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Respiratory System Handout

Biology Lesson 7
functions for mechanical respiration
(external and internal respiration)
provides a conducting system for
exchange of gases, filters incoming
helps control water and temperature and
assists in speech production, sense of
smell and regulation of blood pH
divided into an upper and lower
respiratory tract
The Passageway of Air
Types of Respiration:
1. Cellular Respiration – oxidative process that occurs within cells
2. External Respiration – the exchange of gases between the organism and
The Human Respiratory System
Upper respiratory tract: nostrils – nasal cavity – sinuses – nasopharynx
Lower respiratory tract: larynx – trachea – lungs – alveoli
Muscles involved in breathing:
§ Diaphragm – main muscle that causes expansion of the thoracic cavity; separates
the thoracic cavity and abdominal cavity
§ Intercostal muscles – muscles between the ribs
Control of Breathing
Breathing is controlled by the respiratory center in the medulla of the brain stem; the
rate of breathing is influenced by the level of O2 but more importantly by high levels of
CO 2 or low blood pH.