Respiratory

Respiration

exchange of O2 and CO2 between atmosphere, blood, and cells

Pulmonary ventilation

gas exchange between atmosphere and lungs

External respiration

gas exchange between lungs and blood

Internal respiration

gas exchange between blood and cells

components of respiratory system

Structurally:

• upper respiratory

  • nasal cavity

  • pharynx

  • vocal cords

  • larynx

• lower respiratory

  • lungs

  • bronchi

  • trachea

Functionally:

• conducting zone

  • allows air to enter/exit to alveoli

• respiratory zone

  • gas exchange

  • bronchioles to alveolar sacs

nose

• Function

  • primary entrance/exit for respiration

  • moistens and warms air

  • resonating chamber for speech

  • olfactory receptors

• External nose

  • bony framework: ethmoid and vomer make septum; nasal bone, maxilla, lacrimal, palatine

  • cartilage: septal, alar, lateral

• nares (naris - sing) = nostrils

• internal nose

  • nasal cavity - superior and middle nasal conchae (ethmoid), inferior nasal conchae

  • nasal vestibule - can close w closing cartilage

  • internal naris opens to pharynx

• olfactory mucosa - olfactory epithelium

• respiratory mucosa

  • pseudostratified ciliated columnar epithelium

  • lysozyme and defensins in mucous and serous secretion

  • inspired air is warmed by plexuses of capillaries and veins

  • sensory nerve ending - sneezing

patentcy

open; clear of obstruction

• change in pressure allows breathing to take place

pharynx

• Functions

  • muscular tube from internal nares to C6

  • connects nasal cavity to larynx and esophagus

  • composed of smooth muscle

  • passageway for air and and food

  • resonating chamber for speech

  • houses tonsils

• nasopharynx

  • internal naris to oral cavity

• oropharynx

  • behind oral cavity

  • fauces: posterior opening between tongue and uvula

• laryngopharynx

  • behind epiglottis

larynx

• connects pharynx and trachea

• cartilage: thyroid, arytenoid (vocal cords attached), cricoid

  • epiglottis: root attaches to inside cricoid cartilage; when swallow, will cover opening to trachea

trachea

• extends larynx to primary bronchi

• tracheal cartilage - C shaped

• carina - trachea divides into R and L main bronchi

branching of bronchial tree

conduction zone —>

trachea

main bronchi

lobar bronchi

segmental bronchi

bronchioles

terminal bronchioles

respiration zone —>

respiratory bronchioles

alveolar ducts

alveolar sac

alveoli

• 23 generations of divisions

main bronchi

• R is wider and shorter, more vertical

  • more likely to have food stuck

• L bends more due to cardiac notch

lungs

• apex at point superiorly, base flatter at inferior

• L lung has 2 lobes - superior and inferior sep by oblique fissure

• R has 3 lobes - superior lobe, inferior lobe, oblique fissure and middle lobe w horizontal fissure

• pleura - each lung in own

  • parietal pleura lines thoracic cavity

  • visceral pleura lines lungs directly

  • between is pleural cavity w fluid

    • surface tension for lungs to stick to rib cage

    • reduces friction

• medial view

  • hilum: where blood vessels enter and exit, bronchus, nerves

pulmonary ventilation

atmosphere to lungs

• alternating pressure differences created by contraction and relaxation of respiratory muscles cause air to flow in and out of lungs

boyle’s law

volume of a gas varies inversely with its pressure

the pump in respiration

• chest wall

• respiratory muscles that increase or decrease size of thoracic cage

• nerves and control areas of the brain

normal inhalation/expiration

500 mL

• 250 oxygen entering and 250 CO2 exiting

• 6-8 Lpm

• 12-18 breaths per minute

anatomical dead spaces

air remains in spaces not designated for air exchange/conductive zone (nose, pharynx, larynx, trachea, bronchi)

• ~150 mL

alveolar dead space

when some alveoli cease to act in gas exchange (collapse, obstruction)

control of breathing

• medulla oblongata establishes rhythmic pattern

• cerebrum provides voluntary override

• pons regulate inspiration and expiration

intrapulmonary (intralveolar pressure)

pressure within the alveoli

• muscles cause pulmonary ventilation by alternatively compressing and distending the lungs, causing pressure in alveoli to rise and fall

  • needs to equal atmosphere pressure (will cause air to rush in or rush out)

• inspiration = -1 mmHg

• expiration = +1 mmHg

intrapleural pressure

pressure between lungs and thoracic wall

• lungs have cont. capacity to collapse and recoil away from wall (caused by elastic fibers and surface tension)

• intramolecular pressure between the alveoli will collapse the whole lung; recoil tendency of the lungs can be measured by negative pressure in intrapleural spaces

eupnea

normal quiet breathing

inspiration

1. enlargement of the thoracic cavity

   • contraction of diaphragm (down and flat)

