Respiratory System

Question 1

How are the circulatory and the respiratory system related?

Answer 1

They all concern the transport and delivery of important substances throughout the body
Deliver oxygen to tissues, allowing cells to perform metabolism, generating energy (ATP)
Make the use of branching structures to generate high surface area for exchange of materials

Question 2

How is the blood the link between the respiratory and cardiovascular systems?

Answer 2

Blood carries oxygen throughout the body for delivery, after oxygen diffuses into blood
Oxygen binds to a carrier molecule and is carried throughout the body for delivery to the tissues
Cardiovascular system deposits excess fluid into tissues which is carried away by the lymphatic system

Question 3

What is the overall function of the respiratory system?

Answer 3

Used by body to ensure that the cells have a constant supply of oxygen and can prevent buildup of carbon dioxide in tissues
Oxygen used in last step of chemiosmotic synthesis of ATP
Carbon dioxide is produced by Krebs cycle, need to prevent buildup along with other waste products

Question 4

What are additional functions of the respiratory system?

Answer 4

Traps potentially harmful incoming particulate matter and ushers out of body (protects against disease)
Involved in thermoregulation or regulation of body temperature. Panting increases respiration rate, bringing more water into upper part of respiratory tree that can evaporate and cool the body
Nasal and tracheal capillary beds participate in a method of thermoregulation
Prepares air by moistening, warming, and cleaning it

Question 5

How might a defect in microtubule production affect breathing?

Answer 5

Ciliated cells in the respiratory tract play a role in filtering the air by trapping foreign particles
Microtubules are found in cilia (also Fallopian tubes and ependymal cells of spinal cord)
therefore, defect in microtubules leads to defected cilia and improper filtering of air

Question 6

What is the movement of oxygen and carbon dioxide in the respiratory system governed by?

Answer 6

Changes in pressure differential between the chest cavity and external environment

Question 7

What is the path of air through the respiratory system?

Answer 7

Air enters and moves through the pharynx, larynx, trachea, bronchi, bronchioles, and into the alveoli where oxygen is exchanged for carbon dioxide from the blood

Question 8

Nasal Cavity

Answer 8

Space inside the nose
Structures and substances in nasal cavity act to filter, moisten, and warm incoming air
Nasal hairs at front of cavity trap large dust particles
Mucus secreted by goblet cells trap smaller dust particles that bypass course nasal hair, and moistens air
Capillaries in nasal cavity warm the air

Question 9

How does nasal cavity participate in immune function?

Answer 9

Cilia move mucus and dust back toward the pharynx to be removed by spitting or swallowing
Prevents potentially harmful substances from entering the body

Question 10

Pharynx

Answer 10

Passageway for food and air

Question 11

Larynx

Answer 11

Contains the vocal chords and sits behind the epiglottis, which blocks opening of trachea during swallowing

Question 12

Epiglottis

Answer 12

Cartilaginous structure that rises to block the opening of the trachea during swallowing, preventing entry of food into airway
Nongaseous material that enters the larynx triggers a coughing reflex (forced back out)

Question 13

Trachea

Answer 13

AKA windpipe
Lies in front of esophagus
Composed of ringed cartilage covered by ciliated mucous cells
Mucus and cilia in trachea collect particulate matter and usher back out towards pharynx
Trachea splits into right and left bronchi

Question 14

Bronchi

Answer 14

Splits of the trachea before entering the lungs into right and left branches

Question 15

Bronchioles

Answer 15

Smaller branches off of the bronchi

Terminate in grape-like clusters called alveolar sacs

Question 16

Alveoli

Answer 16

Alveolar sacs are clusters which terminate the bronchioles and contain the alveoli
Location where diffusion of oxygen occurs into adjacent capillaries, where oxygen is picked up by red blood cells
Carbon dioxide diffuses from red blood cells to the alveolus and expelled upon exhalation

Question 17

How does the branching of the airways allow for better gas exchange?

Answer 17

Large surface area allows for increased surface area of gas exchange, thus allowing for very efficient process

Question 18

When does air flow into the lungs? When does it flow out of the lungs?

Answer 18

When airway and alveoli are at a negative gauge pressure, air flows inwards
When airways and alveoli pressure becomes greater than atmospheric air pressure, air flows out towards environment

Question 19

What is the pressure of the chest cavity at rest

Answer 19

Pressure of chest cavity at rest is negative compared to atmospheric pressure
Lungs have natural tendency to collapse inward due to their elasticity, while rib cage expands outwards in opposite direction

Alveolar pressure is equal to atmospheric pressure, so air does not flow inwards

Question 20

When does inspiration begin?

Answer 20

Medulla oblongata of midbrain signals the diaphragm to contract via the phrenic nerve
Diaphragm is a thin sheet of skeletal muscle that is dome-shaped when relaxed, and flattens more upon contraction, expanding chest cavity
Intercostal muscles in ribs help expand chest cavity also
Pressures in airway and alveoli also become negative at this point

Question 21

When does chest cavity shrink?

