Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 9

Homunculus: This is how your brain perceives your body

I. Central Nervous System ( CNS ) Brain and Spinal Cord protected by the skull and vertebrae II. Peripheral Nervous System ( PNS ) 12 pairs of Cranial Nerves from the brain 31 pairs of Spinal Nerves from the spinal cord Two Divisions 1. Somatic Nervous system ( SNS ) 2. Autonomic or Visceral Nervous System (ANS ) a. Sympathetic - Speed things up b. Parasympathetic – Slows things down

Figure 09.02

Figure Nervous System Cells Neurons: Cells that carry impulses from one point to another and store information Neuroglia or Glial Cells – Involved in metabolic and structural support for neurons Four Types are: Astrocytes: Connect blood vessels and neurons form Blood Brain Barrier (BBB), Form Pial Glial Layer a protective layer along the CNS Oligodendrocytes: Produce myelin covering for neurons in the CNS Microglia: Very small until activated by an injury then work as a phagocytes. Alzheimer’s produces a lot of microglia Ependymal Cells – Line canals and produce cerebrospinal fluid (CSF)

Figure Neurons Neurons with short axons in the CNS can reproduce in adults Olfactory nerve cells for smell can reproduce every 40 days Nisal Substance This is Endoplasmic Reticulum involved in protein synthesis Axon Hillock

Figure 09.04

Figure 09.05

Figure Pseudo- Types of Neurons Myelinated – Multipolar: Most common type of neuron. Efferent or motor neuron from CNS to Muscle or Gland Pseudo-unipolar: Afferent or sensory neurons from Receptors to CNS Unmyelinated – Bipolar – neurons for connections found in retina, olfactory epithelium and auditory ganglia and CNS A group of neurons with the same function inside the CNS are called a Nucleus or Nuclei Outside the CNS they are called a Ganglion or Ganglia

Figure 09.07

Figure Synapse – small space between neurons very important for the control and coordination of the nervous system

Figure Movement of synaptic vesicles to axon membrane involves Calcium ions Video

Figure 09.10

Figure One neuron may connect with 10,000 other neurons and you have billions of neurons. These pathways are how memory is stored.

Nerve impulse

Figure 09.13

Nerve impulse Action Potential or Wave of Depolarization A Polarized or Resting neuron is + on the outside and – on the inside due to Na on the outside and K on the inside. When an impulse is initiated gates in the cell membrane open and the two chemical exchange places producing a wave of depolarization that travels down the axon. The nerve will repolarize by diffusion for quick impulses Prolong impulses can cause to neuron to remain depolarized so cannot carry any more impulses it is said to be in a Refractory Period To repolarize this neuron requires an active transport system call the Sodium – Potassium Pump Video

Figure Polarized or Resting Neuron Wave of Depolarization

Figure 09.15

Figure A bundle of many neurons

Figure 09.18

Figure Motor neurons come from the Anterior Horn of the spinal cord so are referred to as anterior horn cells Sensory neurons enter through the Posterior Horn of the Spinal cord so are called posterior horn cells Posterior Horn Anterior Horn

Figure 09.20

Figure Central Nervous System

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Figure 09.23

Figure White matter myelinated neurons Gray Matter Unmyelinated neurons

Figure How do you know if it is hot or cold ?

Figure How did you walk to class ?

Figure 09.27a Gyrus: Top of folds Sulcus : Valleys of folds Increases the surface area of the cortex Meninges: Protective cover of brain 3 layers 1. Dura Mater “ tough mother” outer layer 2. Arachnoid “ Spider web” layer of connective fibers 3. Pia mater “gentle mother” touches brain Diencephalon: Midbrain - Thalamus, Epithalamus and Hypothalamus All sensory input goes through Thalamus before going to Cerebral Cortex. Hypothalamus does many functions for the autonomic nervous system ( Body Temp., Thirst, Appetite, Emotions, Mating, Sleep, Memory, Hormones ) “Bridge” Nerve connection between hemispheres

Figure 09.27b

Figure 09.28

Brodmann’s map based on cell structure and function

Figure 09.29

Figure Cavities filled with cerebrospinal fluid CSF – cools the brain, brings in nutrients and removes waste

Figure 09.31

Figure 09.32

Figure 09.34

Figure “ Horsetail” Lowest point of spinal cord

Figure 09.36

Figure 09.37

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Figure 09.39

TABLES

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