Bio Ch. 11 Notes - BIOL 2221 Fall 2016 Chapter 11 Lecture OutlineFundamentals of the Nervous Tissue and Nervous Tissue 1 Nervous system functions a

Bio Ch. 11 Notes - BIOL 2221 Fall 2016 Chapter 11 Lecture...

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BIOL 2221 Fall 2016 Chapter 11 Lecture Outline—Fundamentals of the Nervous Tissue and Nervous Tissue 1.Nervous system functions a. Sensory input- sensory receptors monitor changes in/outside body b. Integration- processes & interprets sensory input & decides what should be done c. Motor output- activates effector organs (muscles & glands) to cause a response 2. Nervous system organization- Fig. 11.2 & 11.3 a. Central nervous system (CNS)- integrating & control center of nervous system; interprets sensory input & dictates motor output based reflexes, current conditions, & past experience i. Anatomy: dorsal body cavity 1. Brain 2. Spinal cord b. Peripheral nervous system (PNS)- nervous system outside CNS i. Anatomy: extend from brain & spinal cord; communication lines 1. Cranial nerves- carry impulses to & from the brain 2. Spinal nerves- carry impulses to & from the spinal cord ii. Divisions: 1. Sensory (afferent) division- nerve fibers (axons) that convey impulses to the central nervous system from sensory receptors located throughout body; keeps CNS constantly informed of events going on in/outside body 2. Motor (efferent) division- transmits impulses from the CNS to effector organs (muscles & glands); impulses activate muscles to contract & glands to secrete; effect a motor response a. Somatic nervous system- somatic motor nerve fibers conduct impulses from CNS to skeletal muscles; voluntary nervous system allows us to consciously control skeletal muscles b. Autonomic nervous system- visceral motor nerve fibers regulate smooth muscles, cardiac muscles, & glands; involuntary i. Sympathetic division- prepares body for activity or to cope with some stressor; fight, fright, & flight subdivision ii. Parasympathetic division- oversees digestion, elimination, & glandular function; resting & digestion subdivision 3. Neuroglia- aka glial cells; nonexcitable cells of neural tissue that support, protect, & insulate neurons; Fig. 11.4 a. CNS i. Astrocytes- most abundant & versatile; look like branching sea anemones; support & brace neurons & anchor them to their nutrient 1
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supply lines; assist in exchanges b/w blood capillaries & neurons help determine capillary permeability; guide formation of synapses (junctions) b/w neurons; most important job = mopping up leaked potassium ions & recapturing & recycling released neurotransmitters ii. Microglia- small w/ long thorny processes touch nearby neurons & monitor their health & when sense injured neurons they migrate towards them; transform into phagocytes in areas of neural damage & inflammation iii. Ependymal cells- range from squamous to columnar shape; lines central cavities of brain & spinal cord cilia helps circulate cerebrospinal fluid that cushions brain & spinal cord iv. Oligodendrocytes- have fewer processes than astrocytes; line up along thicker nerve fibers in CNS & wrap processes around the fibers to produce myelin sheath insulating covering b. PNS i. Satellite cells- surround neuron cell bodies; same functions as astrocytes ii. Schwann cells- surround all nerve fibers in PNS & form myelin sheaths
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