Ex Phis Exam 2

Functions of the respiratory system

Provides a means of gas exchange between the environment and the body

What are the functions of the respiratory system

Maintain a constant O2 and CO2 levels in blood, acid base balance (rest and exercise)

What is the difference between respiration and ventilation

Ventilation is the process of moving air in and out of the lungs, respiration is ventilation PLUS exchanging of gases in lungs

Internal respiration

At the cellular level

External respiration

At the lung

2 functional zones in the lung

Conducting zone and respiratory zone

Conducting zone

AIr passes through alveoli (anatomical dead space)

What percent of lung volume is conducting zone

10% of total lung volume

Respiratory zone

Where gas exchange occurs (in the alveoli, there are 300-500 million alveoli)

What percent of lung volume is respiratory zone

90% of total lung volume

Surface area of respiratory zone

50 - 75 m squared (half of a tennis court)

Alveolar ducts and alveoli

Alveolar ducts lead to alveoli, which are tiny air sacs in the lungs where gas exchange occurs

Epithelial cells and capillaries

Thin epithelial cells and surrounding capillaries form the respiratory membrane that allows oxygen and carbon dioxide to diffuse between the lungs and blood

Why do we need this much surface area in the lung?

Gas exchange, the more gas exchange, the easier it is to function and do daily activites and tasks (cannot get oxygen to muscles)

What are the two zones in the lungs and what is the function of each

Conducting and respiratory zone. Conducting zone is where air passes through the alveoli nad the respiratory zone is where gas exchange occurs

How does the respiratory zone work

Oxygen moves across the alveoli into the capillaries and for CO2 from the capillaries to the alveoli to be expired

Inspiration at rest

Diaphragm contracts down and ribs move up and out (lungs are expanded)

Expiration at rest

Diaphragm relaxes and moves up and ribs move down and in (lungs passively recoil)

Sea level atmospheric pressure for inspiration and expiration

760 mmHg

Intrapulmonic pressure for inspiration

758 mmHg (air moves down the pressure gradient)

Intrapulmonic pressure for expiration

763 mmHg (air is expired so it moves from high pressure to low)

Boyles law

At constant temperature, pressure and volume inversely proportional

Example of Boyles law

For expiration, pressure is higher (763) so volume is low (because you are blowing out air)

How does the diaphragm act during inspiration

Contracts down

How are resting and exercise pulmonary volumes measured

Using spirometry (lung volumes, capacities, flow rates)

Tidal volume

Amount of air moved per breath

Resting tidal volume

12 breaths per min x ½ a liter each breath = 6 L/min

VE

Minute ventilation

Vital capacity (VC)

Greatest amount of air that can be expired after full inspiration

Resting vital capacity

3.5 - 4.5 L

Residual volume (RV)

Amount of air left in the lungs after full expiration (functions to keep the alveoli open even after maximum expiration)

Resting residual volume

1.5 - 1.9 L

Changes in residual volume

It will stay the same for years (up to about 5), unless there is a big change in smoking, diet, exercise

Total lung capacity (TLC)

Sum of vital capacity and RV

Ventilation at rest

VE + (tidal volume) x frequency of breaths → (0.5 L/breath) x 12 breath/min → 6 L/min

Resting cardiac output

5 L/min

Ventilation during exercise

The rate and depth of inspiration increases during exercise (activation of respiratory muscles which allow for greater pressure changes and more air movement)

How does ventilation change during exercise

Onset of exercise, there is an immediate increase in ventilation (both tidal volume and breathing frequency increase)

Max ventilation

40 breath/min x 3L/breath = 120 L/min

Ventilation increase proportional to metabolic needs of muscle

At low exercise intensity, only tidal volume increases first; at high exercise intensity, frequency or rate increases first

Which increases first, breath depth or breathing rate

Increase tidal volume, so depth

Gases diffusion

Move from areas of high pressure to low pressure

Sites of gas diffusion in the body

Alveoli - capillary interface and tissue capillary interface

Factors that effect gas exchange

Gas solubility, pressure gradient, diffusion pace, and surface area

Gas solubility

More solubility of the gas, the more gas exchange that occurs

Pressure gradient

Greater the gradient, more gas exchange that happens

Diffusion pace

Space between blood, capillary and the alveoil’s (cells of the lungs)

How diffusion pace works

Greater space between the blood and lungs, less gas exchange (if they are closer, more gas exchange)

Surface area

More surface area, more gas exchange

At high intensity exercise, how is ventilation modulated to meet the increased metabolic needs?

