Psio 4.1-4.3

Three functional divisions of nervous system

Sensory (afferent), Integrative (interneurons), Motor (efferent)

CNS components

Brain and spinal cord

PNS components

Cranial nerves + spinal nerves

Somatic nervous system function

Voluntary control of skeletal muscles; sensation from skin, muscles, joints

Autonomic nervous system divisions

Sympathetic (fight/flight) & Parasympathetic (rest/digest)

Enteric nervous system function

Controls GI tract activity

Neuron structural parts

Dendrites, soma, axon hillock, axon, myelin sheath, nodes of Ranvier, axon terminal, synapse

Pseudounipolar neuron function

Sensory neurons

Bipolar neuron locations

Sensory organs (e.g., retina, olfactory epithelium)

Multipolar neuron function

Most common; motor neurons + interneurons

Astrocyte functions

Nourish neurons, store glycogen, regulate K+, take up neurotransmitters, structural support

Ependymal cell function

Produce and circulate CSF; line ventricles; neural stem cells

Oligodendrocyte function

Myelinate CNS axons

Schwann cell function

Myelinate PNS axons

Microglia function

Immune defense; prune synapses for learning

Three meninges layers

Dura mater, arachnoid mater, pia mater

Subarachnoid space contains…

Cerebrospinal fluid (CSF)

Functions of CSF

Cushioning, chemical stability, waste/nutrient exchange

CSF composition

Filtered plasma—glucose, ions (Na+, K+, Cl-, Mg2+), oxygen

Buoyancy effect of CSF

Reduces brain weight from ~1.5 kg to ~50 g

Blood-brain barrier components

Endothelial tight junctions, astrocytes, pericytes

BBB function

Protects brain; highly selective permeability

Four major parts of the brain

Cerebrum, diencephalon, cerebellum, brainstem

Gyri vs. Sulci

Gyri = ridges; Sulci = grooves

4 major lobes of cerebrum

Frontal, parietal, temporal, occipital

Insula function

Interoception; visceral sensation; integrates autonomic info

Prefrontal cortex function

Decision making, personality, impulse control, reasoning, working memory

Premotor cortex function

Plans and coordinates learned movements

Primary motor cortex location

Precentral gyrus

Primary motor cortex function

Voluntary control of skeletal muscle

Primary somatosensory cortex location

Postcentral gyrus

Primary somatosensory cortex function

Touch, pain, temperature, proprioception

Primary visual cortex location

Occipital lobe

Visual association cortex function

Recognition of visual stimuli

Parieto-temporal-occipital association area function

“Where” pathway (dorsal) and “What” pathway (ventral) of visual processing

Fusiform face area function

Facial recognition

Primary auditory cortex function

Receives sound info (pitch, loudness, rhythm)

Auditory association cortex function

Interprets sound as speech/music/noise

Wernicke’s area function

Understanding language

Broca’s area function

Speech production

Broca’s aphasia characteristics

Non-fluent; difficulty speaking but comprehension intact

Wernicke’s aphasia characteristics

Fluent but meaningless speech; comprehension impaired

Association tracts

Connect areas within the same hemisphere

Commissural tracts

Connect hemispheres (e.g., corpus callosum)

Projection tracts

Connect cerebrum with lower brain/spinal cord

Main basal nuclei

Caudate nucleus, putamen, globus pallidus

Basal nuclei functions

Initiate/stop movements; suppress unwanted movement; habits; reward and emotion

Cerebellum functions

Coordination, posture, balance, error correction of movement

Arbor vitae

White matter of cerebellum

Vermis function

Controls trunk muscles

Thalamus main function

Relay station for sensory/motor info; attention filter; consciousness

Hypothalamus controls

Temperature, hunger, thirst, circadian rhythms, autonomic NS, pituitary gland

Epithalamus structures

Pineal gland (melatonin), habenular nuclei (emotion, reward, withdrawal behavior)

Midbrain key structures

Superior colliculi (visual reflexes), Inferior colliculi (auditory reflexes), Substantia nigra (dopamine), Red nucleus (limb movement)

Pons functions

Bridge connecting brain regions; respiration control; sleep; cranial nerves V–VIII

Medulla oblongata functions

Cardiovascular control, respiration rhythm, reflexes (swallow, cough, sneeze, vomit), decussation

Limbic system functions

Emotion, behavior, memory

Key limbic structures

Hippocampus, amygdala, hypothalamus, cingulate cortex, mammillary bodies, fornix, olfactory bulb

Hippocampus function

Learning and memory

Amygdala function

Fear, aggression, emotional memory

Patient H.M. significance

Hippocampus removal → inability to form new memories (anterograde amnesia)