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CNS: The BRAIN HA&P Male – 3.5 lbs; Female – 3.2 lbs Brain mass: body mass is equal!

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Presentation on theme: "CNS: The BRAIN HA&P Male – 3.5 lbs; Female – 3.2 lbs Brain mass: body mass is equal!"— Presentation transcript:

1 CNS: The BRAIN HA&P Male – 3.5 lbs; Female – 3.2 lbs Brain mass: body mass is equal!

2 Embryonic Development  3 weeks old – neural plate forms from ectoderm, and invaginates to form neural grove which deepens to form the neural tube by week four  Neural tube sinks deeper away from ectoderm and differentiates into brain anteriorly and spinal cord develops caudally  Central cavity of neural tube enlarges to form ventricles


4 Embryonic Brain Development

5 Space Restriction on Brain Development  Flextures develop bending forbrain towards brain stem  Cerebral hemispheres grow posteriorly and laterally enveloping diencephalon & midbrain  By 26 th week cerebral hemispheres form convolutions to increase SA (more neurons to occupy limited space)

6 Regions of the Brain  Cerebral Hemispheres  Longitudinal fissure seperates R/L Hemisperes  4 Lobes: Frontal, Parietal, Occipital, and Temporal  Motor, Sensory, and Cognitive Functions  Diencephelon  Thalmus, Hypothalmus, and Epithalmus  Brain Stem  Medulla Oblongata, Pons, Midbrain  Cerebellum  Subconscious coordinated movement and agility

7 Protection of the Brain  Bone  Meninges  3 connective tissue membranes  Protect bv  Contain CSF  Cerebral spinal Fluid (CSF)  Blood Brain Barrier

8 Meninges  Dura Mater (tough mother)  2 layers of strong fibrous connective tissue  Periosteal layer connects to periosteum of skull  Subdural space  Arachnoid (spider)  Middle loose brain covering  Subarchnoid space  w/weblike extensions that attach to the pia mater  Filled w/CSF  Large bv to brain  Pia Mater (gentle mother)  Delicate connecctive tissue  Rich w/tiny bv  Clings to brain following convolutions

9 What is meningitis? A. Inflammation of meninges B. Bacterial or viral infection C. Diagnosed by a lumbar spinal tap D. All of the above

10 Cerebral Spinal Fluid  Liquid Cushion from blows and trauma  Buoyancy reduces brain weight by 97%!  Provides nourishment (similar to blood plasma)  Abundant Na+, Cl-, H+, Less Ca 2+ and K+  Formed by choroid plexus (clusters of roof of ea/ventricle (ependymal cells)  Adults – 500mL produced daily, 150mL replaced ea/8 hrs  Removes waste products  Circulates through ventricles to central canal of spinal cord and subarachnoid space

11 Ventricles  Continues w/ea other & central canal of spinal cord  Lateral ventricles (pair)  3 rd ventricle  4 th ventricle  Cerebral aquaduct

12 Blood-Brain Barrier  Maintains stable environment for the brain  Capillaries are the least permeable in the body (tight junctions)  Selective  Glucose, a.a., some electrolytes move by facilitated diffusion  Bloodbourne metabolic wastes, proteins, some toxins, and most drugs are denied entry  Ineffective against fats, fatty acids, O 2, CO 2, alcohol, nicotine, anesthetics  Incomplete in newborn and premature  Lack of brain barrier in hypothalmus and brain stem (moniter blood, toxins, and vomiting reflex!)

13 The ___________ is the outermost meninx, and forms supportive and protective partitions between some portions of the brain. A. Dura mater B. Arachnoid C. Pia mater D. Ventricles E. Blood brain barrier

14 Cerebral Hemispheres  83% of total brain mass!  Gyri – elevated ridges  Sulci – shallow grooves  Fissures – deep grooves  Anatomical landmarks divide cerebrum into 5 lobes  Longitudinal fissure  Transverse cerebral fissure  Central sulcus  Lateral sulcus  Each hemisphere has 3 regions  Cortex – superficial gray matter  Internal white matter  Basal nuclei – islands of gray matter deep within white matter

15 Cerebral Cortex  Conscious mind  Gray matter: neuron somas, dendrites, glia, and bv  2-4 mm but 40% of brain mass due to convolutions  Billions of neurons in 6 layers  Ea/hemisphere is concerned w/sensory & motor functions of opposite side of body  Divided into localized domains w/specific functions  Motor – control voluntary movements  Sensory – conscious awareness of sensation  Association – receiving input from multiple senses and sending output to multiple areas (complex connections)


17 Motor Areas  Primary motor cortex  Precentral gyrus of frontal lobe of ea/hemisphere  Skilled voluntary movements of skeletal muscles  Premotor cortex  Anterior to precentral gyrus  Learned motor skills of patterned nature (playing a musical instrument)  Coordinates several muscle groups  Broca’s area  Anterior to inferior region of premotor area  Usually only in left hemisphere  Motor speech area (directs muscles used in speech)  Frontal eye field  Anterior to premotor cortex and superior to Broca’s area  Controls voluntary movements of eyes

