Respiratory System Flashcards
(13 cards)
What are the major structures of the mammalian respiratory system?
Pharynx: Passage for air from nose to trachea
Bronchus: Branches from the trachea into each lung
Bronchioles: Smaller branches of the bronchi
Alveoli: Tiny air sacs for gas exchange
Lungs: Contain bronchioles and alveoli
What structures are involved in mammalian ventilation?
Diaphragm: Contracts (flattens) during inhalation, relaxes (curves) during exhalation
Ribs: Move up/out on inhalation, down/in on exhalation
Muscles: Intercostal muscles aid in rib movement
What is the role of alveoli in gas exchange?
Thin walls and large surface area
Surrounded by capillaries
Oxygen diffuses from alveoli → blood
Carbon dioxide diffuses from blood → alveoli
How is the bird respiratory system different from mammals?
Nares instead of nostrils
Syrinx instead of larynx
Air sacs (7–9): Connect to lungs & bones, reduce weight
No diaphragm: Movement drives air flow
Air capillaries replace alveoli
Describe the avian ventilation cycle.
Inhalation 1: Air → trachea → posterior air sacs
Exhalation 1: Air → lungs via ventrobronchi & dorsobronchi
Inhalation 2: Air → anterior air sacs
Exhalation 2: Air → out through trachea and nares
Requires 2 cycles to complete
What is the role of haemoglobin?
Found in red blood cells
Binds up to 4 oxygen molecules
Forms oxyhaemoglobin
Unloads oxygen at tissues, loads CO₂ at tissues
70% of CO₂ dissolves in plasma, not bound to haemoglobin
What is the role of myoglobin?
Found in muscles
Stores oxygen (1 molecule per myoglobin)
Higher oxygen affinity than haemoglobin
Releases oxygen during intense activity
Forms oxymyoglobin
How does foetal haemoglobin differ from adult haemoglobin?
Higher affinity for oxygen
Allows effective diffusion from maternal blood
Crucial since foetus cannot use lungs for respiration
What is the Bohr effect?
CO₂ ↑ → carbonic acid forms → blood pH ↓
Haemoglobin releases more oxygen
Useful during high respiration (e.g., predator chasing prey)
What is oxygen debt?
Occurs after anaerobic respiration
Lactic acid builds up → must be broken down using oxygen
Increased breathing (panting) repays debt post-exercise
How does the body regulate oxygen and CO₂ levels?
Blood receptors detect changes
Adjust breathing and heart rate
Prevents hypoxia (low O₂) and acidosis (low pH from CO₂ buildup)
Describe what happens to a racehorse before, during, and after a race.
Before: Aerobic respiration; low heart and breathing rate
During: Aerobic + anaerobic; increased heart/breathing; lactic acid builds
After: Oxygen debt repaid; breathing/heart rate slowly returns to normal
Compare aerobic and anaerobic respiration.
Aerobic respiration requires oxygen and occurs in the mitochondria. It produces a large amount of ATP and results in carbon dioxide and water as by-products. It’s efficient and supports long-duration activity.
Anaerobic respiration does not require oxygen and occurs in the cytoplasm. It produces far less ATP and leads to the formation of lactic acid, which can cause muscle cramps. It’s used for short bursts of energy and results in an oxygen debt that must be repaid later.
