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Intermediate Human Physiology > Respiratory System > Flashcards

Respiratory System Flashcards

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1
Q

What is respiration?

A

Refers to 3 functions
1) Ventilation - breathing
2) Gas exchange - between lung surface and blood and other tissues of body
3) Oxygen utilisation - energy liberating reactions of all cells

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2
Q

How many lobes are there in the human body?

A

5 lobes (3 right, 2 left)

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3
Q

What is the primary function of the respiratory system?

A

Gas exchanges (O2 for CO2)

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4
Q

What are the secondary functions of the respiratory system?

A

1) Warming and humidifying incoming air
2) Keeping airway clean and sterile
3) Keeping airways open during pressure changes in breathing
4) Keeping alveoli open against surface tension
5) Regulation of air-flow and blood-flow

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5
Q

What structures are found in the upper respiratory tract?

A

1) Nose
2) Pharynx
3) Larynx

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6
Q

What structures are found in the lower respiratory tract?

A

1) Trachea
2) Bronchus
3) Bronchioles

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7
Q

How does air enter and exit the nose?

A

1) Air enters through nostrils (anterior nare - large debris filtered by nasal hairs)
2) Air exits through back of nasal cavity (posterior nare)

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8
Q

What is the nasal cavity?

A

1) 3 curved turbinate bones (nasal concha bones) that churn air as it passes
2) Respiratory mucosa lines the turbinates - warms, moistens and cleans

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9
Q

What are the 3 layers of the nasal respiratory mucosa?

A

1) Pseudo-stratified ciliated columnar epithelium
2) Goblet cells - secrete mucus trapping debris
3) Basement membrane adhering to thick layer of lamina propria

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10
Q

What is the lamina propria in the nasal respiratory mucosa?

A

1) Rich with blood vessels
2) Radiates heat - warm air
3) Has seromucosal glands - secrete mucus and H2O mix

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11
Q

What is the role of respiratory mucosa?

A

1) Goblet cells and seromucosal glands secrete watery mucous - humidifies air, traps particles
2) Enzymes secreted (lysozyme) break down bacteria cell wall
3) Movement of cilia move trapped particles to back of throat - normally swallowed and destroyed by stomach acid

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12
Q

What is the role of the pharynx?

A

Conducts air from nasal cavity to the larynx

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13
Q

What are the 3 regions of the pharynx?

A

1) Nasopharynx
2) Oropharynx
3) Laryngopharynx

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14
Q

What is the surface of the nasopharynx lined with?

A

1) Lined with same pseudo-stratified ciliated columnar epithelium found in nasal cavity
2) Does NOT encounter food

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15
Q

What are the oropharynx and laryngopharynx lined with?

A

1) Stratified squamous epithelium
2) Shared with digestive tract and multiple layers protect against abrasion when swallowing

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16
Q

What is the role of the larynx?

A

1) Prevents food from entering trachea when swallowing
2) Moves, upward pushing against epiglottis, closing lower respiratory pathway
3) Houses vocal chords

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17
Q

What is the structure and function of the trachea?

A

1) Stiffened by hyaline cartilage rings (C-shaped), prevents collapse
2) Conducts air between larynx and primary bronchus

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18
Q

What are the 4 distinct layers of the trachea wall?

A

1) Respiratory mucosa
2) Submucosa
3) Cartilage ring
4) Adventitia

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19
Q

What is the adventitia?

A

Band of loose connective tissue that keeps trachea in place within chest wall

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20
Q

What are the bronchi split into?

A

1) Left and right primary bronchus
2) Primary bronchus divides into 5 secondary bronchi - for lungs five lobes
3) Secondary bronchi branch into 18 tertiary bronchi - provide bronchopulmonary segments, 10 right and 8 left

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21
Q

What are the difference of the bronchi walls compared to trachea walls?

A

1) Less goblet cells
2) Broken ring of smooth muscle fibres - constrict during exhalation
3) Plates of hyaline cartilage are thinner and are less in secondary/tertiary bronchi

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22
Q

What is the role of the bronchioles?

