Human Body Systems

Necessary Life Functions

Maintaining boundaries – Separating the inside of the body from the outside environment.

Movement – Movement of the body, organs, and substances within the body.

Responsiveness – Ability to sense and respond to changes in the environment.

Digestion – Breaking down food into usable nutrients.

Metabolism – All chemical reactions that occur in the body.

Reproduction – Producing new cells or a new organism.

Growth – Increasing the size or number of cells.

Organ Systems

Integumentary System

Function:

  • Protects the body from injury and harmful substances

  • Helps regulate body temperature

  • Provides sensation

  • Helps prevent water loss

Organs/Structures:

  • Skin

  • Hair

  • Nails

  • Sweat glands

  • Oil glands

Interconnections:

  • Works with the nervous system for sensation

  • Works with the circulatory system to regulate temperature

  • Works with the immune system to protect against pathogens

Skeletal System

Function:

  • Provides support and structure

  • Protects internal organs

  • Allows movement with muscles

  • Produces blood cells

  • Stores minerals

Organs/Structures:

  • Bones

  • Cartilage

  • Ligaments

  • Bone marrow

Interconnections:

  • Works with the muscular system to produce movement

  • Bone marrow works with the circulatory system by producing blood cells

  • Protects organs such as the brain, heart, and lungs

Muscular System

Function:

  • Produces movement

  • Maintains posture

  • Produces body heat

Organs/Structures:

  • Skeletal muscles

  • Smooth muscles

  • Cardiac muscle

Interconnections:

  • Works with the skeletal system to create movement

  • Works with the nervous system to control muscle contractions

  • Works with the circulatory system to receive oxygen and nutrients

Nervous System

Function:

  • Controls and coordinates the body

  • Receives and processes information

  • Allows the body to respond to stimuli

Organs/Structures:

  • Brain

  • Spinal cord

  • Nerves

  • Sensory organs

Interconnections:

  • Communicates with all body systems

  • Controls muscles and movement

  • Works with the endocrine system to regulate body functions

Endocrine System

Function:

  • Produces hormones

  • Regulates growth

  • Regulates metabolism

  • Controls reproduction

  • Helps maintain homeostasis

Organs/Structures:

  • Pituitary gland

  • Thyroid gland

  • Adrenal glands

  • Pancreas

  • Ovaries/testes

Interconnections:

  • Works with the nervous system to control body functions

  • Hormones travel through the blood to target organs

  • Helps regulate metabolism, growth, and reproduction

Cardiovascular System

Function:

  • Transports oxygen

  • Transports nutrients

  • Removes waste

  • Transports hormones

  • Helps regulate body temperature

Organs/Structures:

  • Heart

  • Blood

  • Blood vessels

  • Arteries

  • Veins

  • Capillaries

Interconnections:

  • Works with the respiratory system to transport oxygen and carbon dioxide

  • Works with the digestive system to transport nutrients

  • Works with the urinary system to transport wastes to the kidneys

  • Works with the endocrine system to transport hormones

Lymphatic/Immune System

Function:

  • Helps fight infections

  • Removes excess fluid from tissues

  • Absorbs fats from the digestive system

  • Protects the body from pathogens

Organs/Structures:

  • Lymph

  • Lymph vessels

  • Lymph nodes

  • Spleen

  • Thymus

  • Tonsils

Interconnections:

  • Works with the cardiovascular system to return excess fluid to the blood

  • Works with the digestive system to absorb fats

  • Works with the immune system to fight pathogens

Respiratory System

Function:

  • Brings oxygen into the body

  • Removes carbon dioxide

  • Allows gas exchange

Organs/Structures:

  • Nose

  • Pharynx

  • Larynx

  • Trachea

  • Bronchi

  • Lungs

  • Diaphragm

Interconnections:

  • Works with the cardiovascular system to transport oxygen and carbon dioxide

  • Provides oxygen needed by cells

  • Removes carbon dioxide produced by cells

Digestive System

Function:

  • Breaks down food

  • Absorbs nutrients

  • Removes solid waste

Organs/Structures:

  • Mouth

  • Esophagus

  • Stomach

  • Small intestine

  • Large intestine

  • Liver

  • Gallbladder

  • Pancreas

  • Rectum

  • Anus

Interconnections:

  • Works with the cardiovascular system to transport nutrients

  • Works with the lymphatic system to absorb fats

  • Provides nutrients and energy for cells

Urinary System

Function:

  • Removes waste from the blood

  • Produces urine

  • Helps regulate water and salt balance

  • Helps maintain blood pressure

Organs/Structures:

  • Kidneys

  • Ureters

  • Urinary bladder

  • Urethra

Interconnections:

  • Filters waste from blood

  • Works with the cardiovascular system by filtering the blood

  • Works with other systems to maintain water and electrolyte balance

Female Reproductive System

Function:

  • Produces eggs

  • Produces sex hormones

  • Supports fertilization

  • Supports pregnancy and reproduction

Organs/Structures:

  • Ovaries

  • Fallopian tubes

  • Uterus

  • Vagina

Interconnections:

  • Works with the endocrine system through reproductive hormones

  • Works with the cardiovascular system to support pregnancy

  • Works with the urinary system because reproductive and urinary structures are located in the same region

Male Reproductive System

Function:

  • Produces sperm

  • Produces sex hormones

  • Delivers sperm for reproduction

Organs/Structures:

  • Testes

  • Epididymis

  • Vas deferens

  • Seminal vesicles

  • Prostate gland

  • Penis

  • Urethra

Interconnections:

  • Works with the endocrine system through testosterone and other hormones

  • Works with the urinary system because the urethra is involved in both systems

  • Works with the cardiovascular system to transport hormones and nutrients to reproductive organs

Major System Connections to Remember

Respiratory + Cardiovascular = Oxygen is brought into the lungs and transported by the blood.

Digestive + Cardiovascular = Nutrients from food enter the blood and are transported around the body.

Urinary + Cardiovascular = Kidneys filter wastes from the blood.

Nervous + Muscular = Nerves control muscle movement.

Skeletal + Muscular = Bones and muscles work together to produce movement.

Nervous + Endocrine = Both control and coordinate body functions.

Endocrine + Reproductive = Hormones control reproduction and development.

Lymphatic/Immune + Cardiovascular = Lymph returns excess fluid to the bloodstream and helps protect the body.

Integumentary + Nervous = Skin contains sensory receptors that detect changes in the environment.

Digestive + Lymphatic = The lymphatic system helps absorb fats from the digestive tract.