Cellular Biology: Functions, Nutrition, and Systems Explained

Cellular Biology: Functions, Nutrition, and Systems

All living things are composed of cells. In multicellular organisms, cells consist of a plasma membrane, nucleus, cytoplasm, and organelles. Cells perform vital functions necessary for life: nutrition, relationships, and reproduction. In multicellular beings, cells are grouped into tissues, tissues into organs, organs into systems, and finally, all these form a complete living being.

Internal Environment and Homeostasis

The internal environment is regulated by homeostatic mechanisms, which are controlled by the brain. Nutrients from the digestive tract are broken down into simpler substances that are absorbed into the animal's internal environment. Aquatic animals obtain oxygen dissolved in water, while terrestrial animals obtain oxygen from the air. The urinary system filters blood to remove toxic products from the internal environment.

Circulatory System

The circulatory system transports substances between cells and the digestive, excretory, and respiratory systems. It consists of a circulating fluid, vessels, and a pumping system that ensures constant movement of the fluid.

Interaction and Reproduction

Living beings interact with each other and their environment. This involves collecting stimuli, a system that coordinates and regulates bodily activities, and organs that carry out responses. Sexual reproduction involves the union of two special cells, gametes, during fertilization, which can be external or internal depending on the organism's environment.

Development and Classification

After fertilization, an egg is formed and develops into a complete individual. During development, the egg is surrounded by protective structures. Animals are classified as oviparous, viviparous, or ovoviviparous based on how the egg develops and is nourished.

Nutrition Processes

Nutrition is the set of processes that allow living things to obtain matter and energy and eliminate waste products. This function involves the digestive, respiratory, circulatory, and excretory systems.

Digestive System

In the digestive tract, consisting of the gastrointestinal tract and glands, food digestion and nutrient absorption occur.

Respiratory System

The respiratory system obtains oxygen and eliminates carbon dioxide. This gas exchange occurs in the lungs, where air arrives after passing through the airways. Respiratory health depends on the quality of the air we breathe. Inspiration involves filling the lungs with air, and expiration involves expelling air.

Circulatory System Details

The heart is a muscular organ divided into four chambers that pumps blood. Blood leaves the heart through arteries and enters capillaries, then returns through veins, ensuring that blood reaches every cell. Blood consists of plasma, which transports nutrients, waste products, and hormones, and blood cells (white blood cells and platelets).

Excretory System Details

The kidneys filter blood to remove waste products, which are then eliminated as urine. Urine flows through the ureters, is stored in the bladder, and exits through the urethra.

Nutrients and Diet

Food provides different types of nutrients (sugars, fats, proteins, vitamins, minerals, and water) that have energy, structural, or regulatory functions. Nutrient requirements depend on age and activity level. A balanced diet and physical exercise are essential for health. Food hygiene, from production to consumption, is crucial.

Health Considerations

Obesity leads to serious health problems and can be prevented with a balanced diet and physical exercise.