2.2 Adaptations for Gas Exchange in animals Flashcards
🧬 Exchange of Materials in Organisms
Need for Exchange:
Cells require oxygen, glucose, and water for metabolism.
They produce waste products (CO₂, nitrogenous waste, water) that must be removed.
🧬 Exchange of Materials in Organisms
Cell Membrane Transport Mechanisms:
Simple diffusion: Gases (O₂, CO₂) & non-polar molecules pass through the phospholipid bilayer.
Facilitated diffusion: Polar/charged substances use specific channel or carrier proteins.
Osmosis: Movement of water through aquaporins or membrane from high to low water potential.
Active transport: Moves substances against the concentration gradient using ATP and carrier proteins.
Endocytosis/exocytosis: Bulk transport of large particles or fluids.
Surface Area to Volume Ratio (SA:V):
🧬 Exchange of Materials in Organisms
Surface Area to Volume Ratio (SA:V):
Exchange happens at surface area, but metabolic needs depend on volume.
As organisms get larger:
Volume increases faster than surface area.
SA:V ratio decreases.
Diffusion becomes less efficient, so specialised exchange surfaces are needed.
🌬️ Factors Affecting Diffusion Rate
SA
↑ SA = ↑ diffusion rate
More membrane means more space for molecules to pass through.
Adaptation: Folding of surfaces (e.g. microvilli in intestines) increases SA.
🌬️ Factors Affecting Diffusion Rate
diffusion distance
↓ distance = ↑ diffusion rate
Shorter paths reduce time for substances to travel.
Adaptation: Thin exchange surfaces (e.g. one-cell thick alveoli or capillaries).
🌬️ Factors Affecting Diffusion Rate
gradient and how this is maintained
↑ gradient = ↑ diffusion rate
Steeper gradient means faster net movement of molecules.
Maintained by:
Ventilation (e.g. lungs bring in O₂, remove CO₂)
Circulation (blood carries O₂/CO₂ to and from tissues)
Cell respiration (uses O₂, produces CO₂)
Water movement (e.g. fish moving keeps fresh water flowing over gills)
Turbulence (mixes water, increases O₂ availability)
🦠 Unicellular Organisms (e.g. Amoeba) and Gas Exchange
label amoeba
🪱 Flatworms (Multicellular Organisms) and Gas Exchange
🪱 Earthworms and Gas Exchange
Amphibia (Gas Exchange and Circulation):
specialised gas exchange surfaces
in large multicellular animals
help overcome problem of low SA to Vol ration and long diffusion distances
circulatory system - helps maintain conc gradient (brings oxygenated blood to tissue and removes carbon dioxide)Haemoglobin has a high affinity for oxygen and absorbs and transports oxygen.
Generally, these gas exchange surfaces must have:
a large surface area
a short diffusion path
ventilation mechanisms for maintaining a concentration gradient
permeability to gases
moist surfaces so oxygen can dissolve in the water and diffuse across them.
Gas Exchange in Fish
Problem:
Adaptation: Gills
Gas Exchange in Fish
Structure of Gills:
Gas Exchange in Fish
Ventilation in Fish:
Operculum
Gas Exchange in Fish
Blood Supply:
Gas Exchange in Fish
Adaptations in Active Fish:
Gas Exchange in Fish
Gas Exchange in Fish
Gas Exchange in Fish
Ventilation in Fish
Purpose of Ventilation:
Ventilation in Fish
Bony Fish: Positive Pressure Ventilation
Ventilation in Fish
Ram Ventilation (in some sharks):
Ventilation in Fish
Bony Fish vs RAM
Ventilation in Fish
Ventilation in Fish
Countercurrent and concurrent blood flow in fish gills
🦈 Cartilaginous Fish (e.g., sharks)
Countercurrent and concurrent blood flow in fish gills
🐟 Bony Fish
Countercurrent and concurrent blood flow in fish gills
💡 Why Countercurrent is Better:
The gas exchange system in mammals consists of the following:
Larynx
this is the ‘voice box’ and contains the vocal cords enabling sounds to be produced.
The gas exchange system in mammals consists of the following:
Trachea
a pipe that connects the lungs to the pharynx; it has C-shaped rings of cartilage that prevent the trachea collapsing when pressures in the lungs are negative.
The gas exchange system in mammals consists of the following:
Bronchi
two bronchi branch off the lower end of the trachea delivering air to each lung. Rings of cartilage prevent the bronchi collapsing.
The gas exchange system in mammals consists of the following:
Bronchioles
smaller branches from the bronchi delivering air to all parts of the lung; muscle permits constriction to control the flow of air in and out of the alveoli.
The gas exchange system in mammals consists of the following:
Alveoli
the site of gas exchange, these consist of sacs of air surrounded by flattened (squamous) epithelia. The large number of alveoli give a massive surface area to the lungs and the flattened epithelial cells give a short diffusion path. The alveoli are surrounded by capillaries which maintain a concentration gradient. The blood contains haemoglobin which transports oxygen away from the gas exchange surface. Carbon dioxide diffuses from the plasma into the alveoli to be excreted.
The gas exchange system in mammals consists of the following:
Pleural membranes
these surround the lungs and secrete pleural fluid. The pleural membranes are involved in negative pressure breathing.
The gas exchange system in mammals consists of the following:
Ribs
protect the heart and lungs.
The gas exchange system in mammals consists of the following:
Intercostal muscles
these sit between the ribs, contraction of these muscles raises the rib cage in ventilation.
The gas exchange system in mammals consists of the following:
Diaphragm
a muscle that separates the thorax and abdomen, contraction of this muscle pulls the diaphragm down in ventilation.
Structure and Function of the Trachea
1. Ciliated Epithelium
Structure and Function of the Trachea
2. Cartilage Rings
Structure and Function of the Trachea
3. Smooth Muscle
\
A - rings of cartilage
B - containing Goblet cells
C - oesophagus
D- ?
Adaptations of the Alveoli for Gas Exchange
Inspiration (breathing in):
In expiration (breathing out):
The muscles relax and the opposite to the image below happens:
Ventilation in mammals
- negative pressure ventilation mechanism
- bringing oxygenated air to lungs, removing carbon dioxide rich air from lungs, to maintain conc gradient between blood and alveoli
Gas Exchange in Insects
Water Conservation Adaptations
Insects have a high surface area to volume ratio, making them prone to water loss.
To reduce desiccation, their body is covered in a chitin exoskeleton with a waterproof waxy layer.
As a result, gas exchange cannot occur across the body surface.
Gas Exchange in Insects
Gas Exchange Structures
Spiracles: Small openings on the exoskeleton that allow gases to enter and exit.
Tracheae: Tubes lined with chitin that branch from the spiracles. Chitin prevents the tubes from collapsing.
Tracheoles: Fine tubes that extend close to cells – this is where gas exchange takes place.
Gas Exchange in Insects
Mechanism of Gas Exchange
tracheole
Structure and Control of Spiracles in Insects
Location & Arrangement
Structure and Control of Spiracles in Insects
Function & Adaptation
Structure and Control of Spiracles in Insects
Control Mechanism
Structure and Control of Spiracles in Insects
Spiracular Fluttering
Ventilation in Insects
Inhalation (Air In)
Ventilation in Insects
Exhalation (Air Out)
Insect Flight Muscle and Gas Exchange
🪶 High Metabolic Demand
Insect Flight Muscle and Gas Exchange
🧬 Tracheole Penetration
Insect Flight Muscle and Gas Exchange
⚡ During Flight
