Neuroscience: Neurons, Brain Structures, and Nervous System Functions

Neuron

A nerve cell that transmits information via electrical and chemical signals

Dendrite

Receives information from other neurons via synapses

Soma (cell body)

Contains the nucleus; groups form gray matter

Axon hillock

Junction of the soma and axon where action potentials begin

Axon

Transmits information via action potentials

Myelin sheath

Fatty insulation that speeds neural conduction; white matter

Nodes of Ranvier

Gaps between myelin that increase conduction speed

Telodendria

End branches of the axon

Terminal boutons

End buttons containing synaptic vesicles that release neurotransmitters

Synapse

Junction between neurons where neurotransmitters are released

Glial cells

Support neurons, provide nutrients, and aid long-term memory

Astrocytes

Form the blood-brain barrier and transport nutrients

Schwann cells

Myelin cells of the peripheral nervous system

Oligodendrocytes

Myelin cells of the central nervous system

Microglia

Clean up damaged tissue via phagocytosis

Central Nervous System (CNS)

Consists of the brain and spinal cord

Peripheral Nervous System (PNS)

Includes spinal nerves, cranial nerves, and sensory receptors

Spinal nerves

31 pairs that serve the body

Cranial nerves

12 pairs that arise from the brainstem

Superficial senses

Temperature, pain, and touch from skin and mucous membranes

Deep senses

Sensation from muscles, tendons, ligaments, and joints

Somatic sensory

Pain, temperature, pressure, stretch, and vibration

Kinesthetic sense

Sense of body movement

Special senses

Vision, hearing, taste, smell, and touch

Somatic Nervous System (SNS)

Voluntary motor control

Autonomic Nervous System (ANS)

Involuntary regulation of organs

Sympathetic nervous system

Prepares body for action (fight or flight)

Parasympathetic nervous system

Promotes rest and digestion

Efferent nerves

Carry motor information from the brain to muscles and glands

Afferent nerves

Carry sensory information to the brainstem

Mixed cranial nerves

Have both sensory and motor functions

Special cranial nerve functions

Senses or branchial arch muscles

General cranial nerve functions

Functions found throughout the body

Trigeminal nerve (CN V)

Both; facial sensation and mastication

Facial nerve (CN VII)

Both; facial expression, taste anterior 2/3 tongue, tears, saliva

Glossopharyngeal nerve (CN IX)

Both; taste posterior 1/3 tongue, swallowing, saliva

Vagus nerve (CN X)

Both; parasympathetic control of heart, lungs, GI; speech and swallowing

Accessory nerve (CN XI)

Motor; neck and shoulder movement

Hypoglossal nerve (CN XII)

Motor; tongue movement

Forebrain (prosencephalon)

Develops into telencephalon and diencephalon

Telencephalon

Cerebral lobes, white matter, basal ganglia

Diencephalon

Thalamus, hypothalamus, pituitary gland, optic tract

Midbrain (mesencephalon)

Auditory and visual processing

Hindbrain (rhombencephalon)

Pons, cerebellum, and medulla oblongata

Cerebrum

Thought, learning, speech, emotions, and voluntary movement

Thalamus

Relay station for sensory information except smell

Hypothalamus

Regulates homeostasis and links nervous and endocrine systems

Pituitary gland

Master control gland for hormone secretion

Pons

Relay between cerebrum, cerebellum, and spinal cord

Medulla oblongata

Controls breathing, heart rate, swallowing

Cerebellum

Coordinates and regulates muscle activity

Brainstem

Connects brain to spinal cord and controls vital functions

Cerebral arteries

Supply blood to anterior, middle, and posterior cerebrum

Basilar artery

Supplies cerebellum, brainstem, and occipital lobes

Circle of Willis

Equalizes blood flow and pressure in the brain

Spinal cord

Conducts sensory and motor information between brain and body

Gray matter

Cell bodies and processing areas

White matter

Myelinated fiber tracts

Dorsal roots

Afferent sensory fibers entering the spinal cord

Ventral roots

Efferent motor fibers exiting the spinal cord

Cauda equina

Collection of spinal nerves below the conus medullaris

Left hemisphere

Dominant for language and controls right side of body

Right hemisphere

Controls left side and artistic abilities

Precentral gyrus

Primary motor cortex

Postcentral gyrus

Primary somatosensory cortex

Broca's area

Speech production

Wernicke's area

Language comprehension

Frontal lobe

Motor planning, inhibition, speech production

Parietal lobe

Sensory processing and integration

Temporal lobe

Auditory processing and language

Occipital lobe

Visual processing

Subcortex

Brain structures beneath the cortex

Basal ganglia

Voluntary movement, muscle tone, executive functions

Limbic system

Emotion, memory, motivation

Amygdala

Emotion regulation and fear response

Hippocampus

Memory formation and spatial navigation

Corona radiata

Projection fibers connecting cortex to CNS

Corpus callosum

Commissural fibers connecting hemispheres

Arcuate fasciculus

Association fibers connecting Broca's and Wernicke's areas

Insular lobe

Integration of emotion, perception, and motor speech planning

Lesion

Damaged area of tissue

Hemorrhage

Ruptured blood vessel

Thrombosis

Local blood clot blocking flow

Embolism

Clot traveling from another area

Aneurysm

Ballooning of blood vessel wall

Cerebrovascular accident (CVA)

Stroke due to blocked or ruptured vessel

Transient ischemic attack (TIA)

Temporary stroke with restored blood flow

Ischemia

Lack of blood supply causing cell death