Exchange Surfaces Flashcards
Why do multicellular organisms need specialised exchange surfaces?
They have high metabolic activity so have a high demand for oxygen and produce lots of waste to be removed
Larger diffusion distances than unicellular so diffusion alone is too slow
Low surface area to volume ration so need for oxygen outgoes the supply
What are 4 features of an efficient exchange surface?
Increased surface area
Thin layers
Good blood supply
Ventilation in mammals
Describe the structure and components in the trachea?
C shaped rings of cartilage to prevent collapse and allow food down the oesophagus
Ciliates epithelial and goblet cells
Smooth muscle and elastic fibres to allow expansion and recoil
Describe the structure and components in the bronchi?
Rings of cartilage to prevent collapse
Ciliates and goblet cells
Elastic fibres and muscle to allow expansion when need more oxyge and recoil
Describe the structure and components in the bronchioles?
Smooth muscle to proved strength and support- keep open and control air flow
Elastic fibres to allow stretch and recoil
Ciliates and larger have goblet cells
Describe the structure and components in the alveoli?
Squamous epithelium
Elastic fibres for stretch and recoil
Large surface area
Moist surface - lung surfactant
Describe what happens in inspiration?
External intercostal and diaphragm contract
Rib cage moves up and out and diaphragm flattens
Increases volume and decreases pressure of thorax below atmospheric pressure
It is an active process
What contracts in forced expiration?
Internal intercostal muscle
Define vital capacity
The volume of air that can be breathed in when the strongest possible exhalation of air is followed by the deepest intake of breath
Define tidal volume
The volume of air that moves in and out of the lungs with each resting breath
Define breathing rate
The number of resting breaths taken per minute
Define oxygen uptake
Amount of O2 consumed by an organism
Describe a spirometer and how it works
Consists of an oxygen chamber with a movable lid
Person breaths into chamber through mouth peice, moving the lid up and down
The movements are recorded by a pen attached to the lid which writes on a roaring drum = spirometer trace
Or hooked to motion senser and data logger records movements
Soda line absorbs co2
Ventilation in boney fish
- Mouth of fish opens, so _______ ______ is lowered
This increases the volume in the _______ ______ and lowers the pressure below the surrounding pressure - Water _____ __
- Mouth closes and ______ _____ raises
Decreasing volume and ________ pressure - Water moves into ____ _______ which increases its pressure
- __________ is forced open and water moves out across gills
Buccal cavity Buccal cavity Flows in Increasing Gill cavity Operculum
How does the gills have a large surface area?
They are divided into gill filaments which split into many gill lamellae
How do fish make their exchange system very efficient?
Their countercurrent flow
Blood flows in the opposite direction to the water over the gills
This means oxygen concentration is higher in water than the blood across the full length of the lamellae
Gas exchange in insects
- Air moves into the insect via ________
- Oxygen travels down concentration gradient towards cells via _____ and then smaller ________ to respiring tissues
- Oxygen dissolves in the _________ _____in the tracheoles
- _________ _________ ________ change the volume and pressure of the body to move air in and out of spiralled
Spiracles Tracheae Tracheaeoles Tracheole fluid Rhythmic abdominal movement
How can you dissect fish gills?
Push back the operculum and cut off gills with scissors
Cut the gill arch at the top and bottom of the bone
Place in water to see gill filaments
How to dissect an insect
Place dissecting puns in legs
Remove piece of exoskeleton from the abdomen
Fill abdomen with saline solution with a syringe
Tracheae should show up silvery as they are filled with air
what is the average tidal volume?
0.4 dm^3
between 0.3 and 0.7
what are the structures involved in mammalian gas exchange system? how do each increase efficiency o gas exhange?
nasal cavity large surface area and good blood supply , warms air • mucus secreting cells , trap dust and microbes • moist surfaces , increase humidity and reduce evaporation from surfaces in lung
trachea • cartilage rings , stop it from collapsing • ciliated epithelium and goblet cells secrete mucus , trap dust and microbes and move them towards stomach
bronchi/bronchioles • smooth muscle , allows air to move in and out and maintains high concentration gradient of O2 / CO2 and to control airflow
alveoli • thin (epithelial) wall , reduces diffusion distance • collagen / elastic fibres , elastic recoil to help squeeze air out during exhalation • large number / provide large surface area , to increase rate of diffusion • good blood supply / capillaries , maintains high concentration gradient • surfactant , allows gases to dissolve
diaphragm/ intercostal mucles
• contract to increase volume in lungs ,
reduce pressure and cause inspiration
how do you calculate SA:V ratio?
SA/V
always x:1
