nervous system overview (48.1) sensory input –transmit information light, sound, touch, heat...
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Nervous system overview (48.1)
• Sensory Input– Transmit information
• Light, sound, touch, heat smell, taste, etc
• Integration– CNS (central nervous system)
• Brain and nerve cord analyzes and interprets
• Motor Output– PNS (peripheral nervous system)
• carries information into and out of CNS
• Transmission triggers an activity or causes an effect such as muscle contraction
Fig 48.3
• Neural cell/Neuron– Branched dendrites
• Receive signals from other neurons
• Shorter, highly branched
– Single axon• Transmits signals to other
neurons• Longer
– Synaptic terminals (fig 48.4)
• Axons / dendrite junctions• Pass information through
chemical neurotransmitters
– Glia• Supporting cells to
nourish, insulate, and regulate fluids
Brain and embryonic developmentAfter gastrulation…• Neural plate forms
– Dorsal orientation– “cephal to caudal” direction
• Neural tube forms– Infolding of plate, forming groove and
crest– Fuses to form tube– Cephal end enlarges = brain– Rest is spinal cord
• Mesoderm– Coelom formation– Somites give rise to segmented
structures
• Endoderm– Gastrovascular development
Fig 47.13
• Forebrain Cerebrum – Two hemispheres
• Left: logical, temporal, language• Right: Spatial, abstract, artistic, gestalt
(perceiving “whole” rather than parts)
– Cerebral Cortex• Outer gray matter
– Highly infolded (high surface area)• Sulcus (folds) between gyrus (tissue)• Increased s/a = more gray matter and
generally more intelligence
– Lobes are connected by underlying white matter
• Corpus callosum is the main L/R connection
– Frontal lobes• Primary motor cortex (motor skills),
muscle control, speech, smell, memory, and integration from other areas
– Parietal lobes• Somatosensory, touch, pressure stimuli
– Temporal lobes• Hearing, balance
– Occipital lobes• Visual centers (visualizing an event or
how to spell something)
• Thalamus– Two egg-shaped masses– Cerebral sensory impulses and
emotional center (limbic system)• Along with Amygdala (fight or flight)
– Plays role in process:• Sensation, Motor activities, waking up,
learning, memory
• Hypothalamus– Connects to pituitary
• Stores hormones for regulation in endocrine system
– Homeostatic control functions• Autonomic controls, physiological
emotions, body temp., thirst and satiety, circadian rhythms
• Midbrain– White matter masses connects to
cerebrum and cerebellum– Visual and auditory reflex centers
• HindbrainBrain stem and cerebellum– Pons connects upper and lower center
• Respiratory center with hypothalumus
• Cerebellum• Athletic brain: refining and directing motor
activities• “athletic memory”
• Medulla oblongata• Autonomic reflexes: cardio regulatory, blood
pressure, respiratory, vomiting, couching
Brain ventricles and CSF• Ventricles are remnants
of early hollow tube• Filled with Cerebral
Spinal Fluid– Derived from blood
plasma; with lots of ions– Liquid cushion– “fatty” brain mass
“floats”, protected, supported, w/o rigid or sharp edged structures
Peripheral Nervous System – radiates to and from CNS & includes Somatic (SNS) and autonomic (ANS)Somatic: mechanoreceptors, pain, chemo-, photo-, thermoreceptorsAutonomic: unconscious visceral reception; antagonistic (opp. Effects)
ANS Sympathetic ANS Parasympathetic