Bio 269 Exam 3 -Casotti WCU

Respiration Components

4 Steps from air to cellular level

-breathing air into alveoli, O2 from lungs to vasculature while CO2 from vasculature to lungs

-respiratory diffusion/ External Respiration (across respiratory membrane) by pulmonary capillaries

-bulk transport (movement of gas along pressure gradient) by systemic capillaries

-cellular diffusion/ internal respiration

Dalton's Law

-atmosphere follows this law

-The total pressure of a mixture of gases is the sum of the individual pressures (Ptotal=P1+P2+P3...)

-total = 760 mmHg at sea level, less on top of a mountain

Henry's Law

-gases dissolve in liquid in proportion to their partial pressure

-equilibrium will be reached

-as O2 dissolved in blood, gas changes state of matter

-doesnt take into account solubility

2 Factors affecting gas ability to cross alveolar membrane

-temperature: lower temperature, faster diffusion (not in humans bc maintain constant body temperature)

-Solubility: ability to dissolve in liquid

Order of solubility of gases (highest to lowest)

CO2 > O2 > N2

Does Nitrogen cross membrane?

No because not very soluble

Would we survive with more CO2 in air than O2?

No bc CO2 easily diffused so not enough O2 and we would die

Alveolar Gases

-O2, CO2, N2, H2O (vapor)

-in alveoli at any time, contains more CO2 and H2O than O2

How is there more H2O in our lungs than atmosphere?

We breathe in dry air, when pass by moist surface, picks up H2O particles to prevent drying out alveoli

Where does oxygen diffuse from and to?

alveoli to pulmonary capillaries

Where does carbon dioxide diffuse from and to?

pulmonary capillaries to alveoli

Why is gas different in alveoli than in the air?

-O2 diffuses into blood, Co2 diffuses in opposite direction

-humid air within the lungs

-air in alveoli is a mixture of new and old air (bc not all air is expelled each breath)

How do you maximize new air and minimize old air in alveoli?

By taking a deep breath

4 Circuits in the body

-systemic

-coronary

-pulmonary

**NEW: bronchial circuit**

2 ways humans can alter gas composition in lungs

-increase rate of breathing

-increase depth of breathing

Where is bronchial artery located?

-branches off aorta

-brings oxygenated blood to the tissues of the lungs

Where is the bronchial vein located?

-how deoxygenated blood leaves the tissues of the lungs

-joins the pulmonary vein to return to the heart

Where is blood partly oxygenated? Fully oxygenated?

-partially: most of pulmonary vein, aorta, bronchial artery

-fully: in pulmonary vein directly after the lungs until bronchial vein joins

Partial pressure of O2 and CO2 in atmosphere

pO2: 159mmHg

pCO2: 0.3 mmHg

Partial pressure of O2 and CO2 in alveoli (external respiration)

pO2: 105 mmHg

pCO2: 40mmHg

Partial pressure of O2 and CO2 in left atrium (after alveoli)

pO2: 100mmHg (bc brochial vein joins and deoxygenates some blood)

pCO2: 40 mmHg

Partial pressure of O2 and CO2 in systemic capillaries (internal respiration)

pO2: 40 mmHg

pCO2: 45 mmHg

Partial pressure of O2 and CO2 in right atrium (after systemic capillaries)

pO2: 40 mmHg

pCO2: 45 mmHg

Pressure Gradient: Oxygen

pO2 in deoxygenated blood is 40 mmHg

pO2 in alveoli is 104 mmHg

Pressure Gradient: Carbon Dioxide

pCO2 in deoxygenated blood is 45 mmHg

pCO2 in alveoli is 40 mmHg

How is the same amount of O2 and CO2 exchanged in the alveoli?

Although partial pressure difference are very large, CO2 is 20x more soluble than O2

difference of: pO2 > pCO2

solubility: O2 < CO2

*Cancel each other out*

Importance of Surface Area

-allows for fast diffusion of CO2 and O2 (increased contact of alveoli and pulmonary capillaries)

-human lung: 70m^2

Factors decreasing surface area

-emphysema: membranes of alveoli deteriorate, decreasing surface are

-can result from tumors, increased mucus, smoking for many years

-only 75% surface area remaining, volume stays same

Ventilation

bringing fresh air into the lungs

Perfusion

bringing blood to an organ (aka lungs)

EX: IV w saline is body perfused w fluid

Difference between size of alveoli

Large: high pO2, low pCO2

Small: low pO2, high pCO2

Ventilation-perfusion coupling

-Coupling of the amount of air with the amount of blood supply

-Couple Ventilation (air in alveoli) with perfusion (blood vessels)

-Vasodilate around large alveoli, vasoconstrict around small alveoli

Where does blood bring more dexoygenated blood to: small or large alveoli?

