m11 + 12 lecture - respiratory system Flashcards
what is the respiratory system responsible for?
- the exchange and maintenance of blood gases and pH
what are the steps in the exchange and maintenance of blood gases and pH?
1) ventilation- airflow through the lungs
2) respiration - at the aveoli/capillaries
3) transport of gases through blood
4) respiration at the capillaries/ tissue cells
- all help to establish cellular respiration/ATP
what are the mechanics of ventilation (necessary components)?
1) air pressure changes -
vent. increases = pressure decrease
vent. decrease = pressure increase
2) intrapleural pressure - enables ventilation
3) compliance - elasticity
4) surfactant - decrease water tension, allows the aveoli to collapse/expand easily
what are some factors affecting ventilation?
- airway resistance
- loss of lung compliance
- loss of airway surface tension
what two actions does ventilation require?
- inspiration
- expiration
what is inspiration?
- it is an active process - contracting muscles which lower the pressure in the lungs to allow air to flow inward to the aveoli
- expansion of the lungs by expanding the rib cage
what are the inspiratory muscles?
1) diaphragm
2) external intercostals
- when contraction occurs - intrapleural pressure is created
—-> a neg. pressure
—-> a suction - lungs stick to the ribs
what is expiration?
- passage of air out of the lungs
— this is a passive process unless there is airway resistance
what is expiration directly initiated by?
- elastic recoil
- forced expiration
what is elastic recoil?
- tendency of the ribcage and lungs to contract to equal atmospheric pressure
- muscle relaxation
what is forced expiration?
- only seen when there is an issue
—> done thru muscular contractions of the - rectus abdominus, obliques, + internal intercostals
—> overcomes airway resistance (blockages)
how does airway resistance affect breathing? (factors affecting ventilation)
- directly effected by the size of the passage way
- bronchioles are the greatest contributor of airway resistance
—> smooth muscle in the bronchioles – dilate, constrict to affect airflow (ex. asthma, bronchitis)
—> irritants (allergens)
what is the reason for loss of airway surface tension? (factors affecting ventilation)
- surfactant decreases surface tension and prevents the tissue from sticking shut
ex.) IRDS - Infant Respiratory Distress Syndrome is a serious breathing problem that occurs in premature babies whose lungs are not fully developed
what is the reason for loss of lung compliance? (factors affecting ventilation)
- the ability of the lung to stretch and recoil
- decreased by anything which would decrease the elasticity of the lungs
ex.)
1) scarring, disease - emphysema, COVID
2) blockage of the bronchioles such as fluid - pneumonia
3) decreased flexibility of the rib cage
what are the different types of breathing?
eupnea - normal breathing rhythm (12-20 breaths)
dyspnea - difficulty (labored) breathing
hypernea - rhythm during exercise
what must there be for gas exchange to occur?
- a pressure gradient
—> exchange is driven by simple diffusion (high to low concentrations)
what is dalton’s law?
- partial pressures of gas
- (ATM) air pressure is 760mmHg
—-> this pressure’s made from the combined pressure of each gas in the atmosphere (1. nitrogen, 2. oxygen, H2O, + CO2) - air pressure is a constant measurement, but the partial pressures will change within each environment
—> if one increases, the others must decrease to maintain air pressure
is the external air the same concentration than the air in our lungs and blood gases?
no, air is much more humid in the lungs to prevent dehydration and drying in the mucus membrane
- % of O2 = 13% = pressure of 104mmHg
- deoxygenated blood = PO2 = 40 mmHg
what is henry’s law?
- gas disassociation into a liquid
—> gas will pressurize into a liquid according to the pressure in the air that it is in contact with (depends of the gas solubility and temperature)
ex.) soda, diving - hyperbaric chamber - bendz
Hg overcomes oxygens insolubility
male = 13-18g/100mL
female = 12-16g/100mL
what two things are needed for external respiration?
ventilation - air flow through the alveoli
perfusion - blood flow in the pulmonary capillaries
- at rest, we use 9-16% of our lungs (bottom)
alveolar air
- decreased ventilation = increased CO2 in the usual alveoli as CO2 increases, BF decreases = vasoconstriction
how is gas exchange maintained?
by the reflex actions of the arterioles
- arterioles dilate or contrict due to the % of CO2 in the alveolar air + blood
—> as air flow increases, this causes the BF to increase
—> as the body’s needs change, the air flow through a region of the lungs will also change
what does an O2 sat count?
the percentage of Hb with O2 attached
- 100% saturation is 100% of the Hb with O2
what is the gas exchange amount in the alveoli? (O2 and CO2)
percentage of O2 in the lungs = 13.7% or 104mmHg
percentage of CO2 in the lungs = 5.2% or 40mmHg
- these are the pressures that drive the gas exchange in the alveoli
what is the gas pressure in the capillaries? (O2 and CO2)
40mmHg of O2
45mmHg of CO2
what is the bicarbonate equation?
CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+
what is the gas pressure in the blood during internal respiration?
O2 = 100mmHg due to limited area on the HB
CO2 = 40mmHg
-O2 will unload and CO2 will be loaded into the blood
what is the gas pressure in the tissues during internal respiration?
O2 - 40mmHg
CO2 - 45mmHg
what is the Bohr effect?
- as CO2 rises and effects the pH, the affinity of Hb for O2 decreases
what ways are O2 and CO2 carried to maintain equilibrium?
- 98.5% of all O2 is carried in hemoglobin
- 1.5% of all CO2 is carried in the plasma
what happens the O2 sat when blood is carried thru the lungs?
- the O2 sat will increase to about 100%
—> most O2 unloading at the tissues, takes place between 70-100% HB saturation in the blood
—> venous blood traveling to the lungs carries around 40mmHg O2 = 70-75% saturation
what are some influences on hemoglobin saturation?
