Respiration basics & Spirometry Flashcards by Emma Vande Wouwer

DRG

Dorsal respiratory group
Fundamental contral -> Initiate inspiration
Generate basic rythm : burst inspiratory AP
Make Inspiratory “Ramp” signal, controls : rate “Ramp” (lungs can fill more rapidly), ceasing point (rate of respiration, shorter ramp -> shorter inspiration)
Most neurons in NST (nucleus of the solitary tract) : sensory information from pontine respiratory group (pneumatoxic & apneustic center), vagus nerve and glossopharyngeal nerve.
Receive info from chemo,bara and stretch receptors
It gives its output to the VRG to modify breating rythm
Goes through spine and connects to muscles : Diaphragm & External intercostal muscles

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VRG

Ventral respiratory group
neurons for inspiration and expiration
inactive in quiet breathing
Contribute to extra respiration when signal “spill” on VRG
Active in forced insipiration and expiration
Goes to spine and connects to accessory muscles : internal intercostal muscle & abdominal muscle

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PRG

Pontine respiratory group

Pneumatoxic and Apneustic centers

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Pneumotaxic center

part of PRG
control rate and pattern of breathing
stronger signal : shorter inspiration & increased RR
It inhibits the apneustic center to make inhalation more or less short -> limit the amount of AP to phrenic nerve -> tidal volume down
without pneumatoxic : longer inhale, lower RR
influence VRG and DRG

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Apneustic center

part of PRG
promote inhalation
constantly stimulate neurons: signal DRG to delay the switch off of the “Ramp”signal
inhibited by stretch receptors and pneumatoxic center
influence VRG and DRG

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Regulation of breathing locations and connections

All in brainstem : medulla, pons
Pneumotaxic center above apneustic center
Both in pons to the dorsal side : towards cerebellum
Then in medulla there is the VRG and DRG
DRG towards dorsal side : to cerebellum
VRG ventral side (side of bumps on brainstem)
Pneumatoxic center connected to apneustic and DRG
Apneustic connected to DRG
DRG connected to VRG

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NTS

Nucleus of the tractus solitarius
DRG neurons
Sensory termination of glossapharyngeal and vagus nerve
Signal from : baro,chemo & stretch receptors

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Inspiratory “Ramp” Signal

Excite the diaphragm for 2 sec -> steady increase volume

Cease for 3 sec -> elastic recoil lungs & chest wall : expiration

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Stretch receptors

on lung
inhibit VRG
Signal to vagi -> DRG
too stretched -> inspiratory "Ramp" goes down RR goes up
=> inflation reflex

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Lungs gaz exchange

Inspiration: O2 in, diaphragm contract -> diaphragm down, chest muscle contract -> lungs expand
Expiration: CO2 out, muscle relax -> lungs back to normal

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O2 trajectory

Nasal cavity -> pharynx -> larynx -> trachea -> Right/Left bronchus -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar duct -> sacs -> alveoli

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Nasal cavity

hair, mucus with lyzozymes to kill bacteria, connected to sinuses ( air cavities, air becomes wet & moist, amplify sound)

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Pharynx

Nasopharynx (right after nasal cavity), orapharynx (right after oral cavity) : they are seperate by the ulva when eating
laryngopharynx: connect to oesophagus and larynx

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Larynx

Blocked by epiglotis when eating such that only air comes in and food goes to esophagus -> connects to pharynx (laryngopharynx)

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Trachea

After Larynx and connects to Right/Left bronchus
Cartilage rings as support
membrane contains (in order of inside to out) :
mucus, globet cells (secrete mucus) and ciliated columnar cells (move mucus to pharynx), basement mebrane, lamina propria, smooth muscle (nerves from autonomic nervous system lies there), cartilage

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Autonomic nervous smooth muscle airways

Sympathetic and parasympathetic nerves
Sympathetic: B2 adrenargic receptors -> increase diameter
Parasympathetic: muscarinic receptors -> decrease diameter

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Right/Left Bronchus

Connect to right/left lung
Right bronchus : wider and more vertical -> swallowed object goes there
3 generations: primary, secondary(lobar) and tertiary(segmental) then bronchioles
Same structure trachea:
membrane contains (in order of inside to out) :
mucus, globet cells (secrete mucus) and ciliated columnar cells (move mucus to pharynx), basement mebrane, lamina propria, smooth muscle (nerves from autonomic nervous system lies there), cartilage

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Bronchioles

<1mm in diameter
after 3 generations of bronchi
15-20generations and each have 50-80 terminal bronchioles
get oxygenated blood from bronchial arteries
Don’t have cartilage unlike Trachea and Right/Left bronchus !!
Instead club cells : secrete glycosaminoglycans (protects epithelium), regenerate & replace columnar cells
membrane contains (in order of inside to out) :
mucus, globet cells (secrete mucus), club cells and ciliated columnar cells (move mucus to pharynx), basement mebrane, lamina propria, smooth muscle (nerves from autonomic nervous system lies there)

Respiratory bronchioles

last bronchioles
have bulges : alveoli
connected to alveolar dyct

Alveolar duct

1.5 -2 millions

connect respiatory bronchioles to alveolar sacs

Alveolar sacs

contains collection of alveoli : gaz exchange location
Pulmonary artery deoxygenated blood -> capillary -> alveoli absorb CO2 and gives back O2 -> pulmonary veins -> heart -> body

Alveoli

mucus (epithelial cells) lined pouches
pneumocyte type 1 (most present)
pneumocyte type 2, bigger and secrete surfactant + regenarate damaged cells

Pleural fluid

circulate in pleural cavity
surfactant
molecules of similar sign : repulse each other -> lubrication
-> not too much friction

Asthma

Obstructive
Chronic inflammation
smooth muscle spasms & increased mucus → narrow → permanent damage → scaring, edema, fibrosis → thickened basement membrane
FEV1 & PEF: amount obstruction
symptoms: dyspnea, chest tightness, wheezing, coughing sputum
Bronchodilators; beta receptor agonist

Spirometry influence

obesity compress diaphragm, lung and chest cavity → FEV1,FVC, FEV1/FVC down Height up → TLC, VC, RV, FVC, FEV1 up age → FVC and FEV1 down women: airway diameter and lung volume down → PEF down

Muscles in respiration

Quiet Breathing: Diaphragm & external intercostal muscles (inspiration) expiration passive Forced expiration: internal intercostal: pull ribs down abdominal muscle (eg: obliques): push diaphragm up and pull ribs down Forced inspiration: Accessory muscles: sternomastoids, scalenes → elevate sternum and upper ribs

Acinus

functional unit of lungs respiratory bronchioles, alveolar ducts, sacs, alevolar gaz exchange with pulmonary arteries

Bronchial arteries

supply pleura and connective tissue

Diaphragm

skeletal muscle seperate abdomen and chest contract and flatten when inhale: vaccum pulls air relax → push air out

Nerve supply

innervated by sympathetic and parasympathetic sympathetic: bronchodilation and vasodilation parasympathetic: bronchoconstriction and vasoconstriction controlled by respiratory centre: in pons and medulla oblongata interactions with chemoreceptors

Tracheobronchial tree

trachea → respiratory bronchioles | 16 generations

Pleura

each lung enclosed in pleural sac 2 membranes: visceral(inner) and parietal (outer) pleura parietal pleura adhere to thoracic wall, diaphragm and mediastinum 4 grooves to extend

Pleural cavity

space between visceral and parietal pleura allow sliding during respiration create surface tension contain pleural fluid

Mediastinum

Loose connective tissue in the thoracic cavity contains heat, vessels, esophagus, trachea, phrenic nerve, cardiac nerves, thoracic duct, thymus, lymph node lungs on the sides, spine in the back center-middle of the thorax

Lung

base on diaphragm apex at the top lie in thoracic cavity separated by mediastinum helium: slit for bronchus, blood vessels, lymphatic vessels, nerves right lung larger: 3 folds heat tilts to left: left lung smaller (2 folds) with cardiac impression / notch

FEV1, FVC, PEF,

Forced expiratory volume in 1 second Forced vital capacity: volume that can be expired after deep inhalation (x axis) Peak expiratory flow: highest point in the graph

Tidal volume

the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied. In a healthy, young human adult, tidal volume is approximately 500 ml

IRV | ERV

Inspiratory reserve volume extra inhaled volume compared to tidal volume max inspired volume Expiratory reserve volume extra exhaled volume compared to tidal volume max expired volume

VC | FR

``` Vital Capacity max of air expired ERV+TV+IRV Functional residual volume volume remaining in lung after normal expiration ERV+RV ```

Total lung volume

6L | IRV+TV+ERV+RV

Spirometry

``` y axis is flow x axis is volume under x axis is inspiration above x axis is inspiration ULN: upper limit of normal LLN: lower limit of normal ```

Obstructive

Residual capacity increase Insipiratory residual volume decrease Total lung capacity increase shifts the spirometry to the right but the loop stays roughly the same volume over time slope is less steep but still reach the max FEV1/FVC ratio changes

Restrictive

IRV, ERV, and RV smaller FEV1/FVC ratio unchanged total lung capacity decrease spirometry shift to left and volume loop is smaller volume over time slope is less steep and don't reach max