Lecture 11 Flashcards
Where is the central pattern generator (CPG) located in the brainstem that controls the basic pattern (inspiration and expiration) of respiration?
- pons
- medulla
What are the inputs to the central pattern generator (CPG) (also called the respiratory center)
- What input provides voluntary control of breathing?
Cortex-behavioral voluntary control
What are the inputs to the central pattern generator (CPG) (also called the respiratory center)
- Which inputs provide involuntary control of breathing? (7)
- peripheral chemoreceptors
- central chemoreceptors
- joint and muscle receptors
- pulmonary stretch receptors
- airway irritant receptors
- cerebellum
- hypothalamus
explain how each of these are involuntary ventilatory control mechanisms
- joint and muscle receptors
- pulmonary stretch receptors
- airway irritant receptors
- Joint and muscle receptors are the proprioceptors- know where body parts are in space
- They will send signals to the brain when exercising to increase respiratory rate and cardiac output
- Lungs have pulmonary stretch receptors
- Do not want the lung to inflate all the way, they will detect this
- Airway irritant receptors
- Will detect noxious particles and you will cough
How does hypothalamus affect respiration?
- temperature regulation
- Hypothermic- RR will decrease
- Hyperthermic- RR will increase
What are the major structures of the CPG (Central Pattern Generator)?
- PRG (Pontine respiratory group)
- Medulla oblongata- contains the inspiratory and expiratory nuclei
What happens in normal quiet breathing for inhalation and exhalation
What happens in forceful breathing
What is the normal rhythmic breathing times
- Inspiration for 2 seconds
- Expiration for 3 seconds
What are 4 things that can interrupt rhythmic breathing
- Vocalization
- swallowing
- parturition
- defecation
Describe the effect transection of the brain stem between the pons and the medulla would have on breathing
- able to breath normally
- Medullary rhythmicity center is still intact
Describe the effect transection of the brain stem between the medulla and the spinal cord would have on breathing.
breathing will stop
What are the 3 elements of respiratory control
- Receptors (Sensors) that gather information (e.g. ↑ PaCO2) and send info via the afferents to
- Controller (Integration Center)- CPG (Central Pattern Generator) in the brainstem which coordinates the information and sends impulses via efferents to
- Effectors (respiratory muscles) which cause adjustments in ventilation and decrease the PaCO2 which decreases the sensor input (negative feedback)
What are the 2 nasal reflexes and what do they do?
- Sneeze reflex – strong inspiration – immediately followed by a vigorous exhalation – most of the gas exhaled through the nasal passages
- Dive reflex – water instilled into the nose or on the surface of the nose
- Cessation of breathing, slowing of heart rate, bronchoconstriction
Hering-Breuer Inflation Reflex does what
- The Hering-Breuer Inflation reflex begins in the proprioceptors of joints and muscles that activate the inspiratory centers of the medulla oblongata to increase ventilation prior to exercise induced oxygen requirements.
- The Hering-Breuer Inflation reflex detects lung expansion with stretch receptors, which limit the amount of lung tissue stretch.
- The amount of stretch is based on the metabolic/ventilatory requirements of the animal.
- If the lungs stay inflated –> expiration has been inhibited –> and the next inspiration will be inhibited.
- The lung has not deflated at this time and thus will inhibit the inspiratory areas from starting to fire for the next breath.
- Eventually, the animal will try to take a breath (inspire) due to the increase in [PCO2].
- The Hering-Breuer Inflation reflex also prevents damage from over stretching the lung (Over-expansion –> potential visceral pleura membrane rupture –> positive air pressure into the thoracic cavity –> pneumothorax (positive air in the thorax) –> Collapsed lung (atelectasis).
What does The Hering-Breuer Deflation Reflex do
- You can visualize this in a normal animal- At the beginning of inspiration, press on the chest –> this will initiate this reflex to cause an immediate inspiration.
- Also, you can clinically utilize this reflex if there is a patient that is experiencing apnea (cessation of breathing)- push on the animal’s chest and deflate the lung more in an attempt to stimulate an inspiration.
What are the 2 peripheral chemoreceptors and where are they located and what innervated by
- Carotid bodies at the bifurcation of the carotid artery near innervated by CN IX
- Aortic bodies above and below the aortic arch near innervated by CN X
- Is the central chemoreceptor accessible by blood through the blood brain barrier (BBB) and associated H+ and HCO3-
- Is the central chemoreceptor accessible by cerebrospinal fluid (csf) and associated H+ and HCO3-?
- yes
- yes
When __________ mm Hg is reached, the animal’s ventilation increases due to decrease in PaO2.
65 mmHg