- temperature - increase will decrease saturation levels
- H+ and CO2 levels are also inversely related to O2 sat (Bohr effect)
- RBC health/ HB #
what quickens O2 saturation of hemoglobin?
- decreased temp.
- increased PO2
- hyperventilation
what slows the O2 saturation of hemoglobin?
- lung Dz
- hypoventilation
- increased temp.
- RBC health
what are the types of hypoxia?
cyanosis is caused by (bluing, increased vitals:
- ischemic —> decreased BF, CHF, arteriole sclerosis
- histotoxic (tissue poisoning) —> cyanide - kills mitochondria
- anemic —> iron deficiency, bleeding
- hypoxemic —> blocking O2, by using CO2 it used up all the HB causing decreased vitals, fatigue, nausea, redness
what is hypoxia?
decreased levels of O2 in the tissues
how is CO2 transported?
- some in plasma - 10%
- some in hemoglobin - 20% (carbaminohemoglobin - blueish COHb)
- 70% of CO2 is changed into bicarbonate
—> the conversion of CO2 into HCO3- is done by an enzyme called carbonic anhydrase in the RBC (helps act as a buffer to the plasma
what is the chloride shift?
- as bicarbonate moves out of the RBC, chloride moves inwards
what is the haldane effect?
- as CO2 changes to HCO3- in the RBC, Hb combines with H+ ions
- this helps to remove excess H+ from the blood
- in the lungs, CO2 is released and H+ combines with leftover HO to form H2O
what happens if CO2 builds up in the blood?
- it will force the blood to become more acidic, dropping the pH
- lowers hemoglobin’s affinity for O2
what does carbonic acid do?
- helps to control the pH of the blood
- can be effected rapidly by changes in breathing
—> shallow breaths will shift the equation to the right, making the blood more acidic
—> rapid breaths can shift the equation to the left, making the blood more alkalotic
what is the arterial pH closely related to?
to CO2 levels in the blood
- respiratory acidosis –> increased CO2 (hypoventilation)
- respiratory alkalosis –> decreased CO2 (hyperventilation)
how is pH regulation done?
- by the regulation of CO2
- respiratory acidosis
- respiratory alkalosis
what is respiratory acidosis?
- caused by elevated CO2 levels (hypercapnea)
- initiates the release of H+ ions into the plasma —> decreases O2 saturation rates
causes: lung Dz, hypoventilation
what is respiratory alkalosis?
- caused by decreased CO2 levels (hypocapnea)
- hyperventilation depletes CO2 levels pulling H+ ions out of circulation
what does the pons do in the respiratory system?
pons
- supervises the regulation and adjustment of breathing
- chemoreceptors and proprioceptors feed (excite) into this area
—-> greatly excited by CO2
what does the the pneumotaxic (pontine) center do?
upper part of the pons
- sends directions into the medulla through the DRG (dorsal respiratory group)
where are the chemoreceptors used by the pons located? (for regulation and adjustment of breathing)
- the carotid sinus
- aortic arch
- brainstem centers
what does the DRG (dorsal respiratory group) do?
group of neurons located in the medulla oblongata that primarily controls the initiation of inspiration (breathing in) by stimulating the diaphragm and intercostal muscles
what causes sleep apnea/SIDS and what does it affect?
- pontine (apneustic) center malfunctions
- influences the rate and rhythm of breathing
what is the hering-breuer reflex?
- stretch receptors in the pleura will inhibit the VRG causing exhalation to prevent over inflation of the lungs
- causes exhalation
respiration is controlled by what in the brain?
- pons
- medullary respiratory center (VRG - inhale and DRG - exhale)
what happens in the VRG (ventral respiratory group)?
inhale
- excitatory to the phrenic and intercostal nerves (diaphragm)
- cyclic pattern of around 12-20 breaths = 500mL/breath
- can be slowed or shut down but alcohol, morphine, sleeping pills, and anesthesia
what happens in the DRG (dorsal respiratory group)?
exhale (relaxes the diaphragm)
- regulated by the pons
- inhibits the VRG
- establishes rhythm or the depth of each breath
what is hypoxic drive?
- in chronic lung disease (ex. smoking)m CO2 receptors become desensitized and the person acclimates to a high level of CO2
- if CO2 is elevated, then O2 decreases
—> O2 sats are low = 80s
what are some types of chronic obstructive pulmonary diseases (COPD)?
- emphysema (m/c)
- chronic bronchitis
- asthma
what are common characteristics of COPDs?
- usually patient history of smoking
- sx of dyspnea
- coughing and frequent lung infections
- usually deaths occurs from respiratory failure
what are common characteristics of emphysema?
- long history of smoking
- causes the deterioration of the respiratory membrane and widespread scarring
- scarring causes loss of the elastic recoil
- loss of elasticity results in the enlarging of the airway and the destruction of the alveolus
- the alveoli open up and the patient has large open cavities in the lungs
- when this happens the patient can’t exhale and develops a barrel chest (“pink puffer”)
- causes the enlarging of the right ventricle
- causing pulmonary hypertension
what are common characteristics of chronic bronchitis?
- inhaled irritants lead to an excess of mucus in the bronchioles
- this blocks the airways and leads to hypoxia (blue bloaters)
causes: smoke and pollution
treatment: inhalers and bronchodilators
what are common characteristics of asthma?
ARDS - acute respiratory distress syndrome
symptoms: chest tightness, coughing, wheezing, dyspnea
causes: allergic reaction to certain pulmonary irritants
—> resulting in severe inflammation (histamine release) of the airways and bronchiole constriction
treatment: antihistamine inhalants
