Lesson 1: Gas Exchange Flashcards
Why do larger multi-cellular organisms need exchange systems?
- small surface area to volume ratio
- cells in the centre of the organisms would not receive anything using only diffusion.
- higher metabolic rate
What are the key features of gas exchange surfaces?
Permeability, thin tissue layer, moisture, and a large surface area.
How is having a good blood supply an adaptation for efficient gas exchange?
maintain a large diffusion gradient, constant diffusion
How is having a moist surface an adaptation for efficient gas exchange?
dissolves gas
How is ventilation an adaptation for efficient gas exchange?
maintains diffusion gradient
How is permeability an adaptation for efficient gas exchange?
pores and openings
How is a concentration gradient maintained at gas exchange surfaces?
With a dense blood vessel network, continuous blood flow, and ventilation (air or water).
describe the nasal cavity
- large SA & good blood supply = warms air to body temperature
- hairy lining = traps bacteria and dust
- moist = increases humidity and reduces evaporation
describe the trachea
- c shape cartilage rings = prevents collapse and allows food down oesophagus
- mucus membrane lining produces mucus to trap dust and bacteria
- smooth muscle to regulate air flow
describe the bronchioles
- small diameter slows air flow = more time for gas exchange in the alveoli.
- high degree of branching also ensures that air is distributed throughout the lungs.
describe surfactant
- dissolves gasses
- reduces surface tension, preventing collapse
What are the adaptations of alveolis for efficient gas exchange?
- Large surface area: numerous + folded
- Short diffusion distance: one cell thin
- Large concentration gradient: surround by an extensive network of capillaries and regular ventilation
What is the difference between type 1 and 2 pneumocytes in structure and coverage %?
type 1:
* covers 95% of alveoli SA
* thin + flat cells
type 2:
- cuboidal cells
- 5%
What is the difference between type 1 and 2 pneumocytes in function?
type 1: gas exchange
type 2: produces surfactant + differentiate into type 1 (when damaged).
summarise ‘inspiration’
- Diaphragm contract – Moves Down
- External Intercostal Muscles contract – move up and out
- Thoracic Volume – Increases
- Thoracic Pressure – Decreases
- Air Flow – In to lungs (to equalise the pressure difference)
summarise ‘expiration’
- Diaphragm – Moves up
- External Intercostal Muscles – move down and in
- Thoracic Volume – decreases
- Thoracic Pressure – increases
- Air Flow – out the lungs (to equalise the pressure difference)
what does tidal volume mean?
the volume of air in each breath
what does vital capacity mean?
The maximum volume of air that can be breathed in and out
what does breathing rate mean?
The number of breaths per minute
what does oxygen uptake mean?
The rate at which a person uses up oxygen (dm3 min-1)
What device is used to measure lung volume?
spirometer
What happens to lung volume after exercise?
tidal volume and **rate of breathing **increases due to taking in more oxygen and removing more carbon dioxide.
What factors can affect your lung capacity?
- age
- body composition
- biological sex
- respiratory disease
- level of physical activity
what is haemoglobin?
protein molecule found within red blood cells
what is the function of haemoglobin?
carries oxygen
what can haemoglobin bind to?
oxygen and carbon dioxide
what is the structure of haemoglobin?
- quaternary structure
- 4 polypeptides
- each polypeptide has a haem group
- each haem group has an iron molecule
what is saturated haemoglobin?
haemoglobin bounded to oxygen molecule(s)
What is cooperative binding of oxygen to haemoglobin?
as oxygen binds to haemoglobin, the affinity for oxygen increases due to shape change making it easier for other oxygen molecules to bind
how many oxygens can a haemoglobin bind to?
8
what does affinity mean?
attraction (for)
How does foetal haemoglobin differ from adult?
higher affinity for oxygen
what happens when a carbon dioxide attaches to a haemoglobin?
oxygen is released and affinity decreases
What structures are involved in the mammalian respiratory system?
Trachea, bronchi, bronchioles, alveoli, and capillaries.
Adaptations of capillary networks.
extensive coverage → efficient transport
Provides good blood supply.
Explain how forced exhalation works.
Internal intercostal muscles contract to pull the ribs down and in.
Abdominal muscles contract to push organs upwards against the diaphragm, decreasing the volume of the chest cavity.
