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AQA biology a level question

What the importance of capillary beds as exchange surfaces? It's in mass transport, the spec says 'The structure of capillaries and the importance of capillary beds as exchange surfaces.' but i cant find it in my textbook.
thank you
Hi sorry you have had no help for so long!

This is not a Q that you can spoon-feed yourself with from a book! It involves drawing info from various parts of the syllabus then presenting it by writing a smoothly-flowing, relevant answer using your brain to make sure you:-

A] keep repeating the word "importance" and "capillary" AND "exchange" again & again!
B] state a large number of brief but highly relevant points/facts/ideas etc
C] show that you know your terminology AND its correct meaning
C] TIP: think of your body from head to toe considering every organ one by one so you do not miss anything [this is to aid memory using a technique called "brainstorming]"

I shall push you off the cliff now [relax NOT literally :confused: - u don't need to start fumbling in :colondollar:your pockets/handbag for a parachute lol]

I] a] head + eyes: choroid has a rich blood supply/capillaries from the ciliary artery, a branch of the ophthalmic artery - important for keeping retina + uvea well-oxygenated + -nourished.
.....b] pituitary has a rich blood capillary supply cos it is an endocrine organ so secretes hormones e.g. GH + FSH DIRECTLY into the bloodstream [typical feature of endocrine glands, yeah - you can mention other glands here e.g. thyroid in the neck; adrenal above kidney.- importance = homeostasis + importance of e.g. [insulin] = precise control of serum glucose level.

II] Chest:
a] alveoli have rich capillary bed - importance = efficient exchange of O2 from air to blood.- O2 needed for respiration ----> energy as ATP
b] myocardium - why?? your turn to answer!!

III] "Belly"
.....a] intestine:- mesenteric arteries [don't worry about name if u cant remember] - villi - rich capillary network [+ microvilli] - importance = absorption of glucose, amino acids, etc. from lumen to blood - needed again for ATP to allow growth, repair + reproduction.
.....b] liver - sinusoids importance = detoxification [first-pass metabolism]; other functions??? yes good: protein synthesis; importance = muscle growth + maintenance of blood pressure [osmolality due to proteins in blood keeps blood vol normal] AND clotting factors - importance = avoid bleeding too much from injuries + prevent infection.
.....c] kidneys [look up]
.......... Bowman's capsule/glomerulus - appearance? + what happens here? "filtration" ring a bell? - good well done! - importance = [why do we need to get rid of toxins, urea, uric acid, drugs?]
..........[ii] proximal tubule cell; reabsorption importance = to retain needed substances, makes sense?

.....c] lower down look up: epididymis; ovary, ovarian follicle - importance of reproduction = perpetuation of species.

`etc etc etc.
if you mention ALL points above + others -----> v gd mark! REMEMBER: what matters is mark, mark, mark just like in hockey what matters is goal, goal, goal!

Be safe!
M [specialist biology tutor]
(edited 1 year ago)

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