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Respiration
Asthma Treatment
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Respiration
• Take up of oxygen from environment
• Release of carbon dioxide
• Respiratory gasses move across
respiratory surfaces by diffusion
Methods of Animal Respiration
• Over cell & skin surfaces
– Cell membrane
– Outer layer of cells
– Skin
• Use of special organs
– Tracheal system
– Gills
– lungs
Respiration Using Cell Membranes
• Used by bacteria & protists
Respiration Using Outer Cells
• Used by sponges, corals, jellyfish & worms
Respiration Using the Skin
• Used by amphibians & some other vertebrates
Respiration Using a Tracheal System
• Used by insects & some spiders
Tracheal system
• Opens to the environment at spiracle
• Series of tubes transports air to cells
Respiration Using Gills
• Used by large aquatic organisms
Gills
• Oxygen flows from water to blood
• Possible because of countercurrent flow
Respiration Using Lungs
• Used by mammals & other large land animals
General Lung Structure
• Microscopic air sacs
• Many blood vessels
• Moist membranes allow gas diffusion
– Oxygen into blood
– Carbon dioxide out of blood
Animal Lung Variation
• Frogs
– Gulp air
– Pump air into lungs
• Birds
– Air sacs in addition to lungs
Human Respiration
• Breathing = moving air in & out of lungs
• Inspiration = taking air in
• Expiration = expelling air
• Average rate = 14-20 breaths per minute
Organs of the Respiratory System
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Nasal cavities
Pharynx
Larynx
Trachea
Bronchi
Alveoli
Nasal Cavities
• Air enters nostrils
• Hairs filter particles
• Air is warmed & moistened
• Moist, mucous secreting
epithelium (moistens air,
helps trap dust & dirt)
covered in cilia
Pharynx
• Begins behind nasal cavities
• Extends to epiglottis
• Passageway for air & food
Larynx
• Cartilaginous box
• Contains vocal cords
• Only carries air
Trachea
• Windpipe
• Tube enforced with cartilage
Bronchi
• Branches at end of trachea
• Enters lungs
• Continues to branch
– Primary bronchi, secondary bronchi, …
• Ends in respiratory bronchioles
• Alveoli at end of respiratory bronchiole
Alveoli
• Region of gas exchange
• Air on one side, blood capillaries on other
Particle Filtration
• Particles are trapped in mucus
• Cilia sweep out particles
Air Flow in Lungs
• Air flows due to pressure differences
– Low pressure causes air to flow in
– High pressure forces air out
• Muscles cause pressure differences
– Diaphragm
– Intercostal muscles
• external – quiet breathing ( expiration a
passive process)
• internal – deep breathing (expiration an
active process)
Inspiration
• Muscles increase volume of thoracic cavity
• Lungs expand to decrease pressure inside
• Air flows into lungs
Expiration
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Stretch receptors activated by expanded lung
Muscles relax
Thoracic volume decreases
Air is forced out
Lung Volumes
• Tidal volume
– Air exchanged per breath
– About 500 ml
– 350 ml reaches alveoli
• Not all air is exchanged
with each breath
– Residual air
Gas Transport to Cells
• Circulatory system transports gasses
External Respiration
• Oxygen & carbon dioxide exchanged
• Exchange works due to diffusion
• Gasses move from high to low concentration
Gas Travel in the Blood
• Oxygen
– 98.5% attaches to hemoglobin on red blood
cells
– 1.5% dissolves in plasma
• Carbon dioxide
– 25% carried on red blood cells
– 6% dissolved in blood
– 69% carried in plasma as bicarbonate ions
Internal Respiration
• Exchange of gasses by body tissue
• Works by diffusion
Chronic Obstructive Pulmonary
Disease (COPD)
• Disorders that block airways & impair breathing
• Fourth leading cause of death
• Common examples
– Chronic bronchitis
– Emphysema
Chronic Bronchitis
• Inflammation of bronchi & bronchioles
• Primary cause is cigarette smoking
– Paralyzes epithelial cells
– Particles are not removed
– Infections are common
Emphysema
• Lungs lose elasticity
• Must work to exhale
Unblocking Airways
• Abdominal thrusts can dislodge blockage
End chapter 29