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Flashcards in the respiratory system Deck (46):

what are the functions of the respiratory / circulatory system

- R: pulmonary ventilation, breathing, inspiration / expiration
- C/R: gas exchange of O2 and CO2 from air to lungs vice versa
- C: transport O2 and CO2 around body systemic BV and tissues / cells
- other: regulation of pH (lungs), olfactory (nose), sound production (larynx)


list aspects of upper and lower respiratory tract

- U: nose, nasal cavity, pharynx
- L: larynx, trachea, bronchi, lungs


describe the functional anatomy (conducting / respiratory zones)

C: conducts air into lungs
- nose, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
- air is adjusted to body temp, humidified, filtered
- anatomical dead space (150mL air)
R: site of gas exchange between air and blood
- respiratory bronchioles, alveolar ducts, alveolar sac, alveoli


what is the external / internal nose

- hyaline cartilage (lateral nasal cartilage, septal cartilage, lateral crus of greater alar cartilage)
- bones (frontal / nasal bone frontal process of maxilla)
- warms / moisturises / filters air, modifying speech
- large cavity in anterior aspect of skull
- palatine / maxillary bones (hard palate), ethmoid bone, nasal conchae (maxillary), nasal septum / vomer (medial wall)
- communicates with pharynx


describe the nasal cavity

- superior / middle / inferior nasal conchae: protrude from lateral walls, increase SA, enhance air turbulence
- respiratory mucosa: mucous / serous contain lysozyme and defensins, ciliated epithelium move contaminated mucous posteriorly to throat
- olfactory mucosa: lines superior cavity, olfactory receptors (form olfactory nerve)


what is the pharynx

- muscular tube (13cm), starts at choana (base of skull) ends at cricoid cartilage (C6)
- nasopharynx, oropharynx, laryngopharynx (becomes oesophagus)
- passage of air and food, resonating chamber (modify quality of voice), immune (adenoids in nasopharynx / palatine / lingual tonsils in oropharynx)
- 2 layers, outer circular and inner longitudinal (similar to intestine), skeletal muscles (swallowing)


what is the larynx

- midline of neck (C4-C6), anterior of oesophagus, attaches superiorly to hyoid bone (U shape)
- connects laryngopharynx to trachea
- airway, routes air and food, voice production
- hollow muscular, 9 cartilages, dense connective tissue


what are the vocal ligaments

- elastic fibres (core of vocal cords)
- opening between them is the glottis
- posterior cricoarytenoid muscles (abduction), lateral cricoarytenoid muscles (adduction), air ruches up from lungs folds vibrate to produce sound


how is voice produced

1. adduction (closed)
2. air exhaled upwards, blows them apart, folds = rapid vibratory pattern
3. phonation: vibration of vocal folds, provides sound source (loudness = pressure, pitch = tension)
4. resonation: modification of voice, chambers of pharynx, oral / nasal / sinus cavities = amplify / enhance quality
5. enunciation: shaping / articulation of sound into language by muscles of pharynx, tongue, and lips


what is the trachea

- windpipe, from larynx to T5, 12cm, 2.5 diameter, anterior to oesophagus
- tubular passage for air
- mucosa: pseudo stratified ciliated columnar epithelium with goblet cells at luminal surface, basal cells, contain cilia
- submucosa: connective tissue , elastic / reticular fibres, seromucous glands
- hyaline cartilage: 16-20 incomplete rings (semi rigid support), posteriorly attach to oesophagus via fibromuscular membrane (trachealis muscle and elastic connective tissue)
- adventitia: outermost layer, connective tissue, encases hyaline cartilage


what is the bronchi

- air passages, 23 orders of branching (bronchial respiratory tree), conducting / respiratory zones
- primary: at T5 divides into right (vertical, shorter, wider, contain incomplete rings of cartilage) and left primary bronchus
- secondary / lobar: 2 in left lung, 3 in right lung (supply lobes of the lungs)
- tertiary / segmental:
- bronchioles
- terminal bronchioles (end of conducting zone, beginning of respiratory zone)
- respiratory zone: respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli


describe histological changes in the different sections of the bronchi

- 1-3: pseudo stratified ciliated columnar epithelium, protection, more than one layer, cilia
- larger bronchioles: simple ciliated columnar epithelium (some goblet / Clara cells)
- smaller bronchioles: simple ciliated cuboidal epithelium (no goblet cells)
- terminal: simple non-ciliated cuboidal epithelium, gas exchange, thin layer of cells


describe structural changes in the different sections of bronchi

- cartilage plates gradually replace rings of cartilage in primary bronchi, disappear in distal bronchioles
- smooth muscle: replaces cartilage, no cartilage = muscle spasms close airways (asthma, allergic reactions)
- ANS: sympathetic (epinephrine = relaxation / dilation) and parasympathetic (norepinephrine = contraction / constriction)


what are the lungs

- from diaphragm to upper margin of first rib (apex)
- mediastinum (separates lungs)
- base (concave, lies over convex diaphragm)
- costovertebral surface (matches rounded curvature of ribs)
- right: 3 lobes, separated by oblique / horizontal fissures
- left: 2 lobes (oblique fissure), 10% smaller, cardiac notch (medially)
- pleura: serous membrane,
- visceral (outer surface of lungs)
- parietal (inner of thoracic and mediastinum)
- intrapleural space: pleural cavity, thin liquid film, prevents separation of pleural sheets, lubrication, friction free movement


describe the conducting zone structures

- lobes are subdivided into bronchopulmonary segments
- segment: small bronchi, bronchioles, terminal bronchiole, respiratory bronchiole
- bronchopulmonary segments supplied by segmental bronchi
- 9 in left lung, 10 in right lung
- segments further divided into lobules (supplied by bronchioles)


what BV supply the lungs

- receive 2 sets of arteries
- pulmonary: carry deoxygenated blood through pulmonary parenchyma
- bronchial arteries: branch of aorta, perfuse the muscular walls of bronchi and bronchioles


what is the respiratory zone

- around 300 million alveoli
- most of lungs volume
- main site of gas exchange
- SA = 50-100 m2


what are alveoli

- cube shape structures surrounded by fine elastic fibres
- sac: 2 or more alveoli with a common opening
- pore: connect adjacent alveoli, allow air pressure throughout lung to be equalised


describe alveoli epithelium

- type 1: simple squamous epithelial cells, continuous lining along walls
- type 2: simple scattered rounded / cuboidal cells, contain microvilli, secrete surfactant and antimicrobial proteins
- surfactant: mixture of phospholipids and lipoproteins (reduces tendency of alveolar wall to collapse, lower tension)
- alveolar macrophages: dust cells, remove cellular debris, keep surfaces sterile


what is the respiratory membrane

- exchange of O2 and CO2 between air spaces in lungs and blood
- 0.5 um thick, air-blood barrier to allow rapid diffusion of gases
- alveolar / capillary walls fused basement membranes (four layers)
1. type 1, type 2, alveolar cells / macrophages (alveolar wall)
2. epithelial basement membrane
3. capillary basement membrane
4. capillary endothelium


what is pulmonary ventilation (external and internal)

- inspiration and expiration of air
- air flows to lungs by pressure (P) differences between atmosphere and alveoli
- external pulmonary: exchange of gases between air and blood
- internal: exchange of gases between systemic capillaries and cells


what are the gas laws

- pressure: of a gas is defined as the force that the gas exerts on the walls of its container
- airflow: driven by pressure gradient
- movement: air moves from regions of higher pressure to lower pressure


what is boyles law

- P and V of gas in closed container are inversely proportional when T is held constant
- V change = P change
- P change = gases flow to equalise pressure (ventilation)


what is atmospheric pressure

- force per unit of area exerted against a surface by the weight of the air above the surface
- reference pressure
- Patm (760mmHg)


