P409 Respiratory System And Its Regulation(In-Focus And In-Review)

Front 1

4 processes of Respiratory & Cardiovascular delivery systems

Back 1

1) Pulmonary ventilation (breathing): movement of air into and out of the lungs

2) Pulmonary diffusion: the exchange of oxygen and carbon dioxide between the lungs/blood

3) Transport of O2 and CO2 via the blood

4) Capillary diffusion: the exchange of O2 and CO2 btw the capillary blood & the metabolically active tissues

Front 2

In-Focus

Back 2

Breathing through the nose helps humidify & warm the air during inhalation and filters out foreign particles.

Front 3

Intrapulmonic & Intrapleural pressure's

Back 3

Rest: 760 / 756 mmHg

Inspiration: 758 / 754 mmHg

Expiration: 763 / 756 mmHg

Front 4

Process of Inspiration and Expiration

Back 4

*note: movement of the ribs & diaphragm can increase and decrease the size of thorax

1) dimension of lungs & thorax increase during inspiration, forming negative pressure that draws air into the lungs

2) During expiration, the lung volume deceases, thereby forcing air out of the lungs

Front 5

In-Review

Back 5

Pulmonary ventilation(breathing) is the process in which air is moved into and out of the lungs. 2 phases inspiration & expiration

Front 6

In-Review

Back 6

-Inspiration: an active process in which the diaphragm & external intercostals muscles contract, thus increasing the volume of the thoracic cage.

-This decreases the pressure in the lungs, causing air to flow in.

Front 7

In-Review

Back 7

-Expiration at rest is normally a passive process.

The inspiratory muscles relax, the elastic tissue of the lungs recoils, returing the throatcis cage to its smaller normal dimensions

-This increases the pressure in the forcing air out.

Front 8

In-Review

Back 8

Forced or labored inspiration and expiration are active processes, dependent on accessory muscle actions

Front 9

In-Review

Back 9

Lung volumes and capacities, along with rates of airflow into and out of the lungs are measured by spirometry

Front 10

Pulmonary Diffusion: 2 major functions

Back 10

1) Replenishes the blood's oxygen supply, depleted at the tissue level by oxidative energy production

2) Removes carbon dioxide from returning systemic venous blood

Front 11

Pulmonary Diffusion: Gas exchange in the lungs (process)

Back 11

Air is brought into the lungs during ventilation, enabling gas exchange to occur btw. Oxygen from the air diffuses from the alveoli into the blood in the pulmonary capillaries, & carbon dioxide diffuses from the blood into the alveoli in the lungs

Front 12

Respiratory Membrane: Components

Back 12

a) alveolar wall

b) capillary wall

c) basement membranes

Front 13

In-Focus

Back 13

Gas exchange only occurs at the alveoli

Front 14

In-Focus: Dalton's Law on partial pressures

Back 14

The total pressure of a mixture of gasses equals the sum of the partial pressures if the individual gases in the mixture

Front 15

In-Focus

Back 15

The greater the pressure gradient across the respiratory membrane, the more rapidly oxygen diffuses across it

Front 16

PO2 & PCO2

Back 16

partial pressure of oxygen & carbon dioxide

Front 17

Oxygen diffusion Capacity

Back 17

-Expressed as the volume of oxygen that diffuses through the membrane each minute for a pressure difference of 1 mmHg

-During exercise ODC can increase 3x resting rate
-Calculated by mean pressure in the pulmonary capillary

Front 18

Partial Pressures of Respiratory Gases (mmHg)

Back 18

O2: Alveolar air- 105
Arterial blood- 100
Venous blood- 40

CO2: Alveolar air- 40
Arterial blood- 40
Venous blood- 46

Front 19

In-Review

Back 19

Pulmonary diffusion is the process by which gases are exchanged across the respiratory membrane in the alveoli

Front 20

In-Review

Back 20

-The amount and rate of gas exchange that occurs across the membrane depend primarily on the partial pressure (P1 - P2) of each gas. Shown by Frick's Law

-Gases diffuse along a pressure gradient moving from an area of high pressure to area of low pressure, thus O2 enters the blood and CO2 leaves it.

Front 21

In-Review

Back 21

-Oxygen diffusion capacity increases as one moves from rest to exercise.

