Mass Transport Exam Q Flashcards
lugworms live in mud where the partial pressure of oxygen is low
explain the advantage to the lugworm of having haemoglobin with a dissociation curve to the left?
- greater affinity for oxygen
- can pick up more oxygen at lungs
- at lower ppO2
in humans, substances move out of the capillaries to form tissue fluid.
describe how this tissue fluid is returned to the circulatory system?
- hydrostatic pressure lower in capillary
- water returns
- by osmosis
- WP lower in blood
- due to proteins in blood
- returns via lymph system
the maximum pressure in ventricle is much higher than that in atrium
explain what causes this?
- ventricle has thicker wall/more muscle
- contractions are stronger
an arteriole contains muscle fibres
explain how these muscle fibres reduce blood flow to capillaries?
- muscle contracts
- arteriole constricts size of lumen
blood flow in capillaries is slow
give advantage of this?
more time for diffusion
kwashiorkor is a disease caused by lack of protein in blood.
this leads to swollen abdomen due to build up of tissue fluid.
explain why a lack of protein in the blood causes a build up of tissue fluid?
- WP in capillary less negative
- less water removed
- by osmosis
use your knowledge of transpiration to explain the changes in the rate of flow in xylem?
- rate of transpiration highest at midday
- because warmer
- more evaporation from leaves due to stomata open
- xylem under more tension
- cohesion between water mol
explain why values for the pressure in the xylem are negative?
water under tension
explain the difference in thickness between pulmonary artery and pulmonary vein?
artery wall contains more collagen
the thickness of aorta wall changes all the time during each cardiac cycle.
why?
- aorta wall stretches
- because ventricles contract
- pressure inc
- aorta wall recoils
- because ventricles relax
- pressure dec
- maintains smooth blood flow
which blood vessel shows greatest variation in wall thickness?
aorta
- has highest SD
explain how water enters xylem from endodermis in the root and is then transported to the leaves?
- casparian strip blocks apoplast pathway
- active transport by endodermis
- of ions into xylem
- lower WP in xylem - water moves in via OSMOSIS
- evaporation from leaves
- creates cohesion between water mol
- water mol bind to xylem (adhesion)
- creates continuous water column
explain the difference in the effect of exercise on systolic and diastolic pressure?
- systolic inc
- as ventricles pump with more force
- diastolic stays same as measured when ventricles relaxing
predict and explain the effect on potential cardiac oupu of daily exercise sessions over a six month period?
- increases cardiac output to a higher max
- training promotes larger stroke vol
- more powerful ventricles
