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Anatomy and Physiology > Respiratory system > Flashcards

Respiratory system Flashcards

1
Q

What are the key functions of the respiratory system?

A

regulation of blood pH - respiratory system changes CO2 levels in blood
produces chemical mediators - lungs produce ACE which is a key component in blood pressure regulation
sound production - involved in speaking, singing and non-verbal communication, as air moves through the vocal cords
provides olfactory sensations - as molecules are drawn into the superior portions of the nasal cavity the olfactory epithelium sends messages to the CNS
protection - microorganisms can be prevented from entering the respiratory system from the atmosphere (by nasal hair) or they can be removed from respiratory surfaces (by coughing)

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2
Q

How is the respiratory system structurally divided?

A 
upper respiratory tract (URT) and lower respiratory tract (LRT) 
conducting zone (carrying gases) and respiratory zone (gas exchange)
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3
Q

What are the organs of the respiratory system?

A

the nose, pharynx, larynx, trachea, two bronchi, bronchioles, alveoli, two lungs and muscles of breathing (i.e. intercostal muscles and diaphragm)

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4
Q

The nose is divided into which two portions?

A

external nose and nasal cavity

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5
Q

What does the external nose consist of?

A 
hyaline cartilage (for slight flexibility), nasal bones and extensions of the frontal and maxillary bones
the nostrils (external nares) are on the under surface of the external nose
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6
Q

What are the walls of the nostrils formed by?

A

lateral nasal cartilages (below the nasal bones) and the alar cartilages

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7
Q

How does air enter into the vestibule (anterior portion of the nasal cavity)?

A

via the flexible tissues of the nose

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8
Q

What is the structure and function of the vestibule epithelium?

A

contains coarse hairs that extend across the nostrils

large airborne particles get trapped and cannot enter the nasal cavity

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9
Q

What is the nasal cavity?

A

a large space situated below the nasal bones and above the oral cavity
lined with mucous membranes and muscle
joins the external nose anteriorly and posteriorly and connects with the pharynx via two internal nares (choanae)

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10
Q

The nasal cavity is divided into which two regions?

A

small superior region - contains olfactory epithelium

large inferior region - lined with pseudostratified ciliated columnar epithelium and goblet cells

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11
Q

What is the nasal septum?

A

a perpendicular partition which divides the right and left sides of the nasal cavity
the anterior nasal septum consists of septal nasal cartilage
the rest of the nasal septum is formed by the vomer, vertical plate of the ethmoid, maxillae and palatine bones

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12
Q

What is the hard palate (floor of the nose) formed by?

A

the palatine process of the maxillae and the palatine bone

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13
Q

Which two ducts open into the nasal cavity?

A

paranasal sinuses and nasolacrimal ducts

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14
Q

What helps to keep surfaces of the nasal cavity moist and clean?

A

paranasal sinuses secrete mucus

nasolacrimal ducts drain tears

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15
Q

What acts as resonating chambers involved in sound production as we speak or sing?

A

paranasal sinuses and the nasal cavity

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16
Q

The walls of the nasal cavity contain which three shelf-like projections?

A

superior, middle and inferior nasal conchae

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17
Q

What are the functions of the conchae?

A

to divide the nasal cavity into channels (meatuses)
to increase SA of internal nose and prevent dehydration by catching water droplets in exhalation
they contain many blood vessels so as inhaled air passes through the nasal cavity the conchae and meatuses deliver heat and moisture
the conchae contain goblet cells to secrete mucus that moistens the air and traps dust particles
cilia propel the mucus towards the pharynx where it can be swallowed or spat out

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18
Q

What is the pharynx?

A

a hollow muscular structure involved in both the respiratory and digestive systems

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19
Q

Where is the pharynx positioned?

A

it starts at the internal nares and extends as far as the cricoid cartilage
it lies behind the nasal and oral cavities and in front of the cervical vertebrae

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20
Q

What is the structure and function of the pharynx?

