Nervous System Organization November 6 2019 Nervous System

Nervous System Organization November 6, 2019

Nervous System Fun Facts Which “fact” is false? 1) All body functions are controlled and regulated by the nervous system 2) There are more neurons in the brain there are stars in the Milky Way galaxy 3) The left side of the body is controlled by the right side of the brain and vice-versa 4) The brain reaches maturity at around 25 years of age. The endocrine system also controls and regulates some body functions, especially metabolism, growth, and reproduction.

Nervous System Functions The nervous system has three major functions: 1) Sensory input 2) Integration 3) Motor output

Nervous System Functions 1) Sensory input – the body gathers information, or stimuli, from the internal or external environment Ex) seeing a bright light

Nervous System Functions 2) Integration– the body processes information and makes a decision about what should be done Example: “decision” to initiate flight – orfight response

Nervous System Functions 3) Motor Output– the body activates muscles or glands to effect a response. Example: moving your arm to grab a chip

Nervous System Functions Which function(s) are demonstrated in these examples? �You hear a buzzing sound. Sensory input �You weigh the pros and cons of two different universities, and make a choice. integration �You move your leg Motor output �You touch a hot stove and jerk your hand back. Sensory input, integration, motor output

Nervous System Organization The nervous system can be organized by structure and by function.

Nervous System Organization Structurally, the nervous system is organized into �The central nervous system, which consists of the brain and spinal cord, and which acts to integrate (interpret & issue instructions for) stimuli �The peripheral nervous system which consists of all the nerves outside the brain and spinal cord. These receive stimuli and effect responses in muscles and glands.

Nervous System Organization The peripheral nervous system can be further divided into: 1) Afferent or sensory neurons - bring stimuli to CNS -- affect the body by internal or external information 2) Efferent or motor neurons -- carry a signal from CNS -- cause muscles or glands to respond -- effect a change / response Mneumonic: A comes before E

Nervous System Organization The efferent / motor neurons can be further divided into: 1) Somatic neurons - neurons that control skeletal muscles - mostly voluntary 2) Autonomic neurons -- neurons that control smooth and cardiac muscle and glands - involuntary

Nervous System Organization Determine which parts of the nervous system are involved in these: You hear a buzzing sound. You weigh the pros and cons of two different universities, and make a choice. You move your leg You touch a hot stove and jerk your hand back.

Nervous System Organization Determine which parts of the nervous system are involved in these: You hear a buzzing sound. Afferent (peripheral) and CNS You weigh the pros and cons of two different universities, and make a choice. You move your leg You touch a hot stove and jerk your hand back. Central nervous system CNS and somatic (efferent, peripheral) 1) Afferent (peripheral) 2) Central nervous system 3) somatic (efferent, peripheral)

Neural Tissue: What do you see?

What do you see? Researchers estimate that the brain has 10 X as many glial cells as neurons But see this

Neuroglia All nervous tissue cells except neurons are known as neuroglia, or glial cells. “nerve glue”

CNS Neuroglia Astrocytes (star-cell) � Exchange nutrients between blood and neurons � protect neurons from harmful materials. � “blood brain barrier” � Control flow of blood through brain (what is measured in MRI) � Control extracellular environment � change shape � release calcium and ‘glial transmitters’; uptaking ions and neurotransmitters � Digest waste � Moderate the behavior of neurons Astrocytes are the most abundant glial cell and may be the cells responsible for thought

CNS Neuroglia Microglia �Shaped like astrocytes, but smaller, and don’t connect neurons to blood vessels �Digest debris, bacteria, and dead brain cells Ependymal Cells �Line the cavities of the brain and the spinal cord �Produce and circulate cerebrospinal fluid

CNS Neuroglia Oligodendrocytes �Wrap around axon of CNS neurons, creating a fatty myelin sheath that insulates neurons �Each oligodendrocyte wraps around the axons of several neurons �Allow for efficient nerve impulse propagation Multiple sclerosis (MS) is an autoimmune disease characterized by the gradual destruction of the myelin sheath

Name the cell!

Name the cell!

PNS Neuroglia Schwann Cells �Form myelin sheaths around peripheral neuron axons �Many Schwann cells per neuron �Give peripheral neurons some ability to regenerate Satellite Cells § Surround body of peripheral neurons § Function not fully understood – may have similar function as astrocytes? ?

Think, Pair, Share (5 minutes) Scholar whose birthday is earlier in the month. . . �Identify the two PNS glial cells, determine which cells in the CNS have similar function, and describe the similarities and differences in each pair of cells. Scholar whose birthday is later in the month … § Identify two similarities and one difference between astrocytes and microglia § Explain the location and function of ependymal cells

Oligodendrocytes vs Schwann Cells

Neuron Anatomy The cell body contains the nucleus and organelles

Neuron Anatomy Processes carry information. • Dendrites receive and carry messages towards the cell body. • The axon generates messages and usually carries them away from the cell body. • There may be 100’s of dendrites, but only 1 or 2 axons. • The end of the axon branches into 100’s or 1000’s of axon terminals

Neuron Anatomy Schwann cells wrap around most PNS axons, forming the myelin sheath. Nodes of Ranvier are gaps in the myelin sheath / spaces between Schwann cells. What cells cover the axons of CNS neurons? What cells cover the body of PNS neurons?

Neuron Anatomy Schwann cells wrap around most PNS axons, forming the myelin sheath. Nodes of Ranvier are gaps in the myelin sheath / spaces between Schwann cells. What cells cover the axons of CNS neurons? oligodendrocytes What cells cover the body of PNS neurons? Satellite cells

Congo Line Review Write one question that you think might be on an exit ticket on the front of a note card. It should be something that can be answered in a sentence or less. Write the answer on the back.

Closure �What were our objectives and what did you learn about them? �What was our learner profile trait and how did we exemplify it? �How does what we learned today relate to our unit question and TOK connection.