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Nervous Tissue
Lecture Unit 2
Question | Answer |
---|---|
The Nervous System | Body's primary communication & control system. Other control system is the Endocrine system. |
Structural Organization of the Central Nervous System (CNS) | Brain, Spinal cord |
Structural Organization of the Peripheral Nervous System (PNS) | (All Nerves) Cranial nerves-12 pairs, Spinal nerves-31 pairs, Ganglia (mass of cell bodies). |
Functional Organization | Sensory (Afferent) Division and Motor (Efferent) Division. SAME DAVE. |
Sensory (Afferent) Division | Transmit information FROM RECEPTORS TO CNS. Divided into somatic and visceral sensory. |
Motor (Efferent) Division | Transmit information FROM CNS TO MUSCLE OR GLAND. Divided into somatic and autonomic motor. |
Somatic Sensory | Receives sensory information form skin, fascia, joints, skeletal muscles, special senses. |
Visceral Sensory | Receives sensory information from viscera. |
Somatic Motor | VOLUNTARY. Nervous system: innervates skeletal muscle |
Autonomic motor | INVOLUNTARY. Nervous system: innervates cardiac muscle, smooth muscle, glands. Further divided into sympathetic and parasympathetic. |
Cytology of Nervous Tissue | Neurons: Excitable cells that transmit nerve impulses. Glial cells: Non-excitable cells that support and protect the neurons. Nerve glue. |
Neuron Characteristics | High metabolic rate-need constant glucose and oxygen. Longevity-live and function for over 100 years. Only cells like this. Nonmitotic-during fetal development lose ability to divide. |
Primary tumor of the CNS | May form in the meninges (meningiomas) or glial cells (gliomas). Neurons incapable of becoming tumors-can't divide. These tumors originate w/i the brain. Brain tissue is the source. |
Secondary tumor of the CNS | Forms in another site but spreads to the brain (lung, skin, or breast cancers). |
Neuron anatomy | Dendrites, Cell body, nucleus, Axon hillock, Axon, Neurofibril node (Node of Ranvier), Myelin sheath, Synaptic knobs. Be able to label picture! Know pathway! |
Dendrites | Carry impulses towards the cell body. Soma can have only one or many dendrites. Receive input and transfer to cell body for processing. |
Cell Body | AKA: Soma. Neuron control center. Contains nucleus and organelles. Comprise "gray matter." Form clusters in PNS called ganglia. Form clusters in CNS called nuclei. |
Axons | Most neurons have 1 axon (anaxonic neurons have none). AKA nerve fiber. Carry impulses away from cell body to another cell. Transmits its output info to other cells. Ends branch into synaptic knobs. |
Structural Neuron Classification | How many structures come off cell body. Unipolar-sensory afferent neurons Bipolar-special senses, uncommon in humans. Multipolar-motor efferent neurons. Most common type. |
Functional Neuron Classification | Sensory (afferent)-from sensory receptors to CNS. Dorsal side. Interneurons-lie between motor and sensory neurons; entirely confined to CNS. Motor (efferent)-From CNS to muscles or glands. Ventral side of spinal cord. Be able to label picture! |
Glial Cells of the CNS (4) | Astrocyte, Ependymal cell, Microglial cell, Oligodendrocyte |
Astrocyte | CNS. Star cell. Control ionic environment. Helps form blood-brain barrier. Babysits neuron. Intermediate between blood and neuron. |
Ependymal cell | Lining ventricles of CNS. Help produce and circulate cerebral spinal fluid (CSF). CSF is clean, filtered plasma. |
Microglial cell | Macrophages of CNS. Immune cell. |
Oligodendrocyte | Forms myelin sheaths in CNS on more than one neuron. One cell myelinates multiple axons. Extensions create myelin sheath. |
Glial Cells of the PNS (2) | Satellite cell, Neurolemmocyte. |
Satellite cell | Dorsal root ganglia of PNS. Protects and regulates nutrients for cell bodies in ganglia. Protects and provides nutrients for soma. |
Neurolemmocyte | AKA Schwann cell. Myelinates PNS axons. Is Myelin sheath of PNS. No extensions. Cell wraps around axons and becomes myelin sheath. Myelinates 1 section of 1 axon. |
Myelin Sheath | Made by oligodendrocytes in the CNS & neurolemmocytes (schwann cells) in the PNS. Protective, white, fatty coating. Supports, protects, & insulates axon. Increases speed of conduction-nerve impulses jump from node to node. Neurofibril nodes (of Ranvier) |
Nerves | Neurons traveling together. A cable-like bundle of parallel axons. |
Three connective tissue wrappings of nerves | Endoneurium-surrounds individual axon. Perineurium-surrounds individual fascicles. Epineurium-surrounds whole nerve. |
Synapses | Site at which neurons communicate with other neurons, glands, or muscles. |
Parts of Synapses | Preynaptic neuron (Neuron before synapse). Synaptic vesicles contain neurotransmitters. Synaptic cleft (space in between). Postsynaptic neuron (Whatever connected to on other side). Label!! |
Amyotrophic Lateral Sclerosis | ALS or Lou Gehrig Disease. Fatal degeneration of the somatic motor system. Atrophied muscles cause breathing, speaking, & swallowing difficulties. No effective treatment or cure. Doesn't affect mind. Trapped. Cause of death: diaphragm goes-can't breathe. |
Multiple Sclerosis | Autoimmune disease. Patches of myelin in brain and spinal cord destroyed. Affects 1/1000 people. Symptoms: blindness, weakness, clumsiness. nervous system full of scars. Symptoms wax and wane. Vary from person to person-how many neurons involved. |
Anencephaly | Disorder at the cranial end of the neural tube. Substantial or complete absence of a brain-only brain stem forms. Infants rarely live longer than a few hours following birth. Usually detected w/ prenatal ultrasound. Most miscarry. |
Spina Bifida | Disorder at the caudal end of the neural tube. Vertebral arch is not fully formed. Mild: spina bifida occulta. Severe: spina bifida cystica. Increased intake of Vit B12 & folic acid of pregnant women decreases incidence. |