Bio 141 Lesson 10

What is hypercapnia and what happens to respiration?

A condition created when carbon dioxide levels increase and the depth and rate of breathing increases

When you blow up a balloon (forced expiration), which of these muscles contracts forcing the abdominal organs upwards?

Abdominals (obliques, transversus)

Most carbon dioxide is transported from the tissues to the lungs by

As bicarbonate ions in plasma

During transport in the blood, to which part of the hemoglobin molecule does oxygen attach?

Iron atoms of the heme

During transport in the blood, where on the hemoglobin molecule does carbon dioxide attach

Amino acids of globin

Oxygen travels from the alveoli into the lung capillaries

Because the PO2 in the capillaries is 40 mm Hg and the PO2 in the alveoli is 100 mm Hg

If the blood has an acid pH, the lungs will

Blow off more carbon dioxide

Which most accurately describes why air moves in and out of the lungs during respiration?

Boyles's Law: Pressure changes caused by changes in lung volume allow air to enter the lungs during inspiration and air to move out of the lungs during expiration

According to the Bohr effect:

Decreased blood pH (acidosis) will weaken the HbO2 (oxyhemoglobin) bond and promote oxygen unloading

Erythrocytes (red blood cells) have a biconcave shape. The cell membrane contains a network of spectrin proteins. How do these structural features complement the physiological functions of the erythrocytes?

Erythrocytes have a biconcave shape that is almost like a donut. Their cell membranes contain a network of spectrin proteins. The primary function of erythrocytes is to bind oxygen and transfer the oxygen into the tissues where it's most needed. Their biconcave shape allows for a greater surface area for gas exchange. The protein spectrin allows the erythrocytes to change shape and squeeze through the capillaries. In the capillaries the oxygen the erythrocytes carry can diffuse into the plasma. Without the biconcave shape or spectrin proteins the erythrocytes would not be as efficient at their job.

The amount of air that can be forcibly expired beyond the tidal volume is

Expiratory reserve volume

During inspiration, which of these muscles assists the prime mover (the major muscle of inspiration)? As the prime mover contracts and moves downward increasing the volume of the thoracic cavity, these muscles contract and lift the rib cage, increasing the thoracic diameter.

External intercostals

The alveoli in the lungs are made up of a single layer of squamous epithelial cells covered with capillaries. This forms the respiratory membrane. Consider the role of the respiratory membrane in respiratory exchange. This illustrates complementarity of structure and function because

Gas exchange can occur by simple diffusion across this very thin respiratory membrane

Air moves out of the lungs when the pressure inside the lungs (intrapulmonary pressure) is

Greater than the pressure in the atmosphere

Consider the chemical factors that regulate respiration. What chemical stimuli will stimulate the peripheral chemoreceptors in the carotid and aortic bodies? What is the resulting effect on the medullary respiratory centers? How are the rate and depth of breathing affected? Explain whether this is a positive or negative feedback mechanism and why.

Hyperpnea is increased ventilation in response to metabolic activity. When we exercise our respiratory needs have to be adjusted. Working our muscles consumes a lot of oxygen and produces a lot of carbon dioxide. This means ventilation must be increased so hyperpnea occurs. Unlike hyperventilation, hyperpnea does not drastically alter blood oxygen or carbon dioxide levels.

What is the relationship between hyperpnea and exercise?

Hyperpnea is increased ventilation in response to metabolic activity. When we exercise our respiratory needs have to be adjusted. Working our muscles consumes a lot of oxygen and produces a lot of carbon dioxide. This means ventilation must be increased so hyperpnea occurs. Unlike hyperventilation, hyperpnea does not drastically alter blood oxygen or carbon dioxide levels.

Why will breathing into a paper bag help a person who is hyperventilating?

Hyperventilation causes hypocapnia; breathing into a paper bag to rebreath the expired air which is rich in carbon dioxide; this restores the level of carbon dioxide.

Which describes hyperventilation?

