Respiratory system Flashcards
What is cellular respiration?
metabolic processes use O2
CO2 is produced
Describe what is meant by the respiratory quotient (RQ)
Ratio of CO2 to O2
What does RQ depend on?
Amount of food consumed
What is external respiration?
Exchanged of O2 and CO2 between environment and organism
List the 4 steps of external respiration
- ventilation
- O2 and CO2 exchange between air in alveoli and blood in capillaries
- transport of O2 and CO2 in blood to tissues
- exchange between tissues and blood
What composes the upper respiratory tract?
nose
pharynx
larynx
What composes the lower respiratory tract?
trachea
bronchial tree
lungs
The trachea and bronchi have rigid tubes and rings of cartilage to avoid ______
collapsing
Bronchioles have no _____, and have ____ muscle walls.
cartilage
smooth
Alveoli are the site of ___ ______
gas exchange
List the 4 primary functions of the respiratory system
Exchange of gases between air and blood
Homeostatic regulation of body pH
Defence agains pathogens
Vocalisation
Type 1 alveolar cells are __ cell thick, and Type II cells secrete ______
1
surfactant
In alveoli, the pores of Kohn allow ____
airflow
Large surface area and thinness of alevoli/capillary wall leads to efficient ___ _______
gas exchange
The diaphragm is made of _____ muscle that separates the _____ cavity and the ______ cavity
skeletal
thoracic
adbominal
The pleural sac is a ____ layered, closed sac separating each ____ from the thoracic wall
double
lung
Name the 3 pressures to consider in ventilation
atmospheric
intra-alveolar
intrapleural
Air enters the lungs when alveolar pressure is ___ than atmospheric pressure
Air flows out of the lungs when alveolar pressure is ____ than atmospheric pressure
less
more
What is Boyle’s law?
At any constant temp., pressure exerted by a gas varies inversley with the volume of gas
Change the container ___ can change pressure
size
Volume in the lungs depends on what?
Difference in pressure
stretchability
What is pressure difference also called?
Transpulmonary pressure (TP)
Describe the equation to calculate TP
TP = Palv - Pip
Palv is air pressure inside alveoli = pressure inside lungs
Pip is pressure in intrapleural fluid = pressure outside lungs
What are the major inspiratory muscles and what activates them?
Diaphragm - phrenic nerve
External intercostal muscles - intercostal nerve
Due to ______ and flattening of the diaphragm the thoracic cavity enlarges by ____. This ________ intrapleural pressure, which increases lung volume, which lowers ______ pressure above/below atmospheric pressure and air enters the lungs
contraction 75% decreases intra-alveolar below
In expiration, the inspiratory muscles ____, so the size of the thoracic cavity _____. The intrapleural pressure _____ and lungs are compressed. Intra-alveolar pressure ______ above atmospheric pressure so air moves out of the lungs.
relax
decreases
increases
increases
What are the major expiratory muscles?
Abdominal wall muscles
Internal intercostal muscles
What allows lungs to rebound if stretched?
elastic recoil
What does compliance mean in terms of the lungs?
effort needed to stretch lungs
Why do lungs have the ability to recoil|?
Highly elastic connective tissue in lungs
Alveolar surface tension
Is there a larger stretch of alveoli after inspiration or expiration?
inspiration (7mmHg)
What does the law of LaPlace based on surface tension in the lungs state?
If air pressure in large alveoli is greater than small, the small alveoli will collapse and air flows into large alveoli
Type II alveolar cells have phosloplipd molecules that _____ surface tension of lining of alveoli so pressure needed to hold alveoli open is reduced.
lower
What is the main determinant of airway resistance?
Diameter of conducting airway
What determines diameter of a conducting airway?
Length of system
Viscosity of substance flowing
Radius of tubes
Mucus accumulation in airways can increase/decrease resistance
increase
In the bronchioles collapsible tubes increase/decrease airway resistance
increase
How do you calculate pulmonary ventilation?
tidal vol x respiratory rate
How do you calculate alveolar ventilation?
(tidal vol - dead space) x respiratory rate
In pulmonary circulation, the concentration of O2 and CO2 in arterial blood is relatively ______
constant
At rest 250ml O2 min-1 consumed and 200ml CO2 min-1 produced
So what is the RQ?
