Biology: Aerobic Cellular Respiration and Gas Exchange

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Questions and Answers

What is the main product of aerobic cellular respiration along with thermal energy?

Carbon Dioxide (correct)

Water (correct)

Glucose

Oxygen

Why do larger, multicellular animals require special organ systems for gas exchange?

All cells are in direct contact with the environment.

Most cells do not directly contact the external environment. (correct)

They can rely solely on diffusion for oxygen supply.

They generate energy exclusively from anaerobic respiration.

Which process describes the diffusion of oxygen into body cells?

Gas exchange (correct)

Cellular metabolism

Aerobic respiration

Respiratory ventilation

What energy currency do cells generate through the process of aerobic cellular respiration?

Adenosine triphosphate (ATP) Signup and view all the answers

What happens to ATP when it releases energy for cellular processes?

It transforms into ADP and a free phosphate (P). Signup and view all the answers

What is the primary purpose of a circulatory system in multicellular organisms?

To deliver nutrients and oxygen while removing waste Signup and view all the answers

Which of the following best describes a closed circulatory system?

Blood is pumped within a network of closed vessels Signup and view all the answers

In which circuit does blood travel from the heart to the lungs for oxygenation?

Pulmonary circuit Signup and view all the answers

What physiological function is NOT performed by the circulatory system?

Regulating cellular reproduction Signup and view all the answers

Which statement accurately describes hemolymph in an open circulatory system?

Hemolymph bathes organs for nutrient and gas exchange Signup and view all the answers

What is the primary function of hemoglobin in red blood cells?

To bind and transport oxygen throughout the body Signup and view all the answers

What type of blood cells are responsible for fighting infections?

White blood cells Signup and view all the answers

Which component of blood has the highest water content?

Plasma Signup and view all the answers

What occurs during vasodilation in arterioles?

Blood vessels relax to increase diameter Signup and view all the answers

Which of the following statements about veins is false?

Veins carry oxygenated blood in systemic circulation Signup and view all the answers

How does the intercellular matrix of blood help maintain osmotic pressure?

Through the presence of dissolved proteins and ions Signup and view all the answers

What is the role of precapillary sphincter muscles?

To control blood flow into capillary networks Signup and view all the answers

Which blood component is primarily involved in preventing blood clotting?

Platelets Signup and view all the answers

What condition can result from weakened vein valves as people age?

Spider veins Signup and view all the answers

How does elasticity in artery walls affect blood flow?

It allows arteries to expand and contract to regulate blood pressure. Signup and view all the answers

What is the normal range for diastolic blood pressure?

80 mm Hg Signup and view all the answers

Which of the following is not a common symptom of low blood pressure?

High fever Signup and view all the answers

What initiates the heartbeat in the heart's conduction system?

Sinoatrial node Signup and view all the answers

What is the primary consequence of untreated high blood pressure?

Damage to heart and arteries Signup and view all the answers

Which chamber of the heart pumps oxygenated blood to the body?

Left ventricle Signup and view all the answers

Which lifestyle factor is NOT associated with increased risk for high blood pressure?

Regular physical activity Signup and view all the answers

What term describes the relaxation phase of the cardiac cycle?

Diastole Signup and view all the answers

Which blood vessels supply oxygen and nutrients to the heart muscle itself?

Coronary arteries Signup and view all the answers

What is the primary purpose of heart valves?

Prevent blood from flowing backwards Signup and view all the answers

How does prolonged high blood pressure affect the arteries?

Leads to overstretching and damage Signup and view all the answers

Which waveform on an electrocardiogram represents ventricular depolarization?

QRS complex Signup and view all the answers

Which condition may result from untreated high blood pressure affecting the kidneys?

Kidney failure Signup and view all the answers

What happens during the 'lub' sound of the heartbeat?

AV valves close Signup and view all the answers

Which factor does NOT contribute to the risk of developing varicose veins?

Smoking Signup and view all the answers

What is the primary role of the respiratory membrane in the alveoli?

To facilitate gas exchange by being thin and permeable Signup and view all the answers

Which structural feature of the human respiratory system assists in protecting the lungs from foreign matter?

Cilia and mucus lining the trachea Signup and view all the answers

How does the partial pressure of oxygen in the alveoli compare to the surrounding air?

It is lower than that of the surrounding air Signup and view all the answers

What percentage of oxygen is typically found in the atmosphere?

20.9% Signup and view all the answers

What role does hemoglobin play in oxygen transport in the blood?

It binds to oxygen to form oxyhemoglobin Signup and view all the answers

During which phase of ventilation do the external intercostal muscles contract?

Inspiration Signup and view all the answers

What happens to the pressure in the lungs during expiration?

It increases Signup and view all the answers

What is the primary method by which carbon dioxide is transported in the bloodstream?

Reacts with water to form carbonic acid Signup and view all the answers

What causes altitude sickness when climbing to high altitudes?

Low density of oxygen molecules in the air Signup and view all the answers

What is the vital capacity of the lungs?

Maximum volume of air exhaled after maximum inhalation Signup and view all the answers

What triggers an increase in breathing rate due to changes in blood chemistry?

Accumulation of hydrogen ions Signup and view all the answers

What is the role of erythropoietin (EPO) during reduced oxygen supply?

Stimulates red blood cell production Signup and view all the answers

What is the typical lifespan of a red blood cell?

90-120 days Signup and view all the answers

What is the main consequence of decreasing oxygen supply in altitude conditions?

