrospinal fluid (CSF).

CSF Circulation

CSF is produced by the choroid plexus in the ventricles and flows through the ventricles and subarachnoid space, providing buoyancy, protection, and environmental stability to the brain.

Blood-Brain Barrier (BBB)

A barrier that regulates the substances that can enter the interstitial fluid of the brain, protecting neurons from exposure to drugs and variations in normal substances.

Lobes of the Brain

Frontal, parietal, temporal, occipital, and insula lobes, each with specific functional areas.

Motor Areas of the Brain

Located in the precentral gyrus of the frontal lobe, responsible for controlling voluntary skeletal muscle activity.

Sensory Areas of the Cortex

Responsible for receiving, processing, and storing sensory information, such as touch, temperature, and proprioception.

Association Areas

Integrate and interpret sensory information, allowing for conscious awareness and higher intellectual functions.

Cerebral Nuclei

Paired masses of gray matter buried deep within the cerebral hemispheres, involved in motor control, emotions, and sensory integration.

Diencephalon

Composed of the epithalamus, thalamus, and hypothalamus, responsible for sensory relay, autonomic control, endocrine regulation, and other functions.

Nerve signals

Relayed to the cerebral cortex and stimulate the sensation of thirst.

Suprachiasmatic nucleus

Directs the pineal gland to secrete melatonin at certain times of the day.

Limbic system

Controls emotional responses such as pleasure, aggression, fear, rage, contentment, and sex drive.

Anterior nucleus

Stimulates fluid intake and acts as the "thirst center".

Arcuate nucleus

Regulates appetite and releases GnRH, GHRh, and PIH.

Mammillary body

Directs olfaction sensations and controls swallowing.

Paraventricular nucleus

Produces oxytocin primarily.

Preoptic area

Regulates body temperature as the "thermostat".

Supraoptic nucleus

Produces ADH.

Ventromedial nucleus

Produces hunger and satiety sensations, acting as the "safety center".

Brainstem

Connects the cerebrum, diencephalon, and cerebellum to the spinal cord.

Midbrain

Superior portion of the brainstem, containing motor tracts, substantia nigra, and reticular formation.

Substantia nigra

Produces dopamine, affecting movement, emotional response, and pleasure/pain.

Tegmentum

Sandwiched between substantia nigra and periaqueductal gray matter, issues involuntary motor commands.

Pons

Bulging region on the anterior part of the brainstem, containing respiratory centers and cranial nerve nuclei.

Medulla Oblongata

Connects the brain and spinal cord, contains pyramids, and regulates vital functions.

Cerebellum

Coordinates muscle actions, stores movement memories, and receives proprioceptive information.

Limbic System

Composed of multiple structures that process and experience emotions.

Reticular Formation

Processes sensory input, maintains mental alertness, and regulates muscle tone.

Higher Order Brain Functions

Include memory, learning, and reasoning, involving complex networks and axon arrays.

Development

Myelination of CNS axons continues throughout the first 2 years, brain growth is 95% complete by age 5.

Cranial Nerves

12 pairs of nerves with various sensory, motor, and autonomic functions.

Spinal Cord

Part of the CNS, provides a link between the brain and body, and is protected by the vertebral column and meninges.

Gray Matter

Centrally located in the spinal cord, composed of neuron cell bodies, dendrites, unmyelinated axons, and glial cells.

White matter

Peripherally located and composed of myelinated axons.

Gray matter

Contains three horns - posterior, anterior, and lateral - with different cell bodies and functions.

Sensory pathways

Transmit ascending information from sensory receptors to the CNS.

Motor pathways

Transmit descending information from the brain to muscles and glands.

Spinal nerves

Formed from the union of an anterior root and a posterior root.

Nerve plexuses

Networks of interwoven anterior rami that occur in pairs on either side of the body.

Reflex arc

A rapid, preprogrammed response of muscles or glands to a stimulus.

Somatic nervous system

Includes sensory input from special senses, skin, muscles, and joints, and motor output to control skeletal muscle.

Autonomic nervous system

Includes involuntary motor output to cardiac muscle, smooth muscle, and glands.

Lower motor neurons

Innervate skeletal muscle fibers in the somatic nervous system.

Sympathetic nervous system

Preganglionic axons reside in the thoracic and lumbar regions of the spinal cord.

Parasympathetic nervous system

Preganglionic axons extend through cranial nerves and sacral regions of the spinal cord.

Sympathetic pathways

Include spinal nerve pathway, postganglionic sympathetic nerve pathway, splanchnic nerve pathway, and adrenal medulla pathway.

Interactions between parasympathetic and sympathetic divisions

Most organs are innervated by both divisions of the ANS.

Autonomic reflexes

Help maintain homeostasis and include stretch reflex, Golgi reflex, withdrawal reflex, and crossed-extensor reflex.

Neurotransmitters and receptors in ANS

Acetylcholine and norepinephrine are the main neurotransmitters, and cholinergic and adrenergic receptors are involved.