Respiratory Study Questions Flashcards
What are the key functions of the respiratory system?
- Gas exchange: oxygen delivery and carbon dioxide removal
- Regulation of pH of body fluids: CO2 + H2O ←→ H+ + HCO3=
- Temperature control
- Voice production
What are the two key respiratory gases?
Oxygen and Carbon Dioxide
What is partial pressure?
The amount of pressure exerted by a particular gas in a mixture
-Influenced by the # of molecules
What is a gas exchange membrane? How do gases get to the exchange membrane? How do they cross it?
- Layers of tissues that separates the internal tissues from the external environment – “breathing organ”
- Reach the membrane by convection transport (ventilation and circulation)
- Cross membrane via diffusion
In mammals and birds, what membranes do gases need to cross?
Mammals - Alveolar membrane and Capillary membrane
Birds - No alveoli, so parabronchi is site of gas exchange
Mvmt between parabronchi and air capillary by diffusion
What factors control the rate of gas diffusion?
- Membrane surface area
- Difference in partial pressures
- Distance btwn 2 partial pressures (membrane thickness)
- The gas, the temperature, the phase, membrane permeability
Why is it advantageous to have an expansive, but very thin gas exchange membrane?
Thinner membrane = less distance to travel therefor faster exchange.
Expansive = more area to pass through so more area to exchange.
List the parts of the respiratory system: (10)
Conducting Airways:
1. Nasal passages
2. Pharynx
3. Larynx
4. Trachea
5. Mucous cells
6. Bronchi, bronchioles, alveoli
Part of the lungs
Alveoli
Other Components:
-Diaphragm
-Intercostal muscles (external and internal)
-Pulmonary artery
-Pulmonary veinPharynx
Cavity at the back of nasal passages and the mouth
Larynx
Regulates air flow, expels foreign objects, contains vocal cords
Trachea
Long tube
Mucous cells _______ while ciliated cells ___________.
Mucous - lubricate
Ciliated - remove impurities
Alveoli
Gas exchange surface, thin walled, excellent blood supply
Pulmonary artery takes _________.
Blood to lungs
Pulmonary vein takes _________.
Blood from lungs to the heart
What are the major muscle groups involved in breathing in mammals? In birds?
Breathing animals:
-External and internal intercostals
-Abdominal muscles
Birds:
-Internal intercostals
-Thoracic musclesDescribe how air moves through the airways in mammals.
- O2 diffuses across the alveolar membrane and capillary endothelium
- High PO2 (air in alveoli) to low PO2 (blood in capillaries)
- CO2 moves in opposite direction
Conducting vs. Respiratory airways
Conducting: Airway up until gas exchange (i.ei. nasal cavity, air sacs)
Respiratory: Site of gas exchange (i.e. alveoli, parabronchi)
What are the parts of the avian respiratory system?
Nasal cavity Larynx Trachea Anterior and posterior air sacs Parabronchi Lungs
Air sacs help with…
Movement of airflow through the parabronchi because birds do not have a diaphragm.
-Lungs are less elastic and do not change volume so the air sacs make up for that by their ability to expand and contract
What part do mammals have that birds do not?
Pharynx
The mammal’s lungs ________ than the avian’s.
Stretch farther
Inspiration in mammals requires…
Coordinated muscle contraction by the external intercostal muscles and diaphragm.
3 Steps for Inspiration in mammals
- Rib cage pulled up and out (external intercostal)
- Diaphragm descends which creates a vacuum
- Lungs volume expands, air pulled into airways
Steps for Expiration in mammals
Expiration is muscle relaxation normally.
- Neurons of inspiration are inhibited
- muscles relax
- rib cage returns to ‘normal’ position
- pressure increases pushes air out of alveoli
- Internal intercostals and the abdominal muscles are involved when it is forced expiration by bringing internal intercostals and abdominal muscles up to further force air out of lungs
Why is the composition of air in the alveoli different from that in the atmosphere?
