Thorax and Breathing Flashcards
work of respiration
- requires muscular effort
- lungs do not contain muscles and therefore cannot move on their own - therefore require assistance
mechanisms of respiration
- the thoracic rib cage acts as a mechanical pump for the lungs
- lungs must stick to the walls of the thoracic cavity
- muscles acting on the ribs and bony thorax drive the pump
breathing apparatus
- pulmonary apparatus - lungs and airways
- chest wall - rib cage wall, abdominal wall, diaphragm and abdominal content
- pulmonary - chest wall unit
the rib cage
- rib cage is connected to thoracic vertebrae - T1 -12 which is important bc twelve ribs attach from those vertebrae
- also costal cartillages, sternum (manubrium, body of the sternum, xiphoid process/ xiphisternum), two clavicles
structures of the rib cage - superior thoracic apeture
- space connecting thoracic cavity to head, neck, and upper limb
- made by border of T1, rib 1 and the manubrium of the sternum
- passes through the space of - carotid arteries, jugular veins, phrenic nerve, vagus nerve, trachea and oesaphagus
structure of rib cage - inferior thoracic opening
- space connecting thoracic cavity to abdominopelvic cavity
- made by costal margin - 12th rib and T12
passes through - oesophagus, descending aorta, vena cava, phrenic nerves
structure of the rib
- twelves pairs of ribs
- ribs elevate and depress - hinged on the posterior vertebral column at costovertebral joints
- 1-10 attatch to the the sternum anteriorly via a costal cartillage
- a typical rib articulates posteriorly w a costal facet on the transverse process of its own thoracic vertebra and the body of the vertebra above
- rib bones articular wuth costal cartilages
- costal cartillages articulate with the sternum (rins 1-10) - directly (1-7) and indirectly (8-10)
costosternal joints
cartiliginous joints, slightly mobile but allow twisting and bending
difference bw costosternal joints and costovertebral joints
- costosternal joints - cartiliginous joints, slightly mobile but allow twisting and bending
different to - costovertebral joints - these are synovial joints which - highly flexible and allow for greater hinging to take place on that posterior side
types of ribs
- ribs 1-7 = -these ribs directly attach from rib to our costal cartillage then to the sternum
- false ribs - connect to sternum hw they join up together
- floating ribs still attach posteriorly to our vertebrae but do not attach to the sternum
rib movements
- costovertebral joints - elevation and depression of ribs occur
- bine shape will remain firm and strong - extends anterior posterior dimension
> true ribs lift up (pump handle movements) - sternum moves anteriorly and increases the anteroposterior volume
> false rib lift upwards ( bucket handle movements) - ribs move superiorly and laterally - increases lateral volume - elevation and depression of all ribs act to expand and depress the rib
muscles of the the thorax: thoracic diaphragm
- lie bw thoracic + abdominal cavities -primary muscle of inspiration
- attaches to the inferior border of the rib cage, xiphoid process, vertebral column and central tendon
- thoracic cavity is an upwardly domed shape = contraction of the muscular diaphragm causes diaphragm to flatten / lower > pulled down within the thoracic cavity
- upward shape to flatten - flattening is for inspiration and increase size of thoracic cavity
innervated by general somatic efferent neurons in phrenic nerve - fron CN 3-5- needed for inspiration to keep us alive
muscles of thorax: intercostal muscle
lie between pairs of adjacent ribs - two main sets of muscles which have been supplied by the intercostal nerves
what are external intercostal muscles used for
inspiration
external intercostal muscles- explain inspiration
- attach from rib below to rib above - R12-1 = 11 pairs
- fibers run in a hand in pocket orientation
- fibers begin near vertebral column and end at angle of rib - fascia
towards sternal aspects - elevate ribs - increase size of thoracic cavity
what are internal intercostal muscles used for?
