#2 Notes 1BIO 3422 – Human Physiology, TandyNervous System NotesThe 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)- Sensory Side- sensory receptors gather information from outside of body and take it to the CNSo Afferent Nerves – take sensory information to the CNS Cell body in PNS Connected to efferent nerves via interneuronso Types of Information from outside  CNS Somatic Senses – touch, cold, stretch, vibration (on surface of body) Special Senses – sight, smell, taste, balance, hearing Visceral Senses – inside of body Output (Efferent Division) o Efferent Nerves – take information from CNS  effector organs inside the body  Cell body in CNS Connected to Afferent nerves via interneuronso 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 parasympathetico go to cardiac and smooth muscle, and glandso 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 - Enterico Autonomic nerves on walls of gastrointestinal system Glial Cells Connecting cells, do not conduct Action potentials, but necessary to proper functioning  In PNSo 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 CNSo Oligodendrocytes – produces myelin for the CNS Provides myelin for multiple different axons Produces similar myelin as the Schwann Cells doo Astrocyte - role in formation of “blood brain barrier” 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 o Meninges 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 choroidplexuso 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 brain- Arachnoid Layer – middle; spidery web appearanceo 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, tougho 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 spaceProtection 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 braino 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 aroundo Cortex = outer shell/portiono Highest level of functiono Perception of sensory, understand sensationo Voluntary movement – when you decide to activate a somatic motor neuron (to skeletal muscle) it all begins in a portion of the cerebral cortexo Control of language (spoken and written language)o Personality o Sophisticated mental events (thinking, memory, creativity, etc)o Gray matter = outside; white matter = insideo 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 gyruseso 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 4to that area in the body (hands, lips, face) – correlates with better control of that areao 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