Transcript Anatomy and Physiology with Integrated Study Guide Third

Chapter 14
Lecture Slides
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Respiratory System
Anatomy
 Body cells require
 Constant supply of oxygen
 Constant removal of carbon dioxide
 Both respiratory and cardiovascular systems
contribute to fulfilling this requirement
 Respiration is the overall process of gas
exchange between atmosphere and body
cells
 Respiration involves four events
1.
2.
Movement of air in and out of the lungs, which is call
ventilation
External respiration
 Gas exchange between air and blood in lungs by diffusion
3.
Transport of gases between lungs and body cells
 Cardiovascular system
4.
Internal respiration
 Gas exchange between blood and body cells by diffusion
14.1 Organs of the Respiratory
System
 Subdivisions
 Upper respiratory
system
 Portion not located in the
thorax
 Lower respiratory
system
 Portion located in the
thorax
 Nose
 Nasal bones support the nose bridge,
remaining is supported by cartilage
 Nostrils allow air to enter and leave
nose
 Has hairs to filter large particles and
insects
 Nasal cavity is the interior nose chamber
 Palate (roof of mouth) separates it from oral
cavity
 Hard palate
 Soft palate
 Nasal septum divides cavity into R and L sides
 Three nasal conchae project from lateral walls
 Increase surface area of nasal cavity
 Lined with pseudostratified ciliated columnar
epithelium
 Goblet cells in epithelium produce mucus
 Moistens incoming air and traps particles
 Air is warmed by blood vessels in mucus membrane
 Cilia move trapped particles to pharynx where they can be swallowed
 Destroyed by gastric juice in stomach
 Paranasal sinuses are air filled cavities
in the bones around the nasal cavity
 In the ethmoid, frontal, maxillary, sphenoid
bones
 Functions
 Lighten the skull
 Sound resonating chambers during speech
 Open into nasal cavity
 Lined with ciliated mucus membranes
 Pharynx
 Also called the throat
 Passageway posterior to nasal and oral
cavities, extending to larynx and esophagus
 Muscular wall covered in a mucus
membrane
 Consists of three parts
 Nasopharynx
 Oropharynx
 Laryngopharynx
 Auditory tubes
 Equalize air pressure
on each side of
tympanic membrane
 Tonsils
 Clumps of lymphatic tissues
at openings to pharynx
 Sites of immune responses
 Three sets of tonsils
 Palatine tonsils
 Pharyngeal tonsil
 Lingual tonsils
 Larynx
 Cartilagenous, boxlike
structure
 Passageway for air
between pharynx and
trachea
 Thyroid cartilage
 Adam’s apple
 Cricoid cartilage
 Connects to trachea
 Epiglottis
 Flap that prevents food
from entering larynx
 Supported by ligaments
that extend from hyoid
bone
 Vocal cords
 Folds of mucus
membranes
 Relaxed during breathing
 Contract and vibrate to
produce sound
 Glottis is the opening
between the cords
 Changes that occur during swallowing
 Goal is to prevent food from entering pharynx
and direct food to esophagus
 Muscles lift larynx upward
 Epiglottis folds over to cover glottis
 Food is directed into esophagus
 If food or drink enters larynx, coughing occurs
 Trachea
 Tube that extends from larynx into thoracic cavity
 Branches to form primary bronchi
 C-shaped cartilagenous rings support trachea
 Hold airway open during breathing
 Open portion allows esophagus to expand during swallowing
 Lined by ciliated mucus membrane
 Mucus traps particles
 Cilia move particles upward to pharynx
 Bronchial Tree
 Trachea divides into R and L primary bronchi
 Enter R and L lungs
 Primary bronchi
branch into
secondary bronchi
 One for each lung
lobe
 Secondary bronchi continue to branch into smaller tubules
 Establishes a bronchial trees
 Bronchi possess cartilagenous rings
 Bronchioles




Very small tubes lacking cartilage
Possess smooth muscle
Lined with simple cuboidal epithelium
Cannot remove foreign particles effectively
 Terminal bronchioles form alveolar ducts
 Alveolar ducts terminate in alveoli
 Alveoli




~300 million per lung
Surface area ~75m2, holding ~6,000ml of air
Site of respiratory gas exchange
Filled with watery fluid to aid diffusion
 Surfactant prevents alveolar collapse during exhalation
 Reduces attraction between water molecules
 Lungs
 Cone-shaped and separated by heart and mediastinum
 Consist of alveoli, air passageways, blood and lymphatic
vessels, and connective tissues
 Lungs are divided into lobes
 L lung has two lobes
 R lung has three lobes
 Lobes are supplied with a secondary bronchus, blood and
lymphatic vessels, and nerves
 Lungs are surrounded by serous membranes
 Visceral pleura
 Attached to lung surface
 Parietal pleura
 Lines thorax wall and mediastinum
 Pleural cavity
 Potential space between the two pleurae
 Filled with serous fluid to reduce friction
 Helps keep the pleurae pressed together
Respiratory System
Physiology
14.2 Breathing
 Process that exchanges air between atmosphere
and alveoli
 Air moves along a pressure gradient
 Air moves from high pressure region to low pressure
region
Three important breathing pressures
1.
