M14: C02 transportation & Regulation of Ventilation Flashcards
3 forms of C02 transport
- DISSOLVED C02 (7%)
- CARBINOHEMOGLOBIN (23%)
- carries on pr- (globin) component of hemoglobin - BICARBONATE IONS
- C02 binds with water to form carbonic acid
- H2C03 dissociates into hydrogen and bicarbonate ions (rxn that buffers pH changes)
haldene effect
releasing O2 from Hbg increases Hbg affinity for C02
carbon dioxide transport: internal respiration
REACTION DRIVER: high PP C02 created by tissue cells, need to move into RBC
- C02 IN from tissues
- C02 + water = carbonic acid
- carbonic acid breaks down into bicarbonate and H+ ion
CHLORIDE SHIFT - bicarbonate leaves the cell. replaced by Cl- to equalize charges
BOHR EFFECT - H+ ion binds to hemoglobin
- decreased pH causes right shift in oxy-hem disassociation curve, O2 leaves to tissues more easily
HALDENE EFFECT - as O2 leaves hemoglobin, affinity for C02 increases, takes on leftover C02
carbaminohemoglobin
carbon dioxide and hemoglobin after the release of oxygen by the hemoglobin to a tissue cell
C02 transport: external respiration
- REACTION DRIVER: C02 pulled out of RBC in lung because of low C02 pressure in alveoli
- C02 reformed by carbonic acid + water
- carbonic acid reformed by bicarbonate and H+ ions
- to get bicarbonate: REVERSE CHLORIDE SHIFT: bicarbonate into cell, Cl- out
- to get hydrogen: H+ released from hemoglobin, hemoglobin increased affinity for O2 and pulls it into cell from lungs.
- H+ release causes C02 release from hemoglobin, goes to lungs
regions of respiratory control in the brain
brainstem (medulla oblongata)
- DORSAL RESPIRATORY GROUP
- sends signals for inspiration - VENTRAL RESPIRATORY GROUP
- forceful inhalation: stimulated by dorsal respiratory group, nerves stimulate nerves for accessory breathing muscles
- forceful exhalation: activates muscles of forceful expiration
- PRE-BÖTZINGER (superior): thought to play a role in breathing rhythm - PONTINE RESPIRATORY GROUP (in pons)
- switching between inspiration and expiration
- may stimulate dorsal respiratory group
Hering-Breuer reflex
- inhibitory breathing signal
- stretch receptors in lungs
process of rhythmic ventilation
STARTING INSPIRATION
- input from receptors that monitor blood gases, temp, muscle movement
- medullary response centre neurons spontaneously establish basic rhythm
- sends APs to respiratory muscles
INCREASING RESPIRATION
- increased motor neuron activation - deeper breaths
- lasts ~2sec
STOPPING INSPIRATION
- neurons gets input from stretch receptors in lungs
- inhibitory neurons activated
- muscles relax = expiration
- lasts ~3sec
regions chemoreceptors
CENTRAL chemoreceptors (medulla oblongata)
- detect decreases in pH and increases in C02 pressure in CSF
PERIPHERAL
- carotid artery and aortic body
- detect changes in pH, pressure C02 and pressure O2
regions of body that can alter respiration, do they increase of decrease breathing rate
BRAIN
- central chemoreceptors (increase)
- cerebrum, voluntary control (increase/decrease)
HEART
- peripheral chemoreceptors (increase)
LUNGS
- Hering-Breuer reflex: stretch receptors (decrease)
MUSCLES
- proprioceptors (increase)
SENSORY RECEPTORS
- touch, temp and pain
- e.g. sneeze reflex, temp changes to account for changes in metabolism
carbonic anhydrase
converts water and C02 into carbonic acid
where is respiratory control centre located in the brain
brain stem, primarily medulla oblongata
portion of medullary respiratory centre involved in normal breathing
DORSAL RESPIRATORY GROUP
(cells found in dorsal side of medulla oblongata)
- INHALATION: sends signals to muscles to stimulate inspiration (PHRENIC NERVE to diaphragm, INTERCOSTAL NEREVE to external intercostal muscles)
- EXHALATION: signal inhibited/not activated, muscles relax
intercostal muscles used in exhalation
internal intercostals
regions within medualla oblongata that regulate breathing
DORSAL RESPIRATORY GROUP
VENTRAL RESPIRATORY GROUP