what is intrapulmonary pressure

- intra-alveolar P: Palv/Ppul, pressure in alveoli, 760 mmHg, fluctuates with breathing, equalises with Patm
- intra-pleural P: Pip, pressure in pleural cavity, always negative in comparison 754-6mmHg, two inward forces promote lung collapse / elastic recoil / decrease SA, hence one outward enlarges lungs


what are the relationships between the different pressures

- Palv and Pip = transpulmonary pressure, keeps airways open, increased pressure = larger lungs
- pneumothorax if Pip > Palv, lungs collapse, following trauma


what are respiratory muscles

- most important, dome shaped, skeletal muscle, partition between thoracic / abdominal
- innervated by phrenic nerve
- 3 holes: inferior vena cava, oesophagus, aorta
- contraction: enlarge T cavity diameter and V, 75% airflow entering lungs during normal breathing
- pregnancy / obesity (prevent diaphragmatic flattening)
external IC:
- superficial, elevate ribs
- increase T cavity V, 25% air entering lungs


what are accessory muscles of inspiration / expiration

- minimum contribution, deep, forceful movement
- sternocleidomastoid: elevates sternum
- scalene: elevates first 2 ribs
- pectoralis minor: elevates 3-5 ribs
- internal IC: deeper, pulls ribs inferiorly, forced expiration, increase P in A / T cavities
- external / internal oblique, transversus / rectus abdominus (downward rib movement, increase intra-abdominal P)


describe process of inspiration (active)

1. inspiratory muscles contract (diaphragm descends, external intercostals contract - rib cage rises)
2. thoracic cavity V increases
3. lungs are stretched (intrapulmonary V increases)
4. intrapulmonary P drops, boyle’s law, lower than atmospheric P (758 mmHg)
5. air (gases) flows into lungs down its P gradient until intrapulmonary P is equal to atmospheric P


describe process of expiration (passive)

1. inspiratory muscles relax (diaphragm rises, external intercostals relax - rib cage descends due to elastic recoil of costal cartilage)
2. thoracic cavity V decreases
3. elastic recoil of lungs; intrapulmonary V decreases
4. intrapulmonary P rises (762 mmHg), greater than the atmospheric P
5. air flows out of the lungs down its P gradient until intra-pulmonary P is equal to atmospheric P
- forced expiration is an active process (abdominal / internal IC)


overview of inspiration / expiration and changes in pressure / volume

- inspiration: P inside lungs decrease, V increases, pleural cavity P = more negative = chest wall expands 0.5 L air movement
- expiration: P inside lungs increase, V decrease, pleural cavity P = less negative = chest wall retracts 0.5 L air movement


how does airway resistance influence pulmonary ventilation

- friction in the air passageways causes resistance
- decreases air passage, causes breathing movements to become more strenuous
- greatest resistance to air flow occurs in the midsize bronchi.
- smooth muscle: walls of airways, ANS, relaxation / dilation = inspiration vice versa
- COPD: chronic obstructive pulmonary disease / asthma, continuous contraction, decrease diameter, closing of airways continuously


how does alveolar surface tension influence pulmonary ventilation

- molecules of fluid lining alveoli are attracted to each
- produces surface tension that constantly draws the alveoli to their smallest possible dimension
- surfactant: type 2, reduce alveolar surface tension, reduce inward force
- deficiency of surfactant: collapse of alveoli after expiration, difficulty filling lungs with air


how does lung compliance influence pulmonary ventilation

- compliance: measure of lungs capacity to expand V as result of a change in pulmonary P
- high: easily expand
- low: resistance to expand
- pulmonary fibrosis: low, elastic replaced by collagen, lose ability to inflate during inspiration
- emphysema: high, elastin = degraded, destruction of lung tissue, easily inflate, reduce capacity to recoil (forced expiration)


what diseases are caused by decreased lung compliance

pulmonary fibrosis: scarring and thickening of tissue around alveoli
- shortness of breath, dry cough, fatigue, weight loss
- chest x-ray, CT, pulmonary function testing, bronchoscopy / biopsy
- treated: corticosteroid, oxygen therapy, rehabilitation
tuberculosis: caused by mycobacterium tuberculosis, - large lesions leading to tissue death, healing by fibrosis / scaring
- cough, fever, weight loss, night sweats, tiredness, loss of appetite, blood stained sputum
- chest x-ray, sputum sample
- treatment: antibiotics to obtain eradication of bacteria (6 months)


what disease is caused by increased lung compliance

emphysema: rupture of inner wall of alveolar sacs
- 1 large air space instead of many little ones
- cough, wheezing, shortness of breath, difficulty to expire
- chest x-ray, CT, pulmonary function testing
- treatment: bronchodilator, inhaled steroid, antibiotic, rehabilitation, oxygen therapy


describe the process of gas exchange (external respiration)

1. oxygen diffuses from alveolar air (Po2 105mmHg high) into blood of pulmonary capillaries (Po2 40mmHg low)
2. continues until Po2 of pulmonary capillaries matches Po2 of alveolar air
3. CO2 diffuses from deoxygenated blood in pulmonary capillaries (Pco2 45mmHg high) to alveolar air (Pco2 40mmHg)
4. continues until Pco2 blood reaches 40mmHg


how is gas / CO2 transported in the blood

- gases transported as liquid, dissolves in proportion to its partial pressure
- more CO2 dissolved in blood than O2 because CO2 is 24x more soluble than O2
- air we breath is mostly N2, very little dissolves = very low solubility
- CO2 never free
- combined to form carbonic acid or carbonate


how is oxygen transported in blood

- 1.5% plasma and 98.5% bound to haemoglobin (Hb) in RBC (oxyhaemoglobin)
- heme portion = 4 iron atoms = 4 O2 atoms
- higher Po2 = more O2 combines with Hb


what is the oxygen haemoglobin dissociation curve

- relationship between partial pressure of O2 and percent saturation of Hb and Po2
- depends on: Po2 and affinity between O2 and Hb
- high Po2 in lungs: loading portion of O2-Hb curve
- low Po2 in tissue: unloading portion of O2-Hb curve (75% saturated)
- Po2 > 60: almost flat, little change in saturation
- Po2 < 60: very steep small changes greatly reduce O2 in Hb


how does the respiratory system react to exercise

- recruiting reserve capacity
- rest 5 L min, small cardiac output 2/3 physiological dead space
- exercise: >15 L min, more capillaries conduct blood, increase cardiac output, no reserve, no physiological dead space


what is cystic fibrosis

- genetic disorder, epithelial transport of Cl in membrane of cells
- mucous secreted in airways, closure of airways, multi organ failure, infection of lungs, malnutrition


what are the effects of smoking

- arteriosclerosis: deposition of fatty plaques on inner wall of arteries
- emphysema (enlarged alveolar sacs)
- chronic bronchitis (swollen passages, increase mucous)
- pathophysiological changes: increase neutrophils, chronic inflammation


what controls the respiratory system

- respiratory muscles: brain stem, reticular formation of medulla oblongata and pons
- pneumotaxic area: inhibitory impulses to DRG (limit inspiration)
- apneustic area: stimulatory impulses to DRG (prolong inspiration)
- inspiratory area: dorsal respiratory group (DRG), basic rhythm, excitatory impulses to diaphragm (phrenic), and intercostals (intercostal)
- expiratory area: ventral respiratory group (VRG), inspiratory / excitatory neurons, forceful breathing, excite accessory muscles


what chemical factors influence the respiratory system

- C chemoreceptors: ventrolateral area of medulla (H+ and CO2)
- P chemoreceptors: aortic and carotid bodies (H, CO2 and O2)
- stimulate change in respiratory muscles, change in CO2 and O2


what higher brain centres influence the respiratory system

- cortical controls: defensive mechanism, allows to hold breath during toxic environment, water, smoke, fumes
- hypothalamus: limbic system (influence of emotional stimuli / hyperventilation, pain anxiety)
- body temp: rise acts to increase rate (loss of heat)