Ch. 49: Nervous Systems [pg. 1062-1067]- Nervous Systems consists of circuits of neurons and supporting cells- Evolution led to modification 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 + nervesTest 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 reflexes, or the bodyʼs automatic response to stimuli.- Reflexes, 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 filled with CSF (Cerebrospinal fluid).- Cushions brain; filters 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 reflex).- 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 = fight or flight 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 49.11. 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 “fight-or- flight” response in stressful situations.Test 4 Book Notes! BIOL11082. 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 fingers of the right hand. Would you also expect an effect on sensation from those fingers?! 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 filaments is required for muscle function- Muscle cell function relies on microfilaments, the actin components of the cytoskeleton. - Microfilaments function is cell motility.- Muscle contraction is a result of microfilament movement powered by chemical energy (ATP).- Vertebrate Skeletal Muscle- Skeletal Muscle moves both bones and body.- Composed of many smaller and smaller units.- Muscle fiber = “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 fiber, myofibrils exist, which are formed of thin and thick filaments.Test 4 Book Notes! BIOL1108- Thin filaments (orange above) consist of two strands of actin and two strands of a regulatory protein coiled around each other.- Thick filaments (purple above) are staggered arrangements of myosin molecules.- Skeletal muscle is also called striated because the regular