Where is the trachea located?
anterior to esophagus from the larynx to the 5th thoracic vertebra
what tissues: trachea
pseudostratified ciliated columnar epithelium w/musous secreting glands
also, 16-20 incomplete (C-shaped) rings of hyaline cartilage w/smooth muscle and elastic connective tissue stabilizing open ends of rings
Bronchi: 2 primary bronchi connect what to what at what point?
the trachea to lungs at the hilus
describe the RIGHT primary bronchi
1. Right: more vertical, shorter, and wider due to heart's position
2. continuation of incomplete rings of the trachea
3. tissue is pseudostratified ciliated columnar epithelium
describe the Secondary or Lobar Bronchi
1. 1 per lung lobe (2 in left lung, 3 in right lung)
2. branch into TERTIARY or SEGMENTED bronchi which branch in to BRONCHIOLES which branch into TERMINAL BRONCHIOLES (about 6500 per tertiary bronchus)
As smooth muscle increases, what decreases?
what does smooth muscle do/function?
bronchioles can be constricted or dilated in order to control flow
also, ciliated columnar epithelium becomes cuboidal in terminal bronchioles
Where are lungs/location?
they lie w/in the parietal and visceral pleura (2 layers of serous membrane)
lobules are subdivisions of what?
lobes of each lung
lobules consist of what parts?
1. a lymphatic vessel 2. an arteriole 3. a venule 4. branch from terminal bronchiole to respiratory bronchioles to alveolar ducts to alveolar sacs to alveoli (150 million oper lung ALL WRAPPED IN CONNECTIVE TISSUE
the lobules, consisting of all their parts are wrapped up in what type of tissue?
name the types of alveolar walls
1. Type I cells: simple squamous epithelium which line the walls
2. Type II cells: septal cells which produce surfactant (phospholipid and lipoprotein) allowing lungs to expand against the surface tension of water
3. alveolar macrophages available to phagocytize particulate matter which has made it this deep into the respiratory system
What do you find in the walls of the alveoli of the lungs?
Type I cells, Type II cells and alveolar macrophages
Which type of alveolar cells contain septal cells? What do they do?
these cells produce surfactant, which allows lungs to expand against the surface tension of water
How is gas exchanged between alveoli and blood?
Diffusion! Capillary network is extensive.
REGARDING VENTILATION: Pertaining to gas pressure and volume, describe Dalton's Law
the total pressure of a mixture of gases is the sum of the pressures of the individual gases
According to Dalton's Law, what percent of the pressure is due to nitrogen and what percent to oxygen and what percent due to CO2?
according to Dalton's Law, the pressure of a single gas is known as what?
according to Dalton, the delta of P02 is ?
160mm Hg (760 mm Hg X .21)
the pressure of a gas in a closed container is inversely proportional to the volume of the container
this is the Boyle's Law equation, P being pressure, V being volume
According to Boyle, gass pressure w/in a container can be changed by altering what?
the volume in the container; i.e if the container is enlarged, the gas molecules are more spread out, decreasing the number of collisions and gas pressure decreases
Henry's Law, describe
the amount of gas that will dissolve in a liquid is determined by the partial pressure of the gas AND the gas's solubility in the liquid
regarding ventilation, describe bulk flow
the movement of air due to pressure differences
what is intrapulmonary pressure?
the pressure measured inside the respiratory tract at the alveoli
when the lungs (alveoli) expand, it will fail to less than atmospheric pressure (usually expressed as negative pressure) and air will tend to flow into that space from the outside
when lungs recoil, what happens to intrapulmonary pressure?
pressure will exceed atmospheric pressure (positive pressure) and air will flow out of lungs
describe intrapleural space
thin, fluid-filled space immediately outside lungs between the visceral pleura and the parietal pleura
in the intrapleural space, the two membranes have what function for lungs?
they stick together and the lungs adhere to the chest wall
also, there is a pressure difference of about 4mm Hg (intrapulmonary)which keeps the lungs expanded into the pleural cavity
the parietal pleur is connected to what and what vessels?
diaphragm inferiorly and rib cage superficially
1. Initiated by muscular action of diaphragm and external intercostals
2. contraction of inspiratory muscles enlarges the size of the thorax
3. results in a decrease in the intrapleural fluid pressure and lungs expand
4. with expansion of lungs, intraalveolar (intrapulmonary) pressure decreases creating a pressure gradient between the atmosphere and alveoli
5. air moves inward due to bulk flow
in exaggerated movements, what accessory muscles are used during inspiration?
scalenes, sternocleidomastoid, serratus anterior and pectoralis minor
Describe steps of expiration
1. inspiratory muscles relax and the elastic properties of the lungs pull the chest wall back in and the diaphragm back up
2. passive activity
3. when not passive: forced using internal intercostals, transversus thoracis, internal obliques, transversus abdominis,, and rectus abdominis
what muscles used during expiration?
internal intercostals, transversus thoracis, internal obliques, transversus abdominis, and rectus abdominis
describe factors affecting pulmonary ventilation
1. surface tension of alveolar fluid: surface tensnion of water lining alveoli draws alveoli inward toward collapsing
2. surface tension must be overcome in order to expand alvelo
3. surfactant produced by Type II cells reduces surface tension
respiratory distress in infants caused by what?
lack of surfactant
compliance of lungs refers to what
ease of stretch in lungs
high compliance means what
little resistance to lung expansion
asthma reduces what?
compliance of lungs
decreased compliance occurs in what conditions?
pulmonary edema, tuberculosis, pulmonary fibrosis
increased compliance occurs in what condition?
airway resistance refers to what?
as the diameter of airways changes either due to constriction or relaxation or mucous accumulations, the flow of air will be affected
changes in lung perfusion and alveolar ventilation refer to what?
control of respiration
how is respiration controlled?
by changing lung perfusion and alveolar ventilation
1. alveloar arterioles constrict when PO2 is low and dilate when PO2 is high; this shifts circulation to areas of the lung with highter concentrations of O2.
