Gas Exchange Flashcards
Gas exchange in fish adaptation
Gill filaments increase surface area
Lamellae enhanced surface area have capillaries for good blood supply and thin surface layer of cells for short diffusion path
Counter current system in fish
Fish have a small surface area to volume ratio so cannot simply refuse oxygen to the body requires requiring a gas exchange surface which is the gills
The girls are four layers and are made up of stacks of a gill filaments each filament is covered with LaMelo creating a large surface area for gas exchange water moves in through the mouth over the gills and lead through the gap in the side of the head there is a short diffusion distance as capillary network in every lamellae.
To maintain the concentration gradient the counter current flow system is an adaptation where water flows over the gills in opposing direction to the blood flow in the capillaries this is so that equilibrium is never reached maintaining the diffusion gradient across the entire lamella
Gas exchange in dicotyledonous plants
Plants require carbon dioxide for photosynthesis oxygen is released as a byproduct of this oxygen is needed for respiration the surface of gas exchange is the mesophyll cells in the leaf they have a large surface area and are inside the leaf gases move in and out of the stomata this can open to allow exchange gases and close if too much water guard cells control the opening and closing of these
Gas exchange in insects
Insects have a high oxygen demand due to activity such as flying
- insects are covered with protective exoskeleton made from chitin which cO2 and oxygen cant easily move through a one
- spiracles on the surface allow gases to diffuse into and out of the body
-these lead to a network of tubes called trachae wide tubes which extend down ad across an insects body
- the walls of the trachae are reinforced by spirals of chitin preventing collapse
- extending from this re thin tubes called tracheoles very close to the cells providing a short diffusion pathway these are single cells extended to form a hollow tube.
There are a larger number of tracheoles providing a large surface area for exchange
Filled w tracheal fluid
Spiracles surrounded by a muscular spinster so that they can open and close preventing any water loss
Control of water loss
Insects have waxy cuticle all over body and hairs around the spiracle to reduce water loss through evaporation. If too much water is being lost the spiracle will close using muscles.
Plants stomata open throughout day
Water enters guard cells making them turgid opening stomatal pore
If plant gets dehydrated guard cells lose water and become flaccid closing the pore
Xerophytes (plants adapted for warm climates)
Stomata sunk in pits ti trap water vapour reducing concentration gradient of water between leaf and air reducing water evaporation from leaf
Layer of hairs on epidermis to trap water vapour round the stomata
Curled leaves with stomata inside protecting them from wind
Reduced number of stomata inside fewer places for water to escape
Thicker waxy waterproof cuticles on leaves and stems to reduce evaporation
Structure of human gas exchange system
As you breathe in the air enters the trachea
This splits off onto two bronchi one leading to each lung
Each bronchus branches off to bronchioles and then in small air sacs called alveoli
This is where gas exchange takes place
Intercostal muscles
Found between the ribs
Three layers of intercostal muscles two of wchich are the internal and the external intercostal muscles
Inspiration
External intercostal and diaphragm muscles CONTRACT
Causing rib cage to move upwards and outwards and the diaphragm to flatten
Volume of lungs increases lung pressure decreases to below atmospheric pressure
Active process requires energy
Air flows down the pressure gradient from trachea to lungs
Expiration
External intercostal and diaphragm muscles relax
Rib cage moves downwards and inwards
Diaphragm curves upwards again becomes dome shaped
Volume or lungs decreases
Pressure goes above atmospheric pressure is forced down the pressure gradient and out of the lungs
Normal expiration is passive
Forced expiration External intercostal muscles relax internal intercostal muscles contract pulling rib cage further down and in
movement of two sets of intercostal muscles is antagonistic
Alveoli structure
Wall is made from a single layer of thin flat cells called alveolar epithelium
Walls of capillaries made from capillary endothelium
Walls of alveoli contain elastin
This helps alveoli recoil after inhaling or exhaling air
Gas exchange in alveoli
Oxygen defuses out of the alveoli across the alveoli epithelium and the capillary endothelium into haemoglobin in the blood carbon dioxide defuses into alveoli from the blood
Factors affecting rate of diffusion
Thin exchange surface alveoli epithelium is only one Celtic meaning there is a short diffusion pathway
Large surface area there are millions of alveoli meaning large surface area for gas exchange
Steep concentration gradient between alveoli and capillaries