Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 73

1 The set point of a variable isa) The value that the variable is always kept at in healthb) The optimal value for the variablec) The point at which the variable is too high to allow normal physiological processesd) The point at which the variable is too low to allow normal physiological processes

2 Most homeostatic mechanisms rely ona) Negative feedbackb) Positive feedbackc) Glycolysisd) All of the above

3 Which of the following is essential for negative feedback?a) A stimulusb) A sensorc) A control centred) All of the above

4 Which of the following hormones increases blood glucose?a) Insulinb) Glucagonc) Oxytocind) Thyroxine

5 Low blood glucose is clinically referred to asa) Isoglycaemiab) Hyperglycaemiac) Hypoglycaemiad) Endoglycaemia

6 Which of the following would be regarded as a normal body temperature?a) 36.9°Cb) 38.2°Cc) 34.9°Cd) 39.1°C

7 Which of the following acts as an endogenous pyrogen?a) Interleukin 2 (IL-2)b) Interleukin 3 (IL-3)c) Interleukin 1 (IL-1)d) Interleukin 4 (IL-4)

8 Which of the following drug groups is frequently used to reduce fever?a) Opioidsb) Diureticsc) Beta blockersd) Non-steroidal anti-inflammatory drugs (NSAIDs)

9 During positive feedbacka) Variables are kept exactly at their set pointb) Variables are kept within their normal rangec) Any deviations from the set point are amplifiedd) Hormones are never involved

10 Which of the following hormones triggers uterine contraction?a) Oxytocinb) Prolactinc) Oestrogend) Progesterone

Chapter summary

Homeostasis is the ability to maintain a relatively stable internal environment that is conducive to the optimal functioning of the body’s cells and tissues. Each variable in the human body has an optimal value known as the set point. Homeostasis relies on negative feedback mechanisms to minimise any deviations from the set point and constrain these deviations within a normal range. When variables are consistently outside of their physiological normal range, pathological states can occur, and medical interventions may be necessary to restore the variable to within its normal range. Positive feedback mechanisms can be thought of as the opposite of negative feedback and here any deviations from the set point are amplified and made greater.