Nervous Systems Brain Development 2007-2008
Nervous system Central nervous system Peripheral nervous system Brain Spinal cord Sensory pathways Motor pathways Sympathetic arousal & energy production fight or flight Parasympathetic calming & back to maintenance rest & digest Somatic (voluntary) nervous system Sympathetic division Autonomic (involuntary) nervous system Parasympathetic division
Types of neurons sensory neuron cell body cell body dendrites axon dendrites interneuron associative cell body motor neuron
Cephalization = Brain evolution Cephalization = clustering of neurons in brain at front (anterior) end of bilaterally symmetrical animals where sense organs are nerve cords associative neurons nerve net nerve ribs radial nerve Cnidarian Simplest nervous system no control of complex actions Echinoderm More organization but still based on nerve nets; supports more complex movement Flatworm Platyhelminthes Simplest, defined central nervous system more complex muscle control
Cephalization = Brain evolution increase in interneurons in brain region central nervous system giant axon brain peripheral nerves brain ventral nerve cords Earthworm Mollusk Arthropod More complex brains connected to all other parts of body by peripheral nerves More complex brains in predators most sophisticated invertebrate nervous system Further brain development ganglia = neuron clusters along CNS
Evolution of vertebrate brain Shark hindbrain Spinal cord Frog Hind: Medulla oblongata Hind: Cerebellum Optic tectum Midbrain Fore: Cerebrum Olfactory tract forebrain Crocodile Bird Cat forebrain forebrain dominant cerebrum Human
Human brain
Functional divisions of brain Hindbrain evolutionary older structures of the brain regulate essential autonomic & integrative functions brainstem pons medulla oblongata midbrain cerebellum thalamus, hypothalamus
Brainstem The lower brain medulla oblongata pons midbrain Functions homeostasis coordination of movement conduction of impulses to higher brain centers
Medulla oblongata & Pons Controls autonomic homeostatic functions heart & blood vessel activity breathing swallowing vomiting digestion Relays information to & from higher brain centers
Midbrain Involved in the integration of sensory information regulation of visual reflexes regulation of auditory reflexes
Reticular Formation Sleep & wakefulness produces patterns of electrical activity in the brain recorded as an ElectroEncephaloGram (EEG) most dreaming during REM (rapid eye movement) sleep
Cerebrum Most highly evolved structure of mammalian brain Cerebrum divided hemispheres left = right side of body right = left side of body Corpus callosum major connection between 2 hemispheres
Lateralization of Brain Function Left hemisphere language, math, logic operations, processing of serial sequences of information, visual & auditory details detailed activities required for motor control Right hemisphere pattern recognition, spatial relationships, non-verbal ideation, emotional processing, parallel processing of information
Cerebrum specialization Regions of the cerebrum are specialized for different functions Lobes frontal temporal occipital parietal
Limbic system Mediates basic emotions (fear, anger), involved in emotional bonding, establishes emotional memory Amygdala involved in recognizing emotional content of facial expression
Simplest Nerve Circuit Reflex, or automatic response rapid response automated signal only goes to spinal cord no higher level processing adaptive value essential actions don t need to think or make decisions about blinking balance pupil dilation startle
Eye Blink or Pain Withdrawal Reflex Gray matter White matter Interneuron Sensory neuron Stimulus Receptor in skin Motor neuron Spinal cord Effector (muscle)
cerebrum cerebellum spinal cord cervical nerves thoracic nerves lumbar nerves Review of nervous system With Mr.A femoral nerve sciatic nerve tibial nerve 2007-2008