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

Continued brain development into multiple lobes, enlargements, and extensions

Fig 49.9

• 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

Meninges

Meninges 2

Reflex arc

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

Taste/smell

Eye

Eye from text

Ear

• Malleus (hammer)

• Incus (anvil)

• Stapes (stirrup)

Cochlea

Cochlea2

Basilar/Tectorial Membrane

Saccule/Utricle

Vestibular apparatus

Macula with Otoliths

Cupula of semicircular canal