Mass transport in animals Flashcards
Define ‘Tissue fluid’
Fluid containing water, amino acids, glucose , fatty acids , ions and oxygen
Why are small molecules able to be pushed out of capillaries at the arteriole end ?
There are tiny gaps
Why is there high hydrostatic pressure at the arteriole end and what does this incur ?
Blood enters capillaries from arteriole end
Creates high hydrostatic pressure
Forcing out smaller molecules
Via ultrafiltration
What is left in the capillary post-filtration ?
Large molecules
Proteins
Red blood cells
What is the effect of the large molecules being left in the capillary ?
Large molecules
Lower water potential
Creating a water concentration gradient to outside
Which end of the capillaries has a low hydrostatic pressure ?
The venule end
How does water and nutrients re-enter the capillary ?
Via osmosis
Due to the concentration gradient established
Is all tissue fluid absorbed , and if not what happens to it ?
No
absorbed into lymphatic system
Drains back into bloodstream by heart
State the characteristics of a vein
Larger lumen
Thinner walls ; low pressure
Valves
State the characteristics of an artery
Narrower lumen
Thicker walls ; higher pressure
Elastic ; stretch in response to pulses
Tissue fluid is formed from blood at the arteriole end of a capillary bed.
Explain how water from tissue fluid is returned to the circulatory system
Proteins remain in capillary
Lowering water potential/establishing water potential gradient
Water diffuses back into capillary via osmosis
Returns back to blood by lymphatic system
Describe the mechanism causing lungs to fill with air
Inhalation
Diaphragm and external intercostal muscles contract
Increasing volume/ capacity in thorax
Air moves down pressure gradient