Increased rate/frequency (breaths/min)

Partial pressure of gases

Each gas exerts a given amount of pressure, this is partial pressure of that gas

Atmospheric gas fractions at sea level (oxygen)

.2093

Atmospheric gas fractions at sea level (nitrogen)

.7904

Atmospheric gas fractions at sea level (carbon dioxide)

.0003

What happens to atmospheric pressure in higher altitudes

It reduces (gets smaller)

Are the gas fractions the same at higher altitudes or are they lower

They stay the same

What is the change in atmospheric pressure due to

Gravity, it causes gas molecules to be close near the ground and temperature

If the atmospheric pressure if 720 mmHg, what is the PO2?

150.7 mmHg

Is the surface area positively or negatively related to gas exchange

Positively, larger surface area allows for more gas exchange

Gas transport

Oxygen must move from atmosphere to alveoli to blood to skeletal muscle (goes down the pressure gradient)

Transport of oxygen in the blood

Can carry 20 mL/O2 /100 mL of blood, 1L O2 /5L blood

Oxygen combining in blood

98.5 combines with hemoglobin and 1.5% dissolves in plasma

Hemoglobin saturation

Depends on PO2 and affinity between O2 and HB

Affinity

Strength of bond between two molecules

A-VO2 difference

Difference between arterial and venous O2, (how much oxygen has been extracted from any muscle tissue)

Arterial O2 content

20 mL O2/100 mL blood

a-vO2 difference at rest

4 -5 mL O2/ 100 mL blood

3 different CO2 transport ways

10% dissolved in plasma, 20% bound to hemoglobin, 70% formed as HCO3- on RBC

Bicarbonate ion

Transports 70% of CO2 in blood into lungs, CO2 + water = Carbonic acid (H2CO3). Occurs in RBC and catalyzed by carbonic anhydrase

What does carbonic acid dissocitate into

Bicarbonate

Equation for carbonic acid dissocitating

CO2 + H2O ←> H2CO3 ←> HCO3- + H+

What is happening during carbonic acid dissociating

Carbon dioxide broken down into bicarbonate and hydrogen and moves around in the blood until it reaches the lungs and then the equation reverses so that carbon dioxide and water and be expired

Where do the parts of the equation diffusion into

Bicarbonate ion diffuses from red blood cells into plasma and H+ binds to hemoglobin

Dissolved carbon dioxide

10% of CO2 dissolved in plasma, when PCO2 is low (in lungs) CO2 comes out of solution and diffuses out into alveoli

Carbanminohemoglobin

No competition for binding spots on hemoglobin because oxygen binds to hemo protein while CO2 binds to globin portion, 20% of CO2 transported bound to hemoglobin

What is VT

Ventiltory threshold is when the body shifts from primarily aerobic metabolism to increased reliance on anaerobic glycolysis and is considered a strong predictor of aerobic performance

Diffusion/pressure gradient at sea level

Pressure: 760 mmHg Diffusion: 60 mmHg

Diffusion/pressure gradient at 4,300 m

Pressure: 460 mmHg Diffusion: 15 mmHg

What happens at high altitudes

Less oxygen gets to muscles

Live High, Train low

If you live at high altitudes and get used to that adaptation you will do better training/competing at lower altitudes and it will give you the best results (get erythropoiesis stimulus during rest and then able to train at higher intensity)

What is the best form of altitude training and how might this improve performance at sea level

Live high, train low is the best form of altitude training - living at high altitude allows for our bodies to detect low oxygen levels and in return release the hormone EPO. EPO stimulates red blood cell production and increases oxygen carrying capacity, allowing us to get more oxygen to the skeletal muscle and compete at higher intensities at sea level.

Describe the bicarbonate buffer system in your own words

In muscle tissue, cellular respiration produced CO2 as a waste product; as one of the primary roles of the cardiovascular system, most of this CO2 is rapidly removed from the tissues by its hydration to bicarbonate ion (via carbonic acid). The bicarbonate ion present in the blood plasma is transported to the lungs, where it is dehydrated back into CO2 and released during exhalation. These hydration and dehydration conversions of CO2 and H2CO3, which are normally very slow are facilitated by the enzyme carbonic anhydrase.

Max exercise a-vO2 difference

15 mL of O2 per deciliter of blood

What is the saturation of high Po2 (in the lungs)

Almost 100%

What is the saturation of low PO2 (in body tissues)

It is declining/ getting low

High Po2

Loading portion of O2 - hemoglobin dissociation curve, small change in HB saturation per mmHg change in PO2

Low PO2

Unloading portion of O2 - hemoglobin dissociation curve, large change in HB saturation per mmHg change in PO2