Module 1 The Nervous System

Reflect on the Big Picture

In this lesson you have examined how the sensations from your eyes and ears at that gathering described in the Big Picture are communicated to the cerebrum of the brain and the occipital and temporal lobes for interpretation. You have examined the medulla oblongata and its role in communicating automatic, involuntary responses such as the control of your breathing rate and heart rate. You have considered the role that the spinal cord plays in communication and the parts of the nervous system that protect these vital structures so that communication continues to establish homeostasis

Lesson Summary

In this lesson you have explored the following focusing questions:

• What are the main structures of the brain and spinal cord, what are their functions, and how are these functions co-ordinated?
• What happens when the information to or from the brain or spinal cord is disrupted or interrupted?

You have examined how all information about the external and internal environment is sent to the central nervous system, which consists of the brain and spinal cord. Various part of the brain, including the cerebral hemispheres, the four lobes of the cerebrum, the cerebellum, the medulla oblongata, the pons, and hypothalamus are responsible for receiving, sorting, interpreting, and co-ordinating information. The central nervous system (CNS) also initiates action in either the somatic or autonomic nervous systems.

The spinal cord functions to receive sensory information via the sensory neurons in the dorsal root and either relays the messages to the brain or initiates an action through a motor neuron in the ventral root. In Lesson 3 you will learn about these neurons and the reflex arc, a major function of the spinal cord.

In Lesson 7 you will learn how multiple sclerosis destroys the insulating layer around the long fibres of nerve cells so that nerve impulses cannot be transmitted quickly or cannot be transmitted at all in the central nervous system (CNS) and peripheral nervous system (PNS).  As a result, muscles cannot respond resulting in the tell-tale symptoms of this disorder.

Glossary

cerebellum: the brain region most involved in producing smooth, co-ordinated skeletal muscle activity; also involved in balance

cerebrum: the largest part of the brain which divides into the left and right hemispheres; contains centres for intellect, memory, consciousness, and language; it interprets and responds to sensory information and initiates the contraction of skeletal muscles

corpus callosum: the bundle of white matter that joins the two cerebral hemispheres; involved in sending messages from one hemisphere to the other effectively informing each half what the other half is doing

hypothalamus: a region of the brain located below the thalamus that acts as a centre of the autonomic nervous system responsible for the integration and correlation of many nervous and endocrine functions; helps to regulate the body’s internal environment, e.g., temperature; produces several hormones that are stored in the pituitary gland located directly below it

medulla oblongata: a part of the brain located between the pons and the spinal cord that controls involuntary responses such as heart rate, breathing rate, constriction and dilation of blood vessels, swallowing, and coughing

occipital lobes: one of the four lobes of the cerebrum, it receives and analyzes visual information that is sent to association centres for recognition of what is being seen

pons: a bridge-like structure that provides linkages with the neurons of the two halves of the cerebrum, the cerebellum, and the rest of the brain

somatosensory cortex: a part of the frontal lobes; receives sensory information from the limbs and body wall

spinal nerves: the 31 pairs of nerves that arise from the spinal cord; spinal nerves have both sensory and motor fibres

thalamus: a region of the brain located at the base of the cerebrum that regulates the flow of information from all the other parts of the nervous system and the sensory system