RQ = 200/250 = 0.8
Is CO2 more or less soluble than O2 in the blood?
CO2 is 30x more soluble
PCO2 varies depending on what?
metabolic activity
blood flow to tissue
During intense exercise, PO2 is ___, and PCO2 is ___
low
high
Large pressure gradients means less/more gas exchange
more
Venous blood from active tissue increases/decreases PO2 and increases/decreases PCO2
decreases
increases
Venous blood is mixed in the left/right atrium
right
What are the 3 factors that determine alveolar partial pressure?
- PO2 + PCO2 inspired air
- minute ventilation
- the rate respiring tissue consumes O2 and produces CO2
When alveolar ventilation exceeds tissue demand PO2 increases/decreases and PCO2 increases/decreases
When alveolar ventilation does not match tissue demand PO2 increases/decreases and PCO2 increases/decreases
increases
decreases
decreases
increases
What protein carries O2 in the blood?
haemoglobin in erythrocytes
What type of curve is the Hb-O2 dissociation curve?
sigmoidal curve
What are the 3 factors affecting affinity of Hb for O2?
Temperature
pH
2,3-DPG
How does temperature affect the affinity of Hb for O2?
As temp increases the curve shifts right
How does pH affect the affinity of Hb for O2?
Bohr effect
Increasing acidity decreases affinity Hb for O2
In lungs, increasing ph decreases acidity, which increases affinity of Hb for O2 loading and the curve shifts to the left
How does 2,3-DPG affect the affinity of Hb for O2?
It binds reversibly to Hb lowering affinity for O2, so the curve shifts right.
Promotes unloading
What process produces 2,3-DPG?
glycolysis
What is myoglobin?
A special Hb that is an O2 binding protein in skeletal muscle
Myoglobin has a _____ affinity for O2 than Hb
higher
Foetal Hb has a different structure and ____ affinity for O2 than Hb
higher
Myoglobin has a _____ affinity for O2 than Foetal Hb
higher
What ion transports most CO2?
bicarbonate ion
CO2 combines with H2O to form _____ ___, which is facilitated by the enzyme _____ _____ in RBCs. Carbonic acid dissociates into H+ ions and the ______ ion.
carbonic acid
carbonic anhydrase
bicarbonate
Describe what is meant by the chloride shift?
The RBC plasma membrane facilitates diffusion of bicarbonate and chloride ions OUT of the rbc.
Describe what is meant by the haldane effect?
Removal of O2 from Hb at tissue cells increases ability of Hb to bind with CO2
The haldane effect promotes loading/unloading CO2, while Bohr effect promotes loading/ unloading O2.
loading
unloading
Acid/base balance affects ___ in the blood
pH
CO2 generates H+ ions, which bind to Hb so makes a ____. Therefore Hb plays a crucial role in maintaining ___ balance
buffer
pH
Hypoventilation increases PCO2 + H+ ions-acidic blood. This causes respiratory ____.
Thus PCO2 + HCO3- _____ and pH ____
acidosis
increase
decreases
Hyperventilation lowers PCO2 + H+ ions-alkali blood. This causes respiratory ____.
Thus PCO2 + HCO3- _____ and pH ____
alkalosis
decrease
increases
What happens if respiratory acidosis persists?
kidney starts to conserve HCO3-
What happens if respiratory alkalosis persists?
Kidneys excrete HCO3-
What is hypoxia?
Low O2 levels in tissues
What is hypoxemia?
O2 deficiency in blood
What is Dysoxia?
Lack of O2 utilisation in tissues
Give examples of respiratory diseases
COPD
chronic bronchitis
emphysema
What 2 parts make up COPD?
chronic bronchitis + emphysema
Describe chronic bronchitis and what the effects excess mucus has
Lung inflammation
Xs mucus causes
- build up in bronchioles
- breeding ground for bacteria
Describe emphysema
Persistant coughing that causes stiff tissues and structural damage
Less functional alveoli available
Why is gas exchange at alveoli rapid?
- thin membrane
- blood vessels close to respiratory membrane
