Chapter 7 Sport Physiology

What are the four separate processes for cardiovascular and respiratory process?

Pulmonary ventilation
Pulmonary diffusion
Transport of oxygen and carbon dioxide by blood
Capillary diffusion

Define pulmonary ventilation

Breathing
Movement of air into the out of the lungs

Define pulmonary diffusion

The exchange of oxygen and carbon dioxide between the lungs and the blood

Capillary diffusion

The exchange of oxygen and carbon dioxide between the capillary blood and metabolically active tissues

Which two processes are referred to as external respiration? Why?

Pulmonary ventilation
Pulmonary diffusion
Because they involve moving gases from outside the body into the lungs and then the blood

What is internal respiration ?

The gas exchange between teh blood and the tissues

What is pulmonary ventilation?

Breathing; the process by which we move air into and out of the lungs

Why is nasal breathing advantageous ?

Because the air is warmed and humidified as it swirls through the bony irregular sinus surfaces. The turbinates churn the inhaled air, causing dust and other particles to contact and adhere to the nasal mucosa. This filters the air.

Define dead space

The pharynx, larynx, trachea, and bronchial tree; also considered the transport zone because gas exchange does not occur in these structures. Exchange of oxygen and CO2 occurs when air finally reaches the smallest respiratory units

What are the smallest respiratory units?

The respiratory bronchioles and the alveoli

What comprises the respiratory zone?

Resp. Bronchioles and alveoli; where gas exchange actually occurs

Two walls of the pleural sacs

The parietal pleura which lines the thoracic wall and the visceral pleura which lines the outer aspects of the lung

What is inspiration?

An active process involving the diaphragm and the external intercostal muscles.

Muscles involved in inspiration

With inspiration, the ribs and sternum are moved by the external intercostal muscles. The ribs swing up and out and the sternum swings up and forward. At the same time, the diaphragm contracts, flattening down toward the abdomen.

Boyle's gas law

Pressure times volume is constant, the pressure within the lungs decreases. As a result the pressure in the lungs (intrapulmonary pressure) isles than the air pressure outside the body. Because the respiratory tract is open to the outside, air rushes into

What other muscles are involved during forced/labored breathing?

Scaleni (anterior, middle, and posterior)
Sternocleidomastoid
Pectorals

What is expiration?

A passive process involving relaxation of the inspiratory muscles and elastic recoil of the lung tissue. As the diaphragm relaxes, it returns to its normal upward, arched position. As the external intercostals relax, the ribs and sternum move back into th

Significance of elastic recoil of lungs.

The elastic nature of the lung tissue causes it to recoil to its resting size. This increases the pressure in the lungs and causes a proportional decrease in volume in the thorax, and therefore air is forced out of the lungs.

Muscles in FORCED expiration

The internal intercostal muscles actively pull the ribs down. This action can be assisted by the latissimus dorsi and quadratus lumborum muscles. Contracting the abdominal muscles increases the intra-abdominal pressure, forcing the abdominal viscera upwar

How do changes in intra-abdominal and intrathoracic pressure help return venous blood back to the heart?

As intra-abdominal and intrathoracic pressure increases, it is transmitted to the great veins, the pulmonary veins and superior and inferior venae cavae, that transport blood back to the heart. When the pressure decreases, the veins return to their origin

What is a spirometer?

A spirometer measures the volumes of air inspired and expired and therefore changes in lung volume. It contains a bell filled with air that is partially submerged in water. As the person exhales, air flows down the tube and into the bell, causing the bell

Define and describe the lung volumes

Tidal volume: the amount of air entering and leaving the lungs with each breath.
Vital capacity: the Greatest amount of air that can be expired after a maximal inspiration
Total lung capacity: the sum of the vital capacity and the residual volume
Function

Pulmonary diffusion functions

It is gas exchange in teh lungs between the alveoli and the capillary blood
Two functions: it replenishes the blood's oxygen supply, which is depleted at the tissue level as it is used for oxidative energy production
It removes CO2 from venous blood retur

Where does pulmonary diffusion occur?

In the capillaries that form a dense network around the alveolar sacs

Blood flow and resistance in lungs at rest

Since blood flow to the lungs is equal to that of the systemic circulation, and there is a substantially lower change in pressure across the pulmonary vascular system, resistance is proportionally lower compared to that in the systemic circulation.

Why is resistance lower in the pulmonary vascular system than the systemic circulation?

The pulmonary blood vessels are thin walled with little smooth muscle

Gas exchange between teh air in the alveoli and the blood in the pulmonary capillaries occurs across the __ __

Respiratory membrane

What is the respiratory membrane composed of ?

The alveolar wall
Capillary wall
Respective basement membranes

Dalton's law

The total pressure of a mixture of gases equals the sum of the partial pressures of the indiviudal gases in that mixture

Henry's law

Gases dissolve in liquids in proportion to their partial pressures, depending also on their solubilityes in the specific fluids and on the temperature. A gas's solubility in blood is a constant and blood temperature also remains relatively constant at res

What is the most critical factor for gas exchange between teh alveoli and the blood?

The pressure gradient between the gases in the two areas. If the pressures on each side of the membrane were equal, the gases would be at equilibrium and would not move. This is not the case, so gases move according to the partial pressure gradient.

Oxygen exchange

Pg. 181

Why is that when blood leaves they lungs it have a PO2 of 105 mmHg, but when it reaches the pulmonary vein it has decreased to 100 mmHg?

