The Organization of the Nervous System The central and peripheral nervous systems The Organization of the Nervous System Drugs will affect any part of this system, so you need to know all of them and basic idea of what they do Central nervous system is one that you will most familiar with – brain and spinal cord (blue) Peripheral nervous system – all other nerves, ones outside of CNS (red) 1

Basic nerve cell structure

3 main types of nerve cells sensory neurone relay neurone motor neurone

Sensory neurons Carries impulses from receptors e.g pain receptors in skin to the CNS( brain or spinal cord)

Relay neuron Carries impulses from sensory nerves to motor nerves.

Motor neuron Carries impulses from CNS to effector muscle to bring about movement or gland to bring about secretion of a hormone

The Nervous System Major division - Central vs. Peripheral Central or CNS- brain and spinal cord Peripheral- nerves connecting CNS to muscles and organs

Peripheral Nervous System 3 kinds of neurons connect CNS to the body sensory motor interneurons Motor - CNS to muscles and organs Sensory - sensory receptors to CNS Interneurons: Connections Within CNS Spinal Cord Brain Nerves key words: peripheral nervous system

Peripheral Nervous System k e l t a ( o m i c ) y p h P r s A u n N v key words: peripheral nervous system; skeletal nervous system; somatic nervous system; autonomic nervous system; sympathetic nervous system; parasympathetic nervous system

Somatic System Nerves to/from spinal cord control muscle movements somatosensory inputs Both Voluntary and reflex movements Skeletal Reflexes Patellar tendon reflex Muscle Motor Neuron Interneuron Skin receptors Sensory Brain

The Somatic nervous system The major peripheral nerves

Autonomic System Two divisions: Control involuntary functions sympathetic Parasympathetic Control involuntary functions heartbeat blood pressure respiration perspiration digestion Can be influenced by thought and emotion

Sympathetic “ Fight or flight” response CENTRAL NERVOUS SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney “ Fight or flight” response Release adrenaline and noradrenaline Increases heart rate and blood pressure Increases blood flow to skeletal muscles Inhibits digestive functions keywords: sympathetic nervous system; fighlt or flight response

Parasympathetic “ Rest and digest ” system CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil “ Rest and digest ” system Calms body to conserve and maintain energy Lowers heartbeat, breathing rate, blood pressure key words: parasympathetic nervous system; rest and digest system

Summary of autonomic differences Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Parasympathetic division (calming) Pupils dilate EYES Pupils contract Decreases SALVATION Increases Perspires SKIN Dries Increases RESPERATION Decreases Accelerates HEART Slows Inhibits DIGESTION Activates Secrete stress hormones ADRENAL GLANDS Decrease secretion of stress hormones key words: sympathetic nervous system; parasympathetic nervous system

Central Nervous System Spinal Cord Brain Brain and Spinal Cord key words: central nervous system; brain; spinal cord

Brain has 2 Hemispheres Left & Right sides are separate Corpus Callosum : major pathway between hemispheres Some functions are ‘lateralized’ language on left music on right Lateralization is never 100% Left Hemisphere Corpus Callosum Right key words: left hemisphere; right hemisphere

Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal key words: cerebral cortex; lobes; frontal; parietal; temporal; occipital

Sensory Information sent to opposite hemisphere Left visual field Right visual Optic nerves Corpus Callosum Left Visual Cortex Right Visual Principle is Contralateral Organization Sensory data crosses over in pathways leading to the cortex Visual Crossover left visual field to right hemisphere right field to left Other senses similar key words: left hemisphere; right hemisphere; visual infomation; touch information

Contralateral Motor Control Movements controled by motor area Right hemisphere controls left side of body Left hemisphere controls right side Motor nerves cross sides in spinal cord Somatosensory Cortex Motor Cortex

Corpus Callosum Major ( but not only) pathway between sides Connects comparable structures on each side Permits data received on one side to be processed in both hemispheres Aids motor coordination of left and right side Corpus Callosum Medial surface of right hemisphere Example : You read a geometry problem in a textbook. The words are seen and the visual forms translated into meaning by the language center in the left hemisphere. To solve the problem you have to imagine a cone shaped object. This is accomplished by centers in the right hemisphere. The solution is written down using language generated by the left hemisphere. What would happen in cases like this if the callosum was damaged ?

