Lecture 28: Respiratory gas exchange and transport

vasoconstriction

When there is decreased O2 in the pulmonary arterioles, it leads to vasoconstriction/vasodilation

vasodilation

what there is decreased O2 in the systemic arterioles, it leads to vasoconstriction/vasodilation

vasodilation

When there is increased O2 in the pulmonary arterioles, it leads to vasoconstriction/vasodilation

vasoconstriction

what there is increased O2 in the systemic arterioles, it leads to vasoconstriction/vasodilation

gas exchange

pulmonary circulation makes ____ _____ efficient

metabolic

systemic circulation matches blood supply to local ____ needs

V/Q ratio

A measurement that examines how much gas is being moved effectively and how much blood is gaining access to the alveoli.

V

rate of airflow is represented by the letter

Q

rate of capillary blood flow to the alveoli is represented by the letter

0.8

the normal V/Q ratio is this

V/Q mismatch

in this, the rate of airflow is not similar to that of blood flow, usually under pathological conditions

Alveolar ventilation, shunting

A low V/Q ratio is produced by the block of _______________ ______________, which cuases the _____________ of blood flow

Dead space

High V/Q ratio is produced by the alveolar blood perfusion being blocked, which causes a ________ ____________ in the airways

Partial pressure

this is the pressure exerted by each gas in a mixture as if the other ones were not there

Henry's law

this states that the amount of dissolved gas is proprotional to its partial pressure in the gaseous phase

simple passive diffusion

gas exchange involves ____ _____ ____ of O2 and CO2 down their own partial pressure gradients 

Bigger, lungs, capillaries

In the lungs, the partial pressure of oxygen is __________(bigger/smaller) than the partial pressure of oxygen in the pulmonary capillaries, therefore oxygen flows from the _______ to the _____________

Smaller, capillaries, lungs

In the lungs, the partial pressure of CO2 is ___________(bigger/smaller) than the partial pressure of CO2 in the pulmonary capillaries, therefore the CO2 flows form the _____________ to the _________

Bigger, capillaries, tissues

At the tissue levels, the partial pressure of O2 is __________(bigger/smaller) in the capillaries than in the tissues, which means that the O2 flows from the __________ to the ___________

Smaller, tissues, capillaries

At the tissue levels, the partial pressure of CO2 is ____________(bigger/smaller) in the capillaries than in the tissues, which means that CO2 flows from the ___________ to the ____________

Ficks law of gas diffusion

this is gas transfer rate = (P1-P2) x (surface area) x (diffusion constant)/thickness of the membrane

Pressure gradient

What is the major determinant of the rate of transfer for most gases?

Smaller, diffusion constant, bigger

The pressure gradient (difference) for CO2 is much ______________(bigger/smaller) than that of O2, however this is compensated because the _____________ _______________ for the rate of diffusion of CO2 is much ______________(bigger/smaller) than that of O2

Emphysema

a condition in which the air sacs of the lungs are damaged and enlarged, causing breathlessness, due to decreased surface area and increased thickness of the membrane

Hemoglobin

Most of the Oxygen in the blood is bound to _________________

Hemoglobin

this is an iron containing molecule that has 4 heme molecules and can bind O2, each one binds 1 O2

True

True or false: the O2 bound to Hb does not contribute to Po2 of the blood

Oxyhemoglobin

this is hemoglobin bound to oxygen

PO2

what is a primary determinant of precent hemoglobin saturation with O2

Increases

The hemoglobin's affinity for O2 ___________(increases/decreases) as more O2 molecules become bound

does not

The O2 bound to the Hb does/does not contribute to the PO2 of the blood

PO2

Hb acts as an O2 storage depot by keeping ____ low

O2

binding of O2 to Hb removes ___ from the blood

PO2

This binding of O2 to Hb reduces ___ and maintains the partial pressure gradient that drives O2 from alveoli into the blood

Increased CO2, increased acid, increased temperature, increased 2-3 BPG

What caues a rightward shift of the signmoidal O2 Hb saturation curve?

More, more

When there is a rightward shift of the Hb curve, __________(more/less) O2 is unloaded from Hb at the tissue levels, which causes _____(more/less) O2 being delivered to tissues

CADET - face right

CO2

Acid

2,3-Diphosphoglycerate

Exercise

Temperature

right (shift)

what is the pneumonic for right shift of the O2Hb curve

Bohr effect

a decrease in the amount of oxygen associated with hemoglobin and other respiratory compounds in response to a lowered blood pH resulting from an increased concentration of carbon dioxide in the blood.

Cabon Monoxide

What causes a leftward shift of the Hb curve?

Increased, decrease

Carbon monoxide causes a leftward shift by causing the affinity for O2 on hemoglobin to be ____________(increased/decreased) which makes the O2 transfer to tissues _____________(increase/decrease)

CO

Does O2 or carbon monoxide (CO) have a higher affinity for Hb

Asphyxiation

deprived of oxygen, however, the individual cannot tell that their cells are deprived of oxygen 

Someone with CO poisoning would die of __________________

Normal

If someone has CO poisoning, their PO2 levels appear ____________(normal, irregular)

Bicarbonate

Most of the CO2 is transported in the blood via what molecule?

Carbonic anhydrase

this is the enzyme that catalyzes the conversion of CO2 to H+ and bicarbonate (HCO3-)

switches through a H2CO3 intermediate

• slow

how does the spontaneous conversion of CO2 and H2O to H+ and bicarbonate happen in the blood

Haldane effect

Deoxygenation of the blood increases its ability to carry carbon dioxide

More

At the tissues, the more dissolved CO2 in the plasma reacts with oxcygen to form H+ and bicarbonate, which allows for __________(more/less) transport of O2 in the tissues

Chloride shift

this is the transporter that is in the red blood cells that exchanges bicarb and chlorine

Peripheral chemoreceptors

these are in the carotid bodies and respond to the decrease in PO2, increased PCO2, or decrease in pH, which causes increased ventilation

pH, PCO2

the main stimulus of peripheral chemoreceptors are changes in ___, usually as a result of the increase in _______

Central chemoreceptors

these are in the medulla and respond to changes in the H+ concentration in the CSF, and in effect can increase ventilation

CO2

The reason why chemo receptors increase ventilation, is because this in effect lowers the partial pressure of ______ in the arteries

Chonic obstructive pulmonary disease

this is the chronic inflammatory lung disease that causes obstructed airflow from the lungs and breathing related problems, including emphysema and chronic bronchitis