Human Body Systems and Functions

Healthy Human Function

• Human function depends on interacting and reacting systems
• Organ systems work together as a single unit to support survival
• Each organ system reacts to internal and external changes to maintain life

Key Concepts

• Cells
• Organs
• Tissues
• Structure and function
• Responses to stimuli
• Systems

Learning Outcomes

• Describe how various body systems work
• Recognize organ and tissue roles in body systems
• Describe how cells help the body function
• Demonstrate how the body responds to changing conditions

Digestive System

• Living organisms need energy from carbohydrates, lipids, and proteins
• The digestive system breaks down food into usable parts
• Mechanical digestion breaks food into smaller pieces, while chemical digestion uses enzymes to further break down large particles.

Digestive System Activity

• Chew crackers and hold in mouth for 5 minutes without swallowing
• Describe taste changes over time
• Compare experiences with classmates
• Identify causes for taste changes

Food's Path Through the Digestive System

• Digestion begins in the mouth with mechanical breakdown by teeth and saliva, which contains salivary amylase to break down starches into smaller sugars

• Saliva moistens food for easier swallowing

• Epiglottis prevents food from entering the windpipe during swallowing

• Peristalsis moves food through the esophagus

• Stomach churns food with gastric juice (mucus, hydrochloric acid, water, and enzymes) which breaks down proteins.

• The stomach slowly releases food into the small intestine

Small Intestine, Pancreas, Liver, and Gall Bladder

• Mechanical and chemical digestion continues in the small intestine
• Pancreas and liver contribute enzymes and bile for further digestion
• Villi and microvilli in the small intestine increase absorption surface area
• Nutrients are absorbed through blood vessel by the villi.
• Large intestine absorbs water and forms feces.

Respiratory System

• The respiratory system supplies the blood with oxygen and removes carbon dioxide
• Breathing involves inhaling and exhaling to move air in and out of the lungs
• The process exchanges oxygen and carbon dioxide in the alveoli

Circulatory System

• The circulatory system delivers nutrients, oxygen, and removes waste
• The heart acts as a pump to circulate blood in two loops: to the lungs and throughout the body.
• Blood vessels (arteries, veins, capillaries) are part of the circulatory system
• Blood contains red blood cells, white blood cells, platelets, and plasma

Heart

• The heart has four chambers (two atria and two ventricles)
• Blood flows through the heart in a specific pattern (oxygen-rich to body; oxygen-poor to lungs)

Arteries, Veins, and Capillaries

• Arteries carry blood away from the heart, veins return blood to the heart
• Capillaries are thin-walled vessels found between arteries and veins. This allows for efficient gas exchange between blood and tissues.

Excretory System

• The excretory system removes waste products from the body
• Waste products include carbon dioxide, urea, water and salts
• The liver converts ammonia (toxic) into urea(less harmful)

The Kidney

• Kidneys are the main organs of excretion.
• They filter blood and produce urine.
• Urine is expelled from the body through the ureters and urethra.
• Urea is produced from waste products.

The Skin

• Skin excretes sweat containing salt.

The Formation of Urine

• The kidneys filter waste products from the blood to form urine
• Blood enters the kidney through the renal artery
• Waste products are removed from the blood and sent to the bladder through the ureters

Testing Artificial Urine

• Urine can reveal diseases
• Testing urine can determine the presence of certain diseases e.g., diabetes or kidney failure
• Lab tests for glucose and protein in urine can be done to detect diseases