Central Nervous System — the first-year Physiology chapter on the brain and spinal cord at work

This is the chapter students open and then quietly close again. The sheet lists twenty-five topics. No other chapter of the subject lists more. But a long list is not the same as a hard idea. Most of these topics are parts of one story: how the body senses, decides and acts.

The NCH syllabus gives “Central Nervous System” chapter eight of Physiology and Biochemistry (HomUG-PB). The central nervous system is the brain and the spinal cord. This piece sorts the twenty-five topics into five groups, so you can see the shape before you start.

Group one: the building blocks

Introduction to nervous system · Neuron · Neuroglia · Receptors · Synapse · Neurotransmitters

A neuron is a nerve cell. Neuroglia are the support cells that sit around neurons and look after them. A receptor is a structure that picks up a stimulus, such as touch or heat. A synapse is the tiny gap where one neuron passes its signal to the next. Neurotransmitters are the chemicals that carry the signal across that gap.

You met the nerve fibre and the neuro-muscular junction in chapter five. The synapse is the same idea, nerve to nerve.

Group two: the simple circuits

Reflex · Spinal cord · Somato-sensory system and somato-motor system · Physiology of pain · Proprioceptors

A reflex is a quick, automatic response. Your hand pulls back from a hot tawa before you think about it. The spinal cord handles many reflexes on its own.

“Somato” means the body. The somato-sensory system carries feelings from the body in. The somato-motor system carries orders for movement out. Pain has its own topic, because it has its own pathways and its own physiology.

Proprioceptors are receptors that tell you where your body parts are, even with your eyes closed. That is how you can touch your nose in the dark.

Group three: the brain, part by part

Brain stem, Vestibular apparatus · Cerebral cortex · Thalamus · Hypothalamus · Internal capsule · Basal ganglia · Cerebellum – Posture and equilibrium

This group is the map. The sheet puts the brain stem and the vestibular apparatus on one line. The vestibular apparatus is the part of the inner ear that senses balance. The cerebellum line says “Posture and equilibrium”. Equilibrium means balance. So balance appears twice in this group. Link the two in your notes.

For each part, learn two things: where it is, and what it does. A single labelled brain drawing, added to as you go, will serve you better than seven separate pages.

Group four: the systems that run across the brain

Limbic system · Reticular formation · Hypothalamus · Autonomic Nervous System (ANS)

Some structures are not one lump in one place. They are networks. The limbic system is linked with emotion and memory. The reticular formation is a network in the brain stem linked with alertness. The autonomic nervous system, or ANS, runs the body’s automatic work, such as the heartbeat and digestion, without your conscious control.

The hypothalamus sits in both group three and group four. It is a part of the brain, and it also connects to the systems here and to the hormones of chapter nine.

Group five: the brain at work

Higher intellectual function · Electroencephalogram (EEG) · Physiology of sleep · Cerebro-spinal fluid (CSF)

Higher intellectual function means thinking, learning, memory and speech. An electroencephalogram, or EEG, records the brain’s electrical activity. You met the ECG, which records the heart. The EEG does the same job for the brain. Sleep is a real physiological state with its own stages, and the EEG is one way it is studied. Cerebro-spinal fluid, or CSF, is the clear fluid that surrounds the brain and spinal cord.

A bridge worth noticing

“Higher intellectual function” has a partner in another subject. The Psychology paper has a chapter called “Understanding Intellect: Attention, memory and its function and expression in Repertory and Materia Medica”. The limbic system has a partner too, in Psychology’s chapter on emotion. The same brain is being studied from two sides. Physiology asks how it works. Psychology asks what it means for the person.

How the chapter sits in the year

This is chapter eight. It needs chapter five, Nerve Muscle Physiology, which gave you the nerve fibre. It leads into chapter nine, Endocrinology, through the hypothalamus. And chapter eleven, Special Senses, builds on the receptors and pathways you meet here.

What to take from it

1. Know the building blocks: neuron, neuroglia, receptor, synapse, neurotransmitter.
2. Explain a reflex, and what the spinal cord does.
3. Place each brain part on one drawing, with its main job.
4. Know the networks: limbic system, reticular formation, ANS.
5. Know what EEG and CSF stand for, and what sleep physiology studies.

The sheet names twenty-five topics and gives no detail. It is long, but it is only names. The pathways and functions come from your textbook and your teachers.

Where to go next on the platform

This piece sits in the first-year Physiology and Biochemistry room. “Central Nervous System: Brain — the first-year Anatomy chapter that closes the subject” gives the structure behind this chapter. “Nerve Muscle Physiology — the first-year Physiology chapter on signals and movement” gives the nerve fibre it starts from. “Psychology in the First Year — the study of mind, for homoeopaths” shows the other side of the bridge.