Human Anatomy: Organ Systems

Nervous System: controls body functions, interprets and responds to stimuli
- Central Nervous System (CNS): brain, spinal cord
- Peripheral Nervous System (PNS): nerves, ganglia
Circulatory System: transports oxygen, nutrients, and waste
- Heart: pumps blood
- Arteries: carry oxygenated blood away from heart
- Veins: carry deoxygenated blood back to heart
Respiratory System: brings oxygen into body, removes carbon dioxide
- Lungs: exchange oxygen and carbon dioxide
- Trachea: airway connecting lungs to throat
Digestive System: breaks down food into nutrients
- Mouth: mechanical and chemical digestion
- Esophagus: food transport to stomach
- Stomach: chemical digestion
- Small intestine: nutrient absorption
- Large intestine: water absorption, waste storage
Endocrine System: produces hormones regulating body functions
- Pituitary gland: regulates hormone production
- Thyroid gland: regulates metabolism
- Adrenal glands: regulates stress response
Immune System: defends against pathogens and diseases
- White blood cells: fight infections
- Lymph nodes: filter out pathogens
- Spleen: filters blood, stores immune cells

Cells: basic structural and functional units
- Cell membrane: regulates what enters and leaves cell
- Cytoplasm: site of cellular activities
- Nucleus: contains genetic material
Tissues: groups of similar cells performing specific functions
- Epithelial tissue: forms linings and glands
- Connective tissue: supports and connects body parts
- Muscle tissue: contracts and moves body
- Nervous tissue: transmits and processes information
Organs: structures composed of two or more tissue types
- Heart: pumps blood
- Lungs: exchange oxygen and carbon dioxide
- Liver: detoxifies, regulates metabolism
- Kidneys: filter waste, regulate electrolytes

Nervous System
- Controls body functions and interprets/responds to stimuli
- Divided into Central Nervous System (brain, spinal cord) and Peripheral Nervous System (nerves, ganglia)
Circulatory System
- Responsible for transporting oxygen, nutrients, and waste
- Heart pumps blood, arteries carry oxygenated blood away from heart, and veins carry deoxygenated blood back to heart
Respiratory System
- Brings oxygen into body and removes carbon dioxide
- Lungs exchange oxygen and carbon dioxide, trachea connects lungs to throat
Digestive System
- Breaks down food into nutrients
- Involves mechanical and chemical digestion in mouth, esophagus transports food to stomach, stomach performs chemical digestion, small intestine absorbs nutrients, and large intestine absorbs water and stores waste
Endocrine System
- Produces hormones regulating body functions
- Pituitary gland regulates hormone production, thyroid gland regulates metabolism, and adrenal glands regulate stress response
Immune System
- Defends against pathogens and diseases
- White blood cells fight infections, lymph nodes filter out pathogens, and spleen filters blood and stores immune cells

Cells
- Basic structural and functional units of body
- Cell membrane regulates what enters and leaves cell, cytoplasm site of cellular activities, and nucleus contains genetic material
Tissues
- Groups of similar cells performing specific functions
- Epithelial tissue forms linings and glands, connective tissue supports and connects body parts, muscle tissue contracts and moves body, and nervous tissue transmits and processes information
Organs
- Structures composed of two or more tissue types
- Examples: heart pumps blood, lungs exchange oxygen and carbon dioxide, liver detoxifies and regulates metabolism, and kidneys filter waste and regulate electrolytes