Human biology chapter 10

Hemoglobin acts as a buffer because ________.

protons released by the dissociation of carbonic acid bind to hemoglobin, preventing large swings in blood pH

Path of air

Air enters throughout the nose or mouth... air travels down the trachea and then enters the bronchi... air travels down smaller and smaller bronchioles... air reaches small sacs called alveoli

From which structures do oxygen molecules move from the lungs to the blood?

Alveoli

Which statement about carbon dioxide transport is FALSE?

An increase in the number of hydrogen ions increases the pH of the blood.

Key events in gas exchange

Breathing moves air in and out of the lungs... oxygen diffuses from alveoli in the lungs into the capillaries... oxygen enters red blood cells where it binds to the protein hemoglobin... oxygen diffuses from the blood to the body's tissues and carbon dioxide diffuses from the tissues to the blood... carbon dioxide leaves the body when we exhale.

Carbon dioxide transport

Carbon dioxide is released from the mitochondria... carbon dioxide diffuses into a capillary.... carbon dioxide is carried to the lungs... carbon dioxide diffuses into an alveolus... air exits through nose or mouth

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

Which statement is correct?

In the blood, oxygen is bound to hemoglobin, a protein found in red blood cells.

Oxygen transport

Oxygen diffuses from the alveoli into surrounding capillaries... oxygen enters a red blood cell... oxygen binds to a molecule of hemoglobin... oxygen is carried through blood vessels to a capillary... oxygen diffuses from the body's tissues.

Which of the following happens when the CO2 level in the arterial blood increases?

The hydrogen ion concentration of the cerebrospinal fluid will increase, stimulating the medulla oblongata to increase the rate and depth of breathing.

True or false. When discussing breathing, we can say that air enters the lungs because the diaphragm contracts and in the process, oxygen passes into the alveoli and then down its concentration gradient from an alveolus to the blood. When we breathe out, the diaphragm relaxes and carbon dioxide passes down its concentration gradient from the blood to the alveolus and then out of the lungs.

True

Which of the following statements about oxygen transport is FALSE?

Under normal circumstances, about 50% of the oxygen is unloaded at the cellular level.

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

acidic

Respiratory centers in the brain that regulate breathing are primarily stimulated by ________.

an increase in the level of CO2 in the blood

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

as bicarbonate ions (HCO3 -)

One's bronchi and bronchioles constrict in response to minor triggers, severely restricting airflow and making breathing very difficult. This describes ________.

asthma

Most of the oxygen transported in the blood is ________.

bound to hemoglobin within red blood cells

Across which vessels does most internal respiration (the exchange of gases between the blood and tissues) occur?

capillaries

During an inhalation, the diaphragm moves ________.

downward

What type of respiration occurs in the lungs?

external respiration

The lower respiratory tract is responsible for ________.

gas exchange in the alveoli

Oxyhemoglobin is ________.

hemoglobin with bound oxygen

Hemoglobin

is a protein that can bind four molecules of oxygen

Venous blood ________.

is transported by pulmonary arteries to the lungs

After blood becomes oxygenated,

it returns to the heart, and is then pumped to body cells.

Carbon dioxide diffuses from the blood into the alveoli when the PCO2 of the alveoli is ________.

lower than the PCO2 of the blood

Tidal volume is ________.

the amount of air respired during restful, relaxed breathing

During inhalation,

the diaphragm and rib muscles contract

The interface between the air and the blood is composed of ________.

the epithelial cells of the alveolus, the extracellular fluid, and the capillary wall

Congestive heart failure affects lung function because ________.

the left side of the heart fails and blood backs up into the pulmonary vessels

Carotid and aortic bodies monitor ________.

the level of O2 in the blood

Inspiration occurs as ________.

the volume of the pleural cavity increases