Larger alveoli to oxygenate the deoxygenated blood

How can you bring more deoxygenated blood to larger alveoli?

vasodilate the pulmonary capillaries that go to large alveoli to maximize amount of O2 blood that comes out and vasoconstrict pulmonary capillaries going to the smaller alveoli

What happens to vessels with alveoli that are low ventilated and well perfused

vasoconstriction

What happens to blood vessels with alveoli that are high ventilated but poor perfused

vasodilation

2 Ways O2 is transported in the blood

1. dissolved in plasma (about 15-18 ml/liter of plasma in body)

2. Bound to respiratory pigment, hemoglobin (about 200 ml/liter of plasma)

Structure of hemoglobin

-2 alpha and 2 beta polypeptide chains

-oxyhemoglobin: ratio of O2 to hemoglobin is 4:1

-deoxyhemoglobin: ratio of O2 to hemoglobin is less than 4:1

Percent Saturation

Expresses average saturation of hemoglobin with oxygen

Percent O2 saturation of deoxyhemoglobin leaving capillaries

75%

-ratio of oxygen to hemoglobin is 3:1

Percent O2 saturation of oxyhemoglobin leaving lungs

100%

-ratio of oxygen to hemoglobin is 4:1

O2 affinity for Hb

O2 has a high affinity for Hb, meaning O2 wants to bind to Hb

Factors decreasing O2 affinity for Hb

-increased body temp

-increased pCO2

-decrease in pH (Bohr effect)

-binding to 2, 3 diphosphoglycerate

What causes an increase in 2, 3 diphosphoglycerate

When exercising, RBC energy rate needs to increase, but not enough O2, so use anaerobic respiration, 2, 3 diphosphoglycerate making harder for O2 to attach to hemoglobin

Causes of hypoxia

-anemic: few RBCS less than 45% hematocrit

-Ischemic: impaired or blocked blood circulation

-Histotoxic: body cells unable to use O2 even though enough is being delivered (EX injesting cyanide inhibiting ETC in mitochondria)

-Hypoxemic: reduced arterial pO2 (CO2 poisoning)

3 ways to transport CO2 in blood

-Dissolved in plasma (7 - 10%)

-Bound to Hb in RBC(20 - 30%)

-converted to Bicarbonate ion in both plasma and RBC(60 - 70%)

CO2 transport from tissue (most to least)

1. FAST, in RBC: CO2 + H2O --carbonic anhydrase--> H2CO3 ---> HCO3- + H+ + Cl-

2. CO2 + Hb ---> HbCO2

3. CO2 dissolved in plasma

4. SLOW, in plasma: CO2 + H2O ---> H2CO3 ---> HCO3 - + H+

Chemical formula for bicarbonate

HCO3-

Chemical formula for carbonic acid

H2CO3

What is the reason for pH decrease in capillaries

carbonic acid production increases

remains in this form until reaches lungs

Formula for carbamino hemoglobin

HbCO2

-meaning at least one molecule fo CO2 attached to hemoglobin

-at the same time, O2 comes off of hemoglobin and goes to tissues and cells of human body

What happens to pH with more CO2 dissolved in blood

decreases (more acidic)

Where does the bicarbonate ion (HCO3-) go once produced inside the RBC? Why?

dissolved into plasma by transport proteins and Cl- dissolves into RBC to stay electrically neutral (CL- isn't an acid or a base so doesn't change pH0

Where does the H+ molecule go once produced in the RBC? Why?

-binds to hemoglobin to make HHb, Hb acts as a buffer

-RBC needs to get rid of H+ so pH can remain stable

Respiration overview

-oxygen utilization varies w activity: @ rest 200ml/min, exercise 6000 ml/min

-importance: breathing increases (rate and depth) due to metabolic demands, regulated by pH of extracellular matrix

What regulates depth and rate of breathing

CO2

Lung Anatomy: Conducting Zone

-trachea

-primary, secondary, tertiary bronchi

Lung Anatomy: Respiratory Zone

-bronchioles

-alveolar ducts

-alveoli

Function of the conducting zone

-Warm, cleanse and humidify air

-Phonation (vocal cords attached to trachea, secondary function)

-Regulation of air flow (dilation/constriction)

Function of the respiratory zone

gas exchange

2 cell types in respiratory zone

-cell type I: squamous allows for fast diffusion, made of H2O, if they get too close together, they will want to bond and collapse the alveoli

-cell type II: larger, secretes biological detergent called surfactant to break bonds between Type I cells and resist collapsing

Membranes that gases must penetrate

-apical epithelium (alveoli)

-fused basement membrane epithelium and basal endothelium

-apical endothelium (capillary)

Diffusion distances of gases

-shorter is better

-measured in microns

Lung Ventilation: Closed compartment

-head, diaphragm, sternum, ribs, and intercostal muscles

-all surround the lungs creating a closed compartment

Lung Ventilation: Pleura

-parietal (chest)

