Essential Nutrients and Human Digestive, Respiratory Systems

Posted on Dec 12, 2024 in Biology

Essential Nutrients and Human Body Function

Food products are natural or processed substances that provide what our cells need to live.

Inorganic Substances

Water: It is the most abundant compound in living organisms and the environment in which life develops from cells.
Mineral salts: These are found in bones and teeth. They are also all salts dissolved in body fluids.

Organic Substances

Carbohydrates: The simplest, such as glucose and maltose, can taste sweet and are known as sugars. Glucose is a sugar that cannot be decomposed into simpler ones. Maltose is formed by the joining of two molecules of glucose. Starch and cellulose are complex carbohydrates that do not taste sweet.
Lipids: These include fats and cholesterol. They are substances that dissolve little or not at all in water. Plant or unsaturated fats are liquid at room temperature and are called oils. Animal or saturated fats are known as tallow. A fat molecule can be decomposed into simpler substances: glycerol and fatty acids.
Proteins: Such as hemoglobin or gluten, these are macromolecules formed by the union of hundreds or thousands of simple molecules called amino acids, of which there are 20 different types.
Vitamins: These organic substances are needed in very small quantities but are essential for the proper functioning of the body.

Mechanical Digestion

This is the set of physical actions that reduce the size of food particles and cause them to move along the digestive tract. These actions include:

Grinding: What the teeth do in the mouth.
Swallowing: The passage of food from the mouth through the pharynx and esophagus. At the same time, the larynx closes to prevent food from passing into the airway.
Movements: Caused by the contraction of the muscles of the gut wall, these include:
- Mixing: This brings food particles into contact with digestive juices.
- Peristalsis: This moves the food along the digestive tract.

Chemical Digestion

This involves the transformation of macromolecules into smaller, soluble nutrient molecules. It takes place:

In the mouth: Where saliva, which contains an enzyme called amylase, begins the digestion of carbohydrates.
In the stomach: Where food is stored and mixed with gastric juice produced by glands in its wall. This juice contains hydrochloric acid and an enzyme called pepsin, which initiates protein digestion.
In the small intestine: Where the digestive process is completed. Juices from the pancreas and intestinal glands are discharged into the duodenum. These juices contain enzymes such as lipase.

Intestinal Absorption

This is the passage of nutrients from the gut to the blood, which occurs in the intestine.

The Function of Food

Structural Function: Used to build our own cells and tissues, and to grow or replace lost materials. This function is performed by protein-rich foods or minerals.
Energy Function: This releases energy so we can perform muscle work or maintain body temperature. Foods rich in carbohydrates or fats have an energy function.
Regulatory Function: This allows all the processes taking place in our body to develop normally. Foods that provide this function are minerals and vitamins.

Food Additives

These are substances added to food for preservation or to change their characteristics.

Genetically Engineered Foods

These are foods containing GMOs or products derived from them.

Digestive Enzymes

These are a class of proteins that accelerate the breakdown of complex substances in food into simpler components, or nutrients.

Caries

A tooth is a living organ. Caries is a disease caused by bacteria that live in the mouth and form plaque on the tooth surface. These microorganisms feed on leftover food and give rise to acids that attack and destroy the enamel. Thus, a hole gradually develops that can reach the pulp.

Constipation

This is a disorder that involves difficulty passing stool because of low mobility in the large intestine and excessive absorption of water in it. It is caused by a diet low in plant products.

Diarrhea

This occurs when there is excessive mobility in the large intestine, accompanied by loose and abundant stools. Diarrhea usually occurs as a result of infection or from eating spoiled food.

Other Disorders

Infections, lifestyle, and consumption of substances such as alcohol or tobacco cause damage to different digestive organs. Examples include gastritis (inflammation of the lining of the stomach), ulcers (sores in the lining of the stomach, esophagus, or duodenum), and liver cirrhosis.

The Respiratory System

This is the air gateway and is responsible for gas exchange between the body and the external environment. It extracts oxygen and expels carbon dioxide.

Parts

Nose and mouth: These are entry routes for air into the respiratory system. From there, air passes into the pharynx.
Trachea: This is a long, flexible tube that is kept open to airflow by cartilage rings in its walls.
Lungs: These are two organs located in the thoracic cavity and protected by the ribs. They are conical in shape, and their base rests on the diaphragm, a dome-shaped muscle that separates the chest cavity from the abdominal cavity.
Alveoli: These are small pockets with very thin walls at the end of the thinnest bronchioles.
Bronchi: These are similar to tracheal tubes that branch like a tree. Initially, there are two.
Bronchioles: These are subdivisions of the bronchi that become progressively thinner.
Larynx: This is shaped like a funnel, and its hard walls of cartilage can be felt in the anterior neck. Inside are the vocal cords.

Why Do Gases Pass Through?

Some oxygen-containing air passes through the walls of the alveoli and the very fine capillaries around them and into the blood. Carbon dioxide, on the other hand, crosses in the opposite direction: from the blood, it passes into the alveoli. However, the walls of the alveoli and capillaries are not actively involved in the passage of these gases. The gases pass through these walls by diffusion.

Upper Respiratory Tract Infections

These are the cause of minor illnesses such as the common cold, or severe ones such as influenza.

Lower Respiratory Tract Infections

If these occur in the ducts themselves, they cause bronchitis; if they occur in the lung tissue, they cause pneumonia.

Chronic Bronchitis

Irritants in tobacco smoke cause abundant secretion of mucus that clogs the airways.

Lung Cancer

Tobacco causes about 90% of all lung cancers and contributes to the development of other tumors.

Glands of the Digestive System

These are represented in two ways:

Distributed along the walls of the digestive tract, such as the gastric glands of the stomach wall and the intestinal glands of the intestinal wall.
Outside the digestive tract, these are called attached glands. They include the salivary glands, pancreas, and liver.

Salivary glands: This includes three pairs of glands whose ducts empty into the interior of the mouth. One pair is located under the tongue, another below the lower jaw, and the third in front of the ears.
Pancreas: This arrowhead-shaped gland is on the left side of the body. It produces pancreatic juice and pours it into the duodenum.
Liver: This is the largest gland in the body. It weighs about 1.5 kg and is located on the right side of the body next to the stomach. It produces bile, which is stored in the gallbladder and released into the duodenum when fatty foods are circulating.