Exchange And Transport Flashcards
Why do multicellular organisms need exchange surfaces?
Diffusion across outer membrane is too slow due to :
- cells are deep within body —> LARGE DIFF DISTANCE
- Low SA:V ratio - difficult to exchange enough over small outer surface for big organism
- higher metabolic rate - use up oxygen and glucose faster
Features of efficient gas exchange and give example in the body?
Large SA: root hair cells provide large SA to increase rate of water uptake/mineral ions by active transport
Thin layer - Alveoli - made of flat cells called ALVEOLAR EPITHELIUM —> decrease diff distance
Good blood supply/ventilation-
Alveoli - have large capillary network , so each alveolus has own blood supply - maintain CONC GRAD
- lungs ventilated , so air is constantly replaced in alveolus
Gills - fresh water passes over them - ventilation
- contain large network of capillaries
Cells and tissues that help gas exchange?
GOBLET CELLS: in ciliated epithelium in trachea
-secrete mucus /traps microorganism/dust —> stop from reaching alveoli
CILIATED EPITHELIUM: tissue found along trachea to bronchi
- each cell has cilia to move mucus/dust/microorganisms away from alveoli, to be swallowed
CARTILAGE: found in tracheal rings
- support trachea
- stops trachea/bronchi collapsing when breathing in
SQUAMOUS EPITHELIUM: on alveoli
- form structure of alveolar wall/thin for diffusion
SMOOTH MUSCLE : in walls of bronchi/bronchioles
- regulate flow of air into longs, by dilating/constricting
ELASTIC FIBRES: allow lung to stretch /recoil , making EXPIRATION A PASSIVE PROCESS
Structure of trachea?
C shaped rings of cartilage - prevent friction from rubbing with oesophagus /keep airway open
Ciliated epithelium : move mucus away from alveoli
Smooth muscle/elastic fibres in walls
Bronchi structure ?
- similar to trachea
Thinner walls /smaller diameter - cartilage is full rings instead of C shaped
Bronchioles structure?
CILIATED EPITHELIUM: doesn’t contain goblet cells
Get smaller as u get closer to alveoli :
LARGER BRONCHIOLES : elastic fibres/smooth muscle - adjust size of airway to vary airflow
SMALLER BRONCHIOLES: only elastic fibres
Alveoli structure?
Alevolar wall has layer of EPITHELIUM
Elastic fibres
Capillary network
Surfactant on alveoli - decrease surface tension - orient collapse
Breathing in mechanism ?
REST : external intercostal muscle contract
- diaphragm flattens /contracts - increase volume of thorax/decrease pressure
- ribcage move up/out
AIR FLOWS INTO LUNGS - ACTIVE PROCESS
Breathing out mechanism: rest/excerise?
External intercostal muscles/diaphragm relax and domes up
Ribcage moves down/in
Thorax volume decrease /pressure increases
AIR FORCED OUT - PASSIVE
Exercise (forced exhalation):
internal IM contract to pull ribcage down/in
Abdominal muscles* contract - increase pressure pf thorax
4 breathing volumes?
Vital capacity - max vol of air that can be breathed in or out in 1 breath
Tidal volume - volume of air breathed in or out during normal breathing
Breathing rate - number of breaths taken in one min
Oxygen uptake - volume of oxygen used up in a given time
Spirometer : how does it work?
Has oxygen filled chamber with movable lid
- person breathes in to a tube connected to oxygen chamber
- as persons breathes in/out, lid over up and down
- this movement recorded by pen attached to lid - writes on rotating drum creating spirometer trace
Or spirometer is hooked to motion sensor - produce electronic signals picked up by data logger
Soda lime is on tube to absorb CO2 from expired air
How can oxygen uptake be calculated from spirometer?
CO2 is removed from exhaled air , so total volume of air available in spirometer DECREASES, as only oxygen left in chamber, which person breathes in
Change in volume is used as measure of oxygen uptake
Features of TRACHEAL SYSTEM in insects?
SPIRACLE: allows air to enter the tracheal system
TRACHEAE: tubes which lead into tracheoles - CHITIN keeps tracheae open
TRACHEOLES: branch into body cells - thin/premeable walls
- contain fluid which O2 dissolves in
How do insects ventilate tracheal system?
Rhythmic abdominal movements - creates mass flow of air in/out tracheal system
Spiracles open/close - allow entering/expulsion of air
Structure of gills in fish?
Each gill arch attached to 2 stacks of filaments - primary lamellae (provide large SA for exchange)
On surface of each filament, there are rows of secondary lamellae (big SA)
- lamellae consist of single layer of flattened cells that cover capillary network (GOOD BLOOD SUPPLY - speed diffusion)
