The Nervous System Why do we have one???

4 main functions  Orientation of body to internal and external environments - ??  Coordinates body activities  Assimilates experiences in order to have memory and intelligence – needed before we can learn (study for a test like its two days before it happens… you’ll remember more)  Programming of instinctual behavior - we have to learn a lot about who we are!

Divided into two main sections CNS = brain and spinal cord PNS = cranial (12pr) and spinal nerves (31pr) = information lines (like corded telephones) CNS= Central nervous system PNS = Peripheral nervous system

Made up of: Neurons or nerve cells Nerve cell bodies (somas) – located in grey matter Nervous tissue Neuroglial cells – supporting cells within nervous tissue

Made up of: Grey matter – collection of neuron cell bodies Nucleus (in CNS)– collection of nerve cell bodies Ganglia (in PNS) – collection of nerve cell bodies White matter – dendrites and axons

Motor nerves – efferent (out of) Takes information out of the spinal cord Allows muscles to move Applies to skeletal & smooth muscles, and glands

Sensory nerves – afferent (in to) Sensory information going into the spinal cord then to the brain

Autonomic vs. Somatic nervous system Autonomic nervous system – controls everything we don’t think about.. Smooth muscles, glands, breathing, etc. = involuntary movement Somatic nervous system – controls the skeletal muscle = voluntary movement

Neuroglial cells Fill in spaces, provide structural frameworks, produce myelin, carry on phagocytosis Microglial: scattered throughout, support neurons, phagocytize bacterial cells and cellular debris Oligodendrocites: occur in rows, provide isulating layers of myelin around axons within the brain and spinal cord

Neuroglial cells Astrocytes: found between neurons and blood vessels, provide structural support – form scar tissue that fills spaces within the CNS Ependymal: epithelial like membrane that covers specialized brain parts and forms inner linings that enclose spaces within the brain. Schwann cells – in PNS, form covering of myelin around axons

Neurons

Neurons are comprised of:  Soma or cell body – includes nucleus of the cell; many dendrites protrude  Axon – protrudes from the soma  Synaptic Knob of axon termnial – most inferior part of the axon; site of connection with a dendrite of another neuron

Neurons are comprised of:  Nodes of Ranvier - Junctions between two Schwann cells  Myelin sheth – sometimes on the axon; made up of the cell body of the Schwann cell; insulator  Schwann cell – neuroglial cell; makes up the myelin sheath

Neurons can be classified into categories: Bipolar Unipolar Multipolar Motor neuron Interneuron Sensory neuron

Process arising from each end of the cell body – one is the dendrite, one is the axon Has only two processes Sensory neurons in eyes, ears, nose… Afferent neurons

 Unipolar neurons/sensory neurons/ afferent neurons  Single process from the cell body, but divides into two branches – dendrite branch is the peripheral process; axon branch is the central process  Sometimes aggregate into ganglia – located outside brain and spinal cord.

Many processes arising from cell body One process is the neuron, the other processes are dendritic Most often lie within the brain or spinal cord Efferent neurons/motor neurons/interneurons

Your assignment  Draw all different types of neurons in your notes (p.211), if you wish, you may make a foldable – not required. This will be checked for credit.  Check your recall pp. 207, 208, 209, 212  Review exercises p 249 Q1, 2, 3, 4, 6, 7  IF YOU HAVEN’T DONE SO…. You need to turn in your lymphatic worksheets (lab 40 and the WS on T & B-cell differentiation) and foldable, show me the finished question sets for Chapter 14!! Check your recall pp. 374, 376, 377, 380 (only under immune response) p. 389 review exercises 8, 9, 12, 14, 15, 16, 21, 23, This work is counted toward your grade!