Bio Ch 34 Mastering Bio

Which lung structure is a tiny sac that functions as an interface between air and blood?

Alveolus An alveolus is a tiny sac in the lung that functions as an interface between air and blood.

_____ in carbon dioxide in your red blood cells, which causes _____ in pH, causes your breathing to speed up.

An increase ... a drop Water and carbon dioxide combine, in the presence of the enzyme carbonic anhydrase (found inside red blood cells), to form carbonic acid, which dissociates to hydrogen ion and bicarbonate. The higher concentration of hydrogen ions leads to a drop in pH.

Blood returns to the heart via the _____.

pulmonary veins Pulmonary veins carry oxygenated blood from the lungs to the left atrium.

Exhalation

6) Diaphragm and rib muscles relax 7) Lung volume decreases 8) Air moves out of alveoli 9) Air moves up bronchioles, bronchi and trachea. 10) Air leaves nose of mouth. During exhalation, the diaphragm and rib muscles relax, decreasing the volume of the lungs. Air leaves the alveoli and flows up the bronchioles, bronchi, and trachea, and exits through the nose or mouth.

The exhalation of air from human lungs is driven by

a decrease in the volume of the thoracic cavity.

Most carbon dioxide is carried from the body tissues to the lungs _____.

as bicarbonate ions (HCO3 -) Most carbon dioxide released from body tissues combines with water to form carbonic acid, which then breaks up into hydrogen and bicarbonate ions.

Some human infants, especially those born prematurely, suffer serious respiratory failure because of

lung collapse due to inadequate production of surfactant.

The primary functions of the _____ are to warm, filter, and humidify air.

nasal cavity The functions of the nasal cavity are to warm, filter, and humidify air.

Sponges, cnidarians, and flatworms lack a specialized gas exchange surface because

nearly all of their cells are in direct contact with the external environment.

The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in

pH.

From the superior vena cava, blood flows to the _____.

right atrium Blood enters the right atrium from the superior and inferior venae cavae.

An advantage of gas exchange in fresh water, compared with gas exchange in air, is that _____

water loss through evaporation across the respiratory surface can be minimized Respiratory surfaces are always moist, and exposure to air results in water loss via evaporation.

In mammals, most gas exchange between the atmosphere and the pulmonary blood occurs in the

alveoli.

Countercurrent exchange in the fish gill helps to maximize

diffusion.

Voice sounds are produced by the _____.

larynx The larynx houses the vocal cords.

Circulatory systems compensate for

the slow rate at which diffusion occurs over large distances.

The amount of oxygen bound to hemoglobin _____.

increases in the presence of high concentrations of oxygen High concentrations of oxygen increase the amount of oxygen bound to hemoglobin.

From the capillaries of the abdominal organs and hind limbs, blood flows to the ____

inferior vena cava Blood enters the inferior vena cava from the capillaries of the abdominal organs and hind limbs.

From the pulmonary veins, blood flows to the

left atrium Blood enters the left atrium via the pulmonary veins.

Which three statements are true of blood flowing through a capillary at the location marked by the green circle?

-Dissolved oxygen in the blood is lowest at this point. -Oxygen diffuses from the water into the blood. -The water surrounding the blood has a low concentration of oxygen. At this point, oxygen-poor blood is entering the capillaries of the lamella. Much of the oxygen in the surrounding water has already diffused into the blood as the water flowed across the lamella, so the water has a fairly low concentration of oxygen. However, the dissolved oxygen in the blood is so low that a gradient still exists and diffusion occurs. Thus, the countercurrent flow pattern makes it possible for oxygen to diffuse into the blood along the entire length of the capillary.

Which barrier(s) must O2 and CO2 cross to pass between air and blood inside lungs?

-capillary wall -epithelial cells -extracellular fluid Gases must pass through all three.

Inhalation

1) Diaphragm and rib muscles contract 2) Lung volume increases 3) Air moves into nose and down trachea, bronchi, and bronchioles. 4) Air enters alveoli 5) O2 diffuses into blood; CO2 diffuses into alveoli During inhalation, the diaphragm and rib muscles contract, increasing the volume of the lungs. Air enters the nose or mouth and flows down the trachea, bronchi, and bronchioles, and into the alveoli.

Oxygen shows cooperative binding to hemoglobin. Cooperative binding has the following effects on the binding and release of oxygen: Oxygen binding to hemoglobin: When one molecule of oxygen binds to one of hemoglobin's four subunits, the other subunits change shape slightly, increasing their affinity for oxygen. Oxygen release from hemoglobin: When four oxygen molecules are bound to hemoglobin's subunits and one subunit releases its oxygen, the other three subunits change shape again. This causes them to release their oxygen more readily. These two graphs show how cooperative binding differs from a hypothetical situation where binding is not cooperative. The x-axis shows the partial pressure of oxygen (PO2). This is a measure of the amount of oxygen present in a tissue. The blue arrows on the x-axis show the partial pressure of oxygen in various tissues of the body. The y-axis shows the oxygen saturation of hemoglobin (O2 saturation). This is the percentage of oxygen-binding sites on hemoglobin molecules that are actually bound to oxygen.

