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Anatomy and Physiology > Respiratory System > Flashcards

Respiratory System Flashcards

1
Q

Respiratory System Overview

A
  • Brain will cease to function, and death will occur if deprived of oxygen for 5-6 minutes
  • Provides constant supply of O2 and removing C02 (waste product)
  • Works cooperatively with the cardiovascular system to conduct gas exchange
    o Collectively referred to as the cardiopulmonary system
    o Blood pumped through –> acts as transport vehicle for O2 and C02
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2
Q

Organs of the Respiratory System

A
  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs –> alveoli
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3
Q

Functional Anatomy of the Respiratory System

A

Gas exchanges between the blood and external environment occur only in the alveoli of the lungs

Upper respiratory tract includes passageways from the nose to larynx
o Serve as a passageway for air moving in and out of the lungs
o Filter and remove foreign particles for inspired air
o Humidify and control temperature of inspired air
o Provide a sense of smell
o Assist with immune defence

Lower respiratory tract includes passageways from trachea to alveoli
o Passageways to the lungs purify, humidify, and warm the incoming air
o Gas exchange occurs at alveoli

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4
Q

The Nose

A

The only externally visible part of the respiratory system
o Nostrils (nares) are the route through which air enters the nose
o Nasal cavity is the interior of the nose
 Deep to nostril is vestibular region
• Contains oily coated nasal hairs (cilia)
• Cilia trap and prevent particles from entering the nose

o Nasal septum divides the nasal cavity

Olfactory receptors are located in the mucosa on the superior surface
o Provide sense of smell

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5
Q

The Nose: Functions

A

Lined with respiratory mucosa, which

o Moistens air
o Traps incoming foreign particles
o Enzymes in the mucus destroy bacteria chemically
o Thin walls can cause nose bleeds

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6
Q

Conchae

A

Conchae are projections from the lateral walls of the nasal cavity
o 3 projections (superior, middle, inferior)
o Increase surface area –> by creating 3 different passageways for filtering inspired air
o Increase air turbulence within the nasal cavity
o Increased trapping of inhaled particles –> by mucous membrane

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7
Q

Palate (roof of the mouth)

A

The palate separates the nasal cavity from the oral cavity
o Hard palate is anterior and supported by bone

o Soft palate is posterior, unsupported by bone, composed of soft tissue
 Hanging from soft palate is the Uvula
• Small mass of CT and muscle fibres
• Believed to play a role in speech and helps prevent food from entering nasal cavity

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8
Q

Paranasal Sinuses

A
  • Cavities within the frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity
Sinuses:
o	Lighten the skull
o	Act as resonance chambers for speech 
o	Produce mucus
o	Warm and moisten inspired air 
o	Strengthen tone of the voice
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9
Q

The Pharynx

A
  • Included in both respiratory and digestive systems
  • Approximately 13 cm long
  • Oropharynx (middle section) and laryngopharynx (lower section) serve as common passageway for air, food and liquid
    o Epiglottis routes food into the posterior tube, the oesophagus
  • Pharyngotympanic tubes open into the nasopharynx (top section)
    o Drain the middle ear
    o Due to this connection –> ear infection can cause an upper respiratory infection
  • Only air passes through the nasopharynx
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10
Q

Tonsils

A

Tonsils are clusters of lymphatic tissue that play a role in protecting the body from infection
o Pharyngeal tonsil (adenoid), a single tonsil, is located in the nasopharynx
o Palatine tonsils (2) are located in the oropharynx at the end of the soft palate
o Lingual tonsils (2) are found at the base of the tongue

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11
Q

The Larynx

A
  • Commonly called the voice box

Functions
o Routes air and food into proper channels
o Plays a role in speech

  • Triangular shaped and located inferior to the pharynx
  • Made of eight rigid hyaline cartilaginous plates
    o Thyroid cartilage (Adam’s apple) is the largest
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12
Q

Epiglottis

A
  • Found between the roof of the tongue and the larynx
  • Spoon-shaped flap of elastic cartilage
  • Protects the superior opening of the larynx
  • Routes food to the posteriorly situated oesophagus and routes air toward the trachea
  • During swallowing, the epiglottis rises and forms a lid over the opening of the larynx
    o Prevents substance from entering the trachea
    o If food or liquid enters trachea –> cough is triggered to expel substance before entering lungs
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13
Q

