Nervous System

Nervous System Functions 1. Sensory – incoming signals 2. Motor - movement 3. Integrative – in brain and spinal cord only (processors/relay terminals)

Parts of a Neuron Soma – cell body Dendrite – receives messages Axon – send messages out Myelin – help speed up messages, made up of Schwann cells

Divisions of the Nervous System Central Nervous System Peripheral Nervous System –Somatic –Autonomic –Enteric

Central Nervous System Brain Spinal Cord Control center, coordinates body functions

Peripheral Nervous System Carry messages to and from CNS Motor and sensory neurons found here. Made of 3 Basic Divisions - Somatic, Autonomic, Enteric

Somatic Nervous Division Cranial and spinal nerves Reflexes – automatic responses to stimuli Body Functions – sensory and motor

Autonomic Nervous Division Involuntary Two divisions –Sympathetic – fight-or-flight responses, speeds up reactions –Parasympathetic – counteracts sympathetic, returns body to normal, slows down heart rate

Enteric Nervous Division -Intestines -directly controls the gastrointestinal system

Brain Weighs approx. 3 lbs 4 parts –Brain stem –Diencephalon –Cerebrum –cerebellum

Brain Cerebrum Corpus Callosum Pituitary Gland Hypothalamus Brain Stem: Pons, Midbrain, Medulla Oblongata Cerebellum Thalamus

Brain Stem – 3 parts Continuous with spinal cord Medulla oblongata Midbrain Pons – (bridge)

Diencephalon – 2 parts Thalamus –Principle relay station for sensory impulses and cognition Hypothalamus – homeostasis –Control of Autonomic Nervous System –Control of pituitary gland –Regulation of emotional and behavioral patterns –Regulation of eating and drinking –Control of body temperature –Regulation of circadian rhythms and states of consciousness

Cerebrum Functions of the 4 lobes Frontal – reasoning, movement, higher level cognition, language Parietal – Pressure, Touch, Pain, Somatosensory Cortex (sensation processing) Temporal – Primary Auditory Cortex, Hippocampus (memories) Occipital – Interpreting visual information

Cerebral Cortex - Sensory Located in the Temporal lobe Primary somatosensory area – receives nerve impulses for touch, proprioception, pain and temperature P. visual area - vision P. auditory area - hearing P. gustatory area - taste P. olfactory area - smell

Cerebral Cortex - Motor Location - Cerebullum P. motor area – movement Broca’s speech area – frontal – speech –Aphasia – inability to speak –Agraphia – inability to write –Word deafness – inability to understand spoken words –Word blindness – inability to understand written words

Cerebral Cortex - Association Somatosensory Association Area – interpret and integrate somatic senses Visual Association Area – takes past visual experiences and relates them to current visual experiences Auditory Association Area – speech, music, or noise Wernicke’s Area – interprets the meaning of speech by translating words into thoughts

Cerebral Cortex – Association cont.d Common Integrative Area – receives, integrates, and relays sensation impulses Premotor Area – motor sequences - ability to write words Frontal Eye Field Area – controls voluntary scanning movements of the eye

Cerebrum – Memory Ability to recall thoughts Controlled by the Limbic System Stored in the temporal lobe i.Short-term memory – seconds or hours ii.Long-term memory – days to years

Cerebrum – 2 hemispheres Left Hemisphere –Controls right side of body, spoken and written language, numerical/scientific skills, reasoning Right Hemisphere –Controls the left side of the body, Musical, artistic, spatial and pattern perception, mental images of sight, sound, touch, smell and taste

Cerebullum 2 nd largest part of the brain Compares intended movements by the motor areas with what is actually happening Balance and Coordination Ataxia – disruption of muscle coordination

Spinal Cord Protection 4 layers – outside in –Wall of Vertebral Canal (bone) –Meninges – 3 layers of connective tissues that protect the brain and spinal cord Dura mater, Arachnoid, Pia mater –Cerebrospinal Fluid –Vertebral ligaments

Spinal Cord Protection Meninges –Dura – outermost, durable Epidural Space – between dura mater and vertebral column Arachnoid - (middle layer, named because of its delicate spider’s web arrangement of collagen and elastic fibers) – continuous with cranial arachnoid Pia Mater – innermost layer, made of collagen and elastic fibers –Sub arachnoid space – between Pia mater and Arachnoid – location of spinal taps to remove Cerebrospinal Fluid –Spinal Tap – can also be used to administer antibiotics, anesthetics and chemotherapy.

Meninges

12 Cranial Nerves NameMotor, Sensory, BothFunction OlfactorySensorySmell OpticSensoryVision OcculomotorMotorEye movement TrochlearMotorEye movement TrigeminalMixedFacial movements VestibulococchlearSensoryEquilibrium, Hearing GlossopharyngealMotorSwallowing AbducensMotorEye Movement FacialMixedFacial Expressions VagusMixedSwallowing and Talking AccessoryMotorMovement of head, neck, back and throat HypoglossalMotorTongue Movement

Special Senses Smell Taste Sight Hearing Equilibrium

Eye Anatomy to KNOW –Cornea, Lens, Retina, Iris, Pupil, Rods and Cones, Sclera, Choroid Coat, Vitreous Humor, Aqueous Humor

Lacrimal glands – secrete tears that destroy bacteria

Sclera – white of eye Cornea - transparent Retina

Visual Pathway Cornea – Lens – Retina – Rods and Cones – Optic Nerve – Optic Tract - Optic Chiasm – Optic Radiations - Primary Visual Cortex in the Occipital Lobe

Vision Facts Emmetropic Eye – normal vision, normal shape Myopic Eye – Nearsightedness, Distant objects are blurry Hypermetropic Eye – Farsightedness, Near objects are blurry. Rods and Cones – process color

Speed of Processing Theory: interference because words are read faster than colors are named. Selective Attention Theory: the interference because naming colors requires more attention than reading words.

Ear Anatomy to KNOW –Auricle, External Auditory Canal, Tympanic Membrane, Malleus, Incus, Stapes, Oval Window, Cochlea, Round Window

The EAR

External Ear Hearing only Lined with skin Ceruminous (wax) glands are present Ends at the tympanic membrane  Pinna (auricle)  External auditory canal

Middle Ear Tympanic Cavity/Tympanic Membrane Contains the Eustacian tube - connects the middle ear with the throat –Equalizes pressure during yawning or swallowing –Three bones span the cavity Malleus (hammer) Incus (anvil) Stapes (stirrup)

Middle Ear  Vibrations from eardrum move the malleus  The bones transfer sound to the inner ear

Inner Ear Maze of Chambers  Cochlea  Vestibule  Semicircular canals

Auditory Pathway Auricle – External Auditory Canal – Tympanic Membrane – Malleus – Incus – Stapes – Oval Window – Cochlea – Choclear Nerve – Medula Oblongata – Pons – Midbrain – Thalmus – Temporal Lobe of the Cerebral Cortex Howhearingworks