A

Conducts air between tertiary bronchi and alveoli

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23
Q

What is the function of the elastic fibres surrounding the alveoli?

A

Holds bronchioles open during breathing and provide elastic recoil

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24
Q

What are the features of the bronchiole walls?

A

1) Ciliate simple columnar - ciliated simple cuboidal
2) Goblet cells and seromucous glands are less with each bronchiole division
3) Cartilage is absent
4) Ring of smooth muscle fibres - contract during exhalation

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25
What are the features of the alveoli?
1) Each alveoli measure about 0.2-0.5mm diameter 2) Cluster of alveoli - alveolar sac 3) Network of capillaries and supportive collagen and elastic fibres are found in narrow interstitial spaces separate alveoli
26
What are type 1 cell alveoli?
1) Simple squamous 2) Main sites of gas exchange
27
What are type 2 alveoli cells?
1) Cuboidal with microvilli 2) Secrete surfactant - complex phospholipids and proteins reducing surface tension, prevents alveolar collapse
28
What are alveolar macrophages (phagocytes)?
Engulf inhaled dust and debris that has escaped defences in the upper airway
29
What is the function of alveolar pores?
1) Allow air to pass between alveoli 2) Provide alternative routes for air if obstruction occurs/some alveoli collapse 3) Allows for gas to equilibrate to allow for maximal gas exchange
30
What is the role of the respiratory membrane in the alveoli?
Site of gas exchange - O2 for CO2
31
What is the mechanism for breathing?
Pressure gradients by air flow into the lungs caused by a 'pump' (thoracic cavity muscles) cause volume changes in thoracic cavity
32
What is the equation for Boyles Law?
Pressure (P) x Volume (V) = Constant (k)
33
What has to happen for air to enter lungs?
1) Lung pressure < atmospheric pressure 2) This increase in volume will decrease pressure (Boyle's law) 3) Lung volume increases for inspiration
34
What has to happen for air to leave lungs?
1) Lung pressure > atmospheric pressure 2) Decrease in volume will increase pressure (Boyle's law) 3) Lung volume decreases for expiration
35
What forms the thoracic cavity?
1) Ribs 2) Spine 3) Sternum 4) Diaphragm
36
What muscles are used for inspiration?
1) External intercostals 2) Diaphragm 3) Scalenes and Sternocleidomastoids (accessory muscles)
37
What muscles are used for forced expiration?
1) Internal intercostals 2) Abdominal muscles (accessory muscles)
38
How does a change in thoracic cavity volume transfer to the lung?
1) Surface tension of alveolar tends to pull lungs inward 2) Abundant elastic tissue in lungs tend to recoil and pull lung inward 3) Elastic thoracic wall tends to pull away from lung
39
What is the pleura?
1) 2 layers of serous membrane (serosa) split in to visceral and parietal 2) Visceral lines lung 3) Parietal lines inside of thorax
40
What is the benefit of having the cavity filled with pleural fluid?
1) Slippery surface aids movement 2) Surface tension holds lungs tight against thoracic wall
41
What is interpleural pressure?
1) Always negative pressure 2) Acts like suction keeping lungs inflated
42
What happens if there is a puncture of the pleural membrane?
1) Loss of negative pleural pressure removes suction that keeps lungs inflated 2) Lung collapses - pneumothorax 3) Each lung is surrounded by its own pleural membrane/cavity so change in 1 lung does not affect other
43
What are the events during inspiration?
1) Diaphragm + external intercostal muscles contract 2) Volume of thoracic cavity increases 3) Intrapleural presure becomes more negative 4) Lungs expand 5) Intrapulmonary pressure becomes negative 6) Air flows into lungs
44
What are the events during expiration?