18 Sensory Areas  Primary Somatosensory cortex  Postcentral gyrus of parietal lobe  Receive information from sensory receptors in skin  Neurons identify body region being stimulated (opposite sides of body correlate w/hemispheres)  Somatosensory Association cortex  Posterior to primary somatosensory cortex  Integrates sensory inputs to understand object being felt  Visual Areas  Extreme posterior tip of occipital lobe & buried deep in medial occipital lobe  Receives visual info from retina of eye  Auditory Areas  Superior margin of temporal lobe

19 Sensory Areas cont’d  Olfactory Cortex  Medial aspect of temporal lobe  Olfactory tracts from superior nasal cavities  Gustatory Cortex  Insula (deep to the temporal lobe)  Perception of taste  Visceral Sensory Area  Cortex of insula posterior to gustatory cortex  Stomach pains, full bladder, lungs bursting, etc…  Vestibular (equilibrium) cortex  Posterior region of insula, deep to temporal lobe  Awareness of balance and your place in space

20 Multimodal Association Areas  Anterior association area  AKA pre-frontal cortex (frontal lobe)  Intellect, cognition, recall, personality, abstract ideas  Judgement, reasoning, persistence & planning  Matures slowly  Posterior association area  Large region of temporal, parietal, and occipital lobes  Recognizing patterns, faces  Wernicke’s Area – understanding written and spoken language  Limbic association area  Cingulate gyrus, parahippocampal gyrus, and hippocampus  Emotional impact & memories

21 Are you Left or Right Brained?

22 Lateralization of Cortical Functioning  Both cerebral hemispheres are used for almost every activity, however there is some division of labor  90% of people have left hemisphere dominance  Meaning left hemisphere has greater control over language abilities, math and logic  And the right hemisphere is associated with intuition, emotion, artistic and musical skills, poetic, creative, and far better at recognizing faces  Typically right handed  10% of people the roles of hemispheres is reversed or shared equally  Typically left handed and male

23 Cerebral White Matter  Responsible for communication between cerebral areas and between cerebral cortex and lower CNS centers  Myelinated fibers bundled into large tracts  Commissures  connects gray areas of two hemispheres (horizontal)  Corpus Callosum –largest (superior to lateral vesicles)  Association Fibers  Connect different parts of same hemisphere (horizontal)  Projection Fibers  Connect cortex to bodys receptors and effectors  vertical

24 Diencephalon  Central Core of forebrain  3 paired structures  Thalmus  Hypothalamus  Epithalmus

25 Thalamus  80% of diencephalon  Large number of nuclei  Gateway to cerebral cortex  Afferent impulses from all senses converge  Information is sorted and relayed to appropriate area of cortex  Crude recognition as pleasant or unpleasant

26 Hypothalamus  Below the thalamus, above brain stem  Extends from optic chiasma to mammilary bodies (nuclei that relay olfactory pathways)  Infundibulum connects to pituitary gland  Visceral control center of body, vital for homeostatic control

27 Homeostatic Roles of Hypothalamus  ANS  Influences hr, bp, pupils, etc  Emotional response (limbic system)  Perception of pleasure, fear, rage, and sex drive  Body Temperature regulation  Monitors & initiates sweating or shivering  Regulation of food intake  response to changes in blood glucose/a.a., hormones  Regulation of water balance and thirst  Response to concentrations of bodily fluids  Regulation of sleep wake cycles  In response to light (visual) cues  Endocrine system functioning  Controls secretions of pituitary gland  Produces hormones ADH and oxytocin

28 Epithalamus  Dorsal portion of diencephelon, roof of 3 rd ventricle  Pineal gland extends from posterior border  Helps regulate sleep wake cycle

29 Brain Imaging  Compare PET, fMRI, CAT, EEG, cerebral angiography

30 Brain Stem  Survival Behaviors  Pathway for fiber tracts  Innervation of the head  3 parts:  Midbrain  Descending motor tracts  Cerebral aqueduct (connects 3 rd & 4 th ventricles  Visual reflex centers  Sound (startle)reflex  Pons  Bulging region  Deep tracts connect brain and spinal cord  Superficial fibers connect motor cortex and cerebellum  Help medulla maintain breathing rhythm  Medulla Oblongata

31 Medulla Oblongata  Motor cortex fibers cross over to opposite side of body before spinal cord  Relay sensory information  Auditory relays  Maintains equilibrium  Autonomic reflex center  Force and rate of heart contraction  Vasomotor center  Rate and depth of breathing  Vomiting, hiccupping, swallowing, coughing, sneezing

32 Cerebellum  11%of total brain mass  Dorsal to pons & medulla  Using input from cerebral motor cortex and sensory receptors provides precise timing of skeletal muscle contraction subconsciously  Smooth coordinated movements  Agility

33 Brain Activities: 1. Limbic System 2. Reticular Formation 3. Sleep 4. Language 5. Memory 6. Brain wave patterns and EEG Each group will create a brief (8 ppt slides) presentation w/pictures on their assigned brain topic of interest! You may use textbooks or internet, be sure to cite sources!

34 Cranial Nerves

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