Sect. 8.2 - Distribution of Gases in the Body

lungs

Organ that provides oxygen to the blood and remove carbon dioxide from the blood

Circulatory and Pulmonary systems

What 2 systems work together to provides oxygen to the blood and remove carbon dioxide from the blood?

pharynx

oxygenated air from the atmosphere is breathed in through the nose and mouth and enters the __________

larynx

forms the entrance to the lower respiratory system (aka voice box)

primary function: prevent food or fluid from entering the lower respiratory system during swallowing

trachea

rigid tube that is located a the opening of the bronchial tree

alveoli

functional units of the respiratory system

350 million

approx how many alveoli per lung

gas diffusion (high to low)

The enormous number of alveoli provides a very large surface area for

true

T or F:

The diffusion rate is further increased by the fact that each alveolus is only one layer thick and the blood capillaries are also one layer thick

alveoli capillaries into pulmonary capillaries

In the lungs, oxygen diffuses form ___________ into the __________

ventilation

movement of air through the respiratory passageways into the alveoli of the lungs, followed by a reversal of air movement out of the lungs

1. Inspiration (inhaling)

2. Expiration (exhaling)

2 phases of ventilation

Insipiration (inhaling)

diaphragm lowers, air pressure within the lungs is less/lower than the atmospheric pressure, so air moves in

↓ diaphragm = ↓ pressure = air IN

Expiration (exhaling)

diaphragm raises, air pressure within the lungs is greater/higher atmospheric pressure, so air moves out

↑ diaphragm = ↑ pressure = air OUT

diaphragm

main muscle of respiration

medulla

Where is the respiratory center of the brain?

lung capacity

viability of passages

muscle function

elasticity

total ventilation depends on (4)

Surfactant

chemical produced in the lungs to maintain the surface tension of the alveoli and keep them from collapsing

Alveolar PCO2

Plasma PO2

Oxygen saturation (SO2)

Fraction of inspired O2 (FIO2)

Respiratory quotient

Lung capacity to transfer oxygen (oxygenation) is measured by devices that utilize calculations internally, such as (5)

Alveolar PCO2

Measurement of Lung capacity to transfer O2:

Partial pressure of CO2 gas found in alveoli

- breath into device; non-invasive

Plasma PO2

Measurement of Lung capacity to transfer O2:

Partial pressure of dissolved O2 in plasma (not attached to hgb); relates directly to oxygen status

- arterial sample (blood stick); invasive

- typically determines hypoxia

hypoxia

decreased oxygen supply to tissues

Oxygen saturation (sO2)

Measurement of Lung capacity to transfer O2:

Ratio of O2 that is bound to hgb, compared with total amount of hgb capable of binding O2

- use Pulse Onyx

Fraction of Inspired Oxygen (FIO2)

Measurement of Lung capacity to transfer O2:

Amount of O2 available for pt to breath

- % of O2 in the ambient air

20.93%

percentage of oxygen in ambient air

**lower in places with high elevation, pollution, wildfires

Respiratory quotient

Measurement of Lung capacity to transfer O2:

The ratio of CO2 being produced to the amount of O2 being consumed

- non-invasive

PCO2

Ventilation is inversely proportional to

true

T or F:

The control of ventilation is one of the most important of all brain function

The rhythm of the muscles that contract must be consistent and automatic as well as be able to accommodate changing metabolic demands

For normal ventilation to occur, what events need to take place?

control the diaphragm

Respiratory-related neurons in the medulla generate signals that are distributed to neurons within the respiratory muscle

The most important of these neurons are those that

phrenic nerve

responsible for the increase in ventilation activity to accommodate an increase in body activity; directly controls the diaphragm

tonic drive

the continuous, repetitive motion of inspiration and expiration

central and peripheral neurons/chemoreceptors that monitor O2, CO2, and pH

The tonic drive develops from main sources, but the most important are

apnea

absence of ventilation

dyspnea

difficult breathing

eupnea

normal breathing (at rest or light exercise)

external convection system

the exchange of O2 for CO2 between the alveoli and pulmonary capillaries in the lungs

internal convection system

the exchange of O2 for CO2 between the blood vessels and tissues

Conditions needed for adequate tissue oxygenation

- Available atmospheric oxygen

- Gas exchange between lungs and arterial blood

- Loading of oxygen onto hemoglobin (each hgb carries 4 oxygen molecules)

