Human Body Systems

Mechanical digestion

Physical breakdown of food, such as chewing and peristalsis.

Chemical digestion

Chemical breakdown of food using enzymes.

Peristalsis

Muscle contractions that move food through the esophagus.

Enzyme

Protein that speeds up chemical reactions in the body.

Esophagus

Tube that connects the throat to the stomach.

Stomach

Organ that mechanically and chemically breaks down food.

Respiratory system

System responsible for gas exchange (oxygen in, carbon dioxide out).

Nasal cavity

Entryway that filters, moistens, and warms air.

Pharynx

Throat; pathway for air and food.

Larynx

Voice box; creates sound.

Trachea

Windpipe; passageway for air to the lungs.

Bronchi

Two branches of the trachea leading to the lungs.

Lungs

Organs where gas exchange occurs.

Alveoli

Tiny sacs in the lungs where oxygen and carbon dioxide are exchanged.

Circulatory system

Transports blood, oxygen, nutrients, and waste throughout the body.

Heart

Muscular organ that pumps blood.

Arteries

Blood vessels that carry oxygen-rich blood away from the heart.

Veins

Blood vessels that carry oxygen-poor blood to the heart.

Capillaries

Tiny blood vessels where exchange with cells occurs.

Pulmonary circuit

Blood path between the heart and lungs.

Systemic circuit

Blood path between the heart and the body.

Skeletal system

Provides structure, protects organs, produces blood cells.

Bone marrow

Soft tissue inside bones that makes blood cells.

Joint

Where two bones meet.

Cartilage

Flexible tissue that cushions bones at joints.

Tendon

Connects muscle to bone.

Ligament

Connects bone to bone.

Muscular system

Enables body movement and functions like breathing and circulation.

Skeletal muscle

Voluntary muscles attached to bones.

Cardiac muscle

Involuntary muscle found in the heart.

Smooth muscle

Involuntary muscle found in internal organs.

Contract

Muscle action that shortens muscle to create movement.

Relax

Muscle action that returns muscle to its resting state.

Integumentary system

Protects body, regulates temperature, and senses environment.

Epidermis

Outermost skin layer; barrier.

Dermis

Middle skin layer with nerves, blood vessels, and glands.

Hypodermis

Deepest skin layer; stores fat.

Sweat gland

Produces sweat to cool the body and remove waste.

Vitamin D

Produced by the skin when exposed to sunlight.

Mechanical digestion

Physical breakdown of food, such as chewing and peristalsis.

Chemical digestion

Chemical breakdown of food using enzymes.

Peristalsis

Muscle contractions that move food through the esophagus.

Enzyme

Protein that speeds up chemical reactions in the body.

Small intestine

Organ where most digestion and nutrient absorption occurs.

Large intestine

Absorbs water and forms waste.

Liver

Produces bile to help digest fats.

Gallbladder

Stores bile produced by the liver.

Pancreas

Produces enzymes that help break down food in the small intestine.

Esophagus

Tube that connects the throat to the stomach.

Stomach

Organ that mechanically and chemically breaks down food.

Respiratory system

System responsible for gas exchange (oxygen in, carbon dioxide out).

Nasal cavity

Entryway that filters, moistens, and warms air.

Pharynx

Throat; pathway for air and food.

Larynx

Voice box; creates sound.

Trachea

Windpipe; passageway for air to the lungs.

Bronchi

Two branches of the trachea leading to the lungs.

Lungs

Organs where gas exchange occurs.

Alveoli

Tiny sacs in the lungs where oxygen and carbon dioxide are exchanged.

Circulatory system

Transports blood, oxygen, nutrients, and waste throughout the body.

Heart

Muscular organ that pumps blood.

Arteries

Blood vessels that carry oxygen-rich blood away from the heart.

Veins

Blood vessels that carry oxygen-poor blood to the heart.

Capillaries

Tiny blood vessels where exchange with cells occurs.

Pulmonary circuit

Blood path between the heart and lungs.

Systemic circuit

Blood path between the heart and the body.

Skeletal system

Provides structure, protects organs, produces blood cells.

Bone marrow

Soft tissue inside bones that makes blood cells.

Joint

Where two bones meet.

Cartilage

Flexible tissue that cushions bones at joints.

Tendon

Connects muscle to bone.

Ligament

Connects bone to bone.

Muscular system

Enables body movement and functions like breathing and circulation.

Skeletal muscle

Voluntary muscles attached to bones.

Cardiac muscle

Involuntary muscle found in the heart.

Smooth muscle

Involuntary muscle found in internal organs.

Contract

Muscle action that shortens muscle to create movement.

Relax

Muscle action that returns muscle to its resting state.

Integumentary system

Protects body, regulates temperature, and senses environment.

Epidermis

Outermost skin layer; barrier.

Dermis

Middle skin layer with nerves, blood vessels, and glands.

Hypodermis

Deepest skin layer; stores fat.

Sweat gland

Produces sweat to cool the body and remove waste.

Vitamin D

Produced by the skin when exposed to sunlight.

Digestive System

Breaks down food into nutrients the body can use, absorbs nutrients, and eliminates waste.

Respiratory System

Brings in oxygen, removes carbon dioxide, helps produce sound, and conditions air (moistens, warms, and cleans).

Circulatory System

Transports oxygen, nutrients, and waste; protects against infection; regulates temperature and fluid levels.

Skeletal System

Supports body, protects organs, produces blood cells, stores minerals, and allows movement.

Muscular System

Enables body movement, supports posture, helps circulate blood, and generates heat.

Integumentary System

Protects body, regulates temperature, senses environment, removes waste, retains moisture, and helps produce Vitamin D.