3.1 - Specialised Exchange of Gases Flashcards
Describe the process by which bony fish respirate
Fish opens its mouth, lowering the buccal cavity
The volume of the buccal cavity increases therefore decreasing the pressure causing water to be sucked in
When the fish closes its mouth, the buccal cavity is raised
This decreases the volume and increases the pressure
The increased pressure forces water out of the cavity across gill filaments
This causes the operculum to open
This allows the water to move out of the gills down a pressure gradient.
Describe inspiration in the lungs
Rib muscles contract causing the ribs to move up
The diaphragm muscles contract which makes the diaphragm move down and out
The volume of the lungs increase
The pressure of air decreases below atmospheric pressure
Air enters the lungs to equalise the pressure.
Describe expiration in the lungs
Rib muscles relax
Ribs move down and in
Diaphragm muscles relax, causing diaphragm to move up
The volume of the lungs decreases
The pressure inside the lungs increases above atmospheric pressure
Describe respiration in larger insects
Flexible walls to ventilate
They can squeeze in and out
Movements of the wings can change the volume of the thorax
Locust in particular can change the volume of their abdomen by closing and opening valves in their spiracles
Ventilation in insects
Air enters pores in their abdomen called spiracles
Air comes through a tube called trachea
These then split into tracheoles which are filled with tracheal fluid
The gases will diffuse in the tracheal fluid where it will diffuse into the cells
Oxygen transport in insects
Tissue fluid and blood fluid are the same(hemolymph)
Insects have a tracheal system
What are the features of a good specialised exchange surface?
Thin walls for short diffusuion
Large SA:V ratio for rapid rate of diffusion
Moist so gases can dissolve first
Good blood supply and well ventilated to maintain a steep concentration gradient
What is the function of the trachea?
Carries fresh, clean air from the environment into the lungs
What are the features of the trachea?
C - shaped cartilage - stops airways collapsing due to pressure in thorax
Goblet cells - lines walls of trachea and secrete mucus to trap pathogens
Ciliated epithelium - waft mucus up to the pharynx to be swallowed and digested
Smooth muscle - allows the airways to contract and expand under pressure
Elastic fibres - h
Features of bronchus?
Smooth muscle Elastic fibres C - shaped cartilage Ciliated epithelium Goblet cells
What is the function of the bronchus?
They carryinspired air from environment to the alveoli for gas exchange
Features of bronchiole
Smooth muscle - contract to control amount of air entering lungs, contract and dilate Ciliated epithelium Elastic fibres Cartilage - Goblet cells(only in larger ones)
Function of bronchiole
Carry oxygen rich air into the lungs and take carbon dioxide out of the lungs
List adaptations of alveoli and describe how they aid its function
Good blood supply so gases can easily diffuse in and out of the blood
Well ventilated - maintain steep concentration gradient with blood
Moist lining - gases can dissolve first before entering blood
Folded - increases their surface area, more oxygen from bronchioles can diffuse into blood
Contain a lung surfacant - stops alveoli collapsing and sticking together
Contain collagen and elastic fibres that can stretch out and recoil to squeeze air out, stops alveoli exploding
Squamous epithelium - thinner walls for a shorter diffusion distance for gases
What happens during an asthma attack?
Cells lining bronchioles secrete histamines
Causes epithelial cells to swell and become inflamed
Smooth muscle in bronchioles contracts airways
Mucus is secreted which reduces air flow through lungs
What is tidal volume?
Volume of air moving in and out of lungs in one resting breath
What is vital capacity?
Largest volume of air that can be moved in and out of the lungs in one breath
What is expiratory reserve volume?
The volume of air that can be exhaled above the normal tidal volume
What is residual volume?
The volume of air left in the lungs following the strongest possible exhalation
How to find breathing rate?
Number of breaths per minute
What is total lung capacity?
Vital capacity + residual volume
How to work out ventilation rate
Volume of air breathed in per minute x tidal volume
What is the function of a spirometer?
Measure how much air is breathed out of the lungs between exhalations and inhalations
What is the operculum and what is its function?
A bony flap that protexts the gills
Helps maintain a constant flow of water through the gills
Why would a fish die in air?
Gill stacks need a constant flow of water to stay separated and have a larger surface area.
In air they would stick together and the surface area would be too small for gas exchange
How are fish gas exchange system adapted for their function?
Large surface area provided by gill filaments
Rich blood supply from lamallae
Thin walls - shorter diffusion
Countercurrent flow - concentration gradient maintained by counter flow of water in opposite direction to blood flow, oxygen constantly moving into blood by diffusion. Happens as oxygen concentration always higher than oxygen concentration.
What is the function of the c - shaped cartilage?
Keep airways open and prevent collapse during inspiration when there is a low pressure in the thorax
also allows some flexibility to move neck without constricting airways
What is the function of the smooth muscle?
Contracts to constrict airways
Reduces flow of air (reduces harmful substances going into lungs;
asthma)
What is the function of the elastic fibres?
DO NOT CONTRACT/RELAX
Stretch when smooth muscle contracts
Recoil (when smooth muscle relax) to help dilate the airway again
What is the function of goblet cells(not in smallest bronchioles)?
Secrete mucus which traps bacteria and other particles to be removed from the lungs to reduce infection
What is the function of the ciliated epithelium?
Waft to and fro to remove mucus from airways up to throat
Function of the blood vessels
Give good blood supply to lung tissue e.g. smooth muscle with oxygen for aerobic respiration or alveoli
Through what system does a fish respirate/gain a constant flow of oxygen into the blood?
Countercurrent Flow
Blood in capillaries moving opposite direction from water flow
So concentration of oxygen in water is always higher than in the blood
Therefore oxygen constantly moves into the bloodstream, more efficient method than reaching an equilibrium
Countercurrent flow system in fish
- Blood always meets water with higher oxygen concentration
- Therefore there is always a concentration gradient along the entire surface of the gill
- Therefore there is always diffusion along the entire surface of the Gill of oxygen into the blood