- Adequate transport (cardiac output)

- Release of oxygen (perfusion) to the tissues

4 O2

Each hemoglobin molecule can bind ____ O2 molecules

bound to hemoglobin

Most of the oxygen transported by the blood to the tissues is

ferrous (Fe2+)

reversible

Hemoglobin can only bind to oxygen in the (ferric / ferrous) state

Binding of O2 is (reversible / irreversible)

histidine

the most important amino acid involved in the binding of hgb to O2 (it binds Fe2+)

oxyhemoglobin

Hgb with O2

deoxyhemoglobin

Hgb without O2

perfusion

the process of blood delivery to a capillary bed in the tissues and the subsequent transfer of oxygen

oxygen status and hemoglobin's ability to deliver oxygen to the tissues

Oxygen transport is based on

1.34ml

One gram of hgb can hold about ________ of oxygen when 100% saturated

1.34mL x hemoglobin (g/dL)

Formular for Oxygen-Carrying Capacity

97-98% saturated

Under normal conditions the hemoglobin is _________% saturated

75%

In the tissues where capillaries and veins exchange gases, mixed venous oxygen saturation is generally ________%

pH

PCO2

temperature

2,3-DPG

Four factors that affect the perfusion rate of oxygen

O2 Saturation Curve

Hgb-Oxygen Dissociation Curve is also known as

curve is positive and sigmoid (S-shaped)

high O2 demand

being warm

produce large amounts of CO2

being acidic

Metabolically active tissues have the following characteristics (4)

**hint: what happens when you work out

high temperatures

_________ temperatures decrease O2 affinity of hgb & O2 is released

Bohr effect

the effect pH has on the relationship between hgb and oxygen

Haldane Effect

removal of oxygen from Hgb increases Hgb's affinity for CO2 (adds CO2 to get rid of from body)

hypercapnia

increased carbon dioxide in the blood

hypocapnia

decreased carbon dioxide in the blood

2,3-Diphosphoglycerate

aka 2,3-DPG

2,3-DPG

a phosphate compound found in RBCs

destabilizes the bond of hgb-O2, releasing O2

decreased O2 affinity

increased levels of 2,3-DPG leads to __________ O2 affinity

hypoxic states

high 2,3-DPG can be observed in what type of state?

glycolysis increases, leading to increased levels of 2,3-DPG and decrease in O2 affinity

increased O2 affinity

decreased levels of 2,3-DPG leads to __________ O2 affinity

left shift

increased pH (acidic)

decreased PCO2

decreased temp

decreased 2,3-DPG

presence of carboxyhemoglobin (decrease in bound O2)

right shift

decreased pH (alkaline)

increased PCO2

increased temp

increased 2,3-DPG

increased affinity of hgb for O2

A left shift on the ODC indicates

decreased affinity of hgb for O2

A right shift on the ODC indicates

left shift

Fetal hgb (HgbF) and other variants cause (right / left) shift

Bicarbonate (HCO3-)

Carbamino (CO2+Hgb) Compounds

Dissolved Carbon Dioxide (dCO2)

Carbonate (CO3-)

Carbonic acid (H2CO3)

five forms that constitutes the total CO2 content (tCO2)

Bicarbonate, Carbamino compounds, Dissolved CO2

three main transporters of CO2 in the body

HCO3- (bicarb)

CO2 is transported in the blood primarily as

~70%

Bicarbonate makes up _______% of tCO2 in plasma

3 ways HCO3- can form

- H2CO3 can dissociated into HCO3- and H+

- HCO3- forms when carbonate (CO3-) combines with H+

- CO2 can combine directly with hydroxyl ions (OH-) to form HCO3-

5-7%

Dissolved CO2 makes up _______% of tCO2 in plasma

15-25%

Carbamino (CO2+Hgb) Compounds makes up _______% of tCO2 in plasma