23-1 chapter 23 respiratory system. 23-2 respiration ventilation: movement of air into & out of...
TRANSCRIPT
23-1
Chapter 23
Respiratory System
23-2
Respiration
• Ventilation: Movement of air into & out of lungs
• External respiration: Gas exchange b/n air in lungs & blood– Transport of O2 and CO2 in the blood
• Internal respiration: Gas exchange b/n the blood & tissues
23-3
Respiratory System Functions
• Gas exchange: O2 enters blood & CO2 leaves
• Regulation of blood pH: Altered by changing blood CO2 levels
• Voice production: Movement of air past vocal folds makes sound & speech
• Olfaction: Smell occurs when airborne molecules drawn into nasal cavity
• Protection: Against microorganisms by preventing entry & removing them
23-4
Respiratory System Divisions
• Upper tract– Nose, pharynx &
associated structures
• Lower tract– Larynx, trachea,
bronchi, lungs
23-5
Nose and Pharynx
• Nose– External nose– Nasal cavity
• Functions– Passageway for air– Cilia cleans the air– Mucous humidifies
(moistens air inhaled)
– Capillaries warm air– Smell– Along with paranasal
sinuses are resonating chambers for speech
• Pharynx– Common opening for
digestive & respiratory systems
– Three regions• Nasopharynx• Oropharynx• Laryngopharynx
23-6
Larynx
• Functions– Maintain an open passageway for air movement– Epiglottis & vestibular folds prevent swallowed material
from moving into larynx (can move to cover trachea)
– Vocal folds are primary source of sound production
23-7
Structure of Larynx
– AKA voice box
– Thyroid cartilage: AKA Adam’s apple • Protects vocal cords • Moves when you
swallow
– Epiglottis: closes off larynx so food & liquid travel down the esophagus
23-8
Voice Production• False vocal cords:
assist w/ hold breath• True vocal cords:
– Space between them called glottis
– Vibration produces sound
– In combination with tongue, mouth, & nose to produce words
23-9
Concept Check1. Name the functions of the respiratory system.
-Gas exchange; regulation of blood pH; olfaction; protection
2. How is the respiratory system divided? Name the parts of each.
-Upper (Nose, Pharynx, Assoc. Structures); -Lower (Larynx, Trachea, Bronchi, Lungs)
3. Name the accessory structures of the nose, and describe their function.
-Cilia (cleans air); Mucus (moistens air), Capillaries (warms air)
4. The larynx is also known as the…-Voice Box
23-10
Trachea
• Windpipe
• Divides to form– Primary bronchi– Carina: Cough
reflex
Insert Fig 23.5 all but b
23-11
Organs of Respiration• Trachea:
– AKA windpipe
– Smooth muscle supported by C-shaped rings of cartilage
• food can travel down esophagus easier
– Passageway for air from larynx to bronchi
– Lined w/ cilia & mucous
23-12
Tracheobronchial Tree
• Conducting zone– Trachea to terminal bronchioles which is
ciliated for removal of debris– Passageway for air movement– Cartilage holds tube system open & smooth
muscle controls tube diameter
• Respiratory zone– Respiratory bronchioles to alveoli– Site for gas exchange
23-13
Organs of Respiration
• Bronchi:– Left & right
primary bronchi branch off trachea
– Lined w/ cilia
– Supported by cartilage
23-14
Bronchial Tree
Primary bronchi
Secondary bronchi
Tertiary bronchi
bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
alveoli
23-15
Bronchioles and Alveoli
23-16
Alveolus and Respiratory Membrane
23-17
Lungs
• Two lungs: Principal organs of respiration– Right lung: Three lobes– Left lung: Two lobes
23-18
Organs of Respiration
• Alveoli:– Extremely thin-
walled sacs covered w/ capillaries
– CO2 & O2 move by diffusion across the respiratory membrane
– About 300 million alveoli in two lungs
– Size of a tennis court
23-19
Organs of Respiration
• Alveoli:– Surfactant lines the
alveoli to aid diffusion & decrease surface tension
– To prevent the alveoli from collapsing & sticking shut
23-20
Pleura
• Pleural fluid produced by pleural membranes– Acts as lubricant– Helps hold parietal & visceral pleural membranes
together
23-21
Concept Check
1. The trachea is also known as…-Windpipe
1. How is the trachea structured & why?
-C-Shaped rings of cartilage (allows passage of food to move easily)
2. Describe the bronchial tree.
23-22
Ventilation
• Movement of air into and out of lungs
• Air moves from area of higher pressure to area of lower pressure (AKA Diffusion)
• Pressure is inversely related to volume
23-23
Inspiration• Breathing in
• When pressure in the lungs is less than the air pressure in the atmosphere
• Diaphragm— will contract and lower, increasing the size of the thoracic cage
23-24
Inspiration
• Increased volume will decrease the pressure & the lungs will expand
23-25
Expiration• Breathing out
• When the pressure inside the lungs is greater than the pressure in the atmosphere
