Respiratory System Part 2 Flashcards
What is natural state of lungs?
Collapsed
What keeps lungs “stuck” to thoracic cavity?
Intrapleural fluid surface tension
What happens to pressure gradient of lungs during inhale?
Decreased
What happens to pressure gradient in lungs during exhale?
Increases
True/False: as lungs expand and volume increases, pressure decreases
True
If pressure in lungs is 760, what is pressure of fluid?
756
Most restful breathing is done by what muscle?
Diaphragm
When diaphragm contracts, happens to lungs?
Lengthen
What muscles increase circumference and width of thoracic cavity?
External intercostal
When lungs equal atmospheric pressure, what happens?
Inhale stops
When muscles relax, pressure increases and volume decreases, what is happening?
Passive exhale
What accessory muscles are involved in forceful breathing?
Sternocleidomastoid
Scalenus
What lift sternum and clavicles to expand thoracic cavity?
Accessory muscles
What muscles are involved in forceful exhalation
Internal intercostal (shrink rib cage)
Diaphragm
Why are nerves of breathing unique?
They are both voluntary and involuntary
What nerves drive rhythmic breathing?
Intercostal nerves
Phrenic nerves
What muscle do phrenic nerves control?
Diaphragm
Where do phrenic nerves connect in spinal cord?
C3-C5
True/False: spinal injury above C3-C5 requires mechanical assistance with breathing
True
Where do intercostal muscles connect to spinal cord?
Thoracic region
Where is brain respiratory center?
Brain stem
Two areas of brain stem that control breathing
Medulla
Pons
What is the most important area of brain stem when it comes to breathing?
Medulla
Group of nuclei in medulla that control restful breathing
Dorsal Respiratory Group (DRG)
Group of nuclei in medulla that control forceful breathing
Ventral Respiratory Grouo (VRG)
Muscles controlled by DRG
Diaphragm
External intercostal
Muscles controlled by VRG
Internal intercostal
Abdominal
What is the pace setter of the medulla?
Pre botzinger complex
What does pre-botzibger trigger first
DRG
If forceful breathing is needed, what does DRG recruit to get more force
VRG ( they trigger muscles)
What does Pons regulate in breathing?
Rate (duration) and depth of breath; longer breath = deeper
What center in Pons shortens inhale?
Pneumotaxic
What center in Pons lengthens inhale?
Aponeuistic
How is pons different than pre-botzinger?
Prebotzinger is a fixed rate that stimulates DRG
Pons changes based on body needs (O2, CO2, pH)
2 types of respiratory control are
1) voluntary
2) involuntary
What type of respiratory control is considered “top down” based on body needs
Involuntary
How many breaths per minute in a rest state?
10-12
Typical volume of a resting breath
500 ml
With physical activity, why do volume and rate increase
Metabolic demand
True/false: Efferent control of breathing is from DRG/VRG and fine tuned by Pons
True
Would brain damage above the brain stem still allow you to breathe?
Yes
If pons was damaged but medulla still working, could you still breathe?
Yes
If vagus nerve snipped and feedback from body was cut off, what happens?
Could breathe at baseline but couldn’t change rate based on metabolic need
Long gasps followed by short exhale (usually from severe brain trauma) is called
Aponeusis
With aponuesis, what happens to to aponeustic center?
It dominates pneumotaxic center and can’t receive input from body
All top down control happens with what condition?
Apneusis
What 2 things do pulmonary receptors respond to?
1) Stretch
2) Irritation
What do stretch receptors protect the lungs from?
Over-inflation
What do irritant receptors protect the lungs from?
Chemical injury
Where are pulmonary stretch receptors found?
Bronchioles smooth muscle
Do Pulmonary Stretch Receptors (PSR) respond to chemical irritation at all?
Yes, but minimally
PSR reflex that kicks in at the beginning of exercise when you are taking huge breaths
Hering-Bruer reflex
What does Hering-Bruer reflex do to breathing?
Makes it shallow and rapid to prevent over-inflation
Where are Pulmonary Irritant Receptors (PIR) found?
In lumen of airway among ciliated columnar epithelial cells
What do PIR do if they sense an inhaled irritant?
Broncho constriction and gasping breaths to minimize exposure
2nd irritant receptors found in alveolar sacs
J-Irritant receptors (“juxta-capillary”)
What do J-irritant receptors do?
Broncho-constriction to prevent irritant from entering blood via gas exchange and damage to this area
What three things in blood influence respiration
PO2, PCO2, pH
Where are peripheral chemoreceptors (PCR) found?
Aortic arch
Carotid sinus
What are PCRs most sensitive to?
PH (some PO2)
Where are central chemoreceptors (CCR) found?
Brain stem
What are CCRs most sensitive to?
PCO2 (some PO2)
Why is PCO2 so important to monitor?
Changes rapidly; predicts O2 change
What does PO2 indicate?
How much O2 bound to hemoglobin
What does PCO2 indicate
Metabolic activity
What PO2 or below will trigger “emergency” and PCRs kick in
60 mmHg
What is hemoglobin saturation when PO2 at 60
92%
How much PCO2 dissolved in plasma
10%
True/False: CO2 dissolved in plasma easily crosses blood brain barrier
True
True/false: CCRs regulate breathing moment to moment
True
How do CCRs regulate arterial PCO2
Increase ventilation to blow off CO2
Acidosis in blood will stimulate which chemoreceptors
Peripheral
