Brain Regions and Protection - BIO 110 - PDF

Professor Lindboom-Broberg (LB) Brain Regions Brain Anatomy Cranial Meninges Brain Stem & Cerebellum Diencephalon Cerebrum Brain Activity & Connections Cranial Nerves Brain Regions Four major brain regions  Cerebrum  Cerebellum  Diencephalon ...

Professor Lindboom-Broberg (LB) Brain Regions Brain Anatomy Cranial Meninges Brain Stem & Cerebellum Diencephalon Cerebrum Brain Activity & Connections Cranial Nerves Brain Regions Four major brain regions  Cerebrum  Cerebellum  Diencephalon  Brainstem Brain Regions Four major brain regions  Cerebrum  Cerebellum  Diencephalon  Brainstem  Cerebrum Hemispheres (right & left) Surface – Gyri: Folds – Sulci: Shallow grooves – Fissures: Deep grooves o Divide hemispheres and cerebral regions Brain Regions Four major brain regions  Cerebrum  Cerebellum  Diencephalon  Brainstem  Cerebellum Coordination Brain Regions Four major brain regions  Cerebrum  Cerebellum  Diencephalon  Brainstem  Diencephalon Epithalamus ​Thalamus ​Hypothalamus Brain Regions Four major brain regions  Cerebrum  Cerebellum  Diencephalon  Brainstem  Brainstem Midbrain Pons Medulla Oblongata Brain Regions Ventricles  Four connected open spaces in the brain that produce CSF Lateral Ventricles (right & left) Third Ventricle – Connected to lateral by Interventricular foramen (right & left) Fourth Ventricle – Connected to the third ventricle by the cerebral aqueduct – Continuous with the central canal (spinal cord)  Professor Lindboom-Broberg (LB) Cranial Meninges Bones Meninges CSF Blood Brain Barrier Brain Protection Cranial meninges  Continuous with spinal meninges  Three layers Cranial Meninges PAD the brain (P-A-D) 1. P – Pia Mater 2. A – Arachnoid Mater 3. D – Dura Mater Brain Protection Cranial meninges Pia mater  Bound to surface of brain Attached by astrocyte processes (sticks to the brain)  Accompanies branches of cerebral blood vessels as they penetrate the surface into the brain Brain Protection Cranial meninges Arachnoid mater  Arachnoid membrane: Superficial layer closest to dura mater  Arachnoid trabeculae: Fibrous strands through subarachnoid space; connect to the pia mater  Subarachnoid space: Between arachnoid membrane/pia mater CSF circulates here Brain Protection Cranial meninges Dura mater  Two fibrous layers; mostly fused No epidural space Periosteal layer (outer layer): fused to cranial bone periosteum Dural space present in some areas – Contains fluid and blood vessels Meningeal layer (inner layer) – Typically fused to arachnoid membrane Subdural space – Present only after trauma Brain Protection Cerebrospinal fluid (CSF)  Clear liquid surrounding CNS Extracted during a lumbar puncture  Functions Support weight of brain Cushion Transport nutrients, chemical messengers, wastes Brain Protection Cerebrospinal fluid  Made from nutrients pulled from the blood  Made by choroid plexus, ependymal cells in each ventricle  Materials diffuse between CSF and interstitial fluid of CNS Brain Protection Cerebrospinal fluid  Circulates through ventricles Lateral  3rd  4th  Exit from 4th Ventricle Continuous with central canal Enter subarachnoid space in the brain – Via aperatures / foramina (3)  Located in subarachnoid space Brain Protection Cerebrospinal fluid  Exits arachnoid space through arachnoid granulations Fingerlike extensions of arachnoid membrane CSF moves into dural space & reabsorbed – Penetrate meningeal layer of dura mater  Professor Lindboom-Broberg (LB) Brainstem & Cerebellum Medulla Oblongata Pons Cerebellum Midbrain Brain Stem Brain Regions  The brains connection to the spinal cord and body Midbrain Pons Medulla Oblongata Functions  Lower functions Autonomic reflexes Visceral controls Brain Stem Medulla Oblongata  Relays information All communication brain  spinal cord  Reflex Centers Coordinates complex autonomic reflexes and visceral functions Cardiovascular centers Respiratory rhythmicity centers Brain Stem Pons  Point of connections Transports AP signals – Ascending Tracts = sensory – Descending Tracts = motor Links cerebellum to everything Controls medullary centers – Apneustric center – Pneumotaxic center Cerebellum Cerebellum  Automatic processing center  Monitors proprioceptive, visual, tactile, balance, and auditory sensations Cerebellum Sensory Motor Cerebellum  Primary functions - Coordination Adjusting postural muscles Crblm – Modifies activities of brainstem centers Programming/fine-tuning movements – Monitors outgoing motor commands (from cerebrum) – Monitors incoming sensory information (from the body) – Refines & adjusts motor commands as needed Cerebellum Cerebellum  Gain of function (i.e., practice) Increased coordination  Loss of function (i.e., cerebellar damage) Decreased coordination during intentional movements Unintentional movements are still smooth Cerebellum Cerebellum  Hemispheres (R & L)  Gray matter – superficial  White matter – deep (arbor vitae) Brain Stem Midbrain  Most complex/integrative part of brainstem  Can direct complex motor patterns at subconscious level  Influences level of activity in entire nervous system Brain Stem Midbrain  Corpora quadrigemina Two pairs of sensory nuclei (right & left) ​Superior colliculus (colliculus, hill) – Receives visual input from thalamus – Controls reflex movements of eyes, head, and neck in response to visual stimuli (Example: