Chapter 13 Nervous System The nervous system allows for communication between cells through sensory input integration of data and motor output 2 nervous divisions Central nervous system CNS Brain and spinal cord Both are protected by Bones skull and vertebral column Meninges 3 protective membranes that wrap around CNS Cerebral spinal fluid CSF space between meninges is filled with this fluid that cushions and protects the CNS Both are made up of 2 types of nervous tissue Gray matter contains cell bodies and non myelinated fibers White matter contains myelinated axons Spinal Cord It extends from the base of the brain and along the length of the vertebral canal formed by the vertebrae The spinal cord functions to provide communication between the brain and most of the body It is the center for reflex arcs Gray matter in the center is a butterfly H shape White matter surrounds the gray matter The Brain 4 major parts Cerebrum largest portion of the brain o Cerebral hemispheres Divided into 4 lobes o Frontal lobe primary motor area and conscious thought o Temporal lobe primary auditory smell and speech area o Parietal lobe primary somatosensory and taste area o Occipital lobe primary visual area o Cerebral cortex thin outer layer of gray matter Primary motor area voluntary control of skeletal muscle Primary somatosensory area for sensory information from skeletal muscle and Association areas integration occurs here Processing centers perform higher level analytical functions in frontal lobe thinking planning solving cognition including Wernicke s Broca s areas both involved in speech Central white matter These two primary areas have skin Diencephalon dream Includes Hypothalamus helps maintain homeostasis hunger sleep thirst body temperature and water balance and controls pituitary gland Below thalamus Thalamus 2 masses of gray matter that receive all sensory input except smell involved in memory and emotions classifies and sends inputs to their areas Pineal gland secretes melatonin that controls our daily rhythms Cerebellum Functions Receives and integrates sensory input from the eyes ears joints and muscles about the current position of the body Is located in the back of the brain Maintains posture Coordinates voluntary movement Allows learning of new motor skills i e playing the piano or hitting a baseball Brain stem Brain stem Includes Midbrain relay station between the cerebrum and spinal cord or cerebellum reflex Pons a bridge between cerebellum and the CNS regulates breathing rate reflex Medulla oblongata contains reflex centers for regulating breathing heartbeat and center center for head movements blood pressure Reticular formation major component of the reticular activating system RAS that regulates alertness Makes the brain ready to receive information through activation of different centers of the brain They re not activated when we re asleep Limbic System oldest structure Responsible for emotions Joins primitive emotions i e fear pleasure with higher functions such as reasoning Can cause strong emotional reactions to situations but conscious thought can override direct our behavior Includes Amygdala imparts emotional overtones Hippocampus important to learning and memory Higher mental functions Learning what happens when we recall and use past memories to gain new information Memory ability to hold a thought or to recall past events Short term memory retention of information for only a few minutes Long term memory retention of information for more than a few minutes and includes the following o Episodic memory people and events o Semantic memory numbers and words Skill memory performing skilled motor activities i e riding a bike Language depends on semantic memory What parts of the brain are active in reading and speaking Peripheral nervous system PNS Nerves and ganglia collections of cell bodies Supplies appendicular skeleton It includes cranial nerves 12 pairs spinal nerves 31 pairs and ganglia outside the CNS Spinal nerves conduct impulses to and from the spinal cord Cranial nerves conduct impulses to and from the brain The PNS is divided into 2 systems Somatic division Soma surface skin Doesn t work with internal organs only skin skeletal o Serves the skin skeletal muscles and tendons o Automatic responses are called reflexes Reflex arc where reflex activity occurs
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