Atmospheric pressure
2.
Intra-alveolar (intrapulmonary) pressure
3.
Intrapleural pressure
 Pressure of air surrounding earth
 760 mmHg at sea level
 Decreases at higher elevations
 Air pressure within the lungs
 Fluctuates during breathing
 Pressure within the pleural cavity
 Normally 756 mmHg
 Called “negative pressure”
 Keeps lungs pressed against thorax walls during breathing
 If it equals atmosphere pressure, lungs would collapse
More info about dealing with higher altitudes:
anthro.palomar.edu/adapt/adapt_3.htm
 Inspiration
 Process of breathing air into lungs
 Air pressure in lungs must be reduced to less then
atmospheric air pressure
 Begins with muscle contraction
 Diaphragm
 Contraction pulls the
diaphragm downward and
flattens it
 External intercostal muscles
 Contraction lifts the ribs
upward and outward
 Contractions increase volume
of thoracic cavity
 Lungs are pulled outward with the thoracic cavity
 Increases lung volume and decreases intra-alveolar
pressure
 Higher atmospheric pressure pushes air towards the
lower intra-alveolar pressure in lungs
 Continues until pressures are equal
 Expiration
 Diaphragm and external intercostal muscles relax
 Thoracic cavity and lungs to return to normal size
 Decreases volume of thoracic cavity and lungs
 High intra-alveolar pressure pushes air out of lungs
 Continues until pressures are equal
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 Forceful expiration
 Contraction of internal intercostal muscles
 Pull ribs down and inward
 Contraction of abdominal muscles
 Force abdominal viscera and lungs upward
 Further decreases volume of lungs
 Increases air pressure in lungs, causing more air to
flow out
14.3 Respiratory Volumes
 Average adult: 12 to 15 quiet breathing cycles per
minute
 Breathing cycle: one inspiration followed by one
expiration
 Volume of air inhaled during quiet or forceful
breathing cycle varies
 Size, age, sex, physical condition
 Volumes 80% or less than normal average indicate
respiratory disease
 Spirometers are used to determine respiratory
volumes
 Produces a spirogram, a graphic record of air volumes
being exchanged
 Tidal volume (TV)
 Volume of air exchanged during quiet breathing
 ~500ml
 Inspiratory reserve volume (IRV)
 Maximum volume of air that can be forcefully inhaled
after a tidal inspiration
 ~3,000ml
 Expiratory reserve volume (ERV)
 Maximum volume of air forcefully exhaled after a tidal
expiration
 ~1,100ml
 Residual volume (RV)
 Volume of air remaining in lungs are ERV
 ~1,200ml
 Keeps alveoli open, preventing lung collapse
 Vital capacity (VC)
 Maximum amount of air that an be forcefully exchanged
 TV + IRV + ERV
 ~4,600ml
 Total lung capacity (TLC)
 VC + RV
 ~5,800ml
14.4 Control of Breathing
 Control is through neurons of the respiratory center
 Located in both the medulla and the pons of the brain
stem
 Medullary Respiratory
Centers
 Controls the rhythmic nature
of breathing
 Consists of two components
 Ventral respiratory group
(VRG)- sets the normal
breathing rhythm
 Dorsal respiratory group
(DRG)- changes breathing
pattern according to sensory
input
 Pontine respiratory group (PRG)
 Coordinates the actions of the medullary respiratory centers
 Alters the rate and depth of breathing
 Adapts breathing to speech, singing, etc…
14.5 Factors Influencing Breathing
• Chemicals
– Important chemical factors include
• CO2
• H+ ions
– Formed when CO2 is carried in blood
– Increase in CO2 causes an increase in H +
• O2
Control of Respiration
 Chemoreceptors detect changes in these
chemicals
 Respiratory center
 Carotid bodies
 Aortic bodies
Control of Respiration
 Respiratory center is sensitive to changes in
CO2 and H+
 Increase in CO2 and H+ causes respiratory