Answer 21

Medulla oblongata stops stimulating the phrenic nerve, causing the chest cavity to shrink
Elasticity and resiliency of lungs, and increased pressure in chest cavity forces air out
Known as expiration, usually passive unless exercising

Question 22

How can expiration become an active process?

Answer 22

Forced expiration is needed during exercise to increase the amount of oxygen delivered to tissues
Shrinking of chest cavity aided by abdominal muscles and set of intercostal muscles distinct from those involved in inspiration

Question 23

Surface tension

Answer 23

Force present in alveoli due to high ratio of surface area to volume, and thin layer of water which has high intermolecular forces that cover the inner surface of the alveolus
Generates pressure that tends to collapse alveolus and oppose lung expansion
Counteracts ability of lungs to expand in response to changing pressure

Question 24

Surfactant

Answer 24

Material composed of amphipathic phospholipids
Coats the alveolar surface and breaks up the intermolecular forces between water molecules, reducing surface tension
Surfactant decreases surface tension and assists the expansion of the lungs

Question 25

When other factors are held constant, how does an increase in volume affect pressure?

Answer 25

As with PV=nRT, we can see that an increase in V with all other variables constant leads to a decrease in pressure Therefore, when the lungs and chest cavity expands, the pressure will decrease

Question 26

What process does alveolar gas exchange use?

Answer 26

Diffusion, tendency of gas to travel towards an area of lower concentration or pressure Differing partial pressures of oxygen and carbon dioxide ensure movement in correct direction

Question 27

What is the composition of the air we breathe and exhale?

Answer 27

Breathe in: 79% N, 21% O, negligible trace gases Breathe out: 79% N, 16% O, 5% CO2, trace gases Lungs: pO2 110mm Hg, pCO2 40 mm Hg Deoxygenated blood in pulmonary capillaries: pO2 40 mm Hg, pCO2 46 mm Hg

Question 28

Differential partial pressure

Answer 28

Causes oxygen to diffuse from 110 mm Hg in lungs to capillaries with 40 mm Hg Causes CO2 to diffuse from 46 mm Hg in capillaries to 40 mm Hg in lungs Blood transported CO2 away from cells as waste, so has high pCO2 compared to alveoli High pO2 in alveoli compared to low pO2 in deoxygenated blood in adjacent capillaries promote diffusion

Question 29

How does O2 and CO2 diffuse

Answer 29

Small nonpolar molecules like CO2 and O2 can diffuse passively through cell membrane

Question 30

Fick’s Law

Answer 30

Rate of diffusion across a membrane is directly proportional to the surface area and differential partial pressure across the membrane Inversely proportional to thickness of membrane

Question 31

What law describes the amount of gas that can be dissolved into the blood?

Answer 31

Henry’s Law Amount of gas that can be dissolved in solution is directly proportional to partial pressure of gas in equilibrium with liquid C = P x solubility (C is conc. Of dissolved gas, P is partial pressure) As partial pressure of gas increases, conc. Of gas dissolved in solution increases

Question 32

Explain how the dissolution of Oxygen in blood occurs

Answer 32

As inhalation occurs, pO2 of O2 rises in alveoli, and therefore O2 diffuses into the capillaries from the alveoli down the concentration gradient. As pO2 of the blood rises, the amount of O2 dissolved in the blood rises until it reaches the high pO2 found in the alveoli Facilitates dissolution of O2 in blood

Question 33

Is the solubility of O2 in blood high enough for sufficient O2 to be dissolved for transport to the body’s cells?

Answer 33

No, the solubility is not high enough Therefore, the body requires hemoglobin to transport O2 98% of O2 in the blood binds rapidly and reversibly with the protein hemoglobin in erythrocytes, forming oxyhemoglobin

Question 34

Hemoglobin

Answer 34

Composed of four polypeptide subunits, each with a single heme cofactor Heme cofactor is organic molecule with an atom of iron at its center Each Four iron atoms can bind with one O2 molecule

Question 35

Cooperativity of Hemoglobin

Answer 35

When one iron atom binds O2 molecule, oxygenation of other heme groups is accelerated When one O2 molecule is released by any heme groups, accelerates release of other O2 molecules

Question 36

What is an oxygen dissociation curve of hemoglobin?

Answer 36

A figure that shows percent of hemoglobin that has bound oxygen at various partial pressures of O2, shows oxygen affinity Similar to modified Michaelis-Menten enzyme curve (although hemoglobin not an enzyme), although increases sigmoidally (S-shaped) instead of linearly % saturation of hemoglobin increases as pO2 increases and then levels off when all subunits have bound O2

Question 37

What environmental factors can affect the oxygen saturation of hemoglobin?

