Human Body Systems

The cardiovascular system, also known as the circulatory system, is a complex network that transports oxygen, nutrients, and hormones to cells all over the body while removing unused products like carbon dioxide. It plays a crucial role in maintaining homeostasis and complete health.

The cardiovascular system formed by blood vessels (arteries, veins and capillaries) and the heart, the cardiovascular system or circulatory system is responsible for blood drive in the human body

The respiratory system helps your body breathe by carrying in oxygen and removing carbon dioxide. Air enters through the nose or mouth, travels down the trachea, and into the lungs via the bronchi. In the lungs, tiny air sacs called alveoli exchange oxygen and carbon dioxide with the blood. Oxygen is brought to the body while carbon dioxide, a waste product, is carried back to the lungs and exhaled. The diaphragm, a muscle below the lungs, helps with the breathing process. This system works closely with the circulatory system to keep your body alive and functioning.

The respiratory system formed by the respiratory tract (nasal cavities, pharynx, larynx, trachea and bronchi) and the lungs, the respiratory system is responsible for absorbing oxygen from the air and rejecting carbon dioxide removed from the cells.

The digestive system breaks down food into nutrients your body can use for energy, development, and repair, and it get rid of waste. Food enters through the mouth, where it’s chewed and mixed with saliva. It then travels down the esophagus to the stomach, where it is further broken down by acids and enzymes. The partially digested food moves into the small intestine, where nutrients are absorbed into the blood. The remaining waste passes into the large intestine, where water is absorbed, and the solid waste is formed. Finally, waste leaves the body through the rectum and anus. Key organs include the mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, and gallbladder.

The digestive system formed by the digestive tract (mouth, pharynx, esophagus, stomach, small intestine, large intestine) and the attached organs (salivary glands, teeth, tongue, pancreas, liver and gallbladder), the digestive system is responsible for digesting food , transforming it into lesser molecules that will be absorbed by the body.

The nervous system controls and coordinates all the activities in your body by sending and receiving signals. It consists of the brain, spinal cord, and nerves. The brain processes information and makes decisions, the spinal cord acts as a highway for messages between the brain and body, and the nerves carry signals to and from muscles, organs, and sensory organs. The system is divided into two parts: the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which includes all other nerves. It allows you to think, move, feel, and respond to the world around you.

Composed of the central nervous system (brain and spinal cord) and peripheral nervous system (cranial and spinal nerves), the nervous system is responsible for capturing, interpretation and answering to received messages.

The sensory system allows your body to detect and respond to changes in the environment using specialized organs and receptors. It consists of five main senses: sight, hearing, smell, taste, and touch, each linked to specific organs: the eyes, ears, nose, tongue, and skin. These organs gather information like light, sound, smell, flavor, or texture, and send signals to the brain via nerves. The brain processes this information, helping you perceive and react to the world around you. Additionally, the sensory system includes balance, temperature, pain, and body position awareness.

Composed of the five senses of the human body (touch, taste, smell, sight, hearing), the sensory system is responsible for sending the info received to the nervous system, which decodes it and sends responses to the body.
The action of touching something is transmitted through the sensory neurons existing in the skin to the nervous system, which sends the response, that is, it will interpret whether the identified surface is smooth, rough, hot or cold.
In the same way, the taste buds send the flavor of the food to the brain, which will receive the identification of its taste (sour, sweet, bitter, salty).

The endocrine system is a network of glands that produce and release hormones, which act as chemical messengers to regulate various body functions such as growth, metabolism, reproduction, and mood. Key glands include the pituitary gland (the “master gland”), thyroid, adrenal glands, pancreas, and gonads (testes in males, ovaries in females). Hormones travel through the bloodstream to target organs, ensuring the body maintains balance (homeostasis). For example, insulin from the pancreas helps control blood sugar, while adrenaline from the adrenal glands prepares the body for “fight or flight” responses.

The endocrine system is made up of glands that perform vital activities, such as the thyroid, pituitary, and sexual glands, among others.
In this way, the glands are responsible for producing hormones that have certain functions, such as: regulating metabolism, defending the body, producing gametes, and developing the body, among others.

The excretory system removes waste and maintains the balance of water, salts, and other substances in the body. Its main organs include the kidneys, which filter blood to form urine, ureters that carry urine to the bladder for storage, and the urethra, which releases urine from the body. Other parts of the excretory system include the lungs (removing carbon dioxide), skin (sweating out salts and water), and the liver (detoxifying harmful substances). By eliminating waste and regulating fluid levels, the excretory system helps maintain homeostasis and overall health.

Composed of the kidneys and urinary tract, the excretory system is responsible for removing waste that the body rejects after going through the process of digesting food.
In other words, the excretory system eliminates substances that are in additional in the body, looking for a process called “dynamic balance” .