Vocal Folds

A
  • Located within the larynx
  • Lined with a mucous membrane which folds to form the vocal cords

True vocal cords
o Vibrate with expelled air
o Allow us to speak

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14
Q

Glottis

A

Includes the vocal cords and the opening between the vocal cords
o Gives vocal cords room to vibrate to produce sound

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15
Q

The Trachea

A
  • Commonly called the windpipe
  • 4-inch-long tube that extends from the end of the larynx to the 5th Thoracic vertebrae

Walls are reinforced with C-shaped rings of hyaline cartilage
o Anterior Rings –> Contains rigid cartilage and prevents trachea from collapsing
o Posterior Rings –> Do not contain cartilage, flexible, allow cartilage to expand

Lined with ciliated mucosa
o Cilia beat continuously in the opposite direction of incoming air
o Expel mucus loaded with dust and other debris away from lungs to larynx and pharynx

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16
Q

Main Bronchi

A
  • Formed by division of the trachea
  • Each bronchus enters the lung at the hilum (medial depression)
  • Right bronchus is wider, shorter, and straighter than left
  • Bronchi subdivide into smaller and smaller branches
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17
Q

The Lungs

A
  • Occupy the entire thoracic cavity except for the central mediastinum
  • Apex of each lung is near the clavicle (superior portion)
  • Base rests on the diaphragm

Each lung is divided into lobes by fissures
o Left lung—two lobes (superior, inferior)
o Right lung—three lobes (superior, middle, inferior)

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18
Q

Lungs - Pleura

A

Serosa covers the outer surface of the lungs
o Pulmonary (visceral) pleura covers the lung surface and dips into fissures
o Parietal pleura lines the walls of the thoracic cavity
o Both secrete fluid which allows for gliding movements during respiration

Pleural fluid fills the area between layers
o Allows the lungs to glide over the thorax
o Decreases friction during breathing

Pleural space (between the layers) is more of a potential space

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19
Q

The Bronchial Tree

A

Main bronchi subdivide into smaller and smaller branches
o Primary Bronchi –> Secondary Bronchi –> Tertiary Bronchi –> Bronchioles
- Bronchial (respiratory) tree is the network of branching passageways
- All but the smallest passageways have reinforcing cartilage in the walls
- Conduits to and from the respiratory zone
- Bronchioles (smallest conducting passageways)

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20
Q

Respiratory Zone Structures and the Respiratory Membrane

A

Terminal bronchioles lead into respiratory zone structures and terminate in alveoli

Respiratory zone includes the: 
o	Respiratory bronchioles
o	Alveolar ducts
o	Alveolar sacs
o	Alveoli (air sacs)—the only site of gas exchange

Conducting zone structures include all other passageways
o Bronchi and Bronchioles as they conduct air to and from the lungs

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21
Q

Alveoli

A
  • Limited amount of gas exchange occurs in the respiratory bronchioles
  • Main sites of gas exchange within the lungs
  • Millions make up the bulk of the lung tissue
  • Simple squamous epithelial cells largely compose the walls
  • Alveolar pores connect neighbouring air sacs
  • Pulmonary capillaries cover external surfaces of alveoli
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22
Q

Respiratory Membrane (air-blood barrier)

A
  • On one side of the membrane is air, and on the other side is blood flowing past
  • Formed by alveolar and capillary walls

Gas crosses the respiratory membrane by diffusion
o Oxygen diffuses across membrane of alveolar sac into the blood
o Carbon dioxide enters the alveoli sac from the blood ‘

Gas exchange occurs rapidly because:
o Large surface area of the lung (unlimited number of sites for gas exchange)

o 02 and C02 only travel from RBC –> capillary wall/membrane –> alveolar wall/membrane
 Membranes are very thin, thus allowing particles to move freely

o Gas always diffuses from area of high concentration to area of low concentration
 C02 is high within the blood but low within lungs
 02 is high within the alveolar sacs but low within blood

Alveolar walls are composed of very thin squamous epithelial cells
o Internal surface is coated by surfactant

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23
Q

Alveolar Macrophages

A
  • Add protection by picking up bacteria, carbon particles, and other debris
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24
Q

Surfactant (a lipid molecule)

A
  • Coats gas-exposed alveolar surfaces
  • Secreted by cuboidal surfactant-secreting cells
  • Reduces tension in the alveoli and prevents them from collapsing
25
Q

Respiratory Physiology

A

Functions of the respiratory system
o Supply the body with oxygen
o Dispose of carbon dioxide

Respiration includes four distinct events (discussed next)
o	Pulmonary ventilation 
o	External respiration 
o	Respiratory gas transport 
o	Internal respiration
26
Q

Four Events of Respiration

A

Pulmonary ventilation
o Continuously moving air into and out of the lungs (commonly called breathing)

External respiration
o Gas exchange between pulmonary blood and alveoli
 Oxygen is loaded into the blood
 Carbon dioxide is unloaded from the blood

Respiratory gas transport
o Transport of oxygen and carbon dioxide via the bloodstream

Internal respiration
o Gas exchange between blood and tissue cells in systemic capillaries

27
Q

Pulmonary Ventilation

A
  • Mechanical process that depends on volume changes in the thoracic cavity
  • Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure
28
Q

Boyles Law

A

o States that the volume of a gas is inversely proportional to its pressure
o Related to breathing due to pressure difference between spaces inside and outside the lungs

o At rest –> Both atmospheric and pressure within the lungs = 760 mm Hg
 When equal –> lung volume does not change, therefore there is no airflow
o For lungs to take in air –> pressure within lungs must be less than the atmospheric pressure
o For lungs to expel air –> pressure within lungs must be greater than atmospheric pressure

29
Q

Pulmonary Ventilation: Two Phases

A

Inspiration = inhalation
 Flow of air into lungs

Expiration = exhalation
 Air leaving lungs

30
Q

Inspiration

A

External intercostal muscles contract
o Lifts ribs upward and outward
o Expand thoracic cavity

Diaphragm muscle contracts downwards and flattens
o Expand thoracic cavity

  • Intrapulmonary volume increases as lungs expand

Gas pressure internally decreases
o While expanding –> pressure falls below atmospheric pressure thus creating a vacuum
 Vacuum (sucking air into lungs) continues until intrapulmonary pressure equals atmospheric pressure

31
Q

Expiration

A

External intercostal muscles and diaphragm relax
o Decreases space within the thoracic cavity

Muscle contraction does not occur
o Normal expiration is a passive process
o When asthma or mucous accumulation restricts passageways or during exercise –> it becomes an active process
 Forced expiration can occur mostly by contraction of internal intercostal muscles to depress the rib cage and expel air from the lungs
 At the same time, abdominal muscles contract to push air out

Largely a passive process that depends on natural lung elasticity

Intrapulmonary volume decreases

Gas pressure increases to approximately 763 mm Hg
o When pressure exceeds atmospheric pressure –> air is expelled

Gases passively flow out to equalize the pressure

32
Q

Intrapleural Pressure

A
  • The pressure within the pleural space) is always negative
  • Major factor preventing lung collapse
  • If intrapleural pressure equals atmospheric pressure, the lungs recoil and collapse
33
Q

Respiratory Volumes and Capacity

A

Total volume for a pair of healthy adult lungs = 6 L of air

Factors affecting respiratory capacity 
o	Size
o	Sex 
o	Age 
o	Physical condition

Tidal volume (TV)
o Normal quiet breathing
o 500 ml of air is moved in/out of lungs with each breath
o Volume of air inhaled within a normal breath

34
Q

Static Lung Volume

A
  • Measures only volumes
  • Can be used to determine whether a deficiency or disorder exists

A person performs a series of breathing manoeuvres
o Initially, person is told to breathe normally for at least 6 breaths (provides measure of tidal volume)
o Then, person breathes in as deeply as possible to measure the IRV
o They then breathe out as deeply as possible to measure ERV
o By adding together, the TV, IRV and ERV the Vital Capacity can be calculated

35
Q

Inspiratory Reserve Volume (IRV)

A
  • Amount of air that can be taken in forcibly over the tidal volume
  • Usually around 3,100 ml
36
Q

Expiratory Reserve Volume (ERV)

A
  • Amount of air that can be forcibly exhaled after a tidal expiration
  • Approximately 1,200 ml
37
Q

Residual Volume

A
  • Air remaining in lung after expiration
  • Cannot be voluntarily exhaled
  • Allows gas exchange to go on continuously, even between breaths, and helps keep alveoli open (inflated)
  • About 1,200 ml

By adding together, the Vital Capacity and the Residual Volume
o Total lung capacity can be found

