List the functions of the nervous system 1 Receiving sensory input sensory receptors monitor numerous external and internal stimuli We are aware of sensations from some stimuli such as vision hearing taste smell touch pain body position and temperature Other stimuli such as blood pH blood gases and blood pressure are processed at subconscious level Integrating Information The brain and spinal cord are the major organs for processing sensory input and initiating responses The input may produce an immediate response be stored as memory or be ignored 2 3 Controlling Muscle and Glands Skeletal muscles normally contract only when stimulated by the nervous system Thus by controlling skeletal muscle the nervous system controls the major movements of the body The nervous system also participates in controlling cardiac muscle smooth muscle and many glands 4 Maintaining Homeostasis The nervous system plays an important role in maintaining homeostasis This function depends on the nervous system s ability to detect interpret and respond to changes in internal and external conditions In response the nervous system can stimulate or inhibit the activities of other systems to help maintain a constant internal environment 5 Establishing and Maintaining Mental Activity The brain is the center of mental activity including consciousness memory and thinking List the divisions of the nervous system and describe the characteristics of each Central Nervous System CNS Consists of brain and spinal cord Peripheral Nervous System PNS Consists of all the nervous tissue outside the CNS nerves and ganglia Contains two functional subdivisions o Sensory Division or Afferent Division Conducts action potentials from sensory receptors to the CNS The neurons that transmit action potentials from the periphery to the CNS are called sensory neurons o Motor Division or Efferent Division Conducts action potentials from the CNS to effector organs such as muscles and glands The neurons that transmit action potentials from the CNS toward the periphery are motor neurons Can be further subdivided Somatic Nervous System Transmits action potentials from the CNS to the skeletal muscles Autonomic Nervous System ANS Transmits action potentials from the CNS to cardiac muscle smooth muscle and glands Can be further subdivided Sympathetic Division Prepares a person for physical activity o Include increasing heart rate and blood pressure dilating respiratory passageways to increase airflow and stimulating the release of glucose from the liver for energy Parasympathetic Division Generally consistent with resting conditions o Stimulates involuntary actions such as digestion defecation o Fight or flight and urination 13 List the parts of the brain Diencephalon o Thalamus o Hypothalamus Cerebrum Cerebellum Brainstem o Midbrain o Pons o Medulla Oblongata 14List the parts of the brainstem and state their functions Midbrain o Superior to the pons o Smallest region of the brainstem o The dorsal part of the midbrain consists of four mounds called colliculi The two inferior colliculi are major relay centers for the auditory nerve pathways in the CNS The two superior colliculi are involved in visual reflexes and receive both touch and auditory input o Contains a black substance called Substantia Nigra which is part of the basal nuclei and is involved in regulating general body movements o The rest of the midbrain consists largely of ascending tracts FROM the spinal cord to the cerebrum and descending tracts from the cerebrum TO the spinal cord or celebellum o Immediately superior to the medulla oblongata and inferior to the midbrain o Contains ascending and descending nerve tracts as well as several nuclei o A bridge between the cerebrum and cerebellum o Responsible for functions such as breathing swallowing and balance chewing and Pons salivation Medulla Oblongata o The most inferior portion of the brainstem and is continuous with the spinal cord o Ascending and descending nerve tracts o Functions in regulation of heart rate and blood vessel diameter breathing swallowing vomiting coughing sneezing balance and coordination o On the anterior surface two prominent enlargements called pyramids extend the length of the medulla oblongata The pyramids consist of descending nerve tracts which transmit action potentials from the brain to motor neurons of the spinal cord and are involved in the conscious control of skeletal muscles 15 State where the cerebellum is located The cerebellum is directly inferior to the brainstem where it is attached by Cerebellar Peduncles Is primarily a function in motor functions Cerebellar peduncles provide sources of communication between the cerebellum and other parts of the CNS 16 List the parts of the diencephalon and state their functions o The largest part of the diencephalon o Most sensory input that ascends through the spinal cord and brainstem projects to the thalamus where ascending neurons synapse with thalamic neurons Thalamic neurons send their axons to the cerebral cortex o Thalamus influences mood and registers an unlocalized uncomfortable perception of Thalamus pain Epithalamus Hypothalamus o A small area superior and posterior to the thalamus o Consists of a few small nuclei which function in the emotional and visceral response to odors and the pineal glands The pineal gland is an endocrine gland that may influence the onset of puberty and may play a role in controlling some long term cycles that are influenced by the light dark cycle o The most inferior part of the diencephalon o Contains several small nuclei that are very important for maintaining homeostasis o Major function in regulation of body temperature hunger thirst and controlling the secretion of hormones from the pituitary gland Minor functions include sexual pleasure rage fear and relaxation after a meal o Contains infundibulum which extends from the floor of the hypothalamus to the pituitary gland o Also contains mammillary bodies which form externally visible dwellings on the posterior portion of the hypothalamus and are involved in emotional responses to odors and in memory 17 List the lobes of the cerebrum and state a function for each The cerebrum is the largest part of the brain It is divided into left and right hemispheres by a longitudinal fissure The folds in each hemisphere are called gyri Gyri realty increase the surface area of the cortex Grooves within the gyri are called sulci Frontal lobe o Important in controlling voluntary