-visceral (lungs)

-pleural fluid

How parietal pleura drives visceral pleura

-fluid in between layers allow for them to "stick" and move together

-lungs forced outward, air coming in lungs is drawn inward, pressure in lungs decreases

Ventilation Steps

1. exchange of air between atmosphere and alveoli (bulk flow, high atmospheric pressure to low lung pressure)

2. Exchange of O2 and CO2 between alveoli and lung capillaries by diffusion

3. Transport of gases by blood (bulk flow)

4. Exchange of gases between blood and tissues by diffusion

Bulk Flow

-the movement of a fluid driven by high to low pressure

F = K (ΔP)

K=constant

ΔP=difference between atmospheric pressure and alveolar pressure (bigger ΔP, more air into lungs)

Inspiration

-inhalation

alveolar pressure < 760

Expiration

-exhalation

alveolar pressure > 760

In ventilation, what pressure changes?

Alveolar pressure

2 Cavities in Lungs

-pleural

-pulmonary

Pleural Cavity

space between 2 the pleura

Pulmonary Cavity

air space inside airways (bronchi-alveoli)

Intrapleural pressure

-pressure within the pleural cavity (fluid)

-we have it bc lung tends to go down to smallest size bc elastic tissue and alveolar fluid (think rubber band)

-chest wall expands and pulls lungs out preventing recoil

Intrapulmonary pressure

pressure of gas inside the alveoli (AKA alveolar pressure)

Inspiration Steps involving pressure

1. Thoracic wall expands

2. Surface tension of fluid causes lungs to be forced out

3. Intrapulmonary pressure decreases, intrapleural pressure decreases

Expiration Steps involving pressure

1. Thoracic wall pushes down on fluid

2. Air pressure in lungs increases (above 760)

3. Intrapulmonary pressure increases, intrapleural pressure increases

Ventilation Graph Steps

1. Beginning inspiration: pressure of gas decreases initially bc volume increases

2. End inspiration: pressure of gas in lungs goes up bc more gas in the lungs

NOW EQUAL PRESSURE 760=760

3. Beginning expiration: gas pressure of alveoli increases bc thoracic wall pushes down on fluid and lungs

4. End expiration: decrease pressure bc more out out of lungs

Air Flow

Flow (F) = ΔP/R

ΔP: change in pressure between atmosphere and alveoli, altered by contraction of inspiratory and expiratory muscles

R: resistance of airways, inversely proportional to the 4th power of the radius

Resistance formula

R= 1/r^4

Lung Complaiance

ΔV/ΔP

ΔV= change in volume

ΔP= change in pressure

-defintion: lungs can change in size rapidly

Athlete's Lung Compliance

-higher than average person

-breathe less times per minute bc theyre bringing in more air w each breath

-lungs are more elastic

-energy saving

Respirometer

-device used to measure extent of respiration

-breathe into tube, upside down container rises and falls, pen draws wave like patterns

Tidal Volume

-normal amount of air breathing in and out

-500ml

Inspiratory Reserve Volume (IRV)

-breathing forcefully in the most air not including tidal volume

-3100ml

Vital Capacity

-forcefully expiring out

-4800ml

IRV+TV+ERV

Expiratory Reserve Volume (ERV)

-volume breathed out that doesn't include tidal volume

-1200ml

Residual Volume (RV)

-air trapped in lungs even after breathing all the way out

-1200ml

Dead Space

-useless air

-about 150ml

-meaning each breath we only bring in ab 350ml of good air

-anatomical dead space: in trachea and bronchioles

-inspired dead space: bad air breathed in

pO2 and pCO2 in "good" and "bad" air

-good air: fresh air, pO2 higher, pCO2 lower

-bad air: dead space air, pO2 lower, pCO2 higher

Alveolar Ventilation

-amount of fresh air breathed into lungs depending on frequency (breaths per minute) and how much air brought in (fresh air tidal volume)

AVR= frequency X tidal volume

-depth is more important

Why do athletes breathe through their nose

increases amount of air brought into lungs and therefore increases O2 being brought in as well

Medullary Respiratory Center

part of the medulla oblongata involved in the neural control of rhythmic breathing

Dorsal Respiratory Group

-a portion in the of the medulla oblongata back of the head where the primary respiratory pacemaker is found

-integrates input info

Ventral Respiratory Group

A portion of the medulla oblongata that is responsible for maintaining breathing rhythm

Pontine Respiratory Center

Smooths out breathing and stems into the dorsal and ventral respiratory groups

What muscles contract during expiration

internal intercostal muscles

What muscles contract during inspiration

external intercostals and diaphragm

Chemoreceptors

-detect chemical changes in body

-2 Types: Central (brain) and Peripheral (aortic and carotid bodies)