To get from the atmosphere into the bloodstream, oxygen must diffuse across 2 sets of membranes (alveolar and capillary) and to be able to cross via diffusion it must go from a high concentration to a low concentration.
Amount of air that comes into and out of the lungs during each breath
Tidal volume
Maximum amount of air that can move into and out of the lungs during breathing.
Vital capacity
Amount of air that cannot be forcefully expired from the lungs.
Residual volume
Amount extra over tidal volume that could be inhaled
Inspiratory reserve volume
Amount extra air that could be exhaled with force.
Expiratory reserve volume
Equation for Respiratory Minute Volume
Tidal volume * RR
What areas of the brain are involved with the control of respiratory rate?
- Normal breathing is reflexive → autonomic neurons in the medulla
- Ventilator neurons in the pre-Botzinger complex of the medulla initiate the breathing rhythm
- Neurons depolarize at a rhythm → action potential → external intercostals & diaphragm → inspiration
-Not depolarized = no action potential, muscles relax, expiration
What different “chemical” factors regulate the respiratory rate? How? Why?
Factors that increase respiration rate:
- Decrease in PO2
- Increase in PCO2
- Decrease in pH
Chemoreceptors are the main sensory input for R.R and keep those 3 constant in the blood.
What non-chemical factors can regulate respiratory rate?
Exercise
Aside from chemical mediators, what else may be involved in controlling respiration during exercise?
a. Motor neurons
b. Sensors in limbs
c. Thermoregulation
d. Psychological factors
Describe airflow through the avian respiratory system during inspiration and expiration.
- Through parabronchi from posterior to anterior
- Posterior air sacs fill with fresh air → go to parabronchi (site of exchange) → stale air from the parabronchi and anterial air sacs is exhaled via primary bronchi
What factors regulate the respiratory rate in birds?
a. CNS control in the pons and medulla
b. Chemoreceptors for PCO2 PO2 and pH
c. Mechanoreceptors
d. Thermoreceptors
Birds hyperventilate in…
Heat stress, activity, and altitude
-Breathe less frequently than similarly-sized mammals but take larger breaths.
Describe the structure of hemoglobin and how it may vary based on the tissue.
a. Hemoglobin = heme (porphyrin group – ring structure with Fe+) + globin (protein chain)
- Blood hemoglobins = 4 heme + globin molecules
- Muscle myoglobins = 1 heme group + globin
What are the key roles of hemoglobin? (4)
a. Increase the O2 carrying capacity of blood
b. Regulation of blood pH (buffer)
c. CO2 transport through the blood
d. O2 storage in tissues (myoglobin)
Describe the relationship between blood PO2 and the oxygen content of the blood.
PO2 is determined entirely by how much dissolved O2 is in the blood.
In what form (i.e. dissolved, bound, etc.) is the majority of blood oxygen?
Bound to hemoglobin
What sets of membranes does O2 need to cross to get from the alveoli to bind to hemoglobin?
a. Alveolar membrane (into and out of cell)
b. Capillary endothelium (into and out of cell)
c. RBC membrane (into cell)
What is meant by the term ‘oxygen carrying capacity’?
- The oxygen content of the blood when all hemoglobin is saturated with O2
- Dependent on how much hemoglobin is in the blood (# of RBC, amount of iron)
What drives oxygen movement from the blood into the tissues and how does this relate back to the oxygen dissociation curve?
- Oxygen must be released from the hemoglobin to diffuse across membranes into the tissues, so its beneficial for less O2 to bind to hemoglobin in the lungs
- Oxygen must be released from the hemoglobin to diffuse across membranes into the tissues.
What do we mean when we say that hemoglobin’s affinity for oxygen is high under a certain physiological situation?
a. How likely it is that O2 will be bound by the hemoglobin at a given PO2
b. At a given PO2
i. High affinity = higher saturation
c. At a given % saturation
i. High affinity = lower PO
