9.4

• The two main divisions of the nervous system are the Central Nervous System (CNS) which includes the brain and spinal cord, and the Peripheral Nervous System (PNS) which includes all neurons that are not part of the CNS.
• The Central Nervous System (CNS) is a specialised system of nerve cells that processes stimuli and propagates impulses.
• The two main divisions of the Peripheral Nervous System (PNS) are the Voluntary (under conscious control) and the Autonomic (not under conscious control).
• The Autonomic Nervous System (ANS) is divided into the Sympathetic and Parasympathetic systems which act antagonistically to regulate the response of effectors such as heart rate.
• The Sympathetic Nervous System (SNS) usually stimulates effectors and coordinates the fight-or-flight response.
• The neurotransmitter of the Sympathetic Nervous System (SNS) is noradrenaline and the ganglia are located near the Central Nervous System (CNS).
• The Parasympathetic Nervous System (PNS) usually inhibits effectors and coordinates the rest/digest response.
• The neurotransmitter of the Parasympathetic Nervous System (PNS) is acetylcholine and the ganglia are located far from the Central Nervous System (CNS).
• The spinal cord is a cylindrical bundle of nerve fibres that runs from the brain stem to the lower back, surrounded by spinal vertebrae, and consists of nerve tissue (neurons, glia, blood vessels).
• The cerebrum, the uppermost part of the brain, is organised into lobes which control voluntary functions such as initiating movement, speech, and thought.
• The medulla oblongata controls a range of autonomous functions, including breathing and heart rate, and is the location of cardioacceleratory and deceleratory centres.
• The cervical spinal nerves control signals to the back of the head, the thoracic spinal nerves control signals to the chest and back muscles, the lumbar spinal nerves control signals to the lower abdomen and back, the sacral spinal nerves control signals to the thighs and lower legs, and the coccygeal nerve transmits signals from the skin on the lower back.
• The spinal cord contains 31 pairs of spinal nerves, with gray matter containing a H-shaped region of neurons and white matter containing myelinated axons.
• The cerebellum may also have a role in cognition, such as attention and language.
• The cerebellum controls the execution (not initiation) of movement, timing, balance, coordination, and posture.
• The hypothalamus, located in the midbrain, includes the anterior pituitary gland which secretes metabolic and reproductive hormones, and is involved in thermo and osmoregulation.
• The mammalian nervous system consists of the Central Nervous System (CNS) which includes the brain and spinal cord, and the Peripheral Nervous System (PNS) which includes all neurons that are not part of the CNS.