Nervous System Divisions

Divisions of the Nervous System

• Sympathetic Nervous System is responsible for the "fight or flight" response
• An increased heart rate and sweating in dangerous situations are examples of the Sympathetic Nervous System
• Parasympathetic Nervous System regulates "rest and digest" functions
• A decreased heart rate after eating is an example of the Parasympathetic Nervous System
• The Enteric Nervous System controls the digestive system
• Intestinal peristalsis to move food through the digestive tract is an example of the Enteric Nervous System

Somatic Nervous System

• It controls the voluntary movement of skeletal muscles
• Lifting an arm to wave is an example of the Somatic Nervous System
• Afferent (sensory) and efferent (motor) pathways are part of this system
• Feeling heat from a stove (afferent) and withdrawing a hand (efferent) is an example

Autonomic Nervous System (ANS)

• It controls involuntary vital functions
• Regulation of heart rate is an example of ANS
• Internal organs, glands, and blood vessels are regulated by ANS
• An example of this regulation is the digestion of food

Spinal Cord

• Gray matter (anterior, posterior, and lateral horns) contains motor neurons in the anterior horns
• White matter (anterior, posterior, and lateral columns) transmits fine sensory and proprioceptive information through the posterior columns

Peripheral Nervous System (PNS)

• Cranial nerves consist of 12 pairs
• The vagus nerve (X) innervates internal organs like the heart and stomach
• Spinal nerves occur in 31 pairs
• The sciatic nerve is the body's longest nerve, controlling muscles in the leg and foot
• Nervous ganglia (sensory and autonomic) have dorsal root ganglia containing sensory neuron cell bodies
• Sensory receptors all over the body such as touch receptors in the skin provide pressure and texture sensations

Functional Division

• The Somatic Nervous System allows for voluntary control

Brain Parts

• Basal ganglia participate in movement control where dysfunction can cause Parkinson's
• The limbic system (amygdala, hippocampus) processes emotion, especially fear, with the amygdala
• The thalamus acts as a relay station for sensory information going to the cerebral cortex

Diencephalon

• The hypothalamus regulates body temperature, hunger, and thirst

Epithalamus

• The epithalamus (pineal gland) secretes melatonin to regulate sleep cycles

Subthalamus

• The subthalamus is involved in motor control, and its lesion can cause involuntary movements

Brainstem

• The mesencephalon controls eye movements and hearing
• The protuberance (pons of Varolio) connects the cerebellum to the rest of the brain
• The protuberance also participates in sleep control
• The bulb raquideo (medulla oblongata) regulates vital functions like breathing and heart rate

Cerebellum

• The vermis coordinates trunk movements and posture
• The cerebellar hemispheres coordinate limb movements and balance