center to increase rate and depth of breathing
 Decrease in CO2 and H+ causes brief apnea
 Carotid and aortic bodies are sensitive to O2
concentration
 Low oxygen levels causes them to send
impulses to respiratory center
Control of Respiration
 Inflation Reflex





Visceral pleurae have stretch receptors
Inspiration stretches the visceral pleurae
Impulses are sent via vagus nerve to respiratory center
Inhibits the formation of impulses causing inspiration
Promotes expiration and prevents excessively deep
inspirations
Control of Respirations
 Higher Brain Centers
 Voluntarily generated
 When a person chooses to alter the normal
pattern of quiet breathing
 Limited in their control
Control of Respirations
 Involuntary impulses
 Emotional experiences and chronic pain
increase breathing rate
 Examples: fear, excitement
 Sudden emotional experience, sharp pain,
or sudden cold stimulus can cause apnea
 Body Temperature
 Increase temperature, increase breathing
rate
 Decrease temperature, decrease breathing
rate
14.6 Gas Exchange
 External respiration
 Gas exchange between
air in alveoli and blood
in capillaries
 Diffusion through the
respiratory membrane
 O2 moves from air
into blood
 CO2 moves from
blood into air
 Internal respiration
 Gas exchange between blood in capillaries and tissue
cells
 Involves diffusion across capillary walls
 O2 moves from blood and into tissues
 CO2 moves from tissues and into blood
14.7 Transport of Respiratory Gases
 Red blood cells play a major role in transport of
both O2 and CO2
 Oxygen Transport
 In alveolar capillaries, 97% of O2 enters RBCs and
forms oxyhemoglobin
 Binds to heme of hemoglobin
 3% is dissolve in plasma
 In body tissues, 25% of O2 is released from
oxyhemoglobin so it can diffuse out of the capillary
 Forms deoxyhemoglobin
 Bond between O2 and hemoglobin is unstable
 If surrounding O2 levels are high (i.e. lungs), hemoglobin
readily binds O2
 If surrounding O2 levels are low (i.e. tissues), hemoglobin
readily releases O2
 Carbon Dioxide Transport
 When CO2 diffuses from capillary blood, it takes
three pathways
1. 7% is dissolved in plasma
2. 23% combines with globin of hemoglobin to
form carbaminohemoglobin
3. 70% enter RBC and combines with water to
form carbonic acid
 Reaction catalyzed by carbonic anhydrase
 Carbonic acid breaks down into H+ and bicarbonate ions
 The reactions forming bicarbonate ions and H + reverse to allow
diffusion of CO2 into alveolar air
Inflammatory Disorders
 Chronic obstructive pulmonary disease (COPD)
 Long-term obstruction
 Chronic bronchitis
 Emphysema
 Bronchitis
 Inflammation of bronchi accompanied by excessive
mucus production partially obstructing air flow
 Acute bronchitis: viral or bacterial infection
 Chronic bronchitis: chronic asthmatics and smokers
 Emphysema
 Due to long term exposure to airborne irritants
 Effects- basically overinflated lungs
 Large spaces form when alveoli rupture
 Air blocked in alveoli due to excess mucus production
 Reduces respiratory surface area and impairs gas
exchange
 Reduced ERV and increased RV result
 Exhaling requires voluntary effort
 Asthma
 Characterized by wheezing and dyspnea
 Due to contraction of bronchiole smooth
muscle
 Causes
 Allergic reactions
 Hypersensitivity to pathogens infecting the
bronchial tree
 Pleurisy
 Inflammation of pleural membranes
 Can have two effects
 Decreases serous fluid production,
 Causes sharp pains during breathing
 Increase serous fluid production,
 Causes increase in pressure on lungs
 Impairs their expansion
 Pneumonia
 Acute inflammation of alveoli caused by virus or bacteria
 Alveoli become filled with fluid, pathogens, and WBCs
 Reduces gas exchange space, resulting in low blood
oxygen levels