Understanding the Human Body: Major Systems

Overview

• The human body is a complex network of:
  • Cells
  • Tissues
  • Organs
• Ten major systems responsible for bodily functions:
  • Skeletal
  • Muscular
  • Cardiovascular
  • Nervous
  • Endocrine
  • Lymphatic
  • Respiratory
  • Digestive
  • Urinary
  • Reproductive

Major Systems and Their Functions

1. Skeletal System

• Composed of over 200 bones.
• Functions:
  • Holds the body together
  • Provides shape
  • Protects organs and tissues
  • Offers anchor points for the muscular system

2. Muscular System

• Has three types of muscles:
  • Skeletal
  • Smooth
  • Cardiac
• Facilitates body movement.

3. Cardiovascular System

• Also known as the circulatory system.
• Components:
  • Heart
  • Blood vessels
  • Blood
• Functions:
  • Delivers oxygen, white blood cells, hormones, and nutrients throughout the body.

4. Nervous System

• A communication network of nerve cells.
• Components:
  • Brain
  • Spinal cord
  • Cranial and spinal nerves
• Functions:
  • Transmits information
  • Coordinates bodily functions

Regulatory Systems

• Infrastructure created by neurons, blood, muscles, and bones allows for other systems to regulate the body's environment:

5. Endocrine System

• A series of glands regulated by the nervous system.
• Functions:
  • Produces hormones and chemicals (e.g., thyroid)
  • Distributes chemicals through the cardiovascular system.

6. Lymphatic System

• Also called the immune system.
• Components:
  • Lymph nodes
  • Lymph vessels
• Functions:
  • Regulates the body's defenses
  • Sends healing agents like white blood cells via bloodstream.

7. Urinary System

• Composed of:
  • Kidneys
  • Ureters
  • Bladder
  • Urethra
• Functions:
  • Maintains electrolyte levels
  • Filters waste from blood
  • Expels waste as urine.

Energy Systems

8. Respiratory System

• Components:
  • Passageways and organs that extract oxygen.
• Process:
  • Air enters through nasal cavities, travels down the throat to the lungs.
  • Lungs extract oxygen and expel carbon dioxide.

9. Digestive System

• Approx. 30-foot series of organs.
• Process:
  • Food enters through the mouth, moves through the esophagus, stomach, and intestines.
  • Nutrients are absorbed; solid waste is expelled through the anal canal.

10. Reproductive System

• Responsible for creating life.
• Components differ by sex:
  • Women: Ovaries, fallopian tubes, uterus, vagina
  • Men: Testes, sperm channel
• Function:
  • Fertilization leads to the formation of organ systems and childbirth.

Conclusion

• Humans are complex organisms.
• Healthy organ systems ensure overall well-being.