Nervous system overview (48.1)

1. 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

2. 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

3. Brain and embryonic development After 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

4. Continued brain development into multiple lobes, enlargements, and extensions Fig 49.9

5. 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)

6. 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 • Hindbrain • Brain 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

7. 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

8. Meninges

9. Meninges 2

10. Reflex arc

11. 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)ANSSympathetic ANS Parasympathetic

12. Taste/smell

14. Eye

15. Eye from text

17. Ear

18. Malleus (hammer) Incus (anvil) Stapes (stirrup)

19. Cochlea

20. Cochlea2

21. Basilar/Tectorial Membrane

22. Saccule/Utricle

23. Vestibular apparatus

24. Macula with Otoliths

25. Cupula of semicircular canal