Class Notes (1,100,000)
CA (620,000)
McGill (30,000)
Nursing (200)
Prof (7)
Lecture

respiration.doc


Department
Nursing
Course Code
NUR1 324
Professor
Prof

This preview shows pages 1-2. to view the full 8 pages of the document.
SUMMARY: RESPIRATION
Functions of the respiratory system:
-Function off the respiratory zone: gas exchange:
oIn the lungs, we add oxygen to the blood and release carbon dioxide in the environment.
oIn working cells, oxygen diffuses from blood to ISF to cells, while metabolic waste products
such as carbon dioxide move in the opposite direction.
oTherefore, both respiratory system and CVS work in collaboration to allow appropriate gas
exchange.
-Functions of the conducting airways:
1. Defence against bacterial infection and foreign particles:
The epithelial cells possess cilia and secrete mucous
Foreign particles stick to the mucous and the cilia constantly sweeps the mucous up into
the pharynx.
Tobacco smoking paralyzes the cilia, thus inhibiting this defence mechanism.
2. Warm and moisten inhaled air
3. Produce sound and speech with the vocal cords
4. Regulation of air flow: smooth muscle around the airways may contract or relax to alter
resistance to air flow.
Anatomy of the respiratory system:
-The respiratory tract:
oAir can enter either by the mouth or the nose
oIf it enters by the nose, it passes through the nasal
septum and the nasal turbinates, which clean the air of big
dust particles.
oAir then passes into the pharynx (common to air and
food), the larynx, and the trachea.
oThe trachea divides into two bronchi, each of which
divides into lobar and segmental bronchi.
oRight main bronchus = 3 lobar bronchi
oLeft main bronchus = 2 lobar bronchi
oThe segmental bronchi
divides further into
smaller branches
oThe smallest airways without alveoli are the terminal
bronchioles
oSurface of the lungs = visceral pleura
-Subdivisions of the conducting airways and terminal respiratory
units:
oThe airways consist of a series of tubes that branch and become
narrower, shorter and more numerous as they penetrate into the
lungs.
-Conducting and respiratory zones:
oConducting zone:
Airways from the mouth and nose openings, all the way
down to the terminal bronchioles.
They conduct air from environment to the respiratory zone.
Since they do not participate in gas exchange, they are said to form the anatomical dead
space.
oRespiratory zone:
Characterized by the presence of alveoli in the walls of the airways.
1

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Begins where the terminal bronchioles divide into the respiratory bronchioles.
Site for gas exchange
Makes most of the lungs
Smallest physiological unit of lungs = acinus (1 respiratory bronchiole)
-Blood supply:
oPulmonary circulation:
Brings mixed
venous blood to the
lungs, allowing for the
blood to get
oxygenated, and then
back to the heart,
where it enters the
systemic
circulation.
Branches from the
pulmonary artery run
with the airways.
When the alveoli are
reached, arterioles
divide into a
capillary bed.
oBronchial (systemic)
circulation:
Supplies
oxygenated blood to
the tracheobronchial tree
Bronchial arteries from the aorta supply the airway walls.
-Alveolar cell types:
oEpithelial cells:
Type I:
Little is known about their specific metabolic activity
Type II:
Produce pulmonary surfactant, a substance that decreases the surface tension of
the alveoli
oEndothelial cells:
Constitute the walls of the pulmonary capillaries
May be as thin as 0,1 micron
oAlveolar macrophages:
Remove foreign particles that may have escaped the mucocilliary defence system of the
airways.
2
You're Reading a Preview

Unlock to view full version

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

-Res
pir
ato
ry
muscles:
oInspiratory muscles:
Principal:
External intercostals: elevate ribs
Parasternal intercartilaginous: elevate ribs
Diaphragm: dome descend, increasing longitudinal dimension of chest and
elevating lower ribs
Accessory:
Sternocleidomastoid: elevates sternum
Scalenus: elevate and fix upper ribs:
oAnterior
oMiddle
oPosterior
oExpiratory muscles:
Quiet breathing:
Expiration results from passive recoil of lungs
Active breathing:
Internal intercostals, except parasternal intercartilaginous muscles: depress ribs
Abdominal muscles : depress lower ribs, compress abdominal contents
oRectus abdominus
oExternal oblique
oInternal oblique
oTransversus abdominus
Summary of events during respiration:
-Inspiration:
oDiaphragm and intercostal muscles contract
oThoracic cage expands
oIntrapleural pressure becomes more subatmospheric
oTranspulmonary pressure increase
oLungs expand
3
You're Reading a Preview

Unlock to view full version