Ventilation and buffer system, O2 regulation etc.

remember this equation dude

CO₂+H₂O → H₂CO₃→ H⁺ +HCO₃^-

• increased co2 in tissues = more H+ ions = more acidic blood = lower pH

• Low pH triggers hemoglobin to unbind CO2 in tissues and it moves down concentration gradient into blood.

• High O2 concentration in blood is now able to move down its concentration gradient into the tissue.. BOOM

What’s oxygen affinity?

how much oxygen is being bound to hemoglobin (saturation)

• remember book example, all hemoglobin binding sites are occupied

• DECREASES at tissues because oxygen is being absorbed by tissues

When is Hb FULLY SATURATED?

at the LUNGS because all hemoglobin binding sites are occupied by oxygen.

oxygen affinity: high OXYGEN saturation in LUNGS and TISSUES, hard at letting go

What determines how much oxygen binds to hemoglobin (saturation)?

the partial pressure of oxygen, positively correlated

How is oxygen saturation affected by other variables?

Hemoglobin OXYGEN affinity depends on

• pH

  • INCREASED pH = RIGHT shift of Hb dissociation curve because of buffer equation (first card)

  • hemoglobin retains LESS oxygen at a lower pH (recall that cascade)

• LESS VENTILATION = LESS CO₂ leaving through exhalation

  • increased CO2 in blood = INCREASED h+ through equation

• TEMPERATURE

  • HIGH temp = RIGHT SHIFT, lower oxygen affinity

What’s the Bohr effect?

how changes in pH (BoHr) affect the ability of hemoglobin to bind and release oxygen

Why is the Bohr effect advantageous?

it helps with unloading blood to tissues through that one CO2 cascade that affects hemoglobin binding sites with decreased pH and allows for CO2 and O2 to move down their concentration gradients.

What’s a peripheral chemoreceptor?

a receptor in the PNS, carotid and aortic bodies, monitor change in ARTERIAL BLOOD

• responds to changes in O₂ and pH in CSF

• FASTER SPEED because no relay of AP in nervous system is needed

• synapse with sensory neurons, causes changes in ventilation

What’s a central chemoreceptor?

a receptor for H+ in the CNS (brainstem) that responds to changes in CO₂ and pH in CSF( maintained by GLIAL cells to PROTECT neurons)

→ sends signal to brainstem → INCREASE ventilation → CO2 decreases, corrects for change in pH

• slower speed

***C for CENTRAL

H+ ions cant cross capillary wall but CO2 can

More CO2 = reacts with water which INCREASES pH

Lots of CO2 in blood = larger partial pressure gradient in capilalry and CSF

What are the BIG 3 that need to be regulated?

• O₂

  • needed to metabolize

• CO₂

  • may cause acidosis

• pH

How does ventilation change pH?

Increased breathing with no change in metabolic rate, more O2 in, less CO2

• recall buffer equation with bicarbonate that’s DEPENDENT ON CO2B, LESS CO2 due to breathing more= LESS H+ = MORE BASIC= HIGHER pH

How does concentration affect diffusion rate?

larger gradient = larger diffusion rate

What does hypertonic mean?

Of the solution relative to the cell, the solution has a higher osmolarity than the cell

What’s the function of osmolarity in kindeys?

allowing for reabsorption through osmotic gradients in the inner medulla.