Key Area 1
(a) Structure of the central nervous system (CNS) and the peripheral nervous system (PNS)
The first part of this key area allows us to re-familiarise ourselves with the nervous system, incorporating some new levels of understanding. We begin to link the structure of the nervous system with the functional life-support it provides, from voluntary, skeletal movements to those involuntary, basic human actions.
Something to Read...
Open the document below and read the mandatory course notes provided by SQA for this Key Area. You may wish to use your home learning time to copy these notes into a jotter or choose a digital presentation format that suits your learning style.
Something to Watch...
Something to look at...
The following diagrams will help put the SQA mandatory course notes into context.
This diagram shows the division of the Nervous System. Structurally, it can be divided into the central nervous system (comprising the brain and spinal cord) and the peripheral nervous system (comprising the nerves).
The diagram below shows how the peripheral nervous system can be further sub-divided into the "somatic" and "autonomic" nervous system.
Somatic Nervous System
The SNS contains sensory and motor neurons and controls the voluntary movement of skeletal muscles. Sensory neurons take impulses from sense organs to the CNS. Motor neurons take impulses from the CNS to muscles and glands.
Autonomic Nervous System
The ANS consists of the sympathetic and parasympathetic systems.The branches of the ANS are described as "antagonistic" in action because nerve action results in opposing effects. These nerves control actions through sensory and motor neurons, conducting impulses to smooth muscle, cardiac muscle and glands. They have opposing effects on:
- Heart rate
- Breathing rate
- Peristalsis
- Intestinal secretions.
The diagram to the right summarises the antagonistic effect of the sympathetic and parasympathetic nervous system on the organ systems of the body.
The sympathetic system speeds up heart rate and breathing rate, while slowing down peristalsis and production of intestinal sections.
The parasympathetic system changes these physiological effects in the opposite way.
Peristalsis describes the contractions of smooth muscle along the length of the digestive tract to move food along.
The adrenal glands, situated above the kidneys, are endocrine glands that secrete a variety of hormones, including adrenaline.
To increase depth of breathing, the bronchioles must widen. This requires the smooth muscle to relax.
You are now ready for your in-class lesson on the division of the nervous system.
You are now ready to move onto Key Area 1b: the structure and function of converging, diverging adn reverberating neural pathways.