Occipital Lobe Input from Optic nerve Contains primary visual cortex most is on surface inside central fissure Outputs to parietal and temporal lobes Occipital Lobe Visual Lobe

Parietal Lobe Inputs from multiple senses Somatosensory Cortex contains primary somatosensory cortex borders visual & auditory cortex Outputs to Frontal lobe hand-eye coordination eye movements attention

Temporal Lobe Contains primary auditory cortex Inputs are auditory, visual patterns speech recognition face recognition word recognition memory formation Outputs to limbic System, basal Ganglia, and brainstem Temporal Lobe

Non-dominant Side Functions (usually the right) Perception of melodies Dominant Side (usually the left) Perception of words Process language related sounds Sequential analysis Increased blood flow during speech perception Process details, individual units Intermediate term memory Long term memory Auditory learning Retrieval of words Complex memories Visual and auditory processing Dominant Temporal Lobe (usually left) Problems Decreased verbal memory (words, lists, stories) Difficulty placing words or pictures into discreet categories Trouble understanding the context of words Aggression, internally or externally driven Dark or violent thoughts Sensitivity to slights, mild paranoia Word finding problems Auditory processing problems Reading difficulties Emotional instability Non-dominant Side Functions (usually the right) Perception of melodies Pitch/prosody Social cues Reading facial expression Increased blood flow during tonal memory Decoding vocal intonation Rhythm Visual learning Non-dominant Temporal Lobe (usually right) Problems Difficulty recognizing facial expression Difficulty decoding vocal intonation Implicated in social skill struggles Trouble processing music Decreased social cues/context Poor visual imagery Decreased selective attention to visual input Decreased recall of nonverbal items – shapes, faces, tunes

Frontal Lobe Contains primary motor cortex No direct sensory input Working Memory Motor Cortex Broca’s Area Contains primary motor cortex No direct sensory input Important planning and sequencing areas Broca’s area for speech key words: cerebral cortex; lobes; frontal; motor functions Frontal lobe is not directly involved in sensation or perception. Its functions are related to motor action (behavior). The motor cortex is the start of nerves that run through the spinal cord to the muscles. Broca’s area organizes sequences of speech movements. Damage leads to productive aphasia Dorsolateral Prefrontal Cortex is important in working memory. WM is short term memory for information needed to maintain a context, to prepare for the next step in a sequence of thought, and /or to inhibit irrelevant responses The wisconsin card sorting task illustrates the importance of working memory in maintaining context and inhibiting irrelevant responses Prefrontal area for working memory

Problems of the PFC (executive dyscontrol) short attention span distractibility lack of perseverance impulse control problems hyperactivity chronic lateness, poor time management poor organization and planning procrastination unavailability of emotions misperceptions poor judgement trouble learning from experience short term memory problems social and test anxiety lying Frontal lobe injury – problems with: Planning          Time Persistence Diligence Inhibiting behavior Controlled by external clues Distracted easily Functions of the PFC (executive control) attention span perseverance planning judgment impulse control organization self-monitoring and supervision problem solving critical thinking forward thinking learning from experience and mistakes ability to feel and express emotions influences the limbic system empathy internal supervision

Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal key words: cerebral cortex; lobes; frontal; parietal; temporal; occipital

Diencephalon Hypothalmus Section between the cerebrum and midbrain Contains 2 structures Thalamus – acts as a relay center and directs sensory impulses to the cerebrum Hypothalamus – regulates and control the autonomic nervous system, temperature, appetite, water balance, sleep, etc. Also involved in emotions such as fear, anger, pleasure, pain and affection Hypothalmus

Mid Brain Midbrain Below the cerebrum and top of the brain stem Responsible for conducting impulses between brain parts and certain eye and auditory reflexes

Cerebellum Below cerebrum Responsible for Cerebellum muscle coordination, balance and posture, muscle tone

Pons Below the midbrain and in the brain stem Responsible for conducting messages to other parts of the brain, chewing, tasting, saliva production and assists with breathing

Medulla oblongata Lowest part of the brain stem Connects with the spinal cord and is responsible for breathing, heartbeat, swallowing, coughing and blood pressure

Spinal cord Continues down from the medulla oblongata Ends at the first or second lumbar vertebrae Surrounded and protected by vertebrae Responsible for many reflex actions and carrying afferent and efferent nerves