1) What is the O2 saturation in the lungs? -Cooperative binding 100% -Noncooperative binding 100% 2) What is the O2 saturation in tissues at rest? -Cooperative binding 50% -Noncooperative binding 70% 3) What percent of O2 is delivered to tissues at rest? -Coop 50% -Noncoop 30% 4) What is the O2 saturation in exercising tissues? -coop 20% -noncoop 50% 5) What percentage of O2 is delivered to exercising tissues? -coop 80% -noncoop 50% As you can see from the table, the cooperative binding of oxygen to hemoglobin is an important adaptation for gas exchange. Cooperativity allows hemoglobin to release much more oxygen to an animal's body tissues. Compare the numbers for cooperative binding (circled in red) to those for noncooperative binding (circled in gold). In a resting tissue, hemoglobin releases 50% of its oxygen. If there were no cooperativity, it would release only 30% of its oxygen. In an exercising tissue, hemoglobin releases 80% of its oxygen. If there were no cooperativity, it would release only 50% of its oxygen.

Which of the following best describes an artery?

Arteries carry blood away from the heart. Both arteries and veins are defined by the direction relative to the heart in which blood is transported.

How is most carbon dioxide transported from tissues to the lungs?

As bicarbonate ions (HCO3−). Carbon dioxide is transported to the lungs mainly as bicarbonate ions in the blood.

True or false? The driving force for the unloading of oxygen from hemoglobin into tissues is the difference in PCO2 levels between the blood and body tissues.

False The PCO2 levels affect the diffusion of carbon dioxide; the driving force for the diffusion of oxygen from hemoglobin into tissues is the difference in PO2 levels between the blood (100 mm Hg when oxygenated) and body tissues (40 mm Hg at rest).

True or false? The pressure inside the human chest cavity is always positive, so the lungs stay relatively inflated even upon exhalation.

False The lungs stay relatively inflated even upon exhalation because the pressure inside the chest cavity is always negative.

Which of the following describes the path taken by oxygen-rich blood?

From the gills to the body tissues Red indicates vessels that carry oxygen-rich blood. In fish, blood picks up oxygen as it passes through the gills. This oxygen-rich blood then travels directly to the body tissues, where the oxygen is used.

Gas exchange involves the transport of two respiratory gases, oxygen and carbon dioxide. Review how each gas is transported between the atmosphere and the cells of your body by completing this exercise.

Oxygen only: - required for cellular respiration - net diffusion from alveoli to lung capillaries Carbon Dioxide Only: - sometimes transported as bicarbonate - net diffusion from body tissues to blood - net diffusion from lung capillaries to alveoli - waste product of cellular respiration Both Oxygen and carbon dioxide: - enters alveoli during inhalation - transported by hemoglobin Gas exchange provides the body's cells with oxygen, which is needed for cellular respiration. -Oxygen diffuses from the alveoli to capillaries in the lungs. -Almost all the oxygen in the blood is bound to hemoglobin. -Oxygen is carried all over the body and diffuses from blood to body tissues. Gas exchange also removes carbon dioxide, a waste product of cellular respiration, from the body. -Carbon dioxide diffuses from body tissues to blood. -Carbon dioxide is transported either in the plasma, bound to hemoglobin, or in the form of bicarbonate. -In the lungs, carbon dioxide diffuses from the capillaries into the alveoli. When you exhale, carbon dioxide leaves the body.

True or false? The lungs of humans form from the embryonic foregut.

True This statement is true. Digestive organs such as the stomach and part of the small intestine also develop from the foregut.

Which of the following statements about the oxygen-hemoglobin interaction is true?

The binding of one oxygen molecule to hemoglobin stimulates the binding of other oxygen molecules. This interaction is called cooperative binding.

Stroke occurs when _____

a blood clot enters the cerebral circulation, blocking an artery and causing the death of brain tissue Once deprived of oxygen, brain cells begin to die within a few minutes. Because brain cells rarely divide in adulthood, they cannot be quickly replaced.

By picking up hydrogen ions, hemoglobin prevents the blood from becoming too _____

acidic If not carried by hemoglobin, hydrogen ions would reduce the pH, or increase the acidity, of the blood.

An increase from pH 7.1 to pH 7.5 around hemoglobin causes

an increase in the affinity of hemoglobin to bind oxygen molecules.

A paleontologist discovers the fossilized heart of an extinct animal. The evidence indicates that the organism's heart was large, well formed, and had four chambers, with no connection between the right and left sides. A reasonable conclusion supported by these observations is that the

animal was endothermic and had a high metabolic rate.

Hemoglobin and hemocyanin

both transport oxygen.

The smallest airway through which inspired air passes before gas exchange occurs in the mammalian lungs is the _____

bronchiole The bronchioles give rise to the alveoli, the site of gas exchange.

During most daily activities, the human respiration rate is most closely linked to the blood levels of

carbon dioxide.

In the blood most of the oxygen that will be used in cellular respiration is carried from the lungs to the body tissues _____.

combined with hemoglobin In the blood most oxygen is transported attached to hemoglobin

Most of the carbon dioxide produced by humans is

converted to bicarbonate ions by an enzyme in red blood cells.

Which of the following organisms has no specialized respiratory structures?

earthworms Earthworms respire through the skin surface.

Which of the following can cause the LDL/HDL ratio to increase and thus increase the likelihood of a myocardial infarction?

eating more trans fats

The hormone that stimulates the production of red blood cells and the organ where this hormone is synthesized are

erythropoietin and kidney, respectively.

The meshwork that forms the fabric of a blood clot is

fibrin.

Dissolved proteins in human plasma include which of the following?

fibrinogen and immunoglobulin only

Blood pH and cerebrospinal fluid pH are affected by carbon dioxide content. This enables the organism to sense a disturbance in gas levels as

the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing.