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HUMANBIOLOGY­MRMORGAN

SPECIALSURFACESFOREXCHANGE
WHY ORGANISMS NEED THEM
All LIVING cells need CERTAIN substances to keep ALIVE:
OXYGEN ­ AEROBIC RESPIRATION

GLUCOSE ­ acts an ENERGY SOURCE OGPFWM
PROTEINS ­ needed for GROWTH & REPAIR
FATS ­ for making MEMBRANES + act as an ENERGY STORE
WATER
MINERALS for MAINTAINING WATER POTEN.…

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Also found at IN ORGANS to REMOVE SUBSTANCES into the transport system
ALVEOLI ­ the WALLS are exchange surfaces to permit GASEOUS EXCHANGE
SMALL INTENSTINE ­ NUTRIENTS are ABSORBED
LIVER ­ LEVELS of SUGAR are adjusted
ROOT HAIRS ­ WATER AND MINERALS absorb

EXCHANGE SURFACE ­ a SPECIALISED AREA that…

Page 3

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When BREATHED OUT ­ it EVAPORATES and is lost
Lungs MUST produce substance SURFACTANT to REDUCE COHESIVE FORCES BETWEEN WATER
MOLECULES
WITHOUT, alveolus would COLLAPSE due to cohesive forces of lining water molecules

MAINTAINING DIFFUSION GRADIENT
RAPID diffusion ­ a STEEP DIFFUSION GRADIENT is needed
Meaning HIGH CONC. Of MOLECULES…

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Chest cavity VOLUME ­ INCREASES
AIR ­ INTO the lungs
EXHALING = EXPIRATION
DIAPHRAGM ­ RELAXES and PUSHED UP by displaced organs
EXTERNAL INTERCOSTAL MUSCLES ­ these RELAX/RIBS FALL
Chest cavity VOLUME ­ DECREASES
AIR ­ OUT of the lungs

TISSUES IN THE LUNGS
THE LUNGS
There is the TRACHEA,…

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C-SHAPED RINGS which keep AIRWAY OPEN when PRESSURE LOW in the lungs
(INHALATION)
NOT COMPLETE RINGS = FLEXIBILITY (neck can be MOVED WITHOUT CONSTRICTING
airway) + allows OESOPHAGUS to EXPAND during swallowing
SMOOTH MUSCLE
Type of INVOLUNTARY MUSCLE; allows for INVOLUNTARY MOVEMENTS e.g. BREATHING and
usually found in SOME INTERNAL…

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Means MORE OXYGENATED AIR INTO lungs/CARBON DIOXIDE ­RICH AIR
OUT
ELEMENTS OF LUNG VOLUME
TIDAL VOLUME:-
The vol. of air MOVED IN & OUT of the lungs with EACH BREATH AT REST
(approx. 0.5dm3)
VITAL CAPACITY:-
LARGEST (max.) vol. of air MOVED IN & OUT of the lungs in ONE…

Page 7

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Person BREATHES IN from a DISPOSABLE MOUTHPIECE ATTACHED (FOR
SAFETY) TO A TUBE CONNECTED TO OXYGEN CHAMBER
OXYGEN used in MEDICAL GRADE (FOR SAFETY)
BREATHING IN oxygen from chamber, causes CHAMBER TO SINK DOWN
BREATHING OUT (into the chamber), causes CHAMBER TO FLOAT UP
MOVEMENT OF CHAMBER is RECORDED using…

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Must also REMOVE WASTES to AVOID TOXIC BUILD UP
SMALL animals DON'T need a SEPARATE TRANSPORT SYSTEM as ALL their
cells are NEAR/SURROUNDED by the EXTERNAL ENVIRONMENT
SMALL ANIMALS = DIFFUSION alone, ENOUGH for their supply of oxygen/nutrients

Animals with 2+ LAYERS OF CELLS, diffusion ALONE = TOO SLOW
3…

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SECOND CIRCUIT: carries the OXYGEN & NUTRIENTS AROUND THE BODY ­ the SYSTEMIC
CIRCULATION
MAMMALIAN HEART adapted to have TWO (2) PUMPS ­ one for EACH CIRCULATION
BLOOD goes through HEART TWICE FOR EACH COMPLETE CIRCULATION of the body
HEART ­ BODY ­ HEART ­ LUNGS ­ HEART
PULMONARY CIRCULATION…

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BOTH sides apply PRESSURE to the BLOOD by SQUEEZING, forcing the blood INTO the
ARTERIES




EXTERNAL FEATURES OF HEART
It sits SLIGHTLY OFF CENTRE to LEFT of the chest cavity with MAIN PART of the heart being FIRM,
RED MUSCLE
2 main PUMPING CHAMBERS are the VENTRICLES
ABOVE ventricles, are…

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