Exchange And Transport Flashcards
Why is diffusion through outer membrane slow in multicellular organisms
Some cells are deep in the body so large diffusion pathway
Difficult to exchange enough substances to large volume through small outer surface
Counter current flow
Blood flows through lamellae in one direction and the water flows over in opposite direction ( maintain favourable conc. gradient)
Conc. of oxygen always higher in water than blood
Gill structure and adaptation
Water enters through fish mouth and leaves over the gills
Gill made of gill filament which increases SA
Gill filament covered in lamellae which increase SA
Lamellae have blood capillaries which move any absorbed gas and have thin surface
Gas exchange in insects
Have air filled pipes called trachea, air moves to trachea via spiracles
Oxygen travels done the conc gradient towards cells
Trachea branch off into smaller tracheoles which have thin permeable walls and go to individual cells
CO2 moves down conc gradient towards spiracles to realise into atmosphere
Use rhythmic abdominal moments to move air in and out of spiracles
Stomata
Allow gas in and out, controlled by guard cells
All cells close to stomata so short diffusion path way
Interconnected air spaces
Increase the surface area of mesophyll layer so has can move around mesophyll cells
Spongy mesophyll layer
Large surface are of mesophyll cells for max diffusion
Site of gaseous exchange needed for photosynthesis
Water conservation in insects
Have rigid exoskeleton, chitin and water proof cuticle
Have small SA:Vol
Open and close spiracles
Water conservation in plants
Water enters the guard cell making them turgid opening stomatal pore
Leaves covered in waxy cuticle
Xerophytes
Layer of hairs on epidermis to trap moist air around stomata (lower WP)
Rolled leaves with stomata inside to protect from wind (traps water vapour)
Reduced number of stomata
Journey of air
Air enters the trachea
Trachea splits into two bronchi, one for each lung
Bronchus then branch into bronchioles
Bronchioles end in alveoli
Inspiration
External intercostal muscles and the diaphragm relax moving the rib cage up and outwards and the diaphragm flattens increasing volume of thoracic cavity
Pressure in thoracic cavity decreased so air moves down trachea
Expiration
External intercostal muscles and diaphragm relax moving the rib cage down and and inwards and the diaphragm becomes curved
Volume of thoracic cavity decreases causing air pressure to increase and air forced out
Forced expiration
The external intercostal muscles relax and the internal intercostal muscles contract pulling the ribcage further down
Alveoli
300 million in each lung and gsve 70m2 surface area
Alveolar epithelium is only one cell thick
O2 diffuses out alveolar and capillarity endothelium into haemoglobin in blood
Pulmonary ventilation
Overall flow of air into lungs in 1 minute
=tidal volume X breathing rate
Expiratory reserve volume
Volume of maximal exhalation after normal exhalation
Residual volume
Volume remaining in the lungs after maximal exhalation
Inspiratory reserve volume
Additional volume that can be inhaled after inhalation of tidal volume
Vital capacity
Maximum volume of exhalation after lungs are maximally filled
Tuberculosis
When infected by TB immune system builds tubercles, WBC fight infection scarring tissue
Reduced tidal volume so breath faster to get enough oxygen
Symptoms: persistent cough, coughing blood, chest pain, short breath and fatigue
Pulmonary fibrosis
Formation of scar tissue in lungs (result of infection or asbestos)
Scar tissues is thicker and less elastic so reduction in amount of oxygen diffusion and less lung expansion
Symptoms: shortness of breath, dry cough, chest pain, fatigue and weakness
Asthma
Allergens stimulate WBC in bronchi which release histamine which makes muscles around bronchioles contract
Airflow reduces so less oxygen enters alveolis
Symptoms: difficulty breathing, wheezing, tight chest, coughing
Emphysema
Caused by smoking or long term exposure air pollution
Foreign particles become trapped in alveoli causing inflammation attracting phagocytes
Phagocytes produce enzyme that breaks down elastin and leads to destruction of alveoli walls
Symptoms: bluish skin, chronic cough, wheezing shortness of breath