The urinary system, a key part of the excretory system, filters and removes waste from the blood while maintaining the body’s fluid and electrolyte balance. It consists of the kidneys, which filter blood to produce urine by removing excess water, salts, and waste products. The urine travels through the ureters to the bladder, where it is stored until it is expelled from the body through the urethra. This system helps regulate blood pressure, maintain pH balance, and ensure proper hydration levels.

Composed of the kidneys and urinary tract (ureters, urinary bladder and urethra), the urinary system is responsible for the making and elimination of urine, thus filtering “filths” from the blood.

The reproductive system enables the creation of offspring and plays a key role in sexual function. In males, it includes the testes (which produce sperm), penis, prostate gland, and other structures that help deliver sperm. In females, the system includes the ovaries (which produce eggs), fallopian tubes, uterus (where a fertilized egg develops), and vagina. The system also produces hormones like estrogen and testosterone, which influence sexual development and function. Reproduction occurs when sperm fertilizes an egg, leading to pregnancy and the development of a new individual.

The human reproductive system is separated into the male reproductive system and the female reproductive system , however, both have the same function, that is, the reproduction of new lives.
Thus, the male reproductive system is moulded by the testicles, epididymis, vas deferens, seminal vesicles, prostate, urethra and penis; while the female reproductive system is formed of the ovaries, uterus, fallopian tubes and vagina.

The skeletal system provides the body with structure, support, and protection for vital organs. It is made up of bones, cartilage, ligaments, and joints. The bones give the body its shape, protect organs like the brain and heart, and serve as levers for movement when muscles contract. Cartilage is a flexible tissue that cushions joints, while ligaments connect bones to one another and help stabilize joints. The system also plays a role in producing blood cells in the bone marrow and storing minerals like calcium. The human body typically has 206 bones that form the axial skeleton (skull, spine, ribs) and appendicular skeleton (limbs and pelvis).

The skeletal system forms and supports the entire human body. It also protects the internal organs and plays an vital role in movement, along with the muscular and articular systems.

The muscular system is responsible for movement, posture, and generating heat. It consists of three types of muscles: skeletal, smooth, and cardiac.

• Skeletal muscles are attached to bones and control voluntary movements like walking and lifting.
• Smooth muscles are found in the walls of internal organs like the stomach and blood vessels, controlling involuntary movements such as digestion and blood flow.
• Cardiac muscle is found only in the heart, where it contracts to pump blood throughout the body.

Muscles work by contracting and relaxing in response to signals from the nervous system, helping the body perform various functions and maintain posture. They also help regulate body temperature by producing heat during activity.

The immune system protects the body from harmful invaders like bacteria, viruses, and other pathogens. It consists of a network of cells, tissues, and organs that work together to identify and destroy foreign substances. Key components include:

• White blood cells (such as lymphocytes and macrophages) that detect and attack pathogens.
• Lymph nodes and spleen, which filter the blood and store white blood cells.
• Bone marrow, where blood cells, including white blood cells, are produced.
• Antibodies, which are proteins created by the immune system to target and neutralize pathogens.
• Thymus, where certain white blood cells (T-cells) mature.

The immune system also has specialized defenses like inflammation and fever to help fight infections. It plays a critical role in preventing illness and maintaining health.

The immune system is made up of a set of elements of the human body that work together to shield it from bacteria, viruses, microbes and diseases. It is a barrier against foreign bodies, the protection of the human body.

The lymphatic system is a crucial part of the immune system, responsible for defending the body against infections and maintaining fluid balance. It consists of a network of lymph nodes, lymph vessels, and lymph, a fluid that contains white blood cells (particularly lymphocytes) that help fight infections.

Key components of the lymphatic system include:

• Lymph nodes: Small, bean-shaped structures that filter lymph and trap pathogens, which are then attacked by white blood cells.
• Lymph vessels: Thin tubes that carry lymph throughout the body, similar to blood vessels.
• Tonsils and spleen: Organs that help filter harmful substances from the body and produce white blood cells.
• Thymus: An organ where certain white blood cells (T-cells) mature to fight infections.

The lymphatic system also helps maintain fluid balance by returning excess tissue fluid to the bloodstream. It plays a key role in immune defense and the absorption of fats from the digestive system.

The integumentary system – or skin – assistances regulate the temperature of the human body, and is responsible for sensitivity (along with the nervous system) but above all it protects the body, making a barrier to external aggressions and stopping the loss of fluid..

• Skin: The largest organ of the body, the skin acts as a protective barrier against pathogens, chemicals, and physical damage. It also prevents dehydration and helps regulate body temperature through sweating and blood flow.
• Hair: Protects the scalp from UV radiation and helps with sensory functions.
• Nails: Protect the tips of fingers and toes and assist with gripping.
• Glands: Sweat glands regulate body temperature, while sebaceous glands produce oils that keep the skin and hair moisturized.

The integumentary system is also involved in producing vitamin D when the skin is exposed to sunlight, and it helps detect sensations like touch, pain, and temperature through specialized receptors.