• Diaphragm— relaxes and rises; decreases the size of the thoracic cage
23-26
Expiration
• Decreased volume will increase pressure & lungs will decrease and push air out
23-27
Internal Respiration
• Exchange of O2 and CO2 between tissue capillaries and tissue cells
• CO2 moves from high concentration in cells to low concentration in blood
23-28
External Respiration
• Conversion of deoxygenated blood to oxygenated blood– Aided by thin
membranes– Large surface area– Narrow capillaries
23-29
Concept Check
1. What is the diffusion?
2. What is the difference between inspiration and expiration?
3. What happens to the diaphragm? Be specific.
23-30
Changing Alveolar Volume
• Lung recoil– Causes alveoli to collapse resulting from
• Elastic recoil and surface tension– Surfactant: Reduces tendency of lungs to
collapse
• Pleural pressure– Negative pressure can cause alveoli to
expand– Pneumothorax is an opening between
pleural cavity & air that causes a loss of pleural pressure
23-31
Compliance• Measure of the ease with which lungs
& thorax expand– The greater the compliance, the easier it
is for a change in pressure to cause expansion
– A lower-than-normal compliance means the lungs and thorax are harder to expand• Conditions that decrease compliance
– Pulmonary fibrosis– Pulmonary edema– Respiratory distress syndrome
23-32
Pulmonary Volumes• Tidal volume
– Volume of air inspired or expired during a normal inspiration or expiration
• Inspiratory reserve volume– Amount of air inspired forcefully after inspiration of
normal tidal volume
• Expiratory reserve volume– Amount of air forcefully expired after expiration of
normal tidal volume
• Residual volume– Volume of air remaining in respiratory passages and
lungs after the most forceful expiration
23-33
Pulmonary Capacities
• Inspiratory capacity– Tidal volume plus inspiratory reserve volume
• Functional residual capacity– Expiratory reserve volume plus the residual volume
• Vital capacity– Sum of inspiratory reserve volume, tidal volume,
and expiratory reserve volume
• Total lung capacity– Sum of inspiratory and expiratory reserve volumes
plus the tidal volume and residual volume
23-34
Spirometer and Lung Volumes/Capacities
23-35
Minute and Alveolar Ventilation
• Minute ventilation: Total amount of air moved into & out of respiratory system per minute
• Respiratory rate or frequency: Number of breaths taken per minute
• Anatomic dead space: Part of respiratory system where gas exchange does not take place
• Alveolar ventilation: How much air per minute enters the parts of the respiratory system in which gas exchange takes place
23-36
Physical Principles of Gas Exchange
• Partial pressure– The pressure exerted by each type of
gas in a mixture
• Diffusion of gases through liquids– Concentration of a gas in a liquid is
determined by its partial pressure and its solubility coefficient
23-37
Physical Principles of Gas Exchange
• Diffusion of gases through the respiratory membrane– Depends on membrane’s thickness, the diffusion
coefficient of gas, surface areas of membrane, partial pressure of gases in alveoli and blood
• Relationship between ventilation and pulmonary capillary flow– Increased ventilation or increased pulmonary capillary
blood flow increases gas exchange– Physiologic shunt is deoxygenated blood returning from
lungs
23-38
Oxygen & Carbon Dioxide Diffusion Gradients
• Oxygen– Moves from alveoli
into blood. Blood is almost completely saturated with oxygen when it leaves the capillary
– C02 in blood decreases because of mixing with deoxygenated blood
– Oxygen moves from tissue capillaries into the tissues
• Carbon dioxide– Moves from
tissues into tissue capillaries
– Moves from pulmonary capillaries into the alveoli
23-39
Hemoglobin and Oxygen Transport
• Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%)
23-40
Transport of Carbon Dioxide
• Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with plasma (7%)
23-41
Herring-Breuer Reflex
• Limits the degree of inspiration and prevents overinflation of the lungs– Infants
• Reflex plays a role in regulating basic rhythm of breathing and preventing overinflation of lungs
– Adults• Reflex important only when tidal volume large as
in exercise
23-42
Ventilation in Exercise• Ventilation increases abruptly
– At onset of exercise– Movement of limbs has strong influence– Learned component– Decreases slightly
• Ventilation increases gradually– After immediate increase, gradual increase
occurs (4-6 minutes)– Anaerobic threshold is highest level of exercise
without causing significant change in blood pH• If exceeded, lactic acid produced by skeletal
muscles
23-43
Disorders• Asthma— spasms of smooth muscle
in the bronchioles
• Lung cancer– Constant irritation produces excess
mucous and puts unnecessary stress on the bronchi
– Alveoli destroyed by WBC’s acting on the irritation
– Structural cells disappear and cancer cells take over
23-44
Disorders
• Emphysema— alveolar walls lose their elasticity– Some alveoli merge and reduce volume– Have to work voluntarily to exhale
• Bronchitis— inflammation of the bronchi– Creates site for infection and increases
mucous
23-45
Disorders
• Pneumonia— infection or inflammation of the alveoli
• Tuberculosis (TB)— bacterial infection that destroys lung tissue and is replaced by non-elastic connective tissue
23-46
Disorders
• Respiratory Distress Syndrome (RDS)– Lack of surfactant makes breathing
difficult – Alveoli are sticking together– Occurs in infants
• Pulmonary Embolism– blood clot obstructs circulation to lung
tissue & tissue dies
23-47
Disorders
• Respiratory Failure– Not enough O2 to maintain metabolism
– Cannot eliminate enough CO2
– Caused by:• Drugs• Stroke• CO poisoning• shock
23-48
Disorders
• Colds and Flu— viral infections
• Sudden Infant Death Syndrome (SIDS)– Crib death– Occurs between 1 week and 12 months– Cause is unknown– Baby stops breathing
23-49
Disorders
• Laryngitis— vocal cords
• Pharyngitis— sore throat
• Rhinitis— lining of the nose
23-50
Effects of Aging
• Vital capacity and maximum minute ventilation decrease
• Residual volume and dead space increase
• Ability to remove mucus from respiratory passageways decreases
• Gas exchange across respiratory membrane is reduced