Human Respiratory System Overview

Human Respiratory System

• Comprises key structures: Nasal Cavity, Oral Cavity, Pharynx, Larynx, Trachea, Bronchus, Alveoli, Bronchioles, Diaphragm, Lungs, and Heart.

Gaseous Exchange

• Occurs in alveoli, where oxygen enters the blood and carbon dioxide exits.
• Oxygen binds to hemoglobin in the bloodstream, allowing transportation throughout the body.
• Carbon dioxide diffuses from the blood into the alveoli for exhalation.

Cellular Respiration

• Blood, pumped from the heart, travels through arteries to smaller vessels, ultimately reaching capillaries.
• Oxygenated blood supplies glucose to cells, aiding in energy production.
• Carbon dioxide produced during cellular respiration is absorbed by capillaries and returned to the heart.

Respiration in Other Animals

• Amphibians like frogs respire through skin in water and through lungs on land.
• Earthworms and leeches exchange gases via their moist skin surface.
• Unicellular organisms such as amoebas respire across their cell membrane.

Respiration Through Air

• Cockroaches use spiracles connected to tracheae for respiratory gas exchange.
• Animals like horses, birds, and monkeys breathe through lungs, utilizing nasal passages for gas exchange.

Respiration Through Gills

• Fish utilize gills, which expand surface area for gas exchange through filaments and capillaries.
• Water enters the fish’s mouth, flows over gills, where oxygen is absorbed, and carbon dioxide is released.

Respiration in Plants

• Plants take in oxygen and release carbon dioxide via stomata regulated by guard cells.
• Stomata open and close to manage gaseous exchange, influenced by environmental conditions.

Mechanism of Breathing

• Involves alternating inhalation (intake of oxygen) and exhalation (release of carbon dioxide).
• Breathing rate varies with activity; it increases during exercise to meet oxygen demands.
• Rib movements and diaphragm adjustments change chest cavity volume, facilitating airflow into and out of the lungs.

Path of Oxygen During Respiration

• Oxygen travels sequentially through: Nostrils → Nasal Cavity → Pharynx → Trachea → Bronchi → Bronchioles → Alveoli → Blood → Cells.

Key Terms

• Respiration: The biochemical process of exchanging gases, critical for cellular functions and energy production.