5b Function And Control Of Respiratory System Flashcards
What are the 4 distinct events that occur in respiration?
Pulmonary ventilation
External respiration
Internal respiration
Respiratory gas transport
Describe the first event of respiration.
Pulmonary ventilation: moving air into and out of the lungs, in essence, breathing
Describe the second event of respiration.
External respiration: Gas exchange between pulmonary blood ad alveoli
Describe the third event of respiration.
Internal respiration: gas exchange between tissue cells and blood in systemic capillaries
Describe the last step in respiration.
Respiratory gas transport: transport of oxygen and carbon dioxide via the bloodstream
What is the difference between internal and external respiration?
Internal respiration is the gas exchange that occurs within the tissues and cells inside in the body, specifically between systemic capillaries and tissue cells, whereas external respiration is the gas exchange that occurs between the oxygen poor blood and the external environment (between alveoli and alveolar capillaries )
What is the relationship between volume and pressure in terms of breathing?
The higher the volume, the lower the pressure and vice versa
Describe the mechanical process that makes pulmonary ventilation possible.
Changes in volume trigger changes in pressure, which lead to the movement of gases, particles, to equalize said pressure
What are the types of pressures that affect pulmonary ventilation? Briefly define
Intrapulmonary pressure: pressure inside alveoli
Intrapleural pressure: pressure inside pleural cavity
Atmospheric pressure: pressure of outside air
What is the intrapleural pressure with respect to the other pressures?
The intrapleural pressure should always be more negative than the other pressures
What are the phases of pulmonary ventilation?
Inspiration: air flows into the lungs
Expiration: air flows out of the lungs
What effect do the phases of pulmonary ventilation have on the intercostals?
Inspiration: contraction of the intercostals
Expiration: relaxing of the intercostals
Changes laterally
What is the pleural cavity?
Thin layer of serous fluid there to prevent friction between the lungs and the chest wall
Bordered by the visceral pleura (touching the lungs) and the parietal pleura (touching chest wall)
What role does the pleural cavity play in respiration?
Allows the lungs to expand when your chest expands
Why must the intrapleural pressure always be ore negative than the other pressures?
It allows for the alveoli/air sacs to open, acting like a vacuum or suction cup
What happens if the intrapleural pressure equals the atmospheric pressure?
Results in acelectasis, the lungs recoil and collapse
What can cause the intrapleural cavity to depressurize?
Opening the pleural cavity
Breaking the seal of the pleural membrane allows for the atmospheric air to enter, equalizing the pressure
What is the average total lung capacity?
6L
What is vital capacity and the average?
4.8 L
Amount of air that can move into and out of lungs (breathable air)
Given by: Vital capacity= TV+IRV+ERV
(Tidal volume, inspiration reserve volume, expiration reserve volume)
What is tidal volume and the average capacity?
Amount of air you exhale in a normal breathe, not exercising, at rest
0.5L
What is residual volume and the average?
The air you cant exhale, no matter how hard you try
1.2L
What is inspiratory reserve volume and the average?
Amount of air that can be taken in over the tidal volume
3.1L
What is the expiratory reserve volume and the average?
Amount of air that can be forcible exhaled after a tidal expiration
1.2 L
What are the key words to remember for external respiration?
Alveoli and alveolar capillaries
What are teh key words to remember for external respiration?
Systemic capillaries and tissue cells
How many O2 molecules can 1 hemoglobin carry?
4 molecules
Is a hemoglobin molecule the same as a red blood cell?
No
Hemoglobin are proteins that carry oxygen, and they are inside RBCs doing their job (millions per cell)
How is oxygen transported in the blood?
MOST oxygen travels attached to hemoglobin and forms oxyhemoglobin (HbO2)
Not all oxygen travels attached to hemoglobin. How is the rest transported?
Dissolved and carried in blood plasma
How is carbon dioxide transported in blood?
MOSTLY transported in the plasma as bicarbonate ion (HCO3-)
Not all carbon dioxide is transported in blood plasma. How does the rest move?
Small amount in red blood cells on hemoglobin, though not at the same binding site as O2
What happens when there is too much CO2 in the blood?
H2CO3 is produced, carbonic acid, resulting in a drop in pH (acidic blood)
What relationship do bicarbonate ion and carbonic acid have?
