Figure 15.1 Fight or Flight? Though the threats that modern humans face are not large predators, the autonomic nervous system is adapted to this type of stimulus. The modern world presents stimuli that trigger the same response. (credit: Vernon Swanepoel) CHAPTER OBJECTIVES After…
Sensory Perception The senses are olfaction (smell), gustation (taste), somatosensation (sensations associated with the skin and body), audition (hearing), equilibrium (balance), and vision. With the exception of somatosensation, this list represents the special senses, or those systems of the body…
Learning Objectives By the end of this section, you will be able to: The defining characteristic of the somatic nervous system is that it controls skeletal muscles. Somatic senses inform the nervous system about the external environment, but the response…
Learning Objectives By the end of this section, you will be able to: Sensory Pathways Specific regions of the CNS coordinate different somatic processes using sensory inputs and motor outputs of peripheral nerves. A simple case is a reflex caused…
Learning Objectives By the end of this section, you will be able to: A major role of sensory receptors is to help us learn about the environment around us, or about the state of our internal environment. Stimuli from varying…
Figure 14.1 Too Hot to Touch When high temperature is sensed in the skin, a reflexive withdrawal is initiated by the muscles of the arm. Sensory neurons are activated by a stimulus, which is sent to the central nervous system, and a motor…
The Embryologic Perspective The development of the nervous system starts early in embryonic development. The outer layer of the embryo, the ectoderm, gives rise to the skin and the nervous system. A specialized region of this layer, the neuroectoderm, becomes…
Learning Objectives By the end of this section, you will be able to: The PNS is not as contained as the CNS because it is defined as everything that is not the CNS. Some peripheral structures are incorporated into the…
Learning Objectives By the end of this section, you will be able to: The CNS is crucial to the operation of the body, and any compromise in the brain and spinal cord can lead to severe difficulties. The CNS has…
Learning Objectives By the end of this section, you will be able to: The brain and the spinal cord are the central nervous system, and they represent the main organs of the nervous system. The spinal cord is a single…