SHS 300 - Respiratory System

functions of the respiratory system

respiration - gas exchange (oxygen and carbon dioxide) that is required for life

ventilation - movement of air (inspiration and expiration)

provides air to power the voice for speech (vibrates the vocal cords)

chest wall components

thorax/rib cage (upper cavity)

diaphragm (between upper and lower cavities)

abdomen (lower cavity)

respiratory organs

lungs

components of the upper airways

oral cavity

nasal cavity

pharynx

separation between the upper and lower airways

larynx

components of the lower airways

trachea

bronchial tree

lungs

components of the sternum

manubrium

corpus/body

xiphoid process

bones of the pectoral girdle

clavicle

scapula

sheets of connective tissue in the abdomen

abdominal aponeurosis (anterior)

lumbodorsal fascia (posterior)

structures that make up the pelvic girdle

coxal bone

sacral and coccygeal segments of the vertebral column

parts of the coxal bone

ilium

ischium

pubis

function of the alveoli

small, bubble-like epithelial cells located in the terminal bronchioles where CO2 and O2 are exchanged

function of the pleurae

translates the movements of the rib cage and abdominal wall to the lungs (so they move as a unit during respiration)

allows inspiration and expiration to be more efficient; prevents structures from collapsing

pleura that covers the inner surface of the rib cage and diaphragm

parietal pleura

pleura that covers the outer surface of the lungs

visceral pleura

main function of the diaphragm

increases thoracic volume and decreases alveolar pressure for inspiration

how the diaphragm moves when it contracts and relaxes

contracts - pulls the central tendon down and forward (increase thoracic volume)

relaxes - displaced upwards by contraction of the abdominal muscles (decrease thoracic volume)

motor innervation of the diaphragm

phrenic nerve - C3, C4, C5

main abdominal muscles - effect on respiratory system

muscles:

• rectus abdominis

• external obliques

• internal obliques

• transversus abdominis

effect:

• compress abdominal contents and increase abdominal pressure

• displace diaphragm up, which decreases thoracic cavity size

how the abdominal wall moves during respiration

inhalation - abdominal wall moves outwards

exhalation - abdominal wall moves inwards

define alveolar pressure

the pressure inside the lungs

passive forces in breathing

elastic recoil of the lung-thoracic unit, torque, and gravity

active forces in breathing

muscle forces

typical chest wall shape for conversational speaking in an upright position

• rib cage wall is larger than resting

• abdominal wall is smaller than resting

  • abdominal wall is displaced INWARDS —> slight elevation of the diaphragm

define inspiratory checking (what muscle group is primarily responsible?)

occurs when the major inhalation muscles (diaphragm and external intercostals) are contracted during the first part of the CONTINUOUS utterance

purpose: maintains positive alveolar pressure by counteracting the elastic recoil of the lungs and chest wall (sustains voice production)

muscle groups that are active during running speech activities (which are the most active?)

main inspiratory muscles (diaphragm and external intercostals)

main expiratory muscles (abdominal muscles)

most active: main expiratory muscles

• starting at a smaller lung volume = less intense contraction of the inspiratory muscles

• continued contraction of the expiratory muscles to force air out and sustain voice production

how breathing changes as we develop (infants to adults)

• pediatric larynx (funnel-shaped) develops into a cylindrical shape as the child grows; also located higher in the neck (serves a protective function)

• smaller diameter of the bronchial tree in children (results in a higher respiratory rate and less sounds/words per breath cycle)

• flatter thorax/diaphragm in children (chest wall only moves up and down)

how breathing changes as we become older (younger adults to older adults)

decreased vital capacity

• increased residual volume and resting level due to stiffer costal cartilages and loss of elasticity/recoil in the lungs

speech

• initiated at a higher lung volume (>60%)

• expend more air per syllable

• use more of the vital capacity when talking

presence of a leaky valve (a gap exists between the vocal folds when they should be completely closed)

location of nerves supplying the rib cage wall muscles in relation to the nerves supplying the abdominal wall muscles

generally higher (closer to the head)

example: the diaphragm is innervated by C3-C5 while the abdominals are innervated by T6-T12

location of control of tidal breathing

brainstem (specifically the reticular formation in the medulla)

how ventilation changes when central chemoreceptors sense a change in the concentration of carbon dioxide in the cerebrospinal fluid

increased rate and depth of breathing

receptors that are stimulated when the lungs and airways are stretched

mechanoreceptors

central nervous system control of tidal breathing

higher cortical pathways can modify respiration input and output

***when overriding autonomic functioning becomes harmful, the autonomic regulation will take over

example: holding your breath

clavicle

scapula

sternum

manubrium

corpus

xiphoid process

true ribs (1-7)

false ribs (8-12)

floating ribs (11-12)

costal cartilage

cervical vertebrae

thoracic vertebrae

lumbar vertebrae

sacrum

coccyx

ilium

ischium

pubis

pelvic girdle

trachea

main bronchi and lobar bronchi

alveoli

subclavius - elevate first rib

pectoralis minor - lifts ribs 2-5 (scapula fixed)

subcostal muscles - lower ribs

pectoralis major - draw sternum and ribs 6-7 up (shoulders fixed)

sternocleidomastoid - elevate sternum and clavicle (head fixed)

transversus thoracis - lower ribs 2-6

serratus anterior - elevate upper ribs (1-8)

scalene muscles - elevate ribs 1 and 2 (head fixed)

external intercostal muscles - lift rib cage upward and outward by “fixing” upper rib and raising lower one

internal intercostal muscles - pulls ribs downward and inward

serratus posterior inferior - lower ribs 9-12

serratus posterior superior - elevate ribs 2-5

levatores costarum - elevate ribs

quadratus lumborum - lower lowest rib (12)

diaphragm - pulls central tendon down and forward

rectus abdominis - compress abdomen and lower ribs and sternum when exhaling

transversus abdominis - compress abdominal wall

external obliques - compress abdomen and depress lower ribs (5-8)

internal obliques - compress abdomen and depress lower ribs (9-12)

A - inspiratory reserve volume

B - tidal volume

C - expiratory reserve volume

D - residual volume

E - vital capacity (IRV + TV + ERV)

F - functional residual capacity (ERV + RV)

G - inspiratory capacity (TV + IRV)

H - total lung capacity (IRV + TV + ERV + RV)