A

pharynx wall consists of skeletal muscle that, when relaxed, maintains patency
contraction of the skeletal muscle helps in the process of swallowing (deglutition)
it acts as a resonating chamber for sound and contains the lymphoid organs (tonsils)

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21
Q

The pharynx is divided into which three regions?

A

nasopharynx, oropharynx, laryngopharynx

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22
Q

What is the structure of the nasopharynx?

A

lies posterior to the nasal cavity and extends to the soft palate
the uvula is the posterior extension of the soft palate
lined with pseudostratified ciliated columnar epithelium
the walls of the nasopharynx contain five openings - two internal nares, two openings that lead to the auditory tubes, and an opening into the oropharynx
the posterior wall contains the pharyngeal tonsil (adenoid)

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23
Q

What is the structure of the oropharynx?

A

extends from the soft palate to the epiglottis
the fauces is the opening from the oral cavity into the oropharynx
lined with non-keratinised stratified squamous epithelium that protects it from abrasion
contains palatine tonsils and lingual tonsils

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24
Q

What is the structure of the laryngopharynx?

A

lined with non-keratinised stratified squamous epithelium
posteriorly the laryngopharynx extends from the epiglottis to the oesophagus
anteriorly it conducts air to the larynx

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25
Q

What is the larynx?

A

a hollow muscular structure that connects the laryngopharynx and trachea

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26
Q

Where is the larynx positioned?

A

midline in the neck, anterior to the oesophagus and from the fourth to sixth cervical vertebrae (C4-C6)

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27
Q

What is the structure of the larynx?

A

larynx wall consists of nine pieces of cartilage
three occur singly (thyroid, cricoid and epiglottis)
six occur in pairs (arytenoid, corniculate and cuneiform)
the cartilages are connected by muscles and ligaments
intrinsic muscles connect the cartilages to each other
extrinsic muscles connect the cartilages to other structures in the throat

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28
Q

What is thyroid cartilage (Adam’s apple)?

A

largest cartilage
present in both males and females but usually larger in males due to the influence of sex hormones in puberty
attached to the cricoid cartilage by the cricothyroid ligament

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29
Q

What is cricoid cartilage?

A

most inferior cartilage
forms the base of the larynx
attached to the first ring of the trachea by the cricotracheal ligament

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30
Q

What is the epiglottis?

A

attached to the thyroid cartilage and projects towards the tongue
the broad portion of the epiglottis is unattached and free to move up and down

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31
Q

How does the epiglottis prevent food and drink from entering the larynx?

A

the larynx and pharynx rise during swallowing
as the pharynx elevates it widens to receive the bolus
the larynx rises simultaneously and the epiglottis moves down to form a lid over the glottis (two true vocal cords and the space between them)
this directs the bolus towards the oesophagus and prevents it from entering the larynx
if small particles enter the larynx then a cough reflex usually expels them

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32
Q

What are the arytenoid cartilages?

A

responsible for sound production

they influence the movement of the mucous membranes (true vocal cords)

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33
Q

What are the corniculate cartilages?

A

found at the apex of each of the arytenoid cartilages

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34
Q

What are the cuneiform cartilages?

A

anterior to the corniculate cartilages

support the vocal cords and lateral aspects of the epiglottis

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35
Q

What is the trachea?

A

tubular passageway for air approx. 12 cm long and 2.5 cm in diameter
made of dense regular connective tissue and smooth muscle that is reinforced with C-shaped rings of hyaline cartilage anteriorly and laterally
posteriorly the trachea has an elastic ligamentous membrane and bundles of smooth muscle (trachealis muscle)
contraction of the smooth muscle narrows the diameter of the trachea
the trachea divides into the right and left primary bronchi

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36
Q

What is the function of the cartilage in the trachea?

A

to protect the trachea and keep the passageway open for air movement

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37
Q

What happens during coughing?

A

smooth muscle contracts and air moves rapidly through it

mucus and foreign objects are expelled from the trachea

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38
Q

What is the mucociliary escalator?

