The Organization of the Nervous System

Appearance by color of tissue

• Gray matter -

Appearance by color of tissue

• Gray matter –

• White matter –

Appearance by color of tissue

• Gray matter –

• White matter –

• Reticular matter -

Description by location

• Dorsal to ventral

Description by location

• Dorsal to ventral

• Anterior to posterior

Description by location

• Dorsal to ventral

• Anterior to posterior

• Medial to lateral

General Divisions of the Nervous System

• Central Nervous System– Brain– Spinal Cord

General Divisions of the Nervous System

• Peripheral Nervous System– Somatic

• Sensory (afferent) and Motor (efferent) neurons• Innervates muscles, bones

General Divisions of the Nervous System

• Peripheral Nervous System– Autonomic

• Innervates glands and smooth muscles like the heart

• Works outside our control• Broken into sympathetic and parasympathetic

nervous systems

Sympathetic and parasympathetic nervous systems

• Sympathetic– Charges the body up

for emergencies– All parts emerge

simultaneously– Examples

• Parasympathetic– Calms the body down

after an emergency– A few parts slow down

at a time after an emergency

– Examples

Comparative Approach to Brain Analysis

• Also called the triune brain model– Reptilian – Brainstem made up of medulla

oblongata, pons and cerebellum– Old Mammalian – limbic system made up of

septum, hippocampus; amygdala, cingulate cortex, hypothalamus, and thalamus

– New Mammalian – cerebral cortex

Localization of Brain Function

• Overall, most activities in the brain come from various regions, yet certain activities seem to be most critical in handling specific functions.

Subcortical areas– (from posterior to anterior regions)

• Medulla oblongata• Pons• Cerebellum• Midbrain• Thalamus• Hypothalamus• Limbic system

– Septum– Amygdala– hippocampus

The Neocortex

• Convoluted surface has 10% of our neurons, and 80% of our brain volume– Gyri– Sulci– Fissures

• Responsible for higher functions such as thought and planning

Lobes of the Neocortex• Frontal

– Motor cortex– Broca’s area

• Parietal– Somatosensory region

• Occipital– Primary visual cortex

• Temporal– Wernicke’s area– Smell and taste areas– Auditory cortex

Lateralization of Function

• Techniques for showing lateralization– Electrical stimulation of awake participants– PET scans show regions for different activities– Strokes, injuries and lesions show specific deficits– EEG patterns– Split brain (commissurotomy) patients– Drugs affecting half the brain– Dichotic listening (different noises to each ear)

Left Brain Specialization

• Speech and language– Receptive auditory language function– Expressive language function– Handedness and language

Right Brain Specialization

• Spatial functions• Pattern recognition• Color distinctions• Musical functions

The Endocrine System

• Comparison to nervous system:– Hormones secreted into bloodstream rather

than neurotransmitters secreted into neural pathways

– Works in minutes to hours whereas nervous reactions are fractions of second to minutes

– Long-lasting effects rather than quick to dissipate

– Both interact with specific receptor sites– Systems overlap in certain parts

Hormones

• Three types: – Steroids– Peptides– Amino acid derivatives

Hormones

• Active in small amounts• Under tight negative feedback control• Rapidly degraded in body

– Steroids and peptides in liver– Amino acids by enzymes in blood

Specific Endocrine Glands• Pineal gland• Hypothalamus• Pituitary gland• Thyroid gland• Parathyroid glands• Adrenal glands• Pancreas• Ovaries and testes• *prostaglandins