Lab 8: Nervous system I – Nervous Tissue, Brain, Spinal Cord, and Cranial Nerves
Lab 8: Nervous system I – Nervous Tissue, Brain, Spinal Cord, and Cranial Nerves
Nervous tissue, structures of the central and peripheral nervous systems
Learning Objectives
When you are prepared for the Test on Week 8 Learning Objectives in Week 9, you will be able to:
- Identify structures of the neuron and describe their functions.
- Identify regions of the brain and describe their functions.
- Identify cerebral lobes and functional areas of the brain.
- Identify meninges of the central nervous system and their functions.
- Describe where cerebrospinal fluid is created, circulates, and is recycled.
- Identify cranial nerves, describing their basic function and whether each is sensory, motor, or both.
- Identify structures of the spinal cord region and their functions.
The nervous system is a complex organ system that sends signals throughout the body to control both voluntary and involuntary functions. The nervous system can detect many different forms of stimuli, integrate those stimuli, and respond to them by sending signals out to the muscle cells or glands. This week we will look at the cells and tissue of the nervous system capable of sending signals and the organs where those signals can be processed and integrated. Next week we will look at the structures capable of detecting stimuli, when we look at the special senses.
Divisions of the Nervous System
The nervous system can be divided into two major regions: the central and peripheral nervous systems. The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else (Figures 8.1 and 8.2). The brain is contained within the cranial cavity of the skull, and the spinal cord is contained within the vertebral cavity of the vertebral column. It is a bit of an oversimplification to say that the CNS is what is inside these two cavities and the peripheral nervous system is outside of them, but that is one way to start to think about it. In actuality, there are some elements of the peripheral nervous system that are within the cranial or vertebral cavities. The peripheral nervous system is so named because it is on the periphery—meaning beyond the brain and spinal cord. Depending on different aspects of the nervous system, the dividing line between central and peripheral is not necessarily universal.
The nervous system can also be organized into functional divisions, based on sensing, integrating, and responding to stimuli (Figure 8.3). The response division is sometimes called the motor division, because it often involves signaling muscle tissue.
Divisions of the nervous system can also be functionally classified as somatic and autonomic. The somatic nervous system (SNS) is responsible for conscious perception and voluntary motor responses. Voluntary motor response means the contraction of skeletal muscle, but those contractions are not always voluntary in the sense that you have to want to perform them. Some somatic motor responses are refl