2. bronchioles dilate in regions of high PCO2 and constrict in areas of lower PCO2; this shifts airflow to those areas which most need to get rid of CO2
3. Hyperventilation at high altitude: vascular constriction and bronchiole constriction
when alveolar arterioles constrict, PO2 is what and do what?
PO2 is low and arterioles dilate
when alveolar arterioles constrict, PO2 is low and arterioles dilate. What does this do to circulation to areas of the lungs?
a shift of circulation to areas of the lung with higher concentrations of O2 occurs.
when bronchioles dilate in regions of high PCO2 and constrict in areas of low PCO2, this shifts airflow to what areas, why?
airflow is shifted to areas that most need to rid themselves of CO2
what happens at high altitudes?
hyperventilation; vascular constriction and bronchiole constriction
chemoreceptors in the respiratory system--where located?
carotid bodies connected to Glossopharyngeal (IX) nerve and aortic bodies connected to Vagus (X) nerve
chemoreceptors in the respiratory system: what functions? Name 4.
1. sense level of H+ and PCO2 concentrations and drastic changes in O2
2. send messages to inspiratory center
3. blood flow is quick so change can be detected
4. send impulses to cardiac and vasomotor centers to increase cardiac output and vasodilation
where are chemoreceptors sensitive to PCO2 levels and pH levels located?
ventrolateral surface of the medulla oblongata
where are baroreceptors located?
in the aorta and carotid sinuses
what is a function of baroreceptors?
when blood pressure falls, they increase respiratory rate
stretch receptors monitor what changes and help what?
changes in volume of lungs; help prevent overexpansion of lungs
what function/respiratory is the medulla oblongata?
this respiratory center of the brain sets rhythm for ventilation and includes both dorsal inspiratory center and ventral expiratory centers
the inspiratory controls in the medulla onset what and what during quiet breathing?
inspiration and expiration
the expiratory center functions during a forced expiration by stimulating what?
what part of the brain is also a respiratory center used for prolonged inspiration and for fine tuning transisiton between inspiration and expiration?
name two types of centers in the Pons and their functions/respiratory
1. apneustic center used for prolonged inspiration
2. pneumotaxic center used for fine tuning transitions between inspiration and expiration
the pneumotxic center of the Pons fine tunes trnsitions between inspiration and expiration by inhibiting what?
the apneustic center (of the Pons)
the cerebral cortex
ventilatory muscles are skeltal; cerebrum exerts SOME control: deciding when to breathe or not breathe (holding breath, etc.)
Describe what happens w/pneumonia
there's an accumulation of fluid in alveoli which thickens the walls of the sacs, causing a long diffusion pathway and slow rate of gas exchange
alveolar walls are destroyed; therefore, a decrease in surface area
lungs lose elasticity so expiration is more difficult; barrel-chested, large FRC
a build-up of connective tissue reduces the compliance in the lungs
an expansion of the lungs becomes very difficult
infant respiratory distress syndrome (IRDS)
typical in prematurely born infants; problem of inadequate surfactant formation; decreased compliance
sudden infant death syndrome "crib death"
respiratory arrest; etiology unknow
movement of oxygen from alveoli to tissues
diffusion rate of oxygen depends upon what?
a. distance between 2 points
b. partial pressure gradient and gas solubilities in lipid
c. anatomical characteristics of respiratory membrane
d. blood flow and airflow are coordinated (blood follows where air flows)
what is the surface area distance of alveoli at peak inspiration?
140m2 in healthy lung
describe the transport of O2 in blood
O2 is physically dissolved in plasma, only 3 ml of O2 can be dissolved in 1 liter of blood at normal alveolar PO2 (1.5%)
How is O2 chemically bound to Hb in erythrocytes?
98.5% of O2 is transported this way-197 ml/l
Hb may be partially or fully saturated
this binding is TEMPORARY and COMPLETELY reversible!
Oxygen-Hemoglobin Dissociation Curve
1. graph depicting what % of Hb is saturated at a given PO2
2. an "S" shaped curve (sigmoidal) which is affected by pH (Bohr effect) and temp. changes
3. O2 may also be bound to myoglobin Fe contains pigment in muscle
Transport of CO2 in blood, describe
8% is physically dissolved in plasma
92% is chemically bound
with Hb: CO2 and Hb; HbCO2 (carbamino hemoglobin) = 185 (carbonic anhydrase)
H2CO3 to HCO3 (bicarbonate) + H+ = 74%
If CO2 concentrations rise and H+ concentrations rise and what else will be raised?
pH; acidity levels
Chemical influences on respiration
an increase in blood CO2, i.e a decrease in pH-acidosis:ventilation rate, depth and force through neural stimulation of phrenic nerves
increase in Hb dissociation of O2 at the tissue level
decrease in blood CO2 (increase in pH or alkalosis) s.a hyperventilation
ventilation rate decreases--apnea occurs
a decrease in O2 concentration what happens?
no reaction normally
severe hypoxia stimulates hyperventilation
effects of CO poisoning
increase in temperature causes?
increase in Hb dissociation
which cranial nerves innervate phrenic nerve?
"Keep the Diaphram alive!"
effects of CO poisoning
body likes CO; Hb can't drop it off, it accumulates Hb, decreases O2 carrying capacity; you go to sleep and can't wake up.
what will they do to you if you have CO poisoning to try to save your life?
put you in a hyperbaric chamber and flood Hb with O2.