1) Diaphragm + external intercostal muscles relax 2) Volume of thoracic cavity decreases 3) Intrapleural pressure becomes less negative 4) Lung recoil 5) Intrapulmonary pressure rises above atmospheric pressure 6) Air flows out of lungs
45
How does airway resistance affect ventilation?
1) Airflow is inversely proportional to resistance - diameter affects resistance 2) Healthy lungs typically offer little resistance
46
What does histamine do to airway resistance?
1) Constricts bronchioles 2) Increases airway resistance - decreasing airflow 3) More difficult to breathe
47
How does adrenaline affect airway resistance?
1) Dilates bronchioles - beta2 adrenergic receptor 2) Decreases airway resistance, increasing air flow 3) Easier to breathe
48
What are beta2 adrenergic receptors?
1) G protein mediated activation of adenylyl cyclase 2) Inhibits Ca2+ release - promotes muscle relaxation - results in greater airway diameter
49
What are the 2 factors that determine lung compliance?
1) Stretchability of elastic fibres within lungs 2) Surface tension within alveoli
50
What can be the result of reduced elastic tissues in lung compliance?
Fibrosis due to low lung compliance
51
What creates surface tension in the lungs?
Strong attraction between water molecules at surface of alveolar fluid - drawing water molecules closer together
52
How does surfactant interfere with water molecule attraction at the surface of alveolar fluid?
1) Reduces surface tension 2) Prevents alveolar collapse 3) Increases lung compliance
53
What are the propeties of surfactant?
1) Principally dipalmitoylphosphatidylcholine (DPPC) 2) Synthesised in Type 2 cells 3) Hydrophilic head inserts into aq. layer 4) Hydrophobic portion in air
54
What is Dalton's law of partial pressure?
1) Total pressure of gas mixture is sum of partial pressures of component gas 2) Law is true regardless of no. of gases present 3) E.g., O2 comprises 20.9% of air at sea level (760mm Hg) - PO2 = 20.9x760 = 158.8mm Hg
55
What is Henry's Law?
The amount of gas which dissolves in a liquid is proportional to partial pressure of gas and its solubility
56
What is the equation for Henry's Law?
k (equilibrium constant, different for every gas, temp. and solvent) = Px (partial pressure of gas x in equilibrium with solution) / Cx (conc. of gas x in solution)
57
Where are the sites of gas exchange for external respiration?
1) CO2 diffuses from pulmonary capillaries into alveoli 2) O2 diffuses from alveoli into pulmonary capillaries
58
Where are the sites for gas exchange for internal respiration?
1) O2 diffuses from systemic capillaries into cells 2) CO2 diffuses from cells into systemic capillaries
59
What 3 factors depends on efficient external respiration?
1) SA and structure of respiratory membrane 2) Partial pressure gradients 3) Matching alveolar airflow to pulmonary capillary blood flow
60
How does partial pressures of alveolar gases differ from those in the atmosphere?
1) Humidification of inhaled air - absorbs some O2 2) Gas exchange between alveoli and capillaries - continuous exchange of O2 and CO2 between alveoli and pulmonary capillaries 3) Mixing old and new air - alveoli do not completely empty between breaths
61
What is ventilation perfusion coupling?
Facilitates efficient gas exchange by maintaining proportionate alveoli airflow to pulmonary capillary blood flow
62
What is the effect of O2 on ventilation perfusion coupling?
1) Regions with low airflow to blood supply have low blood PO2 2) Causes local arterioles to vasoconstrict 3) Blood flow redirected to alveoli with high airflow and more O2 available
63
What is the effect of PCO2 on ventilation perfusion coupling?
1) When airflow through a bronchiole is high compared to blood supply - PCO2 falls 2) Causes bronchioles to constrict, reducing airflow - proportional to local blood flow
64
What 3 factors does internal respiration depend on?
1) Available SA (varies between tissues) 2) Partial pressure gradients 3) Rate of blood flow
