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because it readies the body for the extra work it might
have to do in terms of increased breathing rate, heart
rate, and muscular activity. It prepares the body to
most efficiently flee or defend itself. 2. (a) A prolonged period of stress triggers release
of ACTH from the pituitary (mediated by the
hypothalamus) and brings about the release of
glucocorticoids from the adrenal cortex. These
mediate suppression of the immune system and
metabolism of fats and proteins, which helps Control of Blood Glucose (page 101)
1. (a) Stimulus: Rise in the levels of glucose in the
blood above a set level (about 5.5 mmol per L).
(b) Stimulus: Fall in blood glucose levels below a set
level (about 3.5 mmol per L).
(c) Glucagon brings about the production (and
subsequent release) of glucose from the liver by
the breakdown of glycogen and the synthesis of
glucose from amino acids.
(d) Insulin increases glucose uptake by cells (thereby
lowering blood glucose) and brings about
production of glycogen and fat from glucose in
Biozone International 2009 Photocopying Prohibited 17
2. 3. Fluctuations in blood glucose (BG) and blood insulin
levels are closely aligned. Following a meal, BG rises
sharply and there is a corresponding increase in
blood insulin, which promotes cellular glucose uptake
and a subsequent fall in BG. This pattern is repeated
after each meal, with the evening meal followed by
a gradual decline in BG and insulin over the sleep
(fasting) period. Negative feedback mechanisms
prevent excessive fluctuations in blood glucose (BG)
throughout the 24 hour period. 2. (a) Veins have less elastic and muscle tissue than
(b) Veins have a larger lumen than arteries. 2. Most of the structural differences between arteries
and veins are related to the different blood pressures
inside the vessels. Blood in veins travels at low
pressure and veins do not need to be as strong,
hence the thinner layers of muscle and elastic tissue
and the relatively larger lumen. Extra note: There
is still enough e...
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This document was uploaded on 01/28/2014.
- Winter '13