human physiology unit 3

two major components of pulmonary physiology

• gas exchange

• gas transport

respiration in pulmonary physiology equation

C6H12O6 +6O2 → ATP + 6CO2 +6H20

how many oxygens per respiration cycle move into working tissues?

12 oxygens (6O2)

what do we use to diagnose disease in pulmonary phys

spirometry

respiration can be described as

the o2 and co2 shuttle system

carbonic anhydrase shift equation

CO2 + H20 <=> H2CO2 + H⁺ + HCO3^-

what is H2CO3

carbonic acid

what is HCO3^-

bicarbonate

how do we find the ph in carbonic anhydrase shift equation?

take the concentration if [H+]

-log[h+]=ph

why are acidic environments unfavorable in pulmonary physiology

• decreases O2 carrying capacity which alters all enzymatic reactions of cellular processes

O2 characteristics

• decrease in solubility in fluids

• high energetic tissues increase demand

• 0.3m O2/100 ml

what do respiratory pigments do?

bind o2, co2 h+

ideal respiratory pigment

• a lot of it

• not very heavy

• great o2 carrying capacity

• packaged in rbc

• hydrodynamically good carriers

• carries hemoglobin

oxyhemoglobin

• carried on heme

• reduced hb + o2 <=> HbO2

carbamino hemoglobin

reduced hb + CO2 <=> HbCO2

• carried on peptide chain

• hemoglobin is carrying waste

carboxyhemoglobin

hb (not reduced) + CO <=> HbCO

• carried on heme with 120x the affinity

• CO binds 240x more than oxygen and will lock onto iron - why it is so poisoning

factors of hemoglobin

• mw = 64,450

• 4 subunits, each with one heme

• hemes carry o2

• polypeptide chains carry Co2 (alpha chains or beta chains)

• structural organization affects O2 affinity

• max carrying capacity of 4O2

• Fe3+ is core heme

what percentage of O2 is physically dissolved in gas transport?

About 1.5% of O2 is physically dissolved in plasma.

what percentage of O2 is converted into HbO2 in gas transport?

Approximately 98.5% of O2 is converted into oxyhemoglobin (HbO2) in gas transport.

what percentage of CO2 is physically dissolved in gas transport?

10%

what percentage of CO2 is converted into HbCO2 in gas transport?

30%

what percentage of CO2 is converted as bicarbonate in gas transport?

Approximately 60% of CO2 is converted into bicarbonate (HCO3-) in gas transport.

how does hemoglobin decide which gas to carry?

• cooperatively / Haldane effect

• binds to oxygen and carbon dioxide based on their partial pressures.

cooperativity and hemoglobin w oxygen

• high partial pressure of oxygen increases hemoglobins affinity

Haldane effect

high partial pressure for co2 vs lower partial pressure of o2 will allow for affinity of co2

partial pressures of oxygen from air, lungs, blood, tissues

decreases in that order; diffusion gradient

how to find partial pressure?

percentage of gas x total pressure

high partial pressure can be toxic, give an example

nitrogen narcosis

what does the carbonic anhydrase shift equation give us?

• blood PH!

at a big depth what can happen due to partial pressure?

• increased partial pressure

• nitrogenous narcosis

partial pressure and sea level****

• homeostasis!

• ppO2 = 160

• 1 atm=760mmHg

altitude and partial pressure

• lower partial pressure

• can cause erythropoiesis response due to hypoxia

erythropoiesis

is the process of producing more red blood cells in response to low oxygen levels, often triggered by lower partial pressure at high altitudes.

symptoms of erythropoiesis

• increase in blood viscosity

• increase in blood pressure

• decrease in partial pressure

• nausea

• insomnia

• increase in heart rate

if oxyhemoglobin is saturated it must mean

• relaxed state

• all four oxygen molecules are bound (one per heme group)

• sigmoid shape

hemoglobin and O2 kinetics and increase in partial pressure

• association curve

• will bind with o2

• as the partial pressure rises, the greater the association with hemoglobin

hemoglobin and o2 as partial pressure decreases

• dissociation curve

• release O2

• as the ppO2 falls = lower association with hemoglobin

at what ppO2 do pulmonary capillaries reach 100% saturation of hemoglobin and oxygen?

Typically at about 100 mmHg.

at what percentage of saturation would systemic capillaries be a ppO2 of 40?

Typically around 75% saturation.

myoglobin vs hemoglobin

• Myoglobin has a higher affinity for O2 than hemoglobin.

• It becomes saturated at lower partial pressures of oxygen compared to hemoglobin.

dissociation curve means

• releasing oxygen as the partial pressure of O2 falls

• lower association with hemoglobin

association curve

• binds O2

• partial pressure rises

• greater association with hemoglobin

is oxyhemoglobin an association or dissociation?

• association

Bohr shift

• measures percentage of oxyhemoglobin saturation

• shifts left if more basic (alkaline) conditions

• shifts right if more acidic conditions

What would happen to percentage of oxyhemoglobin saturation in acidic conditions?

• oxygen will be dumped sooner

• larger ppO2

• right shift Bohr

what happens to oxyhemoglobin in alkaline conditions (basic)

• will bind (retain) O2 longer

• shifts left on Bohr

• lower ppo2

right shifts on a Bohr model can be caused by

• increase of carbon dioxide

• increase in acidity

• increase in temp

• increase of 2,3 bisphophoglycerate

what does an increase in 2,3 biphosphoglycerate mean?

higher metabolism

left shifts on a Bohr model can be caused by

• decrease in Co2

• decease in acidity (increase in basicity)

• decrease in temp

• decrease in 2,3BPG

what are our control points on a Bohr model?

pH= 7.4

ppO2= 34mmHg

if someone is hyperventilating what kind of shift will you see on a Bohr model?

left!