A

mucous membrane of the trachea consists of pseudostratified ciliated columnar epithelium and goblet cells
goblet cells secrete mucus which traps foreign particles
cilia propel the mucus towards the pharynx where it is swallowed

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39
Q

What are the lungs?

A

conical-shaped organs located in the thoracic cavity

consist of a wide concave base that rests on the diaphragm and the apex which projects above the clavicle

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40
Q

Where does the bronchus, blood vessels, nerves and lymphatic vessels enter?

A

hilum

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41
Q

How do the lungs accommodate the position of the heart?

A

the left lung is smaller than the right and has an indentation called the cardiac impression

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42
Q

How many lobes does the left lung have?

A

two (superior and inferior)

separated by the oblique fissure

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43
Q

How many lobes does the right lung have?

A

three (superior, middle and inferior)
the transverse fissure separates the superior and middle lobes
the oblique fissure separates the middle and inferior lobes

44
Q

What is the pleural membrane?

A

double-layered membrane of each lung
the parietal pleura is attached to the inside of the thoracic cavity
the visceral pleura is attached to the surface of the lungs
the pleural cavity between the pleura contains pleural fluid which provides lubrication when breathing
the surface tension of the pleural fluid holds the two layers of the pleura together which keeps the chest wall and the lungs in close proximity
the pleura and pleural fluid create a pressure gradient which assists in inflation of the lungs
the pleura compartmentalises the organs of the thoracic cavity which prevents the spread of infection between organs

45
Q

What is the structure of the right primary bronchus?

A

larger in diameter and extends in a more vertical direction than the left
subdivides into three secondary (lobar) bronchi

46
Q

What is the structure of the left primary bronchus?

A

subdivides into two secondary (lobar) bronchi

47
Q

What is the structure of the secondary and tertiary bronchi?

A

secondary bronchi divide into tertiary (segmental) bronchi - ten in the right lung and eight in the left
secondary and tertiary bronchi are supported with plates of overlapping cartilage

48
Q

Where does the bronchial tree receive its blood supply?

A 
bronchial artery (arising from the aorta) 
branches of the pulmonary artery closely follow the bronchial tree as it moves towards the alveoli
49
Q

What is the structure of the bronchioles?

A

small (1 mm diameter or less) continuations of the airway lined with cuboidal epithelium and smooth muscle that allows them to constrict/dilate
each bronchiole divides into 50-80 terminal bronchioles which mark the end of the conducting zone
contain no cartilage, goblet cells or submucosal glands
each terminal bronchiole divides into 2+ respiratory bronchioles which mark the start of the respiratory zone
contain small amounts of muscle and are non-ciliated
further subdivide into 2-10 alveolar ducts that end with alveolar sacs

50
Q

What is an alveolus?

A

a small cup-shaped pouch lined with simple squamous epithelium and supported by a thin elastic basement membrane

51
Q

The walls of the alveoli consist of which two types of cells?

A 
type 1 (simple squamous epithelial cells) - main site for gas exchange
type 2 (cuboidal epithelial cells) - secrete alveolar fluid to keep the surface between the air and cells moist
52
Q

What is surfactant?

A

included in the alveolar fluid
mixture of phospholipids and lipoproteins
lowers the surface tension of the alveolar fluid and maintains patency of the alveoli

53
Q

Where are alveolar macrophages found?

A

in the connective tissue and lumen of the alveoli

54
Q

What is the function of the alveolar macrophages?

A 
last line of defence against inhaled particles
large particles (>10 μm in diameter) are usually trapped by the nasal hair or in the mucus of the URT
smaller particles (2-10 μm in diameter) are usually trapped in the mucus of the bronchi and bronchioles and removed by the mucociliary escalator 
very small particles (<2 μm in diameter) can enter the alveoli where they are phagocytosed by macrophages
55
Q

What surrounds each alveolus?

A

many capillaries which consist of a single layer of epithelial cells and a basement membrane
the alveolar and capillary walls together form the respiratory membrane and allow the diffusion of O2 and CO2 between the air spaces and the blood

56
Q

What is ventilation?

