How Digestive, Respiratory, and Circulatory Systems Work
Digestive System
Overview
The digestive system processes food, converting it into simpler substances that the body can absorb. These nutrients then pass into the bloodstream to nourish the body’s cells.
Digestive Tract
The digestive tract is a 10-meter long duct consisting of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.
Digestive Glands
Digestive glands secrete substances necessary for breaking down food. These glands include the salivary glands, liver, and pancreas.
Digestive Functions
Intake
Intake involves the entry of food into the digestive tract through the mouth. During ingestion, food is mixed with saliva and crushed by the teeth.
Digestion
Digestion transforms food into simpler substances called nutrients. There are two types of digestion:
- Mechanical Digestion: This involves physically breaking down food by chewing, grinding, and mixing. It occurs primarily in the mouth and stomach.
- Chemical Digestion: This involves transforming food into simpler compounds through chemical reactions facilitated by enzymes and other substances.
Respiratory System
Overview
The respiratory system is responsible for taking in oxygen from the air and removing carbon dioxide from the blood. It consists of the lungs and airways.
Respiratory Tract
The respiratory tract includes the nostrils, pharynx, larynx, trachea, bronchi, and lungs. Air travels through these passages to reach the alveoli in the lungs.
Gas Exchange
Gas exchange occurs in the alveoli, where oxygen from the inhaled air diffuses into the blood and carbon dioxide from the blood diffuses into the air to be exhaled.
Breathing Process
Inspiration
During inspiration, the diaphragm contracts and lowers, while the intercostal muscles contract, lifting the ribs. This increases the volume of the thoracic cavity, causing the lungs to expand and draw in oxygen-rich air.
Expiration
During expiration, the diaphragm relaxes and rises, and the intercostal muscles relax, lowering the ribs. This decreases the volume of the thoracic cavity, causing the lungs to deflate and expel carbon dioxide-rich air.
Respiratory Illnesses
Bronchitis
Bronchitis is a bacterial infection of the bronchi that causes difficulty breathing.
Asthma
Asthma is characterized by temporary narrowing of the airways, hindering breathing and potentially leading to oxygen deficiency.
Tuberculosis
Tuberculosis is a contagious bacterial infection that destroys lung tissue and spreads through the air.
Colds and Flu
Colds and flu are contagious viral infections of the respiratory system, with no curative treatment.
Circulatory System
The circulatory system transports oxygen and nutrients to the body’s cells via the blood. It also collects and transports carbon dioxide and waste products away from the cells.
Excretory System
The excretory system is responsible for eliminating waste substances carried by the blood.