-When exercising muscles require more oxygen to be used in the metabolic processes, venous oxygen is depleted and oxygen exchange at the alveoli is facilitated

Front 22

In-Review

Back 22

The pressure gradient for carbon dioxide exchange is less than fro oxygen exchange, but carbon dioxide's diffusion coefficient is 20x greater than oxygen's, so carbon dioxide crosses the membrane readily w/o a large pressure gradient

Front 23

Oxygen Transport(1)

Back 23

oxygen is transported by the blood either combined w/ hemoglobin in the red blood cells or
-(greater than 98%)
dissolved in the blood plasma
-(less than 2%)

Front 24

Oxygen Transport(2)

Back 24

-The limited amount of oxygen carried in the dissolved state(plasma) can not even support the needs of resting body tissues.

-Hemoglobin(protein) allows RBC's to transport 70x more oxygen than can be dissolved in plasma

Front 25

Hemoglobin Saturation

Back 25

4:1- each molecule of H. can carry four molecules of oxygen

Oxygen-Hemoglobin bind= Oxyhemoglobin

binding depends on PO2 in the blood & affinity(bonding strength) btw hemoglobin & O2

Front 26

Hemoglobin Saturation(2)

Back 26

-A high blood PO2 results in near complete H. saturation, which means that the maximal amount of O2 is bound.

-As PO2 decreases so does H. saturation

Front 27

Oxyhemolgobin Dissociation Curve: factors(1)

Back 27

-blood becomes more acidic =shift R

-shift due to decline in pH or Bohr effect.

-pH in the lungs is generally high so blood passing through has a strong affinity for O2, encouraging saturation.

Front 28

Oxyhemolgobin Dissociation Curve: factors(2)

Back 28

-Blood temperature, O2 is unloaded for hemoglobin faster @ higher temperatures

-Exercise, with this comes the ability to unload O2 to the muscles as muscle pH decreases

Front 29

Blood Oxygen-Carrying Capacity

Back 29

is the maximal amount of oxygen the blood can transport.

*depends on blood hemoglobin content

-each 100mL of blood contains 14-18g of hemoglobin(men)
12-16g (women)

-oxygen carrying capacity is approx. 16-24ml per 100ml of blood

Front 30

Carbon Dioxide Transport: 3 forms

Back 30

1) bicarbonate ion resulting from the dissociation of carbonic acid

2) dissolved in plasma

3) bound to hemoglobin(carbaminohemoglobin)

Front 31

In-Focus

Back 31

-Increased temperature and hydrogen ion (H+) concentration (lower pH) in an exercising muscle shift oxygen dissociation curve rightward, allowing more oxygen to be unloaded to supply the active muscle.

-Because of the sigmoid shape of the curve, loading of hemoglobin with oxygen in the lungs ins only minimally affected by the shift.

Front 32

In-Focus

Back 32

The majority of carbon dioxide produced by the active muscle is transported back to the lungs in the form of bicarbonate ions

Front 33

Bicarbonate Ion(1)

Back 33

-majority of CO2 carried in this form
accounts for transport of 60-70% of CO2 in the blood

Front 34

Bicarbonate Ion(2): process of use

Back 34

CO2 and H20 molecules combine to form carbonic acid(H2CO3) catylzed by an enzyme found in RBC's.

Carbonic acid is unstable and quickly disassociates, freeing a hydrogen ion and forming a bicarbonate ion (HCO3-)

Bohr Effect sequence:
CO2 + H20-->H2CO3-->H+HCO3-

Front 35

Chloride Shift

Back 35

-bicarbonate in the red blood cells will move out into the serum. To balance the charges when bicarbonate exits the cell, a chloride anion from the plasma enters the red blood cell. Reverse changes occur in the lungs when carbon dioxide is eliminated from the blood. Here, the exchange of bicarbonate for chloride in red blood cells flushes the bicarbonate from the blood and increases the rate of gas exchange.

-Chloride shift may also regulate the affinity of hemoglobin for oxygen through the chloride ion acting as an allosteric effector

Front 36

In-Review

Back 36

Oxygen is transported in the blood primarily bound to hemoglobin (as oxyhemoglobin)

Front 37

In-Review

Back 37

Hemoglobin unloading of oxygen(desaturation) is enhanced when:
1) PO2 decreases
2) pH decreases
3) Temperature increases

-Each of these conditions can reflect increased local oxygen demand. They increase O2 unloading in the metabolically active tissue

Front 38

In-Review

Back 38

-Hemoglobin is usually 98% saturated w/ O2. This is a much higher oxygen content than our bodies require.