They are a part of the buffer system that maintains blood pH
What is the equation that defines the blood buffer system?
CO2 + H2O= H2CO3= H+ + HCO3-
Where = means interchangeable arrows
Middle: carbonic acid and Last: bicarbonate ion
What parts of teh nervous system, specifically teh brain, control breathing?
Medulla and pons
What is a normal respiratory rate and its fancy name?
12-15 respirations/ min
Eupnea
What causes as an increased respiratory rate and whats its fancy name?
Hyperpnea
Caused by normal physiological conditions like exercise
Describe the neural control of breathing (that pathway) in detail.
Stimulus: CO2 increase in blood causes drop of pH in CSF in medulla OR O2 sensor indicating O2 decrease OR both
To control: afférent, Vagus nerve + Glossopharyngeal nerve, to medulla
At control: pons centers, medulla centers (ventral and dorsal respiratory groups)
Leaving control: medulla sends signal to trigger contractions, efferent, phrenic nerves, intercostal nerves
Result: quickened breathing to expel excess CO2
What is the VRG and where is it found?
Ventral Respiratory Group
Medulla
What does the VRG do?
Pacemaker type, self exciting inspiratory center in the medulla
Synchronizes excitatory and inhibitory stages
What happens when the neurons of the VRG fire?
A burst of nerve impulses (cuz they all fire at once) travels along the phrenic and intercostal nerve to excite the diaphragm and external intercostal muscles
What is the DRG and where is it found?
Dorsal respiratory group, medulla
What does the DRG do?
Integrates input from peripheral stretch receptors (alveolar stretch receptors) and chemoreceptors to control inflammation of lungs (ie, how much it expands)
Differentiate the VRG and DRG.
Ventral respiratory group allows you to breathe and tells you when, drives respiration
Dorsal respiratory group tell you how deep and how long (how much air you take in/ how long you breathe in for), controls respiration
VRG GENERATES RHYTHM OF BREATHING WHILE DRG CONTROLS DEPTH
What is the pontine and where is it found?
Respiratory center found in the pons
What does the pontine do?
Transmits impulses to the VRG of the medulla meant to fine tune the breathing rhythms it generates
Mainly responsible for triggering either hyperpnea or maintaining eupnea
What are the most important factors controlling rate and depth of breathing? Why?
H+ and CO2 levels
High CO2 results in more H+ free in blood and consequently lower pH
How are high levels of CO2 in blood detected by the CNS?
Central chemoreceptos in the brain by the concentration of h+ in CSF, mainly in medulla
(Central cuz central nervous system)
How are high levels of CO2 and H+ detected in the PNS?
By peripheral chemoreceptors (mainly in heart and carotid body artery) are stimulated by CO2 and h+ in blood
Peripheral chemoreceptors in smooth/active muscles are stimulated by H+ from lactic acid
What other physical factors affect respiratory rate and depth?
Increased body temperature
Exercise
Talking
coughing
What other factors affect respiratory rate and depth?
Volition
Emotional factors such as: fear, anger, excitement
Why is it possible for non-physical factor to affect respiratory rate and depth?
The hypothalamus can temporarily override the brains respiratory centres in a state of emotion
What are the conditions of high and low blood pH and their ranges? Symptoms?
<7.35= blood acidosis or just acidosis
-shallow and slow breathing: hypoventilation
>7.45= blood alkalosis or just alkalosis
-deep and rapid breathing: hyperventilation
What effect would hyperventilation have on your pH and why?
Increase the pH because it would lower H+ concentrations
What effect would hypo ventilation have on your blood pH and why?
Decrease in pH, increase in H+ ions, not enough CO2 being expelled
Differentiate hyperventilation and hyperpnea.
Hyperpnea is a result on normal conditions such as exercise whereas hyperventilation is due to emotional factors or other sources of distress
Both however result in increase breathing rate
Describe the homeostatic pathway regarding blood pH regulation.
Chemoreceptors from CNS and PNS send sensory input (either high or low CO2 and H+) to the respiratory centers in the brainstem (pons and medulla) which determine the appropriate response
The centers then send nerve impulses to teh effectors (respiratory muscles) and control frequency and force of contraction, consequently changing rate and depth of ventilation to regulate pH
