Human Body Systems Overview

Human Body Systems Overview

• The human body is composed of interconnected systems, from cellular components to complex organ systems.
• Cells form tissues, tissues form organs, and organs work together to form organ systems.
• Major external body parts include the head, neck, shoulders, trunk (thorax, abdomen, pelvis, back), upper and lower limbs.
• Internal structures include arteries, veins, bones, joints, connective tissue, epithelial tissue, muscles, nerves, organs, and adipose tissue.
• The ten major human body systems include musculoskeletal, cardiovascular, respiratory, lymphatic, nervous, endocrine, integumentary, digestive, urinary, and reproductive.

Musculoskeletal System

• Provides support, strength, movement, and structure to the body.
• Composed of bones, joints, ligaments, tendons, cartilage, and muscles.
• Works closely with other systems, like the nervous system (for muscle movement) and digestive system (muscular tubes in digestive tract).

Cardiovascular System

• Responsible for circulating blood throughout the body, delivering oxygen and nutrients to cells.
• The heart is the central organ, pumping blood through arteries and veins.
• Dependent on other systems: respiratory (oxygenated blood), digestive (nutrients), endocrine (hormone transport), lymphatic (immune cell transport), urinary (waste removal).
• Essential for all body functions.

Respiratory System

• Facilitates gas exchange, taking in oxygen and expelling carbon dioxide.
• Includes lungs (alveoli), nose, pharynx, larynx, trachea, and bronchi.
• Located in the thorax, neck, and head.
• Works closely with the cardiovascular system.
• Alveoli in lungs facilitate oxygen uptake and carbon dioxide release into the air.

Lymphatic/Immune System

• Protects the body from infection and cleans up cellular debris.
• A network of vessels and lymph nodes (hubs of immune cells), bone marrow, spleen, and thymus.
• Includes the skin as a barrier.
• Critical for defending against pathogens and maintaining tissue integrity.

Nervous System

• Sensory and control system, enabling senses, movement, and responses to stimuli.
• Includes the brain (control center), spinal cord (information highway), and neurons (electrical signals).
• Neurons extend throughout the body, linking to the skin, muscles, and other organs.
• Central Nervous System (CNS) includes the brain and spinal cord.
• Peripheral Nervous System (PNS) includes neurons outside the CNS.
• Enables sensations and controls body functions.

Endocrine System

• Regulates growth, development, metabolism, reproduction, and other bodily functions via hormones.
• Works closely with the nervous system and reproductive system.
• Includes glands like thyroid, parathyroid, adrenal glands, pancreas, ovaries, testes, pituitary, pineal, and hypothalamus.
• Hormones are released, transported via blood, and affect all cells, tissues, and organs.
• Regulates various functions including blood sugar, metabolism, growth, stress response, and reproduction.

Integumentary System

• The skin (and associated hair and nails) forms an external protective barrier and is the largest organ.
• Protects underlying tissues and organs from environmental factors.
• Sensory organ for touch.
• Involved in temperature regulation (sweat and hairs).
• Excretes waste.

Digestive System

• Breaks down food into absorbable nutrients and processes waste.
• Involves the stomach, small intestines, large intestines, mouth, salivary glands, esophagus, pharynx, pancreas, liver, and gallbladder.
• Digestive enzymes break down food into simple components (sugars, fatty acids, and amino acids).
• Nutrients are absorbed and circulated via other systems (circulatory/lymphatic).

Urinary System

• Removes waste products, excess water, and minerals from the body.
• Includes kidneys, ureters, bladder, and urethra.
• Kidneys filter blood and send waste to the bladder.
• Bladder stores urine, and then excretes through urethra.
• Regulated by hormones, largely from the endocrine system.

Reproductive System

• Responsible for producing gametes (sex cells) for sexual reproduction.
• Structures vary based on sex (male and female).
• Essential for continuation of species.