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 processes2 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.
Activities: Brief outline answers
Activity 2.1: Evidence-based practice and research (page 36)
High blood calcium is referred to as hypocalcaemia and low blood calcium is referred to as hypocalcaemia.
High blood sodium is referred to as hypernatraemia and low blood sodium is referred to as hyponatraemia.
High blood potassium is referred to as hyperkalaemia and low blood sodium is referred to as hypokalaemia.
Activity 2.2: Evidence-based practice and research (page 40)
The very old and the very young are particularly susceptible to drops in their core body temperature. To avoid hypothermia people need to remain warm indoors in the following ways:
Keep your home at a temperature of at least 18°C
Babies’ rooms should be kept between 16 and 20°C
Keep windows and internal doors shut
Wear warm clothes; the more layers the better
Use a room thermometer to monitor temperature
(NHS, 2019a)
Activity 2.3: Multiple-choice questions (pages 43–4)
1) b, 2) a, 3) d, 4) b, 5) c, 6) a, 7) c, 8) d, 9) c, 10) a
Further reading
Boore J et al. (2016) Chapter 1: Homeostasis in person-centred care, in Essentials of Anatomy and Physiology for Nursing Practice. London: SAGE Publications Ltd.
A textbook to develop your knowledge of human anatomy and physiology that is aimed specifically at nurses.
Tortora G and Derrickson B (2017) Chapter 2: The chemical level of organization, in Tortora’s Principles of Anatomy and Physiology (15th edition). New York: John Wiley & Sons.
In-depth coverage of human anatomy and physiology.
Useful websites
www.sciencedirect.com/topics/immunology-and-microbiology/homeostasis
An overview of homeostasis.
Chapter 3 The cardiovascular system
Chapter aims
After reading this chapter, you will be able to:
describe the key functions of the cardiovascular system;
identify the major structures of the cardiovascular system;
explain what is meant by the pulmonary and systemic circulations;
describe the events of the cardiac cycle;
provide an overview of the coronary circulation and the nature of coronary artery disease (CAD);
describe the structure of arteries, veins and capillaries;
explain how blood pressure is regulated via neural and hormonal mechanisms.
Introduction
Case study: George – myocardial infarction
George was unloading shopping from his car when he suddenly felt a crushing heavy pain in the central part of his chest which spread down the inside of his left arm. By the time he sat down, he was feeling breathless with cold, clammy skin and experiencing a feeling of absolute terror. After ringing for an ambulance George’s wife was told to give him an aspirin to chew on and he was rapidly transferred to the local A&E department where, based on ECG evidence, he was immediately diagnosed with a major myocardial infarction (MI). George quickly had stents fitted in to open up his occluded blood vessels and felt almost immediate relief of his pain.
Cardiovascular disease such as that which led to George’s heart attack is a major cause of death and disability throughout the world. Nurses will spend a great deal of their time caring for patients with a variety of both heart and blood vessel disease. Many of the routine physiological measurements carried out by nurses such as recording heart rate, blood pressure and blood oxygen saturation provide snapshots of the patient’s current cardiovascular status.
This chapter will begin by describing the major functions of the cardiovascular system before examining the structure of the heart and its associated structures. Once you have an understanding of the anatomy of the heart, we
