12-1 Divisions of the Nervous System PDF

12-1 Divisions of the Nervous System  Anatomical divisions of the nervous system – Central nervous system – Peripheral nervous system 1 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Ce...

12-1 Divisions of the Nervous System  Anatomical divisions of the nervous system – Central nervous system – Peripheral nervous system 1 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Central nervous system (CNS) – Brain and spinal cord – Consists of nervous tissue, connective tissue, and blood vessels – Functions to process and coordinate sensory data from inside and outside body – Motor commands control activities of peripheral organs (e.g., skeletal muscles) – Higher functions of brain include intelligence, memory, learning, and emotion 2 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Peripheral nervous system (PNS) – Includes all nervous tissue outside CNS and ENS – Delivers sensory information to the CNS – Carries motor commands to peripheral tissues – Nerves (peripheral nerves) Bundles of axons with connective tissues and blood vessels Carry sensory information and motor commands Cranial nerves connect to brain Spinal nerves attach to spinal cord 3 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Functional divisions of the PNS – Afferent division Carries sensory information From receptors in peripheral tissues and organs to CNS – Efferent division Carries motor commands From CNS to muscles, glands, and adipose tissue 4 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Functional divisions of the PNS – Receptors Detect changes or respond to stimuli May be neurons or specialized cells May be single cells or complex sensory organs (e.g., eyes, ears) – Effectors Target organs that respond to motor commands 5 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Efferent division of PNS – Somatic nervous system (SNS) Controls skeletal muscle contractions Both voluntary and involuntary (reflexes) – Autonomic nervous system (ANS) Controls subconscious actions, contractions of smooth and cardiac muscle, and glandular secretions Sympathetic division has a stimulating effect Parasympathetic division has a relaxing effect 6 © 2018 Pearson Education, Inc.  12-1 Divisions of the Nervous System  Enteric nervous system (ENS) – 100 million neurons in walls of digestive tract As many or more than in spinal cord Use the same neurotransmitters as the brain – Initiates and coordinates visceral reflexes locally Without instructions from CNS – Can be influenced by ANS 7 © 2018 Pearson Education, Inc. Figure 12–1 An Overview of the Nervous System. Central Nervous System (CNS) Information processing (brain and spinal cord) integrates, processes, and coordinates sensory input and motor commands. Peripheral Nervous Sensory information Motor commands within System (PNS) within efferent division (nervous tissue afferent division outside the CNS and the ENS) Somatic nervous Autonomic system (SNS) nervous system (ANS) Parasympathetic Sympathetic division division Smooth muscle Special sensory Visceral sensory Somatic sensory receptors Cardiac receptors receptors monitor smell, monitor internal monitor skeletal muscle taste, vision, organs muscles, joints, Glands balance, and and skin surface Skeletal Adipose hearing muscle tissue Receptors Effectors 8