About 2% of blood is shunted from teh aorta directly to the lung to meet the oxygen needs of the lung itself. This blood has a lower PO2 and renters the pulmonary vein along with fully saturated blood returning to the left atrium that has just completed g

Fick's law

The rate of diffusion through a tissue such as the respiratory membrane is proportional to the surface area and the difference in the partial pressure of gas between the two sides of the tissue
Greater the pressure difference= more rapid diffusion
Inverse

Which has a lower diffusion constant? Oxygen or CO2?

CO2; therefore, even through there is not as greater a difference between the alveolar and capillary partial pressure of carbon dioxide as there is for oxygen, CO2 still diffuses easily.

Oxygen diffusion capacity

The rate at which oxygen diffuses from the alveoli into the blood and is expressed as the volume of oxygen that diffuses through teh membrane each minute for a pressure difference of 1 mmHg
More on pg. 184

Oxygen diffusion capacity during max exercise

During maximal exercise, the oxygen diffusion capacity may increase up to three times the resting rate, because blood is returning to the lungs severely desaturated and thus there is a greater partial pressure gradient from teh alveoli to the blood.

The increase in oxygen diffusion capacity from rest to exercise is caused by a relatively ineffficient, sluggish circulation through the lungs at rest, what makes this sluggish?

There is limited perfusion fo the upper regions of the lungs due to gravity; only the bottom third is used during rest. During exercise, the blood flows through the lungs which elevates BP which increases lung perfusion

How is oxygen transported?

By the blood either 1) combined with hemoglobin in the RBCs (98%) or 2) dissolved in the blood plasma (2%)

Oxyhemoglobin vs. deoxyhemoglobin

When oxygen binds to hemoglobin, it forms oxyhemoglobin; hemoglobin that is not bound to oxygen is referred to as deoxyhemoglobin

What does the binding of oxygen to hemoglobin depend on ?

The PO2 in the blood and the bonding strength (affinity) between hemoglobin and oxygen

Loading portion of oxyhemoglobin dissociation curve

Saturation stays high even with large changes in PO2.

Unloading portion of oxyhemoglobin dissociation curve

Saturation changes quickly with even small changes in PO2, allowing oxygen unloading to tissues.

What can affect hemoglobin saturation ?

If the blood becomes more acidic, the dissociation curve shifts to the right. This indicates that more oxygen is being unloaded (this is known as Bohr Effect)
Blood temperature affects the oxygen dissociation. Increased blood temp shifts curve to the righ

What is oxygen carrying capacity?

The maximal amount of oxygen te blood can transport. It depends primarily on the blood hemoglobin content.

How much hemoglobin in men vs. women?

Men 14-18 g
Women 12-16 g

Each gram of hemoglobin can combine with about ___ ml of oxygen

1.34 ml

Saturation of blood as it passes through lungs

At rest, as the blood passes through the lungs, it is in contact with the alveolar air for approximately 0.75 s. This is sufficiency time for hemoglobin to become 98% to 99% saturated. At high intensities of exercise, the contact time is greatly reduced,

Three ways CO is carried in blood

Bicarbonate ions
Dissolved in plasma
Bound to hemoglobin

Read pg 187 - 188

...

Before oxygen can be used in oxidative metabolism, it must be transported in the muscle to the mitochondria by a molecule called __

Myoglobin

Myoglobin vs. hemoglobin

Similar in structure expect that myoglobin has a much greater affinity for oxygen than hemoglobin. At PO2 values less than 20 mmHg, the myoglobin dissociation curce is much steeper than the dissociation curve for hemoglobin. Myoglobin releases oxygen cont

The rates of oxygen delivery and uptake depend on three major variables:

Oxygen content of blood
Blood flow
Local conditions

What is one example how the unloading of oxygen at the tissue level is hindered?

A reduction in the PO2 of the arterial blood would lower the partial pressure gradient, limiting the unloading of oxygen at the tissue level.

Does blood flow improve oxygen delivery?

Yes

Where are the respiratory centers located?

Medulla oblongata
Pons

What do the respiratory centers do?

They establish the rate and depth of breathing by sending out periodic impulses to the respiratory muscles.

Can the cortex override the respiratory centers?

Yes

Inspiratory area of brain

Dorsal respiratory group"
This area contains cells that intrinsically fire and control the basic rhythm of ventilation.

The expiratory area

Is quiet during quiet breathing; however, during forceful breathing such as during exercise, the expiratory area actively sends signals tot the muscles of expiration.

What two other brain centers aid in the control of respiration

The apneustic area has an excitatory effect on teh inspiratory niter, SR center, resulting in prolonged firing of the inspiratory neurons. Finally, the pneumotaxic center inhibits or "switches off" inspiration, helping to regulate inspiratory volume.

What are the central chemoreceptors stimulated by?

An increase in H+ ionsin the cerebrospinal fluid.

Blood-brain barrier

BB barrier is relatively impermeable to H+ ions or bicarbonate ions. However, CO2 readily diffuses across the BB barrier and then reacts to increase H+ ions. This in turn, stimulates the inspiratory center, which then activates the neural circuitry to inc

Chemoreceptors in aortic arch. Vs. carotid artery

Aortic: sensitive to changes in PO2 and H concentrations (same for carotid)
Carotid: more sensitive to changes in H concentrations and PCO2.

What is the strongest stimulus fo rfor regulation of breathing?

PCO2
More on pg 190

What stimulus is relayed to the expiratory center?

Stretch receptors excessively stressed; the expiratory center responds by shortening the duration of an inspiration, which decreases the risk of overinflatation. (Hering-Breuer reflex)