38
Q

Vital Capacity

A
  • The total amount of exchangeable air

Vital capacity = TV + IRV + ERV
- 4,800 ml in men; 3,100 ml in women

39
Q

Dead Space Volume

A
  • Air that remains in conducting zone and never reaches alveoli
  • About 150 ml during normal tidal breath
40
Q

Functional Volume

A
  • Air that actually reaches the respiratory zone and contributes to gas exchange
  • Usually about 350 ml
  • Respiratory capacities are measured with a spirometer
41
Q

Non-Respiratory Air Movements

A
  • Can be caused by reflexes or voluntary actions

Examples
o Cough and sneeze—clears lungs of debris and dust from lower respiratory tracts and upper respiratory tracts
o Crying—emotionally induced mechanism
o Laughing—similar to crying, emotionally induced
o Hiccup—sudden inspirations, irritation of the phrenic nerves to cause the diaphragm muscle to spasm
o Yawn—very deep inspiration, need for increased oxygen in the lungs

42
Q

External Respiration, Gas Transport, Internal Respiration

A

Gas exchanges occur as a result of diffusion
o External respiration is an exchange of gases occurring between the alveoli and pulmonary blood (pulmonary gas exchange)
o Internal respiration is an exchange of gases occurring between the blood and tissue cells (systemic capillary gas exchange)

Movement of the gas is toward the area of lower concentration

43
Q

External Respiration

A

Oxygen is loaded into the blood
o Oxygen diffuses from the oxygen-rich air of the alveoli to the oxygen-poor blood of the pulmonary capillaries
o Always more oxygen within the alveoli than the blood

Carbon dioxide is unloaded out of the blood
o Carbon dioxide diffuses from the blood of the pulmonary capillaries to the alveoli and be flushed out of the lungs during expiration

Dark-red, deoxygenated blood flowing through the pulmonary circuit –> bright-red oxygenated blood flowing through the systemic circuit to the heart

44
Q

Gas Transport in the Blood: Oxygen in Blood

A

o Most oxygen travels attached to hemoglobin molecules and forms oxyhemoglobin (HbO2 )
o A small, dissolved amount is carried in the plasma

45
Q

Gas Transport in the Blood: C02 in Blood

A

C02 is 20x more soluble than 02
 Most carbon dioxide is transported in the plasma as bicarbonate ion (HCO3 – )
• Important at buffering the blood pH

 C02 is enzymatically converted to bicarbonate ion within the RBC’s
• Newly formed HCO3- diffuse into the plasma
• A small amount is carried inside red blood cells on hemoglobin, but at different binding sites from those of oxygen

46
Q

Gas Transport in the Blood: C02 Diffusing out of the Blood

A

It must be released from its bicarbonate form:
 Bicarbonate ions enter RBC
 Combine with hydrogen ions
 Form carbonic acid (H2CO3 )
 Carbonic acid splits to form water + CO2
 Carbon dioxide diffuses from blood into alveoli

47
Q

Internal Respiration

A
  • Exchange of gases between blood and tissue cells

An opposite reaction from what occurs in the lungs
o Carbon dioxide diffuses out of tissue cells to blood (called loading)
 In blood, C02 binds with water to form carbonic acid –> quickly releases HCO3-
 Most of the conversion from carbonic ions to bicarbonate ions occurs inside RBC’s
 Bicarbonate ions diffuse out into plasma –> then transported

Oxygen diffuses from blood into tissue (called unloading)
 02 is released from Haemoglobin to enter cells

As a result of these exchanges
o Venous blood in systemic circulation is much poorer in oxygen and richer in carbon dioxide than blood leaving the lungs

48
Q

Control of Respiration: Neural Regulation

A

o Activity of respiratory muscles is transmitted to and from the brain by phrenic and intercostal nerves
o Neural centers that control rate and depth are located in the medulla and pons

 Medulla
• Sets basic rhythm of breathing and contains a pacemaker (self-exciting inspiratory center) called the ventral respiratory group (VRG)

• Inspiration Centre stimulates the diaphragm and intercostal muscles
o Achieved by efferent nerve impulses sent through the phrenic and intercostal nerves
o As lungs fill with air –> stretch receptors in the bronchioles and alveoli prevent over inflation of alveolar sacs
o Send nerve impulses to medulla via the vagus nerve to start exhalation

 Pons
• Smoothes out respiratory rate
• Coordinates transition from inspiration to expiration