Altitude sickness Signup and view all the answers

Study Notes

Aerobic Cellular Respiration

Cells require oxygen to survive and obtain energy from food. This process is called aerobic cellular respiration.
Glucose and oxygen react to form carbon dioxide and water, releasing energy.
Approximately 64% of the energy released is thermal energy, and 36% is stored in ATP (adenosine triphosphate).
The ATP molecule is comprised of ADP(adenosine diphosphate), phosphate and energy. ADP + P + Energy → ATP
Cells use ATP for various processes, including growth, movement, and building new molecules, through ATP → ADP + P + Energy.

Gas Exchange and Ventilation

Gas exchange is the diffusion of oxygen into and carbon dioxide out of body cells.
In simple organisms, oxygen diffuses directly through cell membranes.
Multicellular organisms have specialized organ systems (e.g., lungs) for gas exchange.
Gas exchange occurs in both lungs and cells:
- Lungs: Oxygen diffuses from air to the bloodstream, then to cells.
- Cells: Oxygen diffuses from blood into tissue fluid, then into cells, while Carbon Dioxide diffuses from cells to tissue fluid to blood then to lungs.
Ventilation is the movement of oxygen-rich air into and carbon dioxide-rich air out of the lungs.

Respiratory Structures

The human respiratory system features thin, permeable membranes for diffusion, a large surface area for gas exchange, a good blood supply, and a respiratory membrane within the lungs to carry oxygen-rich air.
Lungs are enclosed within the thoracic cavity to protect the respiratory structures, they consist of a respiratory membrane with a large surface area and good blood supply.
Air enters through the nose and mouth, warmed and moistened in nasal passages.
Nasal passages filter and trap dust and airborne particles.
The pharynx directs air to the trachea which is a semi-rigid tube of soft tissue with c-shaped cartilage bands maintaining a consistent open pathway.
Trachea is lined with mucus-producing cells with cilia that further protect the lungs. Cilia sweep trapped materials upward for expulsion.
Bronchi branch into bronchioles, which lead to alveoli - clusters of tiny sacs.
Each alveolus is approximately 0.1-0.2 micrometres in diameter, and there are about 150 million alveoli in each lung.
If all alveoli were spread out, they would cover a tennis court.

Gas Exchange in the Alveoli

Alveoli are saturated with moisture, and air within them is a 37 degrees celsius temperature and saturated with water.
Oxygen dissolves in liquid to diffuse across the respiratory membrane.
The respiratory membrane is incredibly thin (one cell thick), making the distance for gas exchange very short.

Partial Pressures

Air pressure varies with altitude (lower at higher altitudes); partial pressure reflects that of individual gases.
At sea level, atmospheric pressure is 101.3 kPa. Oxygen comprises ~20.9% of air; Carbon Dioxide comprises ~0.0391%.
Partial pressure of oxygen (PO2) and carbon dioxide (PCO2) are calculated proportionally from the amount in the overall air in the atmosphere.
PO2 in alveoli is somewhat lower than surrounding air because of residual air and stale air that remains in the alveoli.
PO2 in alveoli is greater than in capillaries, thus supporting diffusion to the bloodstream.

Oxygen Transport and Diffusion

Oxygen diffuses from alveoli into plasma (the liquid component of blood) due to the pressure gradient.
Hemoglobin is an iron-containing protein in red blood cells that binds to oxygen to form oxyhemoglobin.
Nearly all oxygen is transported bound to hemoglobin (98.5%), with a small amount dissolved in plasma. Hemoglobin increases oxygen carrying capacity of blood 70x..
Blood with hemoglobin carries ~20 mL oxygen per 100 mL blood;
At tissues, oxygen diffuses into body cells. PO2 in the veins is still greater than 0; blood will always contain some oxygen.

Carbon Dioxide Transport and Diffusion

Carbon dioxide (a by-product of cellular respiration) diffuses from tissues into the bloodstream due to a pressure gradient (tissue PCO2 is higher than blood PCO2).
Carbon dioxide transport:
- 7% dissolved in plasma
- 20% bound to hemoglobin (carbaminohemoglobin)
- 73% converted to bicarbonate ions in plasma. Hydrogen ions increase acidity to trigger breathing. Hemoglobin carries hydrogen ions to avoid significant blood pH drops.
In the lungs, CO2 diffuses from blood plasma to the air in alveoli. Bicarbonate and Hydrogen ions re-form CO2 and water in the lungs.

Altitude

Atmospheric pressure decreases with altitude.
Oxygen partial pressure decreases at higher altitudes (despite a constant percentage), limiting oxygen supply to the body.
Reduced oxygen supply can cause altitude sickness.
The body adapts to low oxygen by increasing red blood cell production (stimulated by erythropoietin (EPO)).
Synthetic EPO is banned in competitive sports. Athletes train at high altitude to raise red blood cell counts.

Mechanism of Ventilation

Inspiration:
- External intercostal muscles contract, expanding rib cage.
- Diaphragm contracts and flattens, increasing thoracic cavity volume.
- Lung pressure decreases, causing air to enter.
Expiration:
- External intercostal muscles relax, shrinking rib cage.
- Diaphragm relaxes and curves upward, decreasing thoracic cavity volume.
- Lung pressure increases, forcing air out.

Lung Capacity

Total Lung Capacity: Maximum volume of air in one breath.
Tidal Volume: Normal/involuntary breath volume.
Inspiratory Reserve Volume: Air forcibly inhaled after normal breathing.
Expiratory Reserve Volume: Air forcibly exhaled after normal breathing.
Residual Volume: Air remaining in lungs after forced exhalation, preventing collapse.
Vital Capacity: Maximum air exhaled.

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Description

This quiz covers the essential processes of aerobic cellular respiration and gas exchange. Learn how cells utilize oxygen and glucose to produce energy and how gas exchange occurs in simple versus multicellular organisms. Test your understanding of how these processes contribute to cellular functions and overall metabolism.