Introduction to Animal and Veterinary Anatomy and Physiology

Victoria Aspinall, Melanie Cappello

• Editore: CAB International
• Anno: 2019
• ISBN:
  9781789241174
• Edizione: 4
• Argomento: Medicine
• Categoria: Veterinary Medicine

A sound knowledge of anatomy and physiology is an essential basis for the effective clinical treatment of companion animals and farm animals alike. The fourth edition of this bestselling book continues to provide a comprehensive description of the anatomy and physiology of dogs and cats. The book builds on these foundations with detailed descriptions of exotic small species including birds, and domestic farm animals, including cows, sheep and pigs, as well as the horse. The text: Contains detailed descriptions of the systematic anatomy and physiology of a wide range of animal species.Covers clinical conditions and disease examples related to the individual body systems.Includes applied anatomy tips that relate theory to clinical practice.Is written by expert authors with a wealth of veterinary, animal science and teaching experience.Includes more clinical application examples and question and answer tests to reinforce student learning.Has been updated with more information for animal science students.This text provides an essential basis for all those embarking upon a veterinary, animal science or animal management career.

SECTION 1
The dog and cat

1 Principles of cell biology 3

2 Tissues and body cavities 17

3 Skeletal system 31

4 Muscular system 47

5 Nervous system and special senses 55

6 Endocrine system 73

7 Blood vascular system 79

8 Respiratory system 93

9 Digestive system 103

10 Urinary system 117

11 Reproductive system 127

12 Common integument 149

This section describes the anatomy and physiology of the two most common species treated in small animal veterinary practice: the dog and cat. Following an introduction to cell biology, each body system is covered separately.

CHAPTER
1

Principles of cell biology

KEY POINTS

• All living organisms can be classified into different orders, classes and families linked by certain common characteristics. These groups can be further divided into a genus and species, which describes an individual type of organism.

• The body is made up of a number of systems, each of which has a specific function. These systems form the structural framework of the body or lie within one of the three body cavities.

• Each system consists of a collection of tissues and organs, which are composed of the smallest units of the body – the cells.

• Cells can only be seen under the microscope and all have a basic structure with certain anatomical differences, which adapt them to their specific function within the body.

• Each structure within the cell plays a vital part in the normal function of the cell and therefore in the normal function of the body system that the cell is found in.

• Cells grow and divide by means of mitosis. Each mitotic division results in the production of two identical daughter cells containing the diploid (or normal) number of chromosomes.

• The healthy body contains 60–70% water, distributed into two principal fluid compartments – the extracellular fluid (ECF - surrounding the cells) and the intracellular fluid (ICF - within the cells).

• Body fluids move between these compartments and this movement is controlled by the chemical constituents of the fluid and the physical processes of diffusion and osmosis.

• Body fluids contain inorganic and organic compounds. The structure and percentage of all of these is fundamental to the balance and normal function of the body. Within the body there are many systems involved in maintaining a state of equilibrium – this is known as homeostasis.

‘Anatomy’ and ‘physiology’ are scientific terms used to describe the study of the structure of the body (anatomy) and how the body actually ‘works’ (physiology). In this section, we will study the anatomy and physiology of the dog and cat. In Section 2, we describe the comparative anatomy and physiology of the horse, the most common farm animals and some of the most commonly kept exotic species. We start by looking at the basic unit of the body – the cell – and then work our way through the tissues, organs and systems until the picture is complete.

Animal classification

When studying any aspect of biology it is important to have a basic understanding of the classification system used to group animals. How the species that one may meet in a veterinary practice fit into this classification system should also be understood. Classification is the way in which we ‘sort’ species into orderly groups, depending on how closely they are related in terms of their evolution, structure and behaