RESPIRATORY

4. fever vs hyperthermia

DRG & VRG in control of respiratory 

respiration = gas exchange between atmosphere, blood, cells 

• upper 
• nose, nasal cavity, paranasal sinus, pharynx
• lower 
• larynx, trachea, bronchi, bronchioles, alveoli 

airway branching

• conducting zone 
• nose, pharynx, larynx, trachea, bronchi, bronchioles
• filter, warm, moisten air, conduct air into lung 
• respiratory zone
• bronchioles, alveoli 
• gas exchange

function of respiratory system:

• gas exchange
• regulate blood pH
• filters unwanted materials from circulation
• sound
• olfactory sensation
• protect surface from dehydration, temp change - defend from invasion

respiratory mucosa = conducting zone

• cilia + goblet cells + loose CT

nose & nasal cavity

• cartilage & skin
• external nares/nostrils 
• vestibule 前厅 with coarse hair 
• olfactory epithelium = receptor
• warm, moisten, filter air 
• receive olfactory stimulus
• trap large airborne particles 
• large, hollow resonating chamber modify speech sound

pharynx

• muscular chamber - air & food
• extend between internal nares & entrances to larynx & esophagus
• nasopharynx - respiration only
• oropharynx 
• laryngopharynx 

larynx

• passageway connect pharynx & trachea
• large, unpaired cartilages form larynx body 
• thyroid cartilage = Adam
• cricoid cartilage connect larynx & trachea
• epiglottis prevent food/liquid enter 
• diameter, length, tension in vocal folds produce sound pitch
• male thick, long, larger larynx - lower tones

trachea

• tough flexible tube - 2.5cm x 11cm
• smooth muscle & C shape cartilage ring keep airway open, prevent collapse
• cilia epithelium - debris 

left & right primary bronchi

• carina 
• bronchi wall with cartilage rings
• bronchiole wall smooth muscle 
• ANS

lungs = blunt cone, point superiorly

• parietal pleura attach to thoracic cavity wall
• visceral pleura cover lungs
• pleural cavity between pleura - fill with lubricating fluid

alveolar ducts & 150 million alveoli 

• tiny thin wall sac - spongy
• alveolar capillary surround by network of elastic fiber
• maintain relative position of alveoli & bronchiole 
• recoil during exhale reduce alveoli size & push air out 

respiratory membrane

• gas exchange 
• squamous lining
• endothelial line on adjacent capillary
• fused basement membrane between alveolar & endothelial
• rapid diffusion - small distance, O2 CO2 lipid soluble 

respiratory muscle

respiratory defense system 

• filtrate & remove large particles & pathogens
• components: 
• mucous cells
• mucous glands
• cilia 
• alveolar macrophage

alveoli = membrane

• components:
• Type 1 cells - simple squamous 
• thin cells for gas exchange 
• Type 2 cells/septal cell = stem cells 
• secrete surfactant = lecithin
• reduce surface tension 
• prevent alveoli collapse
• alveolar macrophage/dust cell 
• blood supply = capillary network surround alveoli
• deoxygenated blood enter via pulmonary arteries & bronchial arteries 
• oxygenated blood exit via pulmonary veins & bronchial veins to heart
• ventilation-perfusion coupling 
• hypoxia - vasoconstriction - blood from poorly ventilated areas to well ventilated areas 

gas exchange = between blood & alveolar air 

• external respiration = pulmonary
• pulmonary ventilation/breathing
• gas diffusion
• O2 & CO2 transport between alveolar & pulmonary capillary 
• internal respiration = tissue/cellular respiration  

• partial pressure of gases
• diffusion of molecules between gas & liquid 

O2 transport - 2 ways

• O2 dissolved in plasma 1.5% 0.3mL
• +Hb = oxyHb 98.5% 19.7mL
• saturated blood carry 20mL O2/100mL

factors influence rate of pulmonary & systemic gas exchange 

• diffusion distance
• partial pressure difference of gases
• surface area available 
• molecular weight & solubility of gases

environment factors affect Hb:

• PO2 blood
• blood pH
• temp
• metabolic activity within RBC 

partial pressure

• Dalton's Law
• each gas exerts own pressure
• 760mmHg
• N2 78.6%, O2 20.9%, H2O 0.5%, CO2 0.04
• Henry's Law
• dissolved gas directly proportional to its partial pressure above the solution
• partial pressure increase, solubility increase
• CO2 very soluble, O2 low, N2 very low

PO2 & Hb saturation = OHbDC

• higher PO2 greater Hb saturation
• cooperativity = heme no simultaneous oxygenation - 1 bind increase O2 affinity bind 2nd
• positive allosteric effect - binding lead to conformational change
• shift right: low pH high PCO2 temp DPG
• fetal Hb bind more O2

CO2 transport - 3 ways

• convert to carbonic acid = H2CO3 70% = H + HCO3 
• H + Hb
• HCO3 into plasma by chloride shift 
• +Hb = carbaminoHb 23%
• dissolved in plasma 7%

Haldane effect & Bohr

• effect of O2 on CO2 transport 
• deoxyHb higher CO2 affinity 
• more CO2 enter blood
• more O2 dissociate 
• more CO2 + Hb 
• more HCO3 form

lung volume

• respiratory rate: 12~16 breaths number/min 
• tidal volume: 500mL air moved/breath 
• respiratory minute volume (VE): air amount moved/min = pulmonary ventilation
• respiratory rate x tidal volume
• alveolar ventilation (VA)
• 500mL air enter
• 350mL enter alveolar spaces
• (tidal volume - anatomic deep space) x respiratory rate 
• resting tidal volume (Vt)
• expiratory reserve volume (ERV): after normal exhale
• residual volume: after minimal exhale 
• inspiratory reserve volume: after normal inhale 

lung capacity 

• inspiratory capacity
• functional residual capacity 
• vital capacity
• total lung capacity 

pulmonary function test

• spirometer
• obstructive pulmonary disease
• increased airway resistance 
• COPD, asthma, emphysema
• restrictive disorder
• reduced lung capacity 
• pulmonary fibrosis, pneumoconiosis 

Respiration control @ medulla oblongata 

• dorsal respiratory group (DRG)
• ventral respiratory group (VRG)

    

• pontine respiratory group (PRG) - pons
• neurons active when inhale & exhale 
• transmit impulse to DRG 
• cortical - conscious control avoid inhale noxious gas/water 
• chemoreceptor - central & peripheral 
• hypercapnia = high arterial PCO2
• hypocapnia = low arterial PO2 - hyperventilation

• exercise 
• more O2 consume
• more CO2 produce by muscle
• high CO2 in venous blood 
• high ventilation
• PO2 PCO2 pH remain
• hypoxia 
• low PO2
• ANS 
• emotion hypothalamus 
• SNS PNS - bronchodilation & bronchoconstriction 
• anticipation of strenuous exercise increase respiratory rate & CO by SNS 

CO + Hb

• block O2 binding = fx anemia
• CO poisoning = headache 
• carboxyHb level >15%
• treatment: O2 

age related changes 

• before birth 
• pulmonary vessel collapse
• gas exchange at placenta 
• during birth
• placental connection is lost
• PO2 fall, PCO2 rise
• respiratory center activate
• sudden infant death syndrome
• aging
• low vital & lung capacity
• low O2
• low alveolar macrophage activity
• low ciliary action
• infection risk

smoking

• nicotine constrict terminal bronchiole
• CO + Hb
• irritant cause excess mucus secretion
• inhibit cilia movement
• destroy elastic fibers 
• emphysema 

diseases 

• bronchitis
• inflammation of bronchial wall
• constriction, breathing difficulty
• acute - cold or infection
• chronic - smoking, poor ventilation, pulmonary hypertension, productive sputum 
• asthma
• excess stimulation & bronchoconstriction
• allergy
• type 1 hypersensitivity 
• restrict airflow
• diagnosis: methacholine challenge
• emphysema
• alveolar wall destruction
• abnormal large air spaces 
• reduce lung surface area
• low O2 enter
• SOB
• risk: dust, smoking, air pollution
• chronic obstructive pulmonary disease
• persistent blockage of airflow 
• risk: smoking
• respiratory distress syndrome
• difficult respiration
• alveolar collapse
• Type 2 cells not enough surfactant 
• premature baby
• pneumonia 
• lobule inflammation
• infection
• fluid leak into alveoli 
• compromise membrane 
• pneumothorax
• penetrate chest injury 
• air enter pleural cavity
• atelectasis 
• pulmonary embolism
• blockage of 1 pulmonary artery in lungs 
• DVT 
• COVID-19
• lung cancer
• risk: smoke, radiation, asbestos exposure
• diagnosis: pulmonary nodules
• 15% small lung cancer 
• fast, poor prognosis
• 85% non small cell