1 Anatomy and Physiology Exam 3 GuideNervous SystemOrganization1. List the structural and functional divisions of the nervous system and describe their relationship to each other. - The central nervous system can be thought of as the main computer of the body; it controls everything we do and makes communication throughout the body possible. The nervous system communicates by the use of electrical and chemical signals. One thing to easily memorize is the general process that the CNS (and every part of it) works is by sensory, integration, and then a motor output. Now to get to the divisions: The CNS or central nervous system is the main “computer” of the body. It receives and sends all the stimuli and actions that we perform. The CNS consists of the brain and spinal cord specifically and the PNS or peripheral nervous system consists of the cranial and spinal nerves. The PNS acts like a middleman; conveying information from the outside to the CNS. It does this by carrying impulses to the CNS. The PNS is divided into the sensory (afferent) and the motor divisions (efferent). o Then you could break the motor division into the autonomic and the somatic division. The somatic is your voluntary actions or your muscles. The autonomic is everything you can’t control, like the glands, the smooth muscles, and the cardiac muscles. The sensory division is known as the afferent system, meaning it conducts signals from certain receptors and sends them to the CNS, and the motor division, known as efferent, takes those signals from the CNS and sends them to motor units to cause muscle contraction. The autonomic is broken into the parasympathetic and the sympathetic division. Simply remember that sympathetic is the fight and flight, and parasympathetic is everything else. So to recap everything: o CNS→ PNS→ Sensory and motor→ Motor then goes to Autonomic and somatic → Autonomic goes to parasympathetic and sympathetic.Histology 2. Know all six support or glial cells and what each functions are (that includes those that2may share a function but do so in the CNS or PNS).- Just like how a computer has programs to run efficiently, the CNS has specialized cells that act as the programs. These cells are called the neuroglia, and there are six of them. 4 in the CNS and 2 in the PNS: Astrocytes are the most abundant glial cells in the CNS and these help support the neurons (conducting cells) by supplying nutrition to them Microglia have long processes and these are like the nurses of the neurons. They are there to monitor its health and sense injury. If there is an injury, they turn into macrophages (remember these engulf harmful organisms) to protect the neuron Ependymal cells just line the cavities. There are boring Oligodendrocytes form the myelin sheaths that wrap around the dendrites on the neurons. Highly important in neurological function- In the PNS, the glias serve the same function, but have different names: Satellite cells are the same as the astrocytes Schwann cells are the same as the oligodendrocytes.3. Explain the physiological function of mature neurons.- Neurons are the cells that compose the nervous system and they function to take sensory information, integrate it in the brain as communication, and then send a motor out to a muscle. So they conduct messages throughout the body. They have a long life span—they don’t multiply like other cells. So once they die, they usually are gone for good. Their only fuel source is glucose, so that is how a zero carb diet is stupid and unhealthy. 4. Describe the anatomy of a neuron. - The nervous system, along with the muscular system, is probably the most complicated system in the body. The nervous system controls all of our actions, and without a functioning nervous system, no other cell in our body would really be functional.- The nervous system is like a highway that electrical impulses travel on, and the neuron is the specialized cell that controls these electrical impulses. Briefly, the neuron creates an electrical impulse and this impulse travels down the arms of the neuron to a new destination Now for the anatomy of the neuron: The neuron is just a specialized cell, with the purpose of creating electrical signals. The body of the neuron is called the soma (some things to note are a more specialized ERin neurons and they have structures called nissl bodies in them), and the soma has little branch-like projections arising out of the soma called dendrites. Also attached to the soma is a single long projection called an axon. This is that arm that the electrical impulse travels down, or is propagated.3 The dendrites are the receiving arms for the impulse. So they will receive an impulse from a previous neuron (called the presynaptic neuron) and will propagate it down the axon. The pathway that the action potential, or impulse travels are called tracts in the CNS and nerves in the PNS. 5. Describe the anatomy and function of the myelin sheath, and differentiate between myelinated and unmyelinated neurons. - The AP only takes msec to propagate down the axon, and the neurons have ways to speed up this process. So to speed up conduction, a myelin sheath is wrapped around the axon. This is done by those oligodendrocytes (CNS) and the Schwann cells (PNS). The sheath is pretty much all lipid and works as a capacitance (for you physic people out there. This works to conduct the voltage change fast—10x faster to be exact Without the sheath, the signal is slowed, and these are needed to communicate with body parts, so you would have slow movements, paralysis, tremors---collectively called neuropathy. This is the pathophysiology of Multiple Sclerosis. Also, when the myelin sheath wraps around the axon the speed up conduction, it is attached in sections. Meaning there are spaces between each sheath, called the Nodes of Ravier. The signal “jumps” from node to node. o White matter is the regions in the CNS that have neurons covered in that myelin sheath; so it makes sense that it would appear whiteo Grey matter is the regions in the CNS with no myelin6. Define the structural and functional categories of neurons and compare how the structural class of a neuron relates to its functional class. - In the CNS, they are called nuclei and in the PNS, they are ganglia. By structural, I think Dr. Moffatt’s wantsyou to know different ways neurons are groups. These
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