Respiratory System

Question 1

What part of the brain controls breathing rate?

Answer 1

The medulla oblongata controls respiration by telling the respiratory muscles (mainly the diaphragm) when to contract

Question 2

What is the composition of air entering the alveolus?

Answer 2

Air entering the alveolus has a high partial pressure of oxygen and a low partial pressure of carbon dioxide

Question 3

What is the composition of blood leaving the alveolar capillaries?

Answer 3

The blood leaving the alveolar capillary has just been replenished with oxygen so it has a high partial pressure of oxygen and a low partial pressure of carbon dioxide

Question 4

What form of iron can oxygen bind to?

Answer 4

Iron atoms in heme allow a single oxygen molecule to bind to them when they exsits as **ferrous iron (Fe²⁺)
Heme iron oxidized to ferric iron (Fe³⁺) can’t bind to oxygen

Question 5

Bilirubin

Answer 5

Formed from a heme that has been broken down from hemoglobin
It is transported to the liver and is a component of bile

Question 6

Which gas is more soluble in blood?

Answer 6

Carbo dioxide is more soluble in blood than oxygen

Question 7

In what form do most carbon dioxide travel as in blood?

Answer 7

Most carbon dioxide travel dissolved in the blood plasma as **bicarbonate anion (HCO₃^-)

Question 8

Function of cilia in respiration:

Answer 8

Hair-like projections found on the ciliated respiratory epithelium that lines the respiratory tract
Functions in muccociliary clearance of sweeping mucus and dirt (foreign debris) out of the lungs

Question 9

Where does bicarbonate act as the major buffering system?

Answer 9

The extracellular fluid (which includes the blood plasma and interstitial fluid), maintains a stable pH of around 7.4

Question 10

What is the cause of respiratory acidosis?

Answer 10

• Inadequate breathing (hypoventilation) which causes carbon dioxide to accumulate leading to a drop in pH through carbonic anhydride activity

Question 11

What is the body’s response to respiratory acidosis?

Answer 11

Hyperventilation

Question 12

At which point of breathing is the interpleural pressure at its highest?

Answer 12

The interpleural pressure of the lungs is the least negative (highest) at peak expiration (at the beginning of exhalation, the interpleural pressure begins to rise)

Question 13

Bohr effect:

Answer 13

• States that hemoglobin has decreased affinity for oxygen when the pH is low (which results from high carbon dioxide and H+)
• decreased binding affinity = oxygen released by hemoglobin
• carbon dioxide is converted to bicarbonate anions and protons which produce reduced hemoglobin (H+Hb)

Question 14

What do the peripheral chemoreceptors monitor?

Answer 14

Changes in the concentration of oxygen, carbon dioxide and protons (H+) in arterial blood

Question 15

visceral pleura

Answer 15

• lines the surface of lungs

Question 16

parietal pleura

Answer 16

• lines the inside of the chest

Question 17

interpleural space pressure:

Answer 17

• has negative (lower) pressure relative to the atmosphere
• if stabbed, air rushes in and causes the lungs to collapse

Question 18

pressure in the interpleural space during inhalation:

Answer 18

• during inhalation, the diaphragm contracts, the lung cavity opens up and the volume of the lungs increases which causes the pressure to decrease

Question 19

pressure in the lungs during inhalation:

Answer 19

• volume of lungs increase
• negative pressure relative to the atmosphere is created in the lungs
• this causes air to rush in

Question 20

oxygen dissociation curve: High CO₂

Answer 20

• high [CO₂] causes it to diffuse into the blood and into the RBC
• carbonic anhydrase will then convert it into H₂CO₃
• H₂CO₃ will then dissociate into HCO₃^- and H⁺
• hemoglobin interacts with the H⁺ to form rediced hemoglobin
• reduced hemoglobin has a lower affinity for oxygen, causing oxygen to be released

Question 21

oxygen dissociation curve: low pH

Answer 21

• low pH is caused by high concentration of H⁺
• high [H⁺] forms the reduced hemoglobin
• reduced hemoglobin has low affinity for oxygen
• oxygen is released to the tissues

Question 22

oxygen dissociation curve: high temperature

Answer 22

• at higher blood temperature, hemoglobin is less likely to bind to oxygen and releases oxygen to tissues

Question 23

oxygen dissociation curve: high 2,3-DPG (or BPG)

Answer 23

• decreaes the affinity of hemoglobin for oxygen
• at low oxygen levels, an enzyme catalyzes the synthesis of 2,3-DPG
• high [2,3-DPG] = low affinity of hemoglobin for oxygen
• at high levels of oxygen, hemoglobin inhibits the enzyme that synthesizes 2,3-DPG leading to a low concentration of it

Question 24

what is 2,3-DPG helpful for?

Answer 24

• unloading oxygen during anemia
• providing oxygen at high altitudes

Question 25

process of medulla signaling in respiration:

Answer 25

• when partial pressure of CO₂ increases, medualla stimulates an increase in the rate of ventilation
• the diaphragm (innervated by the phrenic nerve) is signaled to contract
• when lungs infalte, thoracic pressure decreases as the thoracic cavity increases size

repeats over and over again, giving us a steady breathing rate

Question 26

central chemoreceptors

Answer 26

• found within the medulla
• indirectly monitor H⁺ concentration in the cerebrospinal fluid

Question 27

peripheral chemoreceptors

Answer 27

• located in carotid arteries and aorta
• monitor the atrial concentrations of CO₂, O₂ and pH via H⁺

Question 28

respiration in an active body:

Answer 28

• when the body is active, there is increased carbon dioxide production
• the carbon dioxide enters the plasma and is converted to bicarbbonate and H+ ions
• the blood pH drops and respirtory rate increases

Question 29

myoglobin

Answer 29

• hyperbolic curve
• structure does not participate in allosteric cooperative binding due to single subunit shape
• saturates quickly
• releases in situations of very low oxygen “emergency situations”