Human Body Systems: Digestive, Respiratory & Circulatory
Digestive System
Overview
The digestive system processes food, extracting nutrients and eliminating waste. It comprises two main components:
- Digestive Tract: Mouth, pharynx, esophagus, stomach, small intestine, large intestine
- Digestive Glands: Salivary glands, liver, pancreas
Digestive Organs and Functions
Mouth
Food enters the digestive system through the mouth, where it is chewed and mixed with saliva.
Pharynx
The pharynx connects the mouth to the esophagus and directs food towards the stomach. The epiglottis prevents food from entering the trachea.
Esophagus
The esophagus is a muscular tube that transports food from the pharynx to the stomach.
Stomach
The stomach is a muscular organ that mixes food with gastric juices, initiating digestion.
Small Intestine
The small intestine is where most nutrient absorption occurs. It is divided into three parts: duodenum, jejunum, and ileum.
Large Intestine
The large intestine absorbs water and minerals, forming feces for elimination. It consists of the cecum, colon, and rectum.
Digestive Processes
- Ingestion: Intake of food
- Digestion: Breakdown of food into nutrients
- Absorption: Uptake of nutrients into the body
- Egestion: Elimination of waste
Respiratory System
Overview
The respiratory system facilitates gas exchange, taking in oxygen and expelling carbon dioxide.
Respiratory Organs and Functions
Nose
Air enters the respiratory system through the nostrils, where it is warmed and humidified.
Pharynx
The pharynx serves as a passage for both air and food.
Larynx
The larynx contains the vocal cords, which produce sound.
Trachea
The trachea is a tube that carries air from the larynx to the bronchi.
Bronchi
The bronchi branch into smaller bronchioles within the lungs.
Lungs
The lungs are the primary organs of gas exchange, containing millions of tiny air sacs called alveoli.
Gas Exchange
Gas exchange occurs in the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses out.
Circulatory System
Overview
The circulatory system transports nutrients, oxygen, and waste products throughout the body.
Blood Vessels
- Arteries: Carry oxygenated blood away from the heart
- Veins: Carry deoxygenated blood back to the heart
- Capillaries: Connect arteries and veins, allowing for exchange of substances with tissues
Blood Circulation
The circulatory system ensures the delivery of essential substances and removal of waste products, maintaining overall body function.