Bio-Chemistry Theory — the first-year Physiology chapter on the body’s chemistry

The Digestive chapter left your meal as small pieces in the blood. This chapter asks what the body does with them next. How does it turn sugar into energy? How does it store fat, and use it later? What happens to the parts of protein it does not need? Biochemistry is the chemistry of the living body. It answers questions like these.

The NCH syllabus gives “Bio-Chemistry Theory” chapter fourteen of Physiology and Biochemistry (HomUG-PB). It is the last chapter of the subject. The sheet lists seven lines. Most of them carry a list in brackets. This piece takes them in three groups.

Two words first

Two words appear again and again in this chapter.

Chemistry. Under each food type, the sheet asks for its “Chemistry”. This means what the substance is made of and how it is built.

Metabolism. This means all the chemical changes the body makes to a substance. Breaking it down for energy is part of metabolism. Building it up for storage is part of it too.

Group one: the three food types

Carbohydrates. The bracket reads: “Chemistry, Metabolism, Glycolysis, TCA, HMP, Glycogen synthesis and degradation, Blood glucose regulation”.

Glycolysis is the first stage in breaking down glucose, a simple sugar. The sheet prints two sets of letters without spelling them out. TCA stands for the tricarboxylic acid cycle, and HMP for the hexose monophosphate pathway. Your textbook may also give other names for them. Use the names your teachers use. Glycogen is the form in which the body stores glucose. “Synthesis” means building it. “Degradation” means breaking it down. Blood glucose regulation is how the body keeps the sugar level in the blood steady.

Lipids. The bracket reads: “Chemistry, Metabolism, Intestinal uptake, Fat transport, Utilization of stored fat, Activation of fatty acids, Beta oxidation and synthesis of fatty acids”.

Lipids are fats and oils. The list follows a fat through the body. It is taken up from the intestine. It is carried in the blood. It is stored, and later used. Fatty acids are the building blocks of many fats. Beta oxidation is a process that breaks them down for energy. The last item asks how they are built, too.

Proteins. The bracket reads: “Chemistry, Metabolism, Digestion of protein, Transamination, Deamination, Fate of Ammonia, Urea cycle, End products of each amino acid and their entry into TCA cycle”.

Proteins are built from amino acids. Transamination moves an amino group, a small nitrogen-containing part, from one molecule to another. Deamination removes it. That removal leaves ammonia, which is harmful if it builds up. “Fate of Ammonia” asks what happens to it. The urea cycle is how the body turns ammonia into urea, which the kidneys pass out. You met the kidneys in chapter thirteen.

Look at the last item. It sends the amino acids into the TCA cycle, the same cycle as in carbohydrates. That is the key idea of this group. The three food types are not three separate stories. Their paths meet.

Group two: the helpers

Enzymes. “Definition, Classification, Biological Importance, Diagnostic use, Inhibition”. An enzyme is a substance, usually a protein, that speeds up a chemical reaction in the body. Almost every step above needs one. “Diagnostic use” means enzymes can be measured to help find out what is wrong. “Inhibition” means ways an enzyme’s work can be slowed or stopped.

Vitamins. “Daily requirements, Dietary source, Disorders and physiological role”.

Minerals. “Daily requirement, Dietary Sources, Disorders and physiological role”, then “mineral metabolism”.

Vitamins and minerals share one pattern. For each one, learn how much the body needs each day, which foods give it, what it does, and what disorder follows when it is lacking or in excess. This is the nutrition that the Digestive chapter’s title promised. It arrives here. Your textbook will give the figures. This piece gives none, because the sheet gives none.

Group three: the tests

Organ function tests. A short line. These are tests that check how well an organ is working. Chapter thirteen had “Renal functions tests”. This line is wider. Your textbook will say which organs, and which tests.

A study method

For the three food types, draw one large chart. Put the TCA cycle in the middle. Then draw carbohydrates, lipids and proteins as three roads that lead into it. For vitamins and minerals, make a table with the same four columns for every item.

How the chapter sits in the year

This is the last chapter of the subject. It picks up where Digestive System and Nutrition ends. It uses the kidney from chapter thirteen and the hormones of chapter nine, which help control blood glucose. It pulls the whole year together at the level of molecules.

What to take from it

1. Know what “chemistry” and “metabolism” mean in this chapter.
2. Draw the three food types as roads into the TCA cycle.
3. Follow ammonia from deamination to the urea cycle.
4. Know what an enzyme is and why it matters.
5. Build one table for vitamins and one for minerals.

The sheet names the pathways. It does not give their steps, figures or daily amounts. Those 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. “Digestive System and Nutrition — the first-year Physiology chapter on what happens to a meal” comes just before it. “Physiology and Biochemistry in the First Year — how the body works” gives the map of the whole subject this chapter closes.