65
What 2 ways is O2 required from pulmonary capillaries to peripheral tissues?
1) Dissolved in plasma (around 1.5%) 2) Combined to Hb (around 98.5%)
66
What is co-operativity in Hb affinity?
1) Hb shape changes when free of O" (tensed) 2) When in a high PCO2 environment (e.g., lung capillaries), 1 O2 binds and Hb shifts to relaxed state 3) Hb shape change makes it easier for other O2 molecules to bind to another haem group 4) Hb affinity for O2 increases as its saturation increases
67
What is the Hb dissociation curve?
1) Degree of Hb-O2 saturation dependent on level of PO2 2) O2 Hb saturation is expressed as a %
68
What are some key points of the Hb-O2 dissociation curve?
1) 98% saturation - arrives at systemic circulation 2) 75% saturation - leaves capillaries of resting tissue 3) 23% - utilisation coefficient, remaining O2 is 'venous reserve, can sustain life for 4-5mins in event of respiratory arrest
69
What happens when affinity of Hb for O2 decreases?
1) O2 more readily dissociates 2) Right shift in HbO2 dissociation curve
70
What happens if the affinity of Hb for O2 increases?
1) O2 less readily dissociates 2) Left shift in HbO2 dissociation
71
What are the factors affecting the O2-Hb dissociation curve?
1) Body temperature 2) CO2 concentration 3) Plasma pH (Bohr effect) 4) 2,3-diphosphoglycerate (2,3 DPG)
72
How does temperature affect O2-Hb dissociation?
1) Increased temp decreases Hb affinity for O2 2) Shifts curve to the right
73
How does CO2 blood transport affect Hb?
1) 23% CO2 binds predominantly to Hb to form carbaminohaemoglobin CO2 2) Reversibly binds to N-terminal of Hb, not competing for O" binding sites - causes conformational change decreasing Hb's affinity for O2 3) Hb can transport CO2 and O2 simultaneously but binding of 1 tends to inhibit binding of other - Haldane effect 4) Increasing PCO2 shifts Hb-O2 curve to right
74
What is the Bohr effect relating to pH and O2-Hb dissociation?
1) pH affects ability of Hb to bind to O2 2) H+ binds to Hb causing conformational change - decreasing Hb affinity for O2 (increase CO2 drives increase in H+ in RBCs) 3) More acidic pH shifts Hb-O2 curve to the right
75
What will cause a right shift of curve promoting O" release for metabolic need?
1) Higher CO2 production, higher PCO2 (60mmHg) 2) Increased muscle temperature 3) Lower pH - lactic acid, carbonic acid
76
How does 2,3-DPG lead to hypoxia and how does that impact the O2-Hb dissociation?
1) RBCs have no mitochondria - generate energy requirements through fermentation (not using O2 carried) 2) By-product is 2,3-DPG 3) HbO2 inhibits enzyme responsible for 2,3-DPG synthesis 4) Chronic hypoxia increases 2,3-DPG (e.g., high altitude, anaemia) 5) Lower Hb affinity for O2 - shifts curve to the right
77
Give an example of a haemoglobin pathology.
1) Single aa substitution of Hb A beta chain to form HbS 2) Low PO2 causes HbS to come out of solution and cross links to form paracrystalline gel within RBCs 3) Causes sickle shape 4) Reduced flexibility, blocks capillaries BUT resistance to malaria
78
What are the 2 types of breathing?
1) Involuntary/Rhythmic 2) Voluntary
79
What sensory feedback receptors control rhythmic breathing?
1) PCO2 2) pH 3) PO2
80
What is the role of intercostal nerves?
Provide both motor and sensory neurons
81
Where is the inspiratory centre located?
Mainly in medulla oblongata - lower region of brain stem
82
What is the function of the dorsal respiratory groups?
1) Neurons most active during inspiration but some active during expiration 2) Primarily responsible for innervation of diaphragm 3) Receive input from other areas of the brain that influence breathing rate
83
What is the role of the ventral respiratory groups?
1) Neurons active during inspiration and expiration (expiratory neurons) 2) Expiratory neurons inhibit phrenic nerve - diaphragm 3) Primarily stimulate internal and external intercostal muscles
