KIN 3304 1st EditionExam # 2 Study Guide Lectures: 10 - 17Lecture 10 (September 22) The Nervous System can be divided into 2 parts: The Central Nervous System and The PeripheralNervous System. The Central Nervous System consists of the brain and the spinal cord and is responsible for integrating, processing, and coordinating sensory input and motor output. It also holds higher functions such as intelligence, memory, learning, and emotion.The Peripheral Nervous System consists of all of the remaining neural tissue outside of the CNS and it provides sensory information to the CNS and carries motor commands from the CNS to peripheral tissues. The PNS is split into two subdivisions: Afferent PNS and Efferent PNS.The Afferent PNS brings sensory information to the CNS. The afferent division begins at receptors that monitor the environment. There are 3 receptors we talked about:- A dendrite – sensory process of a neuron- A specialized cell or cluster of cells – like a muscle- A complex sensory organ – like the eyeThen the stimulation of the receptor will provide information to the CNS.The Efferent PNS carries motor commands to muscles and glands. The efferent division begins atthe CNS and ends at an effector. An effector could be a muscle cell, gland cell, or another cell that performs a function. The Efferent PNS can further be divided into the Somatic Nervous System and the Autonomic Nervous System.- Somatic Nervous System deals with our muscles and can be voluntary of involuntary.- Autonomic Nervous System deals with things we don’t control.Both the Afferent PNS and Efferent PNS have somatic and visceral sensory receptors. Somatic sensory receptors monitor voluntary things like skeletal muscles. Visceral sensory receptors monitor things that you don’t control like breathing and digesting.*TQ: Know Figure 13.2There are different types of GLIAL CELLS in the CNS and the PNS. The CNS has oligodendrocytes, astrocytes, microglia, and ependymal cells, but we only talked about the Oligodendrocytes and astrocytes. The PNS has satellite cells and schwann cells. We just talked about schwann cells.Astrocytes - CNS- Largest and most numerous glial cells- Have 5 functions:o Control The Interstitial Environment Astrocytes have cytoplasmic processes which increase the SA of the cell so that it can exchange ions to the extracellular fluid of the CNS so that it therefore controls the interstitial environment of CNS. The cytoplasmic processes also contact neurons and isolate them so that the neurons cantmake chemical changes in the interstitial space of the CNS.o Maintain BBB The neural tissues must be physically and biochemically separated from the blood at all times. The cytoplasmic processes of the astrocyte cover the surface of the capillaries within the CNS and provide a blanket, separating the interstitial fluid from the blood so that the hormones and chemicals in blood will not harm the neuronal function.o Create a 3D Framework for CNS Astrocytes have microfilaments throughout the whole cell that provides mechanical strength. Because of this, astrocytes form a framework (like lady liberty being built) that supports the neurons of the brain and spinal cord.o Repair Damaged Neural Tissue After damage to the CNS, astrocytes stabilize the repair and then prevent another injury there by producing scar tissue.o Guide Neuronal Development Astrocytes direct the growth of developing neurons in the embryonic brain by secreting neurotropic factor chemicals.Oligodendrocytes – CNSo The structures of these glial cells compared to astrocytes have smaller bodies but they tie their axons together. Oligodendrocytes improve the function of neurons by wrapping theaxons in myelin. Many axons in the CNS are sheathed by Oligodendrocytes. Oligos expand the plasmalemma, creates a pad around the axon which creates a sheath composed of phospholipids. Myelin Sheaths improve the action potential or nerve impulse speed. The myelin sheath can form along the entire length of the axon. The long myelinated areas are called Internodes. The gaps between internodes are called Myelin Sheath Gaps or Nodes of Ranvier. The area where most myelinated axons are is the white matter of the CNS. The area where there are many UNmyelinated axons, nerves, and dendrites is called the gray matter of the CNS. Loss of myelin  loss of conduction (as in the disease: Multiple Sclerosis)Schwann Cells – PNSo Every peripheral neuron is covered by Schwann cells which are also calledneurolemmocytes. It can only myelinate about 1mm of an axon which is much less than what an oligo can. The sheath of schwann cells is called neurilemma. All Unmyelinated axons are enclosed by schwann cells. Schwann cells also play a role in repairing damagednerves!Now, we’ll talk about NEURONS.A Neurotransmitter is a chemical compound that is released by a neuron to communicate with another neuron.Neurons can be classified into 3 groups: sensory neurons, motor neurons, and interneurons. Sensory neurons detect stimuli in the PNS and send that information to the CNS. Motor neuronscarry instructions from the CNS to peripheral effectors. Interneurons in the CNS process sensoryinformation and coordinate motor activity.There are 3 kinds of Receptors:o Exteroceptorso Provide information about the external environment that are in the form of touch, temperature, pressure and the special senses of sight, smell, and hearing.o Proprioceptorso Monitor the position and movement of the muscles and jointso Interoceptorso Monitor the digestive, cardiovascular, urinary, and reproductive systems and also provide sensations of deep pressure and pain, and tastes.Lecture 11 (September 24) Neuronal Regeneration: Neurons have a limited ability to recover after an injury. After the injury, the chromatophillic substance disappears and the nucleus moves away from where its supposed to be. But there is such a thing called Wallerian Degeneration where at the injury site,the axon deteriorates, macrophages eat the debris, and then schwann cells form a cord that follows the path of the original axon and schwann cells release growth factors to promote axonal regrowth. If this new axon is cut, new axons will emerge within hours. But this isn’t always the case. In a common tearing or crushing of a neuron, the axon will die and new axonsegments will sprout a week or more later.The Rate of Nerve Impulse depends on 2 properties of the axon that the action