Test 4 Book Notes BIOL1108 Ch 49 Nervous Systems pg 1062 1067 Nervous Systems consists of circuits of neurons and supporting cells Evolution led to modi cation of simple recognition response systems allowing mechanism for communication between cells of body Hydras Jellies Cnidarians radial body layout Interconnected nerve cells form a nerve net which functions to contract expand gastrovascular cavity In more complex animals axons of multiple nerve cells are bundled together to form nerves BILATERALLY SYMMETRICAL bodies have even more specialized nervous systems Exhibit cephalization an evolutionary trend clustering of sensory neurons interneurons at the front end of the body These neurons communicate with nerve cells all over body even at dorsal end Nervous system layout often corresponds to lifestyle In vertebrates CNS brain spinal cord PNS ganglia nerves Test 4 Book Notes BIOL1108 Organization of the vertebrate nervous system Brain and Spinal cord work together to form the vertebrates CNS Brain integrative power Spinal cord relays information to and from brain generates basic patterns of movement also acts independent of brain to produce re exes or the body s automatic response to stimuli Re exes which are involuntary protect body e g hand getting burned Spinal Cord of vertebrates located dorsal while nerve cord of invertebrates located ventrally Develops from the hollow nerve cord character of chordates Cavity of nerve cord gives rise to Central Canal and the Ventricles of the brain Both lled with CSF Cerebrospinal uid Cushions brain lters through and drains into veins Carries nutrients in and waste out Test 4 Book Notes BIOL1108 Brain Spinal Cord Both contain white and gray matter Gray matter is on the outside of the brain inside of spinal cord Contains mostly cell bodies of neurons dendrites and unmyelinated axons White matter is inside brain outside of spinal cord Contains myelinated bundles of axons giving white appearance Role of white matter on outside of spinal cord is to relay information from the CNS to motor sensory neurons in the PNS Role of white matter inside brain is to relay information from neurons in the brain to one another allowing learning sensation etc GLIA in vertebrate nervous system Give support nourish and regulate the functioning of neurons Also aid development of the nervous system Located throughout brain and spinal cord Types of Glia Ependymal cells line ventricles cilia help to circulate CSF Astrocytes aid information transfer at synapses Also help form tight junctions of cells lining blood capillaries forming Blood Brain Barrier Oligodendrocytes myelinate axons of the CNS Schwann cells myelinate axons in the PNS Microglia immune cells protect against pathogens Test 4 Book Notes BIOL1108 The Peripheral Nervous System PNS Carries information to smooth muscles glands and endocrine cells Transfers information to and from CNS Afferent neurons carry information CNS Efferent neurons carry information CNS PNS has two efferent components Motor system has neurons that carry signals to skeletal muscles Can be voluntary hand raise or involuntary knee jerk re ex Autonomic nervous system has neurons that regulate cardiac muscle and smooth muscle Is involuntary Has 3 divisions Parasympathetic rest and digest slows body processes Sympathetic ght or ight response speeds up These two divisions are antagonistic as they have opposite effects regulating organ function Enteric active in digestive tract and peristalsis Usually regulated by para and sympathetic divisions Can be independent as well HOMEOSTASIS relies on cooperation of Motor and Autonomic Nervous systems e g Body temp down Hypothalamus signals muscles to shiver also signals Autonomic Nervous system to constrict blood vessels Both help warm body back up CONCEPT CHECK 49 1 1 Which division of the autonomic nervous system would likely be activated if a student learned that an exam she had forgotten about would start in 5 minutes Explain your answer The sympathetic division would likely be activated It mediates the ght or ight response in stressful situations Test 4 Book Notes BIOL1108 2 The parasympathetic and sympathetic divisions of the PNS see Figure 49 8 use the same neurotransmitters at the axon terminals of preganglionic neurons but different neurotransmitters at the axon terminals of postganglionic neurons How does this difference correlate with the function of the axons bringing signals into and out of the ganglia in the two divisions The preganglionic neurons use the same neurotransmitter and function similarly in each division to stimulate postganglionic neurons The postganglionic neurons use different neurotransmitters that generally bring about opposing functions in the same target tissues 3 Suppose a person had an accident that severed a small nerve required to move some of the ngers of the right hand Would you also expect an effect on sensation from those ngers Nerves contain bundles of axons some that belong to motor neurons which send signals outward from the CNS and some that belong to sensory neurons which bring signals into the CNS Therefore you would expect effects on both motor control and sensation Ch 50 Skeletal Muscle Structure Function pg 1103 1110 The physical interaction of protein laments is required for muscle function Muscle cell function relies on micro laments the actin components of the cytoskeleton Micro laments function is cell motility Muscle contraction is a result of micro lament movement powered by chemical energy ATP Vertebrate Skeletal Muscle Skeletal Muscle moves both bones and body Composed of many smaller and smaller units Muscle ber muscle cell Contains many nuclei this represents the muscle cells being made by many fused together during embryonic development this is why we can not make new muscle cells Within each ber myo brils exist which are formed of thin and thick laments Test 4 Book Notes BIOL1108 Thin laments orange above consist of two strands of actin and two strands of a regulatory protein coiled around each other Thick laments purple above are staggered arrangements of myosin molecules Skeletal muscle is also called striated because the regular arrangement of the laments creates a pattern of light and dark bands Each repeating unit of skeletal muscle is called the sarcomere the basic contractile unit of the muscle Thin laments are attached at the Z lines and project toward the center while thick laments are attached at the M line center These two