Hypocapnia occurring when carbon dioxide levels decrease, the depth and rate of breathing increase

This type of hypoxia can occur with chronic obstructive pulmonary disease or at high altitudes. Reduced amounts of oxygen are available. Oxygen therapy can be used to treat this type of hypoxia

Hypoxemic hypoxia

In a healthy individual, the strongest respiratory stimulus for breathing is:

Increased levels of carbon dioxide

What affects the unloading (dissociation) of oxygen from hemoglobin?

Increased temperature. Increased partial pressure of carbon dioxide. Decreased blood pH.

If a person has a tidal volume of 500 ml and breathes at a rate of 13 times per minute, what is their minute ventilation rate? If the dead space for that person is 150 ml, what is their alveolar ventilation rate?

Minute Ventilation Rate = mL of breath x breaths per minute Minute Ventilation Rate = 500mL x 13 breaths per minute = 6,500mL/min or 6.5L/min Alveolar Ventilation Rate = Frequency (breaths/minute) x (Tidal Volume - Dead Space) Alveolar Ventilation Rate = 13 x (500mL - 150mL) = 4,550mL/min or 4.55L/min

Ischemic (stagnant) hypoxia

Occurs when the blood circulation is blocked. Oxygen therapy can be helpful

Which determines the direction of gas movement during respiration?

Partial Pressure Gradient

In the lungs, surfactant:

Prevents the lungs from collapsing by reducing surface tension

Consider the Bohr effect as it relates to the oxygen-hemoglobin dissociation curve. Explain how this is related to oxygen loading in the lungs and oxygen unloading in the systemic capillaries. In your response, describe the effects of cellular metabolism in the systemic tissues compared to the cellular metabolism in the lungs.

The Bohr effect states that oxygen unloading is enhanced by increased temperature, increased partial pressure of Carbon Dioxide or Hydrogen ions, or decreased pH. These all cause a shift to the right on the oxygen-hemoglobin dissociation curve. So when any of the inverse of these factors occurs (decreased temperature, decreased partial pressure of Carbon Dioxide, or increased pH) oxygen unloading decreased but hemoglobin's affinity for oxygen increases. This means when the inverse of these factors is true oxygen loading in the lungs occur. When Bohr's effect happens, oxygen unloading happens within the capillaries. Cellular metabolism of glucose results in the use of oxygen, and production of carbon dioxide. This increases the partial pressure of carbon dioxide and hydrogen ions in capillary blood. This leads to the increased affinity of hemoglobin for oxygen in the lungs and the unloading in the capillaries.

Blood doping is artificially induced polycythemia (increased numbers of erythrocytes). Why would this enhance endurance or speed for an athlete? (Actually blood doping can cause a variety of physiological problems and is banned from Olympic competition.

The increased numbers of erythrocytes result in increased oxygen capacity

Answer the following questions... What type of hypoxia is caused by carbon monoxide (CO) poisoning? Compare the affinity of carbon monoxide for hemoglobin to that of oxygen for hemoglobin. What are the physical characteristics of the gas carbon monoxide that make it difficult to detect? Explain the treatment for carbon monoxide poisoning and the basis for that treatment.

The type of Hypoxia that is caused by carbon monoxide poisoning is called Anemic Hypoxia. During Anemic Hypoxia the affinity of hemoglobin for carbon dioxide is so high that it oxygen cannot bind as easily, reducing the carrying-capacity of the blood. This means the amount of functional hemoglobin is small. Treatment involves inhaling pure oxygen, or often times being put in a pressurized oxygen chamber. This is a chamber filled with pure oxygen where the air pressure is higher than normal. This increased pressured combined with pure Oxygen allows for faster replacement of the accumulated Carbon Dioxide and allows for higher oxygen carrying capacity in the blood. Carbon monoxide is very hard to detect because it has no taste, color, or odor so we cannot detect it without special equipment to do so. This is why some homes have carbon monoxide detectors.

The lung volume that represents the total volume of exchangeable air is the:

Vital Capacity