Answer 37

Carbon dioxide pressure, pH, temperature of blood Increase in pCO2, H+ ion conc., or temperature -> rightward shift of curve Reflect’s hemoglobin’s lower affinity for O2 under these conditions

Question 38

Bohr shift

Answer 38

A rightward shift in hemoglobin’s oxygen dissociation curve due to increasing hydrogen ion concentration (decreased pH) Also when CO2 increases, because increased CO2 causes lowered pH in blood CO2 and H+ ions affect O2 dissociation curve through allosteric effects, binding to deoxygenated hemoglobin and discouraging binding of O2

Question 39

2,3- DPG

Answer 39

AKA 2,3-BPG Chemical found in red blood cells that shifts hemoglobin’s O2 dissociation curve to right by binding deoxygenated hemoglobin and decreasing affinity for O2 Increases in response to low O2 environments, such as high altitudes Ensures all tissues still receive sufficient O2, by releasing O2 at low pO2s

Question 40

What does a rightward shift in the oxygen dissociation curve of hemoglobin indicate?

Answer 40

At the same pO2, percent saturation of hemoglobin with O2 will be lower. Means that more O2 will be left at the tissues at lower pO2s

Question 41

Haldane Effect

Answer 41

Oxygenation of hemoglobin means it has a lower affinity to bind CO2 Facilitates transfer of CO2 from blood to lungs, because where there are high pO2s at the interface between blood and lungs, CO2 will be released and then diffuse into alveoli In tissues, where pO2s are lower, CO2 binds to hemoglobin and is carried to lungs

Question 42

Reduced hemoglobin

Answer 42

Hemoglobin without Oxygen | Can act as a blood buffer by accepting excess protons produced by conversion of CO2 to bicarbonate ion

Question 43

What type of inhibitor is Carbon monoxide to Oxygen binding to hemoglobin?

Answer 43

Competitive inhibitor binds to same location Affinity of hemoglobin for CO is 200x greater than affinity for O2 CO shifts O2 dissociation curve to the left, reflecting heightened affinity in remaining sites for O2 Max saturation is lowered as well, related to amount of CO present O2 does not unload in tissues as it should, so O2 delivery severely limited

Question 44

Where is CO2 at high partial pressures in body?

Answer 44

High in tissues, because produced as a waste product from aerobic respiration and builds up CO2 diffuses back into blood

Question 45

What three forms is CO2 carried in the blood?

Answer 45

1. Dissolved in solution (10x as much as other types) 2. Bicarbonate ion 3. Carbamino compounds (combined with hemoglobin and other proteins)

Question 46

Formation of Bicarbonate

Answer 46

Catalyzed by carbonic anhydrase in reversible reaction CO2 + H2O HCO3- + H+ Predominant direction predicted according to Le Chatelier’s Principle Forward reaction dominates in tissues, forming bicarbonate ion Backward reaction dominates in lungs, forming CO2 for expiration When blood is too basic, forward reaction dominates

Question 47

Chloride Shift

Answer 47

When CO2 absorbed from tissue by RBCs, bicarbonate builds up and is exchanged for chloride into plasma so that blood remains neutral and RBCs release bicarbonate into plasma Chloride shift occurs in opposite direction in the lungs- chloride ions flow into plasma in exchange for bicarbonate ions RBCs then convert bicarbonate back to CO2 to expire

Question 48

Respiratory Centers of Nervous System

Answer 48

Medulla oblongata Regulates breathing rate and can respond to changes in chemical composition of blood Monitor pCO2 with central and peripheral chemoreceptors (located in medulla and carotid arteries/aorta, respectively) High CO2 sensitivity, quickly triggers increased respiration, bc can lead to acidosis, dangerous decreases in pH in blood

Question 49

Is pO2 or pCO2 monitored more closely in nervous system respiratory centers?

Answer 49

In medulla, pCO2 is monitored more closely, because can lead to dangerous acidosis - monitored by central and peripheral chemoreceptors Partial pressure of O2 must drop significantly in order to change respiratory rate - mainly monitored by peripheral chemoreceptors

Question 50

Inspiratory Center

Answer 50

Area in medulla which stimulates inspiration by signaling the diaphragm to contract

Question 51

Expiratory center

Answer 51

Signals muscles that assist in forced exhalation (intercostal) when necessary

Question 52

PH Control

Answer 52

Nervous system controls levels of pH in blood by adjusting breathing rate Increases breathing rate when pH decreases to remove more CO2, thus removing H+ ions in blood

Question 53

What effect does Nitrogen in air have on body?

Answer 53

Nitrogen is extremely stable due to strong triple bond Diffuses into blood, but doesn’t react with chemicals in blood When diving in deep areas, more N diffuses into blood and as divers emerge from water the pressure decreases and gas volume increases This can form dangerous bubbles in the blood if not enough time is allowed to emerge, leading to decompression sickness, can occlude vessels and cause death

Question 54

Hydration of CO2

Answer 54

Conversion of CO2 to bicarbonate | Produces H+, requires H2O