Pretending to throw a ball at someone’s head) ​Inferior colliculus – Receives auditory input from medulla oblongata and pons – Controls reflex movements of head, neck, and trunk in response to auditory inputs (Example: Loud noises) Brain Stem Midbrain  Substantia nigra (nigra, black) Contains darkly pigmented cells Inhibits activity in cerebral basal nuclei  Parkinson’s Disease Progressive CNS degenerative disease – Classically presents with difficult, slow, and shaky movements Substantia nigra cell death – Loss of basal nuclei inhibition – Basal nuclei control subconscious skeletal movements – Muscles do not shut off when they’re supposed to  Professor Lindboom-Broberg (LB) Diencephalon Epithalamus Thalamus Hypothalamus Diencephalon  Thalamus Surrounds the third ventricle  Epithalamus  Hypothalamus Diencephalon Epithalamus  Roof of diencephalon  Extensive choroid plexus  Pineal gland Endocrine structure that produces melatonin (sleep-wake cycles) Posterior epithalamus Diencephalon Thalamus  Superior to midbrain  Deals with sensory information Filters sensory information, passing on only small portion Final relay to cerebral cortex  Each thalamic region connected to specific areas in cortex Diencephalon Thalamus  Superior to midbrain  Deals with sensory information Filters sensory information, passing on only small portion Final relay to cerebral cortex  Each thalamic region connected to specific areas in cortex Diencephalon Hypothalamus  Control and integrative center  Connects it to pituitary gland (master endocrine gland)  May be stimulated by: Sensory information Changes in composition of CSF and interstitial fluid Chemicals in circulating blood (lacks blood brain barrier)  Effects Controls Endocrine System Body Temperature Regulation Autonomic Regulation Feeding Reflexes  Professor Lindboom-Broberg (LB) Cerebrum Basal Nuclei Cerebral Lobes Cortical Functional Regions Cerebrum General Structure  Two hemispheres Right & Left  Surface Gyri: Folds Sulci: Shallow grooves Fissures: Deep grooves – Divide hemispheres and cerebral regions Cerebrum Cerebral lobes  Each cerebral hemisphere divided into regions 1. ​Frontal lobe 2. ​Parietal lobe 3. ​Temporal lobe 4. ​Occipital lobe *​Insula (insula, island) Cerebrum Six functional categories  Cortex Region that receives raw sensory information Cortex Cerebral Lobe Function Motor Frontal Skeletal Muscle Control Somatosensory Parietal Tactile info Visual Occipital Sight Auditory Temporal Hearing Olfactory Temporal Smell Gustatory Insular Taste Cerebrum Six functional categories  Cortex Region that receives raw sensory information Data (0s & 1s) for each “region” within the field – On = 1 – Off = 0  Association area Separate region that interprets cortical data 0s & 1s become a perception (image, sound, taste, feeling, etc) Cerebrum Integrative centers  Receive information from association areas  What does it do? Creates greater information associations Direct motor activities Perform analytical functions  Found in both cerebral hemispheres Language areas typically in left hemisphere* Cerebrum General facts about the cerebral hemispheres  Each hemisphere is connected to the opposite side of the body Sensory in & motor out Crossing over occurs in brainstem and spinal cord  Functions are mostly mirrored; some are unilateral  Imprecise functional mapping Boundaries are indistinct and overlap  Normal individuals use ALL portions of the brain Cerebrum Hemispheric lateralization  Left brain vs. Right brain?  Left cerebral hemisphere Language-based skills (reading, writing, speaking) Analytical tasks (math and logic)  Right cerebral hemisphere Identification of familiar objects by touch, smell, sight, taste, or feel (interpretative centers) Facial recognition, 3D relationships Analyzes emotional context/tone of conversation  Right side controls left & left side controls right Basal Nuclei General organization of Cerebrum  Grey matter is superficial  White matter is deep Basal nuclei of the cerebrum  Gray matter islands deep within cerebral hemisphere  Function Subconscious skeletal muscle tone & movement patterns Ex: control cycles of arm/thigh movements while walking Ex: subconsciously adjusts postural muscles as you lean over  Professor Lindboom-Broberg (LB) Brain Activity & Connections Electrencephalogram (EEG) Waves CNS Tracts & Communication Brain Activity Electrical activity  Electrochemical action potentials create an electrical field Measurable by electrodes placed on scalp Electroencephalogram (EEG): Electrical reading of the brain Electrical patterns observed are called brain waves Brain Activity Abnormal brain activity  Cerebral electrical activity synchronized by “pacemaker” Involves the thalamus  Asynchrony may indicate localized damage or cerebral abnormality Example: tumor or injury in one hemisphere changes its pattern, losing alignment between hemispheres  Seizure: Temporary cerebral disorder accompanied by unusual neural activity (movements, sensations, behaviors) Change in pattern of electrical activity Epilepsies, or seizure disorders = clinical conditions characterized by seizures Cerebrum White matter  Interior of cerebral hemispheres  Connect regions of gray matter Association Fibers: Region to region within hemisphere Commissural Fibers: Region to region between hemispheres Projection Fibers: Cerebrum to lower end