   • contraction of external intercostals (rib cage up and outward)

2. decrease in alveolar pressure drives air inward

deep inspirations

1. neck and chest muscles also contract

   • sternocleidomastoid. pec minor, scalenes

expiration

1. requires no actual contractions: passive

2. relaxation of muscles increases lung pressure, allowing air to move into atmosphere

forced expiration

1. internal intercostals contract, decreasing intrathoracic volume = forced

2. abdominal muscles can drive viscera into diaphragm

spirometry

lung volume changes that occur during respiration can be measured using spirogram

tidal volume (TV)

amount of air moved through the lungs during a normal respiratory cycle

• 500 mL

• about 10-20% of vital capacity

inspiratory reserve volume (IRV)

amount of air that can be forcefully and maximally inspired into the lungs after a normal expiration

• 1900-3000 mL

• 60-70% VC

expiratory reserve volume (ERV)

air that can be maximally and forcefully exhaled after normal expiration

• 700-1200 mL

• 25% of VC

residual volume (RV)

air you cannot move out of the lung after forced expiration

• 1100-1200 mL

• air is not stale; mixes w new air during each breath

maximum inspiratory flow rate or maximum expiratory flow rate

maximum rate of air movement during inhalation or exhalation

inspiratory capacity (IC)

maximum amount of air that can be inspired by an individual

IC = TV + IRV

• 2400-3500 mL

expiratory capacity (EC)

maximum amount of air that can be expired

EC = TV + ERV

• 1200-1700 mL

vital capacity (VC)

maximum volume of gas that can be inspired after maximum expiration

• measured to determine strength of respiratory muscles and other aspects of pulmonary function

• 3-5 L (3100-4800 mL)

VC = TV + IRV + ERV

timed vital capacity (TVC)

fraction of vital capacity that is expired in one second

functional residual capacity (FRC)

amount of air that is remaining in lungs at the end of tidal expiration

FRC = ERV + RV

• 1800-2300 mL

total lung capacity (TLC)

total amount of air which occupies the lung after a maximum respiratory effect

TPC = TV + IRV + ERV + RV

• 4200-5800 mL

forced vital capacity (FVC)

amount of air that can be forcefully expelled from the lungs by expiring as forcibly as possible after a maximum inspiration

• reduced in those with restrictive pulmonary disease

forced expiratory volume (FEV)

portion of VC that is expelled during specific intervals of time

• in one sec = FEV₁ (75-85% of VC)

• in two sec = FEV₂ (94%)

• in three sec = FEV₃ (97%)

obstructive disease will not have normal FEV values

minute resipiratory volume (MRV)

amount of new air moved into respiratory passages each minute

MRV = TV x RR

alveolar ventilation rate (AVR)

flow of gases into and out of alveoli during specific time (minute)

(TV - anatomical dead space)(ml/breath) x RR (breaths per min) = AVR (ml/min)

effect of exercise on lung volumes

• TV and RR will increase bc more oxygen is required by skeletal muscles of body

• hyperpnea

• TV will erode the IRV but other volumes will remain consist including IC

• breath period will decrease as RR increases

obstructive lung diseases

airflow in and out of the lungs is reduced bc expiration is more difficult due to the reduced size of the airways

• asthma, chronic bronchitis, emphysema

• difficulty exhaling all air in lungs

  • closing tendency of airways increased by positive pressure in chest during expiration

  • inhalation not as bad bc the negative pressure allows air to enter more freely

• reductions in rate of forced expiration due to resistance to airflow and reduced airway diameter (all FEV values decrease)

• VC not affected

• Residual volumes may increase

• dyspnea (difficult breathing) can occur

restrictive lung disease

ability to inflate and deflate the lungs is reduced bc of damage to the alveoli (or less surfactant or other things in the way like enlarged liver or spinal curvatures) which restricts a person’s ability to inhale

• alveolar tissue may be damaged (tuberculosis, pneumonia, bronchiogenic carcinoma)

• can also result from stiffness of chest wall, weak muscles, or damaged nerves inhibiting lung expansion

• difficulty fully expanding lungs during inhalation

• hypoventilation

• some lung capacities and volumes will be decreased

• VC reduced bc of reductions in inspiratory and expiratory reserve volumes

• rate that VC can be expelled may remain normal

• FVC would be reduced

surface tension

inwardly directed force in alveoli which must be overcome to expand lungs during each inspiration

• water will cause alveoli to collapse

• surfactants help break surface tension

elastic recoil

ability to return to resting volume when stretching force is released

compliance

ability to stretch

• high compliance stretches easily

• low compliance requires more force to stretch

  • restrictive lung disease

    • fibrotic lung diseases

    • inadequate surfactant production

breath period

duration of each breathing cycle recorded as breaths per second

FEV₁/FVC

proportion of vital capacity that is expired in one second