Chapter 14 The Brain 10 01 2013 The Brain o Rostral towards the front forehead o Caudal towards the back o Divided into the cerebrum cerebellum and brainstem o Contains gray and white matter o White matter is bundled into tracts Meninges o Dura mater arachnoid mater pia mater o Dura mater has two layers o Periosteal layer just deep to the skull in contact with skull o Meningeal layer deep to the periosteal layer o Mostly made up of collagen o Arachnoid mater o Made up of collagen and elastic o Cerebrospinal fluid in here o Pia mater o Covers the surface of the brain o Cannot be separated from the brain Ventricles and CSF o Brain has four ventricles o The floor of each ventricle is lined with capillaries called choroid plexus made up of ependymal cells produce cerebrospinal fluid CSF o Ependymal cells have cilia constantly circulating CSF o CSF provides buoyancy minimizing the impact of its weight Blood Brain Barrier BBB o Brain tissue is irreplaceable so anything that could damage the brain must be prevented from coming in contact o Blood brain barrier made up of tight junctions between endothelial cells making up the walls of the capillaries feeding the brain o Makes sure nothing that can damage the brain can access it o Astrocytes are responsible for making blood brain barrier o Tight junctions are also located in the choroid plexus o What can pass through nutrients glucose oxygen CO2 to get it out o What cannot pass through bacteria any waste products Main Neurotransmitters o Acetylcholine skeletal muscle contraction o Glutamate main neurotransmitter in brain involved in learning and memory o Interneuron o Aspartate analogous to glutamate but in spinal cord o GABA inhibitory o Serotonin throughout CNS involved in sleepiness alertness mood o Endorphins throughout the CNS suppresses pain reduces perception of fatigue runner s high Cerebral Hemispheres o Makes up the majority of brain mass covering the diencephalon and brain stem o Cerebral hemisphere is divided into five lives frontal parietal temporal occipital insula o Frontal lobe reasoning planning problem solving o Parietal lobe motor functions perceptions of things movements experiences o Temporal lobe Making sense of things that we hear speech some memory information o Occipital Sight o Insula taste digestion o Surface of the brain is covered by elevated ridges called gyri Cerebral Hemispheres o Deeper grooves called fissures o Transverse fissure separates occipital lobe from cerebellum o Each hemisphere has a superficial layer of gray matter and a deep layer of white matter Cerebrum o The cerebrum is the part of the brain where our conscious mind is found o Three main areas motor areas sensory areas association areas o All cerebral neurons are interneurons o Left and right side of the brain have different functions o Right side of brain controls the left side of the body and vice versa contralateral Cerebral Cortex Motor Areas o Motor areas control voluntary movements localized to the posterior part of the frontal lobes includes primary motor cortex premotor cortex Broca s area and frontal eye field o Primary Motor Cortex o located in the precentral gyrus of frontal lobe of each hemisphere and contains pyramidal cells o Pyramidal cells controlling specific parts of the body are localized to a specific area of the primary motor cortex can be mapped into a motor homunculus o Premotor cortex o Just anterior to the precentral gyrus o Controls learned motor skills o Coordinates movements of several muscles groups by sending activating impulses to the primary motor cortex o Broca s Area o Inferior and anterior to premotor area o Only present on the left o Directs the muscles in our face and mouth involved in speech o Activated when we prepare to speak and when planning certain production voluntary movements o Frontal Eye Field o Anterior to premotor cortex superior to Broca s area o Voluntary eye movement Higher Mental Functions Language o Broca s Area involved in speech production o Lesion damage o When damaged you could not say words just gibberish o Wernicke s area involved in understanding of written and spoken language logical sentence are saying o When damaged you can still form words but you couldn t form a o Comprehension of what somebody says to you as well as what you o Both located on the left side of the brain o Interconnected to provide understanding of language and production of speech o In corresponding areas on the right side of the brain we comprehend and convey emotions and gestures in speech Cerebral Cortex Sensory Areas o Sensory areas are involved in conscious awareness of sensation mainly in parietal insular temporal and occipital lobes o Primary Somatosensory Cortex o Located in postcentral gyrus of parietal lobe just posterior to primary motor cortex o Receives incoming information from sensory receptors o Spatial discrimination body can be mapped based on homugus o Somatosensory association cortex o Posterior to primary somatosensory cortex many connections o Integrates information from primary somatosensory cortex and between these two regions interprets this information o Damage to this area Not knowing what an object is or what it does by looking at it o Visual Areas o Primary visual cortex receives visual information from the retina of the eyes contralateral o Visual association area makes sense of what we re seeing and puts it together occipital lobe o Primary auditory cortex helps you interpret what you re hearing o Auditory association area helps you remember when you ve heard o Auditory Areas it before o Olfactory cortex o Temporal lobe receives information from smell receptors and makes you aware of what you re smelling o Gustatory cortex within insula receives information from taste receptors o Visceral sensory area within insula allows us to consciously perceive o Hunger stomachache appendicitis full stomach indigestion full o Vestibular cortex within insula allows us to detect the position of our visceral sensations such as bladder uterine pain heads in space Cerebral Cortex Association Areas o Multimodal association areas receive input from several different areas and puts it together into an overall feeling or experience o Information flows from sensory receptors to primary sensory cortex sensory association cortex then to multimodal association cortex o These areas lets us figure out what we re experiencing o Form memories from these sensations o The action is the sent to the premotor