84
What is the role of the pontine respiratory group?
Possible role in neurons switching between inspiration and expiration
85
What happens when inspiration begins firing inspiratory neurons?
1) More and more inspiratory neurons activated 2) Progressively increasing strength of respiratory muscles 3) Lasts approx. 2 seconds
86
What happens when activation of inhibitory neurons cause inhibition of inspiratory neurons?
1) Receiving input from pons, lung stretch receptors and probably other sources 2) Relaxation of respiratory muscles 3) Lasts approx. 3 seconds
87
What does the loose collection of neurons in the medulla oblongata form?
Rhythmicity centre - potential pacemaker activity
88
What are the 2 types of chemoreceptors for the modification of rhythmic breathing?
1) Central chemoreceptors - in medulla oblongata 2) Peripheral chemoreceptors - associated with aorta and carotid bodies
89
What are central chemoreceptors?
1) On the ventrolateral surface of medulla oblongata 2) Chemosensitive area 3) Anatomically distinct from but synaptically connected connected to respiratory control centre
90
What is the effect of PCO2 on central chemoreceptors?
1) Central chemoreceptors are sensitive to pH but H+ cannot cross blood brain barrier (BBB) 2) Arterial CO2 can cross BBB and enter cerebrospinal fluid 3) CO2 generates H+, lowering CSF pH 4) Medullary chemoreceptors responsible for majority of increased ventilation in response to sustained increase in PCO2 5) Response is slow - 2/3mins
91
What is the role of peripheral chemoreceptors?
1) Receive blood via small arterial branches 2) Carotid and aortic bodies send sensory info to medulla via glossopharyngeal and vagus nerves
92
What is the effect of PCO2 on peripheral chemoreceptors?
1) Not stimulated directly by CO2 but by H+ 2) Respond to other circulating acids e.g., lactic acid 3) Response is much faster (min)
93
How does PO2 effect peripheral chemoreceptors?
1) Carotid body chemoreceptors monitor PO2 2) Only responds to PO2 < 60mm Hg 3) At high altitude, PO2 will fall below 40mm Hg 4) Ventilation will increase PO2
94
How can ventilation affect blood pH?
1) Blood plasma pH maintained between 7.35/7.45 by regulation of CO2 by lungs and regulation of bicarbonate and H+ in kidneys 2) Nonvolatile acid H+ buffered by HCO3-, continually produced and kidneys excrete H+ while recovering HCO3- 3) Volatile acids (carbonic acid) released as CO2 is blown off by lungs
95
What is respiratory acidosis?
1) Fall in blood pH below 7.35 2) Caused by inadequate ventilation 3) Rise in arterial PCO2 - increased HCO3- and H+ - lower pH 4) Metabolic acidosis can partially be compensated for by hyperventilation 5) Patients would have low pH, high PCO2
96
What is respiratory alkalosis?
1) Rise in blood pH above 7.45 2) Caused by excessive ventilation (hyperventilation) 3) Fall in arterial PCO2 - decreased HCO3- and H+, gives higher pH 4) Rise in CSF pH induces cerebral vasoconstriction - dizziness 5) Metabolic alkalosis can partially be compensated for by hypoventilation 6) Patients would have high pH, low PCO2
97
What are the neurological responses to ventilation and exercise?
1) Ventilation increases within seconds of exercising 2) Anticipating exercise - learned response 3) Motor cortex - stimulates muscles, stimulates respiratory centre 4) Proprioreceptors - sensory receptors in muscles and joints that respond to changes in body position and stimulate respiratory centre
98
What are the hormonal responses to ventilation and exercise?
1) Circulating adrenaline and noradrenaline released by adrenal medulla during exercise 2) May act directly on respiratory centres 3) Lactic acid is another stimuli - anaerobic respiration

Intermediate Human Physiology (7 decks)

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