Divisions of the Nervous System

What is the the human nervous system?

Body wide system of nerve cells that collects information from the world, processes this information and then takes action by directing organs and muscles via the transmission of electro chemical messages

What does the human nervous system divide into?

• Central nervous system (CNS)

• Peripheral nervous system (PNS)

What does the central nervous system (CNS) do?

Complex processing

What does the central nervous system (CNS) divide into?

• Brain

• Spinal cord

What does the brain do?

All conscious and most unconscious processing

What does the spinal cord do?

Receives and transmits information, some reflex processing

What does the peripheral nervous system (PNS) do?

• Body wide network of messenger neurones

• Sensory (afferent) neurones to CNS

• Motor (efferent) neurones away from CNS

What does the peripheral nervous system (PNS) divide into?

• Autonomic nervous system (ANS)

• Somatic nervous system (SNS)

What does the autonomic nervous system (ANS) do?

• Controls actions of internal glands

• Involuntary system (not under conscious control)

What does the somatic nervous system (SNS) do?

• Controls skeletal muscles

• Voluntary system (under conscious control)

What does the autonomic nervous system (ANS) divide into?

• Sympathetic

• Parasympathetic

What does the sympathetic ANS do?

• Increases bodily activities

• Release of noradrenaline

• Activates stress response (fight or flight)

• Increased heart rate, sweat, breathing rate

• Dilates pupils

• Inhibits digestion (slows)

What does the parasympathetic ANS do?

• Decreases bodily activities

• Release of acetylcholine

• Activates in rest (rest and digest)

• Decreased heart rate, sweat, breathing rate

• Constricts pupils

• Stimulates digestion

What is homeostasis?

Homeostasis is the regulation of the internal environment

What is ‘maintaining homeostasis’?

Normal conditions where there is a balance between sympathetic and parasympathetic systems