Medulla and Pons work together to create a normal rhythmic breathing pattern

49
Q

Non-Neural Factors Influencing Rate and Depth: Physical Factors

A

 Increased body temperature
 Exercise
 Talking
 Coughing

50
Q

Non-Neural Factors Influencing Rate and Depth: Volition (concious control)

A

 During singing and swallowing breath control is important
 Many have held breath underwater to swim
 Respiratory centres will ignore attempts to control breathing when 02 supply in blood is low or blood pH is falling

51
Q

Non-Neural Factors Influencing Rate and Depth: Emotional Factors such as fear, anger and excitement

A

 Panting when frightened –> result from emotional stimulus acting through centres in the hypothalamus

52
Q

Non-Neural Factors Influencing Rate and Depth: C02 Levels

A

Central chemoreceptors constantly monitor changes in cerebrospinal fluid pH
• Decrease –> high level of C02 within body
• When detected –> stimulate the brains inspiratory centre –> sends impulses via the vagus and glossopharyngeal nerves
• Inspiratory centre increases the rate and depth of breathing
• Result is a fresh supply of oxygen and lowered C02 levels

 When metabolism increases –> oxygen consumption increases, and body produces more C02

 The body’s need to rid itself of CO2
• Only chemical which can cross the blood brain barrier

 Increased levels of carbon dioxide (and thus, a decreased or acidic pH) in the blood increase the rate and depth of breathing
• Also lead to more hydrogen ions in the body –> cause pH of CSF to decrease

 Changes in carbon dioxide act directly on the medulla oblongata
 C02 is the main chemical driving force behind respiration

53
Q

Non-Neural Factors Influencing Rate and Depth: 02 Levels

A

 Changes in oxygen concentration in the blood are detected by peripheral chemoreceptors in the aorta and common carotid artery
• Also, mildly sensitive to changes in the C02

 Information is sent to the medulla
 Oxygen is the stimulus for those whose systems have become accustomed to high levels of carbon dioxide as a result of disease

54
Q

Non-Neural Factors Influencing Rate and Depth: Chemical Factors

A

Hyperventilation
• Rising levels of CO2 in the blood (acidosis) result in faster, deeper breathing
• Exhale more CO2 to elevate blood pH
• May result in apnea and dizziness and lead to alkalosis

Hypoventilation
• Results when blood becomes alkaline (alkalosis)
• Extremely slow or shallow breathing
• Allows CO2 to accumulate in the blood

55
Q

Control of Respiration: Summary

A

Normal respiratory rate (eupnoea)
o 12 to 15 respirations per minute

Hyperpnea
o Increased respiratory rate, often due to extra oxygen needs (e.g., when exercising)

Hyperventilation
o Increased rate and depth of breathing
o Exceeds the bodies need to remove C02
o Exhale more C02 than should  results in greater blood pH

Apnoea
o Cessation of breathing

Hypoventilation
o Extremely slow or shallow breathing

56
Q

Chronic Obstruction Pulmonary Disease (COPD)

A

o Exemplified by chronic bronchitis and emphysema

Shared features of these diseases
 Patients almost always have a history of smoking
 Labored breathing (dyspnea) becomes progressively worse
 Coughing and frequent pulmonary infections are common
 Most COPD patients are hypoxic, retain carbon dioxide and have respiratory acidosis, and ultimately develop respiratory failure

57
Q

Chronic Bronchitis

A

o Mucosa of the lower respiratory passages becomes severely inflamed
o Excessive mucus production impairs ventilation and gas exchange
o Patients become cyanotic and are sometimes called “blue bloaters” as a result of chronic hypoxia and carbon dioxide retention

58
Q

Emphysema

A

o Alveoli walls are destroyed; remaining alveoli enlarge
o Chronic inflammation promotes lung fibrosis, and lungs lose elasticity
o Patients use a large amount of energy to exhale; some air remains in the lungs
o Sufferers are often called “pink puffers” because oxygen exchange is efficient
o Overinflation of the lungs leads to a permanently expanded barrel chest
o Cyanosis appears late in the disease

59
Q

Lung Cancer

A

o Leading cause of cancer death for men and women
o Nearly 90 percent of cases result from smoking
o Aggressive cancer that metastasizes rapidly

Three common types
 Adenocarcinoma
 Squamous cell carcinoma
 Small cell carcinoma

Anatomy and Physiology (14 decks)

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