Respiratory Physiology Flashcards
functions of breathing
-get oxygen to blood
-get carbon dioxide out the blood
-warm and humidify air
-protect the lung from hostile environment
volume of oxygen absorbed per minute
250ml
volume of carbon dioxide excreted per minute
200ml
upper airways function
humidify, warm and filter
epithelia found in respiratory
pseudostratified ciliated columnar
asthmatic airway
muscle tightens, increased mucus and swelling
glottis
vocal cords
alveoli
series of tiny stretchy bubbles
upper respiratory
nose, mouth and pharynx
lower respiratory
larynx to alveoli
nasal cavity and paranasal sinuses function
smell, warm and humidify air
- filter out large particles
pharynx function
further warm, mix air and share cavity with digestive tract
larynx function
protects entrance to respiratory tree and allows speech
trachea and large bronchi
filters air, trap particles in mucus, macrophages involved in fighting infection
cartilage function in trachea
maintains rigidity of airway
alveoli cell types
type 1 and type 2
bronchioles function
some filtration, cilia, macrophages and smooth muscle directs air flow
type 1 epithelial cells
97% of alveolar surface, gas exchange and attracts water molecules
type 2 epithelial cells
3% of alveolar surface, produces surfactant and reduce surface tension
surfactant
amphipathic
binds to water and air within the alveoli - reducing the surface tension.
alveoli are able to expand to greater volumes
amphipathic
able to bind to both hydrophobic and hydrophilic molecules simultaneously
defence mechanisms
nose, cilia/mucus, bronch-constriction, constriction and dilation
nose mechanism
stiff hair for filtration
cilia and mucus mechanism
cilia moves mucus upwards to remove foreign material up the lumen - either coughed or swallowed
broncho-constriction
constriction of smooth muscle narrows the lumen and relaxation widens airway
constriction
mediated through ACh receptors and is triggered by irritants like dust and chemicals
dilation
adrenergic receptors that are stimulated by adrenaline or noradrenaline - part of sympathetic response
macrophages and lymphocytes in the lungs
arrive in lung from blood and migrate across membrane and attack micro-organisms
under resting conditions
inspiration is active and expiration is passive
inspiratory muscles
diaphragm and external intercostal muscles
diaphragm
dome shaped muscle attached to lumbar vertebrae, ribs and xiphoid process - does most of the work of breathing
external intercostal muscle
run infero-anterior from rib above to below; contraction pulls the ribs up
accessory inspiratory mucles
used during strenuous exercise
- sternocleidomastoid and scalene
sternocleidomastoid and scalene muscles
anterior part of the neck
-tension cause chest to be pulled up to head
pectoralis major/minor
connect anterior chest to arm - contraction brings chest forwards
expiratory muscles
passive due to elastic recoil of the lung
- internal intercostal and abdominal muscle
internal intercostal
run infero-posterior from one rib to the one below
- contraction pulls ribs down reducing antero-posterior dimensions
abdominal muscle
(six pack muscle)
large muscle which connects the pelvis to xiphisternum
-contraction pulls ribs down
cough reflex
unlearned/automatic defence mechanism to get rid of harmful substances which requires:
-large volume of air
-fast flow of air
step 1 (cough reflex)
-rapid deep inspiration
-brought about by contraction of the diaphragm (phrenic nerve) and the external intercostal muscles (spinal nerve)
step 2 (cough reflex)
-closure of glottis (vagus nerve)
-relaxation of inspiratory muscles
- contraction of expiratory muscles
step 3 (cough reflex)
-high intra-thoracic pressure
-opening of glottis
-rapid expulsion
receptors which detect stimulus
found in pharynx and trachea
- rapidly adapting pulmonary stretch receptors
afferent pathways
vagus nerve to medulla oblongata in the brainstem
efferent
phrenic nerve and spinal motor nerve that travel to muscles
gas exchange
absorb oxygen and excrete carbon dioxide by diffusion
diffusion increased by
larger surface area
thin membrane
high conc gradient
high solubility of gas
diffusion rates for oxygen and carbon dioxide
higher gradient generated for oxygen than for carbon dioxide
-carbon dioxide much more soluble in the alveolar membrane (diffusion rates similar)
air components
21% oxygen
79% nitrogen