• low ppCO2

• low 2,3DPG

if someone is breathing super slowly or choking what kind of Bohr shift would you see?

• right shift

• high ppCO2

• HIGH 2,3DPG

when is low 2,3 DPG found?

• left shifts

• found when you store blood due to low temp (ex. blood transfusion)

respiration is defined as

shuttle system in which oxygen converts to carbon dioxide in the lungs

the goal of carbonic anhydrase

• regulate pH, carrying capacity of hemoglobin, enzyme activity

is carbonic anhydrase reversible at all steps?

yes

for every 100mL blood there is how many mL of O2?

0.3

at depths below sea level atms increase by how many feet

every 33 ft =1atm increase

example 66 ft below sea level = 2 atm

what is the most dangerous increased partial pressure below sea level?

partial pressure of nitrogen - nitrogen narcosis

at 100% saturation what is the ppO2 found in pulmonary capillaries

100 mmHG

75% saturation of ppO2

40 mmHg (found in systemic capillaries)

what does P50 refer to

the partial pressure of oxygen at which hemoglobin is 50% saturated.

at what partial pressure is oxygen reaching 50% saturation in hemoglobin

18 mmHg

if we have a higher p50 level then what does that mean for o2

decreased affinity for O2 in hemoglobin, resulting in less oxygen binding

• hemoglobin isn’t very “sticky”

the p50 can be described as

the half way point!!

2,3 -DPG is a byproduct of what

anaerobic metabolism

what triggers oxidative phosphorylation in CO2/O2 shuttle?

presence of HbO2

what happens to CO2 as a byproduct of ATP production?

• enters red blood cells and carbonic anhydrase splits in into protons (H+) and bicarbonate (HCO3-)

what happens to protons (H+) that are formed by carbonic anhydrase in CO2/O2 shuttle?

binds to make HbH

what happens to HCO3- bicarbonate formed by carbonic anhydrase in co2/o2 shuttle

• it does not bind to hemoglobin

• will diffuse into the plasma

atmospheric air is how much nitrogen and oxygen

79% nitrogen

21% oxygen

negligible amount of other products

blood returning from body tissues has a pco2 of 46 mm and a po2 of 40 what will happen when it comes in contact with aveolar air?

• because alveolar air has a pO2 of 100 mm Hg and they will come in contact, the O2 will diffuse down the concentration gradient to level out

in the CO2/O2 shuttle what happens to HbCO2 and HbH

• travels to the lungs where it releases CO2 and picks up O2

what happens to CO2 overall in the CO2/O2 shuttle?

• 10% is dissolved into plasma

• 30% carbaminohemoglobin HbCO2

• 60% as HCO3-

what is the chloride shift

when bicarbonate ions are pumped into the alveoli, chloride is pumped out to balance electrical charges

what happens in exhalation

in alveoli, HCO3- reunites with H+ to revert to CO2 + H2O and then Co2 is expelled from lungs

overview of CO2 shuttle and chloride shift steps

1. trigger by oxyhemoglobin signals O2 available for oxidative phosphorylation

2. CO2 is produced as byproduct and enters into RBC

3. carbonic anhydrase splits CO2 into bicarbonate and protons

4. bicarbonate diffuses out of plasma and into aveoli and chloride shifts out

5. HbCO2 and protons bind to hemoglobin transporting CO2 back to lungs.

6. exhalation occurs when bicarbonate reunites with protons to convert to CO2 and water

7. resetas hemoglobin is reduced and becomes oxyghemoglobin

8. tissue chloride shift - bicarbonate moves to tissues and chloride moves back into alveoli

what is the greatest way to get rid of co2?

turn into bicarbonate

the conducting zone includes (no gas exchange occurs here)

• nasal passages

• pharynx

• trachea

• bronchioles

nasal passages

bring air in via respiratory cilia and pressure gradients

pharynx

transfers air and food into the trachea

trachea

• smooth muscle that moves air

• some air from here cows to larynx for vocalization; the rest to bronchi

bronchioles lead to what

alveoli, where gas exchange occurs.

respiratory zone (true gas exchange)

• alveoli

the only site of exchange with the atmosphere is

the alveoli of the lungs.

surface area and the respiratory zone

• massive area lowers resistance and slows blood velocity and provides time for oxygen to associate with hemoglobin

Boyles law

P1V1=P2V2

• pressure is inversely proportional to volume

• air falls down a pressure concentration gradient it is not pushed or pulled

inspiration

• requires ATP

• innervated by prehnic nerve which controls diaphragm

• diaphragm and external intercostal muscles contract

• as volume increases pressure decreases (air moves in)

expiration

• passive process

• happens naturally via gravity

• inspiratory muscles relax

• volume decreases, pressure increases, air moves out

alveolar cell type I

covers the surface area

alveolar cell type II

produces surfactant

surfactant

• a lipid/protein mixture that reduces surface tension to prevent lung collapse and promote compliance

• also aids immune defense

macrophages

protects lungs via phagocytosis

smoking and vaping

• incapacitates macrophages and can cause pulmonary fibrosis/emphysema

• prevents respiratory cilia from moving

eupnea, dyspnea, apnea

eupnea- normal

dyspnea- difficult

apnea- absence of breathing

FEV stands for

forced expiration volume

healthy FEV rate

80% or more of air per second

anatomical dead space (Vd)

• air that stays “plumbing” and doesnt reach tissues

TV (spirometry)

tidal volume

= VC-ERV-IRV