-Blood's oxygen-carrying capacity seldom limits performance in healthy individuals.

Front 39

In-Review

Back 39

-Carbon dioxide is transported in the blood primarily as bicarbonate ion. This prevents the formation of carbonic acid, which can cause H+ to accumulate and lower pH.

-Smaller amounts of carbon dioxide are either dissolved in the plasma or bound to hemoglobin

Front 40

Dissolved Carbon Dioxide

Back 40

-Carbon dioxide released from the tissues is dissolved in plasma only

-7-10% is transported this way, comes out of a solution where PCO2 is low, as in the lungs.

-There is diffuses from the pulmonary capillaries into the alveoli to be exhaled

Front 41

Carbaminohemoglobin

Back 41

-When gas binds with hemoglobin, named this cause CO binds with amino acids in the globin part of hemoglobin molecule

-Released from hemoglobin when PO2 is low as in the lungs, allowing CO2 to enter the alveoli to be exhaled

-accounts for 20-30% of exhaled air

Front 42

In-Focus

Back 42

-The a-VO2 difference increases from resting value of about 4-5ml per 100ml of blood up to 15-16ml per 100ml of blood during intense exercise.

-This increase reflects an increased extraction of O2 from arterial blood by active muscles, thus decreasing the oxygen content of venous blood.

**It's improtant to remmeber that the blood returing to the right atrium is coming from all parts of the body, active and inactive.

**Therefore, mixed venous oxygen content will not decrease to values much lower than 4-5ml of O2 per 100ml of venous blood

Front 43

Oxygen Transport in the Muscle(1)

Back 43

-Oxygen is transported via mitochondria by myoglobin, where its used in oxidative metabolism

-Myoglobin dissociation curve is much steeper than the dissoc. for hemoglobin.

-Myoglobin releases O2 content only under conditions in where PO2 is very low

-PO2 at which venous blood is unloading O2, myoglobin is loading O2

Front 44

In-Review

Back 44

-The a-VO2difference is the difference in the O2 content of arterial and mixed venous blood throughout the body.

-This measure reflects the amount of oxygen taken up by tissues

Front 45

In-Review

Back 45

O2 delivery to the tissues depends on:

1) O2 content of the blood

2) blood flow to the tissues

3) local conditions( e.g. tissue temperature, and PO2 level)

Front 46

In-Review

Back 46

Carbon dioxide exchange at the tissues, CO2 leaves the muscles, where its formed, and enters the blood to be transported to the lungs of clearance

Front 47

In-Review: Factors influencing Oxygen delivery and Uptake

Back 47

-Exercise increases blood flow through the muscles-->

- Muscle activity increases muscle acidity because of lactate production, as muscle temperature and carbon dioxide concentration are increased by metabolism.

**All these changes increase oxygen unloading from hemoglobin molecule, facilitating oxygen delivery and uptake by the muscles

Front 48

Carbon Dioxide Removal

Back 48

CO2 exits the cells by diffusion in response to the partial pressure gradient btw the tissue and capillary blood---> Muscles generate CO2 through oxidative metabolism---> CO2 diffuses out of the muscles and in the blood to be transported to the lungs

Front 49

Process involved for Respiratory Regulation(1)

Back 49

1) medulla oblongata and Pons centers establish rate and depth of breathing sending out periodic impulses to respiratory muscles---> central and peripheral chemoreceptors(aortic arch) stimulate the inspiratory muscles--->

Front 50

Process involved for Respiratory Regulation(2)

Back 50

the external intercostal and diaphragm muscles contract to increase the volume of the thorax, drawing air into the lungs---> Stretching of the lungs triggers the expiratory centers to contract the intercostals and abdominal muscles---> Causing the thoracic volume to decrease and force air out of the lungs

Front 51

Process involved for Respiratory Regulation(3)

Back 51

During forceful breathing, exercise the expiratory area actively sends signals to the muscles of expiration

Breathing is also affected by the changing chemical environment in our body---> sensitive areas in the brain respond to changes in CO2 and H+ levels(central chemoreceptors) by an increase in H+ ions in the cerebrospinal fluid

Front 52

Process involved for Respiratory Regulation(4)

Back 52

PCO2 is the strongest stimulus for the regulation of breathing

Front 53

Goal of Respiration

Back 53

Maintain appropriate levels of blood and tissue gases and to maintain proper pH for normal cellular function