Organ Systems

Pancreas:

produces enzymes critical to function of the digestive system and regulates blood sugar levels by secreting insulin and glucagon as a vital part of the endocrine system.

Digestive

Main components: Mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus.

Main Functions: The main functions of the digestive organ system are to break down food, absorb nutrients, and eliminate waste. It starts with ingestion in the mouth, followed by mechanical and chemical digestion in the stomach and small intestine. Nutrients are primarily absorbed in the small intestine, while the large intestine reabsorbs water and compacts waste into feces for elimination. Accessory organs like the liver, pancreas, and gallbladder aid digestion by producing enzymes, bile, and other secretions.

Circulatory

Main Components: Heart, blood vessels, blood

Main Functions: The circulatory system transports oxygen, nutrients, hormones, and waste products throughout the body. It includes the heart, blood, and a network of vessels—arteries, veins, and capillaries. The heart pumps oxygen-rich blood to tissues and returns carbon dioxide-rich blood to the lungs. It also helps regulate temperature, distribute immune cells, and maintain homeostasis through blood pressure regulation.

Respiratory

Main Components: Lungs, trachea, other breathing tubes

Main Function: The respiratory system is responsible for gas exchange, bringing oxygen into the body and expelling carbon dioxide. It includes the nasal passages, trachea, bronchi, lungs, and alveoli. Oxygen diffuses into the bloodstream through alveoli in the lungs, while carbon dioxide diffuses out to be exhaled. This system also helps regulate blood pH and contributes to voice production.

Immune and Lymphatic

Main Components: Bone marrow, lymph nodes, thymus, spleen, lymph vessels.

Main functions: The immune system defends the body against pathogens like bacteria, viruses, and parasites. It includes white blood cells, the lymphatic system, spleen, thymus, and lymph nodes. The lymphatic system helps return fluid to the bloodstream and filters it for pathogens. The immune system also plays a role in removing dead or damaged cells and initiating inflammation and other protective responses.

Excretory

Main Components: Kidneys, ureters, bladder, urethra.

Main Functions: The excretory system removes metabolic waste from the body and maintains water, salt, and pH balance. It includes the kidneys, ureters, bladder, and urethra. The kidneys filter blood to produce urine, which carries out nitrogenous wastes like urea. This system also plays a critical role in regulating blood pressure and overall fluid balance in the body.

Endocrine

Main Components: Pituitary, thyroid, pancreas, adrenal, and other hormone-secreting glands.

Main Functions: The endocrine system is made up of glands that secrete hormones into the bloodstream to regulate body functions such as metabolism, growth, reproduction, and stress response. Major glands include the pituitary, thyroid, adrenal glands, pancreas, and gonads. These hormones act on target cells and organs to maintain homeostasis and are often regulated by feedback loops involving the hypothalamus and pituitary gland.

Reproductive

Main Components: Ovaries or testes and associated organs.

Main Functions: The reproductive system enables humans to produce offspring. In males, it includes the testes and associated structures that produce and deliver sperm. In females, it includes the ovaries, uterus, and related structures that produce eggs, support fertilization, and nurture a developing fetus during pregnancy. This system also produces sex hormones that influence secondary sexual characteristics and reproductive cycles.

Nervous

Main Components: Brain, spinal chord, nerves, sensory organs

Main Functions: The nervous system coordinates all bodily activities by transmitting signals between different parts of the body. It consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves). It processes sensory information, controls motor responses, and regulates involuntary functions like heart rate and digestion. It also enables higher functions such as learning, memory, and emotions.

Integumentary

Main Components: Skin and its derivatives, such as hair, claws, sweat glands.

Main Functions: The integumentary system includes the skin, hair, nails, and associated glands. It acts as the first line of defense against physical injury, infection, and dehydration. The skin helps regulate body temperature through sweating and blood vessel dilation or constriction. It also plays a role in sensory perception and synthesizes vitamin D when exposed to sunlight.

Skeletal

Main Components: Skeleton (bones, tendons, ligaments, cartilage)

Main Functions: The skeletal system provides the rigid framework that supports the body and protects vital organs such as the brain, heart, and lungs. It includes bones, cartilage, ligaments, and joints. Besides enabling movement in coordination with muscles, it also stores minerals like calcium and phosphorus and houses bone marrow, which produces blood cells through hematopoiesis.

Muscular

Main Components: Skeletal muscles

Main Functions: The muscular system is responsible for producing movement in the body, both voluntary and involuntary. It consists of skeletal muscles, which attach to bones and enable movement; smooth muscles, which control involuntary functions like digestion and blood vessel constriction; and cardiac muscle, which keeps the heart beating. Muscles also help maintain posture, stabilize joints, and generate heat to maintain body temperature.