Nervous system

• Organ Systems


  • Group of organs that perform closely related functions
• Types of neurons

  • Sensory
  • Motor
  • Interneurons
• Nervous System

  Messages carried by the nervous system are electrical signals called impulses
• Synapse


  Location where a neuron can transfer an impulse to another cell
• Tissues


  • Group of similar cells that perform the same function
• Human Nervous System

  • Divided into two major divisions: Central Nervous System (CNS) and Peripheral Nervous System (PNS)
• Peripheral Nervous System


  • Receives information from the environment and relays commands from the CNS to organs and glands
• Lobes of the Brain: Occipital Lobe


  • Associated with interpreting visual stimuli and information
• Lobes of the Brain: Frontal Lobe


  • Associated with reasoning, motor skills, higher level cognition, and expressive language
• Organs


  • Group of tissues that work together to perform complex functions (e.g., sight)
• Nerve Impulse


  Impulse begins when a neuron is stimulated by another neuron or the environment
• Although each of the 10 organ systems has a different set of functions, they all work together to maintain homeostasis
• Levels of Organization in a multicellular organism

  • Cells -> tissues -> organs -> organ systems
• Neurons


  Cells that transmit impulses in the nervous system
• Central Nervous System


  • Relays messages, processes info, and analyzes info
• Neurotransmitters


  Chemicals used by neurons to transmit an impulse across the synapse
• Lobes of the Brain: Temporal Lobe


  • Associated with interpreting sounds, language, and memory formation
• Lobes of the Brain: Parietal Lobe


  • Associated with processing tactile sensory information such as pressure, touch, and pain
• Brain


  • Enclosed within the skull, composed of Forebrain, Midbrain, and Hindbrain
• Damage to the occipital lobe can cause visual problems such as difficulty recognizing objects, an inability to identify colors, and trouble recognizing words
• Certain kinds of information (reflexes) are processed in the spinal cord
• The spinal cord is enclosed in a bony cage called the vertebral column and surrounded by membranes called meninges
• Somatosensory cortex


  Essential to the processing of the body's senses, located in the parietal lobe
• The peripheral nervous system connects different parts of the body with the CNS, allowing both voluntary and involuntary actions
• The peripheral nervous system forms the communication network between the CNS and the body parts
• The spinal cord is a cylindrical bundle of nerve fibers and associated tissues enclosed within the spine, connecting all parts of the body to the brain
• The somatic nervous system plays a vital role in initiating and controlling the movements of the body and processing sensory input
• Cranial nerves send electrical signals between the brain, face, neck, and torso, helping with taste, smell, hearing, sensations, facial expressions, eye blinking, and tongue movement
• Nerve structure

  Contains bundles of nerve fibers, either axons or dendrites, surrounded by connective tissue
• Visual cortex


  Receives and interprets information from the retinas of the eyes, located in the occipital lobe
• The peripheral nervous system lies outside of the CNS and consists of nerves that branch out from the brain and spinal cord
• Parietal lobe


  Located in the middle section of the brain, associated with processing tactile sensory information such as pressure, touch, and pain
• Reflex is a quick, automatic response to a stimulus, examples include sneezing and blinking
• The spinal cord is concerned with spinal reflex actions and the conduction of nerve impulses to and from the brain
• Spinal cord is the main communications link between the brain and the rest of the body
• The peripheral nervous system is further subdivided into the somatic nervous system and the autonomic nervous system
• Types of nerve fibers in the PNS

  • Afferent nerve fibers - responsible for transmitting messages from tissues and organs to the CNS
  • Efferent nerve fibers - responsible for conveying messages from CNS to the corresponding peripheral organ
• Sensory nerves contain only afferent fibers, while motor nerves have only efferent fibers; mixed nerves contain both types of fibers
• The somatic nervous system regulates conscious controlled activities, conducts impulses from the brain and spinal cord to skeletal muscle, and controls movement and sensory input
• Sympathetic Nervous System


  • Located near the thoracic and lumbar regions in the spinal cord, stimulates the body's fight-or-flight response by regulating heart rate, respiration, pupillary response, and more