Chapter 26 - 26 Coordination by Neural Signaling C H AP T E...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
524 Octopus Sea urchin Clam Getting a Head H ow do you defi ne a head? Whether you describe a head as an anterior demarcation of the body or an anterior region con- taining a brain and sense organs, it is clear that echinoderms, such as sea urchins, don’t have one. Sea urchins depend on all those spines to protect them, rather than running away quickly on their many tube feet. What about the clam compared to the octopus? The inactive clam spends its life digging in the sand and does not have a head. But the octopus, in addition to all those creeping arms, does have a head. You might mistake the visceral hump for part of the head, but it is not. Its head is where you see the eyes, because that is where the brain is. An octopus needs its brain, eyes, and arms to go after its prey. A head is a defi nite advantage to a predator. Good eye-appendage coordination helps a lot too. CHAPTER OUTLINE Functions of the Nervous System Are Carried Out by Neurons 26.1 Vertebrates have well-developed central and peripheral nervous systems 526 26.2 Axons conduct nerve impulses 528 26.3 Propagation of a nerve impulse is speedy 529 26.4 Communication between neurons occurs at synapses 530 26.5 Neurotransmitters can be excitatory or inhibitory 530 The Central Nervous System (CNS) Consists of the Spinal Cord and the Brain 26.6 The spinal cord communicates with the brain 534 26.7 The cerebrum performs integrative activities 535 26.8 The other parts of the brain have specialized functions 536 26.9 The limbic system is involved in memory and learning as well as in emotions 538 The Vertebrate Peripheral Nervous System (PNS) Consists of Nerves 26.10 The peripheral nervous system contains cranial and spinal nerves 539 26.11 The somatic system can respond quickly to stimuli 540 26.12 The autonomic system controls the actions of internal organs 541 Drug Therapy and Drug Abuse Affect Neurotransmitter Concentrations 26.13 Certain neurotransmitters are known to affect behavior and emotional attributes 542 26.14 Certain drugs are more likely to be abused 543 APPLICATIONS HOW LIFE CHANGES Evolution of the Nervous System 532 HOW SCIENCE PROGRESSES If You Don’t Snooze, You’ll Lose! 537 26 Coordination by Neural Signaling
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Student Dolphin Rainbow trout Crab Grasshopper Do whales have a head? Marine verte- brates, whether a fi sh, a whale, or a duckbill platypus, tend to have a head region that is not distinct from the rest of the body. If you were asked to cut off the head of a fi sh, where would you cut—the choice is yours! The more streamlined their bodies, the better aquatic animals can move in the water. If we compare the crab to a grasshopper, we can see that the land animal has a more defi- nite head. The scavenger crab uses its claws to bring food that might float or swim away to its mouth, but the grasshop- per has no claws. The herbivorous grasshopper has a head that can bob up and down to reach its stationary food on land.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern