2 Notes 1 BIO 3422 Human Physiology Tandy Nervous System Notes The Nervous System Split into the Central Nervous System the brain and spinal cord and the Peripheral Nervous System everything else Afferent nerves and Efferent nerves connect via interneurons connecting neurons inside of CNS Input Afferent Division from outside of body and take it to the CNS Sensory Side sensory receptors gather information o Afferent Nerves take sensory information to the CNS Cell body in PNS Connected to efferent nerves via interneurons o Types of Information from outside CNS Visceral Senses inside of body Output Efferent Division Somatic Senses touch cold stretch vibration on surface of body Special Senses sight smell taste balance hearing o Efferent Nerves take information from CNS effector organs inside the body Cell body in CNS Connected to Afferent nerves via interneurons o 2 Divisions Somatic Motor Neurons voluntary Nerves leaving CNS that only go to skeletal muscle Voluntary Only these go to skeletal muscle Autonomic Division automatic Sympathetic Nervous System fight or flight Parasympathetic Nervous System rest and digest Both sympathetic and parasympathetic o go to cardiac and smooth muscle and glands o Both systems go to many places in the body dual innervation in many cases have opposite effects Heart sympathetic heart speed up parasympathetic heart rate slow down Enteric o Autonomic nerves on walls of gastrointestinal system Glial Cells Connecting cells do not conduct Action potentials but necessary to proper functioning In PNS o Schwann Cells make myelin for the PNS Provide insulation around a nerve 2 Notes 2 Wraps around localized portion of neuron and the cell membrane of the Schwann Cell creates the myelin Only affects a single neuron in one area Many Schwann Cells necessary to make myelin for a peripheral axon Help conduct signals more rapidly with salutatory conduction In CNS o Oligodendrocytes produces myelin for the CNS Provides myelin for multiple different axons Produces similar myelin as the Schwann Cells do o Astrocyte role in formation of blood brain barrier o Meninges Protect the brain from things in the blood that might be toxic to it Between each cell in capillary pores and lipophilic substances can get in and out of capillaries because they can diffuse through cell membrane Through large pores hydrophilic substances can leave Astrocyte helps with formation of tight junctions in capillaries to block pores No effect of lipophilic molecules but prevents movement of hydrophilic molecules creating blood brain barrier Hydrophilic can only get in and out with a specific carrier that allows it to move across and gain access to brain Alcohol lipophilic and can get to brain easily Antibiotics hydrophilic and cannot protect against infection in brain need special lipophilic antibiotics for brain infections 3 layers surround entire CNS brain and spinal cord protection etc this is the meninges pia moter arachnoid and dura moter In order from brain skull Brain Ventricles cerebrospinal fluid produced here by the choroid plexus brain o Also interacts with the subarachnoid space because the CSF will be taken up by this space Pia moter very inside Fragile layer adherent to surface of Arachnoid Layer middle spidery web appearance o Sub Arachnoid Space cerebrospinal fluid here that is absorbed by arachnoid villi and put into the venous blood system via the blood in the dural sinus Constantly making spinal fluid it circulates through CNS in sub arachnoid space and it is eventually reabsorbed into the venous blood system Spinal fluid is a mechanism by which things can diffuse across into the brain 2 Notes 3 Dura Moter outer layer thick tough o Creates a Dural Sinus carries venous blood In Spinal Cord Spinal cord stops in the lumbar spine and has nerve roots for the rest of the spine Covered with meninges and there is spinal fluid here Epidural on top of the dura moter anesthetic Spinal tap stick needle through dura moter to get to the arachnoid space Protection of the CNS Cranium encloses the brain vertebral column encloses the spinal cord CNS wrapped by the meninges the dura moter the arachnoid and the pia moter Surrounded by CSF created by the choroid plexus and stored in the arachnoid space absorbed by the arachnoid villi in the dural space The blood brain barrier limits access of blood borne substances to the brain o Tight junctions in capillaries via the astrocytes that block the pores in the capillaries and prevent the movement of hydrophilic substances into the brain Parts of the Brain Cerebral Cortex outer part all the way around o Cortex outer shell portion o Highest level of function o Perception of sensory understand sensation o Voluntary movement when you decide to activate a somatic motor neuron to skeletal muscle it all begins in a portion of the cerebral cortex o Control of language spoken and written language o Personality o Sophisticated mental events thinking memory creativity etc o Gray matter outside white matter inside o Surface of brain divided by sulcus depressed valley in the brain mountain in brain gyrus Central Sulcus starts at top and runs to temporal lobe divides between the parietal and frontal lobes Delineates to important gyruses o Pre Central Gyrus in front of the central sulcus Primary Motor Cortex fires off when you decide to move a muscle Nerves oriented in specific pattern for all people Motor Homunculus shows how nerves laid out in regard to motor nerves and which part of the brain fires to move that part of the body Nerves that go to sensitive areas of the body will have more space in the motor homunculus because more nerves will go 2 Notes 4 to that area in the body hands lips face correlates with better control of that area o Post Central Gyrus behind central sulcus Primary Somatosensory Cortex discrimination identity and location of sensory information Sensory Homunculus each part of brain specific for a part of the body to brings sensory information to the brain Basal Nuclei Basal Ganglia o 3 different ones in the central portion of the brain form a shell around another structure thalamus o inhibits muscle tone makes muscles relax and move well if stiff and unable to move joints then you have a problem in your basal ganglia if not working well cog wheel rigidity restriction when trying to move joints and you see tension of the muscle Moving fluidly basal ganglia moving correctly o Inhibits useless patterns of movement Ex tremors like with