Lec 1-Structure And Function Resp Sys

Question 1

Cellular respiration

Answer 1

• Utilization of oxygen in metabolism of orgo molecs

Question 2

External respiration

Answer 2

• Exchange of oxygen and CO2 between lungs and blood

Question 3

Internal respiration

Answer 3

• Exchange of oxygen and CO2 between bloodstream and tissues/cells

Question 4

Main function of resp sys

Answer 4

• Supply tissues with oxygen and dispose of CO2 generated by cell metabolism

Question 5

Ventilation system

Answer 5

• Energy gen by tissues is result of oxidation of food substrates — O2 in
• Byproduct of oxidative metabolism is CO2 — CO2 out, accumulation of CO2 would result in acidification of bodily fluids
• Eliminating CO2 is equally important, if CO2 accumulates, bodily fluids will acidify. Lungs and kidneys work together to make acid/base balance

Question 6

Functions of resp sys

Answer 6

1. Provide O2
2. Eliminate CO2
3. Acid/base regulation (w/ kidneys)
4. Phonation (speech sounds)—air moves past vocal chords to make sounds
5. Host defence—innate systems to keep lungs healthy
6. Alterations in arterial chem messengers, either by removal or inactivation, or by producing/activating others
7. Trap and dissolve blood clots from systemic circulation

Question 7

Organization of resp sys

Answer 7

1. Air in thru nasal cavity or mouth
2. Air ends up in pharynx at back of throat
3. Pharynx splits into 2—either esophagus and GI tract (food) or larynx (air)
4. Epiglottis prevents liquid/food from going down airway, host defence response is to cough it back up
5. Trachea looks stripy, stripes are cartilage rings. Airway has a lot of cartilage therefore is very stiff so it doesn’t collapse.
6. Bigger bronchi are supported with cartilage, smaller ones aren’t so they can easily collapse or get obstructed
7. Diaphragm separates thoracic and abdominal contents. As you breathe in, it contracts/flattens/moves down, giving us more space in thoracic cavity for air to move into lungs
   **diagram on slides

Question 8

Relationship between blood vessels and airways

Answer 8

• To get gases in/out, we need a blood supply
• Everytime airways divide down, blood vessels will divide down with it (pulm circulation)
• 23 generations of splitting, ending up with 10000s of little airways (aka bronchioles)
• In all airways (conducting zone) function is to get air down to alveoli where oxygen can move in and CO2 can move out
• Capillaries lie over alveoli, allows blood flow in airways to uptake O2 and give out CO2

Question 9

Terminal vs respiratory bronchioles

Answer 9

• Terminal bronchioles: Smooth, no alveoli, part of conducting zone, just want to conduct air down to alveoli
• Resp bronchiole: have gas exchange units ???

Question 10

Gas exchange

Answer 10

• Oxygen has fast transport from air into blood and CO2???

Question 11

What surrounds the lungs?

Answer 11

• Lungs are sucked open when you breathe in bc intrapleural space changes pressure
• Visceral pleura is attached to outer surface of lung
• Parietal pleural membrane is attached to interior thoracic wall and diaphragm
• Visceral and parietal pleura are separated by thin layer of intrapleural fluid that lubricates pleural surfaces as they slide over eachother during breathing
• Pressure in intrapleural fluid space is intrapleural pressure (Pip), Pip is less than atmospheric pressure. Lungs have many elastic fibres, they want to collapse back in on themselves but chest wall wants to move opp direction—pressure between them is less than atmospheric pressure

Question 12

What is pleurisy?

Answer 12

Inflammation of the pleura, often caused by viral infections

Question 13

Muscles used for respiration—inspiration

Answer 13

• Normal, quiet, tidal breathing
• Caused by skeletal muscles **
• Taking in 500mL of air per breath on avg
• Main muscle of inspiration is the Diaphragm, it contracts/flattens, increases size of thoracic cavity
• External intercostal muscles attached to ribs move ribcage up and out, they also contract
• Contraction of diaphragm and ext inter muscles causes ??? which sets up for inspiration
• Accessory muscles: scalene and sternomastoids

Question 14

Muscles used for respiration—expiration

Answer 14

• Normal, quiet breathing
• Expiration is passive—i.e. no muscles working in opposition to force breath out, it just happens when muscles stop contracting. Means there is no main muscle of expiration, only accessory
• Accessory muscles: internal intercostals and abdominal muscles

Question 15

Physiological zones of airways

Answer 15

• Phys zones are either the conducting zones or the respiratory zone
• Conducting is a low resistance path for air flow, defends against microbes/toxic chemicals, warms and moistens air, phonation
• Resp is responsible for gas exchange

Question 16

Graph on slide 13

Answer 16

**

• Beyond terminal broncioles, crosssectional area of airways is so great, due to large # of branches, that fwd velocity of inspired air falls and diffusion takes over as dominant mech of air movement
• Conducting zone is approx 150mL volume, or 30% of normal breath. AKA anatomic dead space

Question 17

Non-resp functions of lung— Host defence

Answer 17

• Big particles will stay in nasopharynx—get stuck to mucous
• Small particles will get to bronchi—will get removed by mucociliary clearance
• Tiny particles will get to alveoli—they dont have any mucous, so their host defence is macrophages. Macrophages will migrate to lymphatic sys to clear, or diffuse up airway to mucociliary clearance and clear there

Question 18

Non-resp functions of lung—Host defence: Mucociliary clearance

Answer 18

• Particles will stick to mucous
• Airway epithelial cells have cilia that move 1 way. Tip of cilia reaches bottom of mucous so mucous only moves 1 direction. This allows mucous to move from lungs to back of throat you you can cough it up
• Point is to keep airways sterile/clean
• Cystic fibrosis is a result of failure of mucociliary clearance

Question 19

Non-resp functions of lung— Metabolic function

Answer 19

• Angiotensin I is converting to angiotensin II by ACE (angiotensin converting enzyme)
• add maybe

Question 20

When is the transfer from conductive to resp

Answer 20

Transfer from conductive to resp happens at 16th generation of division
Switches here from moving air to actually breathing/gas exchange