Gas exchange and limiting water loss Flashcards
What is PVR and how do we calculate it
Pulmonary ventilation rate is the total volume of air that is moved into the lungs during 1 minute
PVR = tidal volume x breathing rate
Tidal volume is volume of air taken in each breath when at rest
Breathing rate is number of breaths a person takes in 1 minute
What adaptations do insects have to reduce water loss
Small surface area: volume ratio to minimise area over which ater is lost
Waterproof coverings over the body
Spiracles which are little holes that can open and close to reduce water loss and allow gas exchange
How does the end of tracheoles being filled with water help an insect with gas exchange
During major activity the insect starts to respire anaerobically which produces lactic acid which dissolves in the water reducing the w.p. of the muscle cells.
Water from the end of the tracheoles then moves in to muscle cells by osmosis making the final phase a gas rather than a liquid allowing for faster diffusion as oxygen diffuses faster through a gas than liquid
How are the gills of a fish adapted for gas exchange
LSA provided gill lamellae making diffusion efficient
Thin epithelium means a short diffusion pathway between blood and water
Water and blood flow in opposite directions this is called the counter current flow which maintains a constant gradient along the entire length of the gill lamellae
Circulation of blood replaces blood that is saturated with oxygen maintaining a constant concentration gradient
Ventilation replaces water as oxygen is being removed from it by fish
Explain the movement of oxygen in to the gas exchange system of an insect during activity
Abdominal pumping involves CO2, abdominal pumping increases the pressure inside the body of the insect, pressure inside insect is now greater than atmospheric pressure forcing CO2 out the body down the concentration gradient and allowing O2 to move in
How is a leaf adapted for gas exchange
No cell is far from a stomata therefore a short diffusion pathway
LSA of mesophyll cells for rapid diffusion
What adaptations do plants have to help reduce water loss
Thicker cuticles create a barrier over which water cant escape from
Rolling up of leaves creates an area of still humid air which decreases the concentration gradient between the outside and inside of leaf preventing water loss
Hairy leaves trap still moist air which reduces the concentration gradient between inside and outside of leaf which reduces water loss by evaporation
Sunken stomata trap an area of still moist air which cant be blown away which reduces concentration gradient inside and outside leaf which reduces water loss by evaporation
Describe the mechanism of breathing in
External intercostal muscles contract whilst internal intercostal muscles relax which moves the ribs up and out which increases the volume and decreases the pressure of the thorax
The diaphragm also contracts moving it down which further increases volume and decreases pressure of thorax.
Increased volume results in a decreased pressure
This means the atmospheric pressure is greater than the pulmonary pressure which forces air to move into the thorax down the concentration gradient
Describe the structure of the lungs
Trachea is a flexible airway that allow air to move up and down and is supported by rings cartilage
Tracheal walls are made up of cilia and goblet cells (cilia waft mucus containing pathogens up to the mouth and goblet cells produce mucus)
Bronchioles made up of muscle lined with epithelial cells, this muscle allows them to constrict and relax controlling airflow into alveoli
Between alveoli there is collagen and elastic fibres, lined with an alveolar epithelium which is 1 cell thick allowing for a SDP
What is FEV and FVC
Forced expiratory volume is the greatest volume of air a person can breathe out in 1 second
Forced vital capacity is the greatest volume of air a person can breathe out in a single breath
How does oxygen in the air reach capillaries surrounding the alveoli
Down the trachea down the bronchi and down the bronchioles all down a concentration gradient then diffuse across the alveolar epithelium and diffuse across the capillary epithelium
What is each intercostal muscle used for
Internal intercostal muscle allows for forced exhalation, they depress the ribs and decrease space in the chest cavity
External intercostal muscles allow for forced and quiet inhalation, they raise the ribs and expand the thorax
Describe the mechanism of breathing out
Internal intercostal muscles contract whilst external intercostals relax which moves ribs down and in which decreases the volume and increases pressure of the thorax
The diaphragm relaxes moving it up which further decreases volume and increases pressure of the thorax
Decreased volume results in an increased pressure
This means that pulmonary pressure is greater than atmospheric pressure causing air to be forced out of lungs down the concentration gradient
Explain the movement of oxygen into the gas exchange system of an when at rest
Oxygen gets used up in aerobic respiration which reduces concentration of oxygen at tracheoles creating a diffusion gradient allowing oxygen to diffuse in down the concentration gradient
Explain how the CCF works
Blood and water flow in opposite directions
Blood passes water with a higher oxygen concentration
This maintains a steep concentration gradient across the whole of the gill lamellae and faster diffusion
Describe gas exchange in insects
Internal network of tubes called tracheae. Tracheae are supported by rings of chitin which prevent them from collapsing
Tracheae divide into smaller dead end tubes called tracheoles which extend throughout the whole insects body tissues providing a SDP from tracheoles to any cell
