Nervous System

• The nervous system is highly integrated to detect, process, and act on data all the time
• Levels of organization in the nervous system

  • Central nervous system
  • Peripheral nervous system
• Autonomic nervous system complementary forces


  • Sympathetic division: mobilizes the body into action
  • Parasympathetic division: relaxes the body
• Neurons, or nerve cells, respond to stimuli and transmit signals
• Neurons


  • Respond to stimuli and transmit signals
• Motor neurons


  Transmit impulses away from the central nervous system to the body's muscles and glands, mostly multipolar
• Interneurons


  Live in the central nervous system, transmit impulses between sensory and motor neurons, most abundant and mostly multipolar
• Myelin sheath


  Insulating layer on axons that helps conduct impulses faster
• Synapse

  The meeting point between two neurons, turning the structure of the nervous system into an actual system
• Neurotransmitters diffuse back out after delivering their message and may degrade or get recycled
• Neurotransmitter activity

  1. Neurotransmitters deliver messages, then pop back out of receptors

  2. Some diffuse back across the synapse and are re-absorbed by the sending neuron (reuptake)

  3. Others are broken down by enzymes in the synaptic cleft or sent away by diffusion
• Major Divisions of the Nervous System are the CNS and PNS
• Nerves can be sensory or motor
• CNS is made up of the brain and spinal cord
• PNS consists of all other nerves outside of the CNS
• Central Nervous System serves as the main processing center for the entire nervous
• Brain is an organ located within the skull that functions as organizer and distributor of information for the body
• Main three parts of the brain; Cerebrum, Cerebellum, Brain Stem
• Cerebrum is a large, upper part of the brain that controls activity and thought
• Cerebellum is the part under the cerebrum that controls posture, balance, and coordination
• Brain Stem is the part that connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate, and blood pressure
• The Spinal Cord serves as the channel for signals between the brain and the rest of the body, and controls simple musculoskeletal reflexes without input from the brain
• Spinal nerves are nerve fibers that extend outward from the spinal cord through openings called intervertebral foramina.
• Nerves carry messages back and forth between the central nervous system (the brain and spinal cord) and all other parts of the body.
• Sensory neurons transmit sensations or impulses from receptors throughout the body to the central nervous system.
• Motor neurons send impulses away from the central nervous system to cause muscles to contract or glands to release hormones.
• Sensory neurons transmit sensations or information about changes within or outside the body to the central nervous system.
• Motor neurons send commands from the CNS to muscles or glands throughout the body.
• Sensory neurons transmit information about sensations from receptors throughout the body into the CNS.
• Interneurons connects the spinal motor and sensory neurons
• Peripheral Nervous System (PNS) connects the central nervous system to the organs and limbs
• The divisions under the PNS are the Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS)
• Sympathetic division prepares the body for action by increasing blood pressure, heart rate, respiration, and other functions that increase energy availability.
• Somatic Nervous System is responsible for voluntary movements, such as walking, talking, etc.
• Autonomic Nervous System controls involuntary actions like heart rate, breathing, digestion, etc.
• Parasympathetic is the rest and digest response, slows the heart rate and digestion
• Spinal nerves are thirty-one pairs of nerves that arise directly from the spinal cord and supply sensory and motor information to different regions of the body
• Cranial nerves are twelve pairs of nerves that originate from the brainstem and innervate various parts of the head and neck
• Reflexes are rapid responses to stimuli without conscious thought or control
• Cranial nerves are twelve pairs of nerves that originate from the brainstem and carry sensory or motor signals between the central nervous system and various parts of the head and neck