Lecture Notes

Human Physiology

Ole H. Petersen, Ole H. Petersen

• Publisher: Wiley-Blackwell
• Year: 2019
• ISBN:
  9781119648352
• Edition: 5
• Topic: Medicine
• Subtopic: Nursing

Lecture Notes: Human Physiology provides concise coverage of general physiology for medical students as well as students of biological sciences, sport science, pharmacology and nursing.

This fifth edition of the ever popular Lecture Notes: Human Physiology has been thoroughly revised and updated by a new international team of authors. The simple structure and systems-based approach remain, with a new clean layout for ease of reading and colour now incorporated to aid understanding.

Lecture Notes: Human Physiology:

• Provides more focus on pathophysiology for clinical relevance
• Is the perfect introduction for medical and allied health care students
• Now includes physiology of pain and increased coverage of heart and the vascular system
• Includes a completely revised chapter on the nervous system.

Chapter 1
Cell Physiology

Physiology is the science of the functions and phenomena of living things. The aim of this book is to explain human physiology, but many of the underlying experimental data have been derived from animal experiments. Our bodies contain vast numbers of cells, which are the fundamental units of all living organisms.

1.1 Cells

Physiology is about how cells work and about how their environment is maintained so that the cells can function optimally.

Mammalian cells are very small, of the order of 10⁻⁵ m in diameter. This is about midway between people (of the order of 1m) and atoms (10⁻¹⁰ m). A person has about as many cells — about 10¹⁴ — as a cell has molecules.

Although the detailed structure of cells is not revealed fully by light microscopy, due to its limited resolution (0.2 μm), some of the major features can be observed in living cells by specifically staining individual components (Fig. 1.1). The cellular ultrastructure in all its complexity can be observed in electron micrographs of fixed tissue (resolution approximately 1nm (10⁻⁹ m)).

In order to power cellular functions, there is a need for a continuous supply of matter (for example, glucose or amino acids), which can be transformed to generate usable energy in the form of adenosine triphosphate (ATP). The mitochondria (Fig. 1.1) are the principal powerhouses of the cell, and this is where the main synthesis of ATP takes place. The details of metabolism are the domain of biochemistry.

Every cell is surrounded by fluid (extracellular fluid, ECF) and for normal cell function the composition of this bathing fluid must be maintained constant. This ECF is the medium through which all exchanges between cells and the external environment occur. The constancy of the ECF, necessary for the well being of the cells, is maintained by homeostatic mechanisms that monitor and regulate its temperature, osmotic pressure, pH and composition. Much of physiology is the story of homeostasis.

1.2 Homeostatic mechanisms

The composition of the ECF, and therefore the cell environment, is maintained constant through homeostatic mechanisms that monitor and regulate the functions of the circulatory system, the alimentary system, the respiratory system and the renal system. This monitoring and regulation is coordinated through the nervous and endocrine systems and requires receptors, central integration and output to the effectors.

Homeostatic mechanisms are triggered by alteration in some physiological property or quantity and act to produce a compensating change in the opposite direction, so as to return the system as close as possible to the normal situation (so-called negative feedback control). Minimum requirements are:

Fig. 1.1 Some of the important organelles and their distribution in a secretory cell (exocrine). The nucleus is surrounded by an extensive endoplasmic reticulum. The granules, containing material to be secreted (for example digestive enzymes in exocrine glands or hormones in endocrine glands) are clustered in one part of the cell, which is typical for exocrine cells. The mitochondria are predominantly localized on the border between the granules and the basolateral part of the cell containing the endoplasmic reticulum and the nucleus. (Modified from Petersen, O.H., Tepikin, A.V. & Park, M.K. (2001) Trends Neurosci, 24, 271–76.)

1. 1 receptors, specialized to detect alterations in particular variables;
2. 2 effectors, e.g. the circulatory system that carries nutrients and O₂ to the cells and removes metabolic waste products, including CO₂; the alimentary system that provides nutrients to the body; the respiratory system that carries out exchanges of gases with the external environment; the renal system that allows losses of unwanted solutes and water from the body; and the musculoskeletal system;
3. 3 coordinating and integrating mechanisms, linking 1 to 2. These are nervous and hormonal.

Nervous system

In essence this consists of afferent nerve fibres linking receptors to coordinating systems in the brain and spinal cord, and efferent nerve fibres that carry information from the coordinating systems to the effector organs. There are two major subdivisions of the efferent system: the somatic nervous system uses skeletal muscles as effectors for purposive behaviour and reflex actions; the autonomic nervous system sends its efferents to glands, the heart, and smooth muscle in hollow organs and blood vessels.

Endocrine system

This comprises cells, often arranged in groups called glands, which secrete hormones into the blood that affect the function of target cells throughout the body. Hormonal actions are generally slower and less sharply localized than those of the nervous system; they are, however, under the control of the nervous system through hormones produced in the brain (in the hypothalamus and the pituitary gland) that influence the other endocrine glands.

1.3 The importance of water in the body

About 60% of the body is water, the special properties of which are uniquely suited to life. Of this fluid, some 67% is in the cells (intracellular fluid, ICF) and 33% is extracellular (ECF). The ICF is high in K⁺, the positive charge of which largely balances the negative charges of organic solutes. The ECF ...

Table of contents

• Cover
• Table of Contents
• Contributors
• Preface
• List of Abbreviations
• Chapter 1: Cell Physiology
• Chapter 2: Cellular Communication
• Chapter 3: Introduction to the Nervous System
• Chapter 4: Signalling in the Nervous System
• Chapter 5: Muscle
• Chapter 6: Sensory Systems
• Chapter 7: Special Senses
• Chapter 8: Motor System
• Chapter 9: Higher Nervous Functions
• Chapter 10: Pain
• Chapter 11: Endocrine System
• Chapter 12: Reproduction
• Chapter 13: Blood
• Chapter 14: Introduction to the Cardiovascular System
• Chapter 15: Cardiovascular System—The Heart
• Chapter 16: Vascular System
• Chapter 17: Cardiovascular Regulation, Regional Circulation and Circulatory Adjustments
• Chapter 18: Respiration
• Chapter 19: Digestive System
• Chapter 20: Kidney
• Chapter 21: Fluid and Electrolyte Balance
• Chapter 22: Energy Metabolism
• Chapter 23: Temperature Regulation
• Chapter 24: Exercise
• Appendix 1: Units of measurement
• Appendix 2: Basic Concepts of Acid–Base Chemistry
• Index
• End User License Agreement