Respiratory System

1
Respiratory System

• Chapter 23

2
Functions of the Respiratory System

• Supply oxygen and dispose of carbon dioxide
• Enable speech production
• To accomplish this, 4 independent processes,
  collectively called respiration must occur
• Pulmonary ventilation
• External respiration
• Transport of respiratory gases
• Internal respiration (gas exchange between blood
  tissue cells)
• Only the first two processes are the direct
  responsibility of the respiratory system.
  However, the other two must occur in order for
  oxygen to be obtained and for carbon dioxide to
  be removed.

3
Pulmonary Ventilation

• Movement of air into an out of the lungs so that
  gases in the air sacs (alveoli) of the lungs are
  continuously changed and refreshed.
• This air movement is known as ventilation or,
  more commonly, breathing.

4
External Respiration

• Ventilation
• exchange of air between lungs and atmosphere
• Gas Exchange in pulmonary capillaries
• Oxygen and Carbon Dioxide
• Diffusion, based on concentration gradient
• Breathing largely involuntary activity

5
Transport of Respiratory Gases

• Transport of O2 and CO2 between lungs and tissue
  cells of the body
• Accomplished by cardiovascular system
• Blood is the transporting fluid

6
Internal Respiration

• All cells require oxygen for metabolism
• All cells require means to remove carbon dioxide
• Gas exchange occurs at cellular level
• Also simple diffusion, based on concentration
  gradient

7
Structures of Respiratory System

• Upper respiratory tract
• Nose/Mouth
• Pharynx
• Epiglottis
• Lower respiratory tract
• Larynx
• Trachea
• Bronchi
• Lungs
• Bronchioles
• Alveoli

8
The Nose

• Nose is the only externally visible part of the
  respiratory system
• Numerous functions
• Airway for respiration
• Moistens and warms entering air
• Filters inspired air and cleanses it of foreign
  matter
• Resonating chamber for speech
• Houses olfactory receptors
• Mouth can be used in lieu of the nose as an
  airway for respiration.
• Air will be less treated

9
The Pharynx

• Nasopharynx
• adenoids or pharyngeal tonsils
• oropharynx
• palatine tonsils
• laryngopharynx
• larynx

10
Epiglottis

• Oropharynx and laryngopharynx serve as a common
  passageway for both food and air
• Epiglottis acts as a lid or flap that covers the
  larynx and trachea (airway) so food does not
  enter the lungs.

11
Larynx

• voice box
• Three main functions
• Patent (open) airway
• Switching mechanism to route food and air into
  proper channels
• Voice production (houses vocal cords)

12
Trachea

• Windpipe or airway
• Mucous membrane lining with cilia
• Smooth muscle with c-shaped cartilage rings
• divides into two branches bronchi
• no gaseous exchange

13
Bronchi

• Bronchus singular
• c-shaped cartilage rings with smooth muscle
• Each bronchi divides into bronchioles
• Terminate in air sacs called alveoli

14
Lungs Pleural Coverings

• Two circulations
• Pulmonary circulation
• Bronchial circulation
• Innervated by parasympathetic and
• (rare) sympathetic motor fibers
• Each lung enclosed in pleura
• parietal pleura (outer)
• visceral pleura (inner)
• Lubricating pleura fluid

15
Gross Anatomy of the Lung
16
Alveoli

• air sacs
• Alveolar wall membranes one cell thick and
  surrounded by capillaries
• Location of gaseous exchange