expiration
internal intercostal muscles - explain expiration
- attach from rib above to rib below - from R1-R12 =11 pairs
- fibers run opposite to external muscles - begin near sternal aspect and end at vertebral column
- depress ribs - decrease size and volume of thoracic cavity
what are the accessory inspiratory muscles
- thoracic volume can further increased by use of accessory
muscles - anterior cervical group - scalene group and sternocleidomastoid -
elevate top and anterior rib cage - posterior and lateral thoracic group - extend vertebral column and expend rib cage - deep extensor back muscles/ superficial back muscles, serratus posterior and latissimus dorsi
accesory EXPIRATORY muscles
- thoracic volume can be quickly decreased by use of large abdominal muscles
- rectus abdominus, internal and external obliques, transversus abdominus - pulls down on lower ribs and causes expiration
- squeezes abdomen, transferring upward pressure on diaphragm
BREATHING FOR SPEECH > pulmonary - chest wall unit
- for the lungs to expands they need the rib cage to also expand ( lungs are not attached to ribs) - musculature must contract in order to have movement of the ribs
- pleural membranes and fluid act to link rib cage movements to lung movements
pleural cavities and membranes
- function is to link movement of the rib cage walls to lung movement via interpleural pressure
- negative pressure created between the visceral and parietal pleural membranes - due to fluid link
ventillation - breathing
- movement of air into and out of the lungs
- continue the cycle of inspired air and expired air
- respiration cycle - one complete inhalation and exhalation - about four seconds when at rest
- respiration rate - number of breaths per minutes - roughly 15 cycles per minute
tidal volume
amount of air that moves in or out of the lungs within each respiratory cycle
- inspiraratory reserve volume
- amount of air that you can force that can be forcibly inhaled after and above the normal tidal volume - normally kept in reserved but is used in deep breathing
> amount of extra air (> tidal volume) during forceful breaths in
inspiratory capacity
total airs in inspiration, including TV and insipratory reserve volume
expiratory reserve volume
expiratory reserve volume - amount of air abouve TV that is exhaled during a breath
how is air moved - clue = diffusion
- air is driven by a pressure gradient - diffusion
- air moves from high pressures in atmosphere to low pressure in intra-alveolar space
Boyles law
increase volume decrease pressure - vice versa
mechanism of breathing - inhalation
- increase thoracic cavity size
- decrease in pressure as more space for same amout of gas
- pressure outside is greater than pressure inside
- air rushes in - high to low diaphragm is flattened
mechanism of breathing - exhalation
- decrease in thoracic cavity size
- increase pressure - less space for same amount of gas
- pressure inside is greater than pressure outside
- air rushes out - high to low diaphragm is domed
normal respiration cycle
- adults completere between 12 and 18 cycles per minutes
- normal respiratory cycle = inspiration takes up to 40% of th cycle while expiration takes up 60% of the cycle
breathing in conversational speaking
- inspiration takes up 10% and expiration takes up 90% of the cycle
- speech is produced on exhaled air - slower exhalation
active forces and their relationship to movement of breathing
- forces brought about by muscle movement
- dependant on air volumes in the system
- greater volume requires greater forces - usually recruit more muscular contractions
eg. diaphragm, external intercostal muscles etc. contract and they allow respiratory to take place
passive forces and their relationship to movement of breathing
- nautral recoil forces of stretched or twisted structures - ribs, muscles and lungs
- gravity
types of respiration - focus on inspiration for this one
- driven by negative pressures
quiet inspiration
- thoracic diaphragm increases vertical dimension of thorax
forced inspiration
- external intercostals elevate ribs
- muscles act to increase 3D dimensions of the thorax - accessory muscles (scale, back muscles)
- more air is getting pulled into the lungs
types of respiration - especially focus on expiration
- driven by positive pressures
quiet expiration
- system is restored to a resting position after respiration
- driven by forces of torque, elasticity and gravity (helping return muscles to resting position)
- diaphragm will recoil back to its naturally domed positions and internal intercostals that inferiorly move that depress the ribs)
forced expiration
- internal intercostals depress ribs and reduce size of the thorax
- abdomen is compressed by abdominal muscles
- more air is pushed out of the lungs
neural control of tidal breathing
- “automatic” breathing controlled
by the brainstem breathing centers (medulla) - tidal breathing is under strong afferent
influence from chemoreceptors and
mechanoreceptors
control of special acts of breathing
- voluntary acts of breathing (breath- holding, glass blowing, speaking, singing) are controlled by higher brain centers
- commands from higher brain centers can integrate with and override brainstem breathing centers, they can also be sent directly to spinal nerves
spinal nerves important for breathing
- rib cage wall - cervical through lumbar (L) 2
- diaphragm - C3-C5
- abdominal wall - thoracic (T) 7 through L 1
chronic obstructive pulmonary disease (COPD)
- an umbrella term for a number of lung diseases that prevent proper breathing - three of the most common COPD conditions are emphysema, chronic bronchitis and chronic asthma
- no cure for COPD - management can slow disease progression and relieve symptoms