A

the process by which oxygen and carbon dioxide are exchanged between the atmosphere and somatic cells

57
Q

What are the three distinct phases of ventilation?

A

pulmonary ventilation - inhalation and exhalation of air involving the exchange of air between the atmosphere and the alveoli
external respiration - the diffusion of gases between the alveoli and the pulmonary capillaries across the respiratory membrane
internal respiration - the diffusion of gases between blood in the systemic capillaries and the tissues

58
Q

What happens during inhalation?

A 
external intercostal muscles contract
diaphragm contracts
volume of the thorax increases
pressure inside the thorax decreases
air rushes into the lungs to maintain a pressure equilibrium
59
Q

What are the names of the accessory muscles of inspiration involved in increasing the size of the thoracic cavity in times of deep forceful inhalations?

A 
sternocleidomastoid muscles (run between the mastoid process and the sternum and lift the sternum)
scalene muscles (lift the first two ribs)
pectoralis minor muscles (lift the third to fifth ribs)
60
Q

What happens during exhalation?

A 
external intercostal muscles relax
diaphragm relaxes
volume of the thorax decreases
pressure inside the thorax increases
air rushes out of the lungs to maintain a pressure equilibrium
61
Q

What happens in times of forceful exhalations?

A

contraction of internal intercostal muscles and abdominal muscles

62
Q

How does the surface tension of the alveolar fluid affect airflow?

A

surfactant disrupts the hydrogen bonds of water which reduces surface tension

63
Q

How does lung compliance affect airflow?

A

lungs and chest wall that expand easily have high compliance
lungs and chest wall that resist expansion have low compliance
related to two factors - elasticity and surface tension
elastic fibres in the lungs stretch easily
surfactant reduces surface tension
lungs usually have high compliance but this is reduced by degenerative lung diseases that cause scarring

64
Q

How does airway resistance affect airflow?

A

smooth muscle of bronchioles alters size of lumen
bronchoconstriction reduces airflow
stimulated by airborne irritants (e.g. in asthma), the PNS or release of histamine (in anaphylaxis)
bronchodilation increases airflow
stimulated by the SNS and release of adrenaline (epinephrine) which binds to Beta-2 receptors and causes relaxation of smooth muscle in bronchial wall

65
Q

How does smoking increase the likelihood of developing chronic obstructive pulmonary disease (COPD)?

A

smoking paralyses the cilia of the bronchial tree
this reduces the effectiveness of the mucociliary escalator in clearing the lungs of mucus
the resulting congestion can cause infection and inflammation causing scarring of the lung tissue
over time the tissues become less elastic and the bronchioles become even narrower

66
Q

What are some of the main symptoms of COPD?

A

productive and persistent cough
frequent chest infections often requiring antibiotics
shortness of breath which progressively gets worse; occurring initially with exercise, but then occurring with non-strenuous activities, and finally at rest, and eventually needing oxygen therapy

67
Q

What device can be used to measure the volume of air exchanged during breathing?

A

spirometer

68
Q

What is respiratory rate?

A

number of breaths per minute

12-16

69
Q

What is tidal volume (VT)?

A

volume of air inhaled/exhaled in one breath

500 ml

70
Q

What is minute volume (MV)?

A

volume of air inhaled/exhaled per minute (litres)

tidal volume x respiratory rate

71
Q

What is the alveolar ventilation rate?

A

actual volume of air per minute that reaches the respiratory zone

72
Q

What is inspiratory reserve volume (IRV)?

A

volume of air that can be inhaled with maximum effort above tidal inspiration
male - 3100 ml
female - 1900 ml

73
Q

What is expiratory reserve volume (ERV)?

A

volume of air that can be exhaled with maximum effort above tidal exhalation
male - 1200 ml
female - 700 ml

74
Q

What is residual volume (RV)?

A

volume of air left in the lungs after exhalations with maximum effort - keeps alveoli inflated between breaths
male - 1200 ml
female - 1100 ml

75
Q

What is vital capacity (VC)?

A

volume of air exhaled with maximum effort after maximum inspiration (VT + IRV + ERV = VC)
male - 4800 ml
female - 3100 ml

76
Q

What is inspiratory capacity (IC)?

A

maximum volume of air inhaled after a normal exhalation (VT + IRV = IC)
male - 3600 ml
female - 2400 ml

77
Q

What is functional residual capacity (FRC)?

A

volume of air left in the lungs after exhalation (RV + ERV = FRC)
male - 2400 ml
female - 1800 ml

78
Q

What is total lung capacity (TLC)?

A

maximum volume of air the lungs can hold (RV + VC = TLC)
dependent on age, gender and height
male - 6000 ml
female - 4200 ml

79
Q

Passive diffusion is governed by which two gas laws?

A

Dalton’s law and Henry’s law

80
Q

What is Dalton’s law?

A

the total pressure of a gas mixture is the sum of the partial pressures of the individual gases

81
Q

What is Henry’s law?

A

at the air-water interface, for a given temperature, the amount of gas that dissolves in the water is determined by its solubility in water and its partial pressure in air

82
Q

What is external respiration?

A

gas exchange between lungs and blood

83
Q

What is internal respiration?

A

gas exchange between blood and tissues

84
Q

How is oxygen transported in the blood?

A

1.5% dissolves in plasma
98.5% binds with haemoglobin in erythrocytes
each haemoglobin molecule has four iron-containing haem groups which bind one O2 molecule
oxygen and haemoglobin bind reversibly to form oxyhaemoglobin
when all four haem groups carry an O2 molecule the haemoglobin molecule is 100% saturated
to enter the tissue cells O2 must dissociate from haemoglobin and dissolve in the plasma

85
Q

What is the oxygen-haemoglobin dissociation curve?

A

shows the ability of haemoglobin to bind with O2 at the alveoli and release it into the peripheral tissues
the S-shaped curve describes the relationship between the partial pressure of oxygen (x axis) and oxygen saturation (y axis)
as more O2 molecules bind haemoglobin, the affinity becomes greater, and PO2 increases until the maximum amount that can be bound is reached
as the curve plateaus, increasing PO2 will not lead to significant increases in saturation

86
Q

What are the factors affecting the affinity of haemoglobin for oxygen?

A

partial pressure of oxygen, acidity (pH), partial pressure of carbon dioxide, temperature, BPG (2,3-bisphosphoglycerate)

87
Q

How does the partial pressure of oxygen affect the affinity of haemoglobin for oxygen?

A

the higher the PO2 the more O2 can bind with haemoglobin
PO2 is high in pulmonary capillaries so large amounts of O2 bind to haemoglobin
PO2 is low in tissue capillaries so O2 dissolved in plasma diffuses into tissue cells

88
Q

How does acidity (pH) affect the affinity of haemoglobin for oxygen?

A

as pH decreases the affinity of haemoglobin for O2 decreases (curve shifts to right)
more O2 dissociates from haemoglobin

89
Q

How does the partial pressure of carbon dioxide affect the affinity of haemoglobin for oxygen?

A

when CO2 binds with haemoglobin it has a similar effect to that of pH (curve shifts to right)
as CO2 levels rise it causes haemoglobin to release more O2

90
Q

How does temperature affect the affinity of haemoglobin for oxygen?

A

as temperature rises more O2 dissociates from haemoglobin
heat is a by-product of metabolic reactions so more metabolically active cells produce more heat
this promotes the release of O2 from haemoglobin (curve shifts to right)

91
Q

How does BPG (2,3-bisphosphoglycerate) affect the affinity of haemoglobin for oxygen?

A

BPG is formed when erythrocytes break down glucose to form ATP
BPG decreases the affinity of haemoglobin for O2
more O2 dissociates from haemoglobin
increased levels are formed by certain hormones (thyroxine, human growth hormone, adrenaline and testosterone)

92
Q

When must you be careful in applying pulse oximetry?

A

anaemia - not enough functioning haemoglobin
dyes - some surgical procedures involve the injection of dyes into the blood to trace blood flow which affect light transmission through the blood and directly influence the pulse oximeter causing false readings
hypothermia - the body reduces heat loss from the skin by constricting peripheral blood vessels
nail polish - some nail polish and false fingernails may cause false readings

93
Q

How is carbon dioxide transported in the blood?

A

7% dissolves in plasma
23% combines with haemoglobin and plasma proteins to form carbaminohaemoglobin
70% transported as bicarbonate ions

94
Q

How is CO2 transported as bicarbonate ions?

A

as CO2 diffuses into erythrocytes in systemic capillaries it reacts with water in the presence of carbonic anhydrase (CA) to form carbonic acid (H2CO3)
carbonic acid dissociates into hydrogen (H+) and bicarbonate (HCO3-) ions
bicarbonate ions diffuse into plasma and chloride ions diffuse into erythrocytes which maintains the electrical balance between the plasma and erythrocyte cytosol
this reaction is reversed as blood passes through the pulmonary capillaries and CO2 is exhaled

95
Q

What are the neural mechanisms that control breathing?

A

neurons in the medulla oblongata and pons (responsible for involuntary control)
neurons in the motor cortex (responsible for voluntary control)

96
Q

How does the medulla oblongata regulate inspiration?

A

contains inspiratory neurons
nerve fibres travel from these neurons and synapse with neurons in the cervical and thoracic regions
impulses then travel via phrenic nerves to the diaphragm and intercostal nerves to the external intercostal muscles
these muscles contract and inhalation occurs

97
Q

How does the medulla oblongata regulate forced expiration?

A

contains expiratory neurons
nerve fibres travel from these neurons and synapse with neurons in the cervical and thoracic regions
impulses cause contraction of the abdominal and internal intercostal muscles, which further decreases the size of the thoracic cavity in forced expiration

98
Q

How does the pneumotaxic centre in the upper pons and the apneustic centre in the lower pons regulate ventilation?

A

pneumotaxic centre sends inhibitory impulses to the inspiratory area to ensure the lungs do not overfill with air
the duration of inhalation is decreased and the rate of breathing is increased when the pneumotaxic centre is active
apneustic centre sends stimulatory impulses to the inspiratory area to produce a prolonged, deep inhalation

99
Q

How does the motor cortex regulate breathing?

A

impulses from the motor cortex travel via corticospinal tracts to respiratory neurons in the spinal cord, bypassing brainstem respiratory centres
the ability to voluntarily control breathing is limited due to build-up of CO2 and H+ ions
when CO2 and H+ ions increase to a certain concentration, the inspiratory centre is stimulated and nerve impulses travel to the diaphragm and intercostal muscles and breathing resumes
the limbic system and hypothalamus can also stimulate the respiratory centre
feelings of pain and emotional stimuli can alter respiration (e.g. crying and laughing)

100
Q

Chemoreceptors are found in which two general locations?

A

centrally (brainstem) and peripherally (carotid and aortic bodies)

101
Q

What is the function of central chemoreceptors?

A

to monitor the pH of the CSF

102
Q

What is the function of peripheral chemoreceptors?

A

to monitor changes in blood

messages are sent to the respiratory centre via the vagus and glossopharyngeal nerves respectively

103
Q

How do chemoreceptors function?

A

they participate in a negative feedback mechanism that maintains the levels of pH (7.35-7.45), PCO2 (4.7-6.0 kPa or 35-45 mmHg), and PO2 (>10 kPa or >75 mmHg
if these parameters change from their normal range, chemoreceptors will stimulate the inspiratory area and the rate and depth of breathing will change

104
Q

What happens if there is an increase in PCO2?

A

pH decreases
inspiratory area will become more active
rate and depth of breathing will increase (hyperventilation)
excess CO2 is exhaled and pH increases

105
Q

What happens if there is a decrease in PCO2?

A

central and peripheral chemoreceptors are not stimulated
stimulatory impulses are not sent to the inspiratory area
the area sets a moderate rate until CO2 accumulates and PCO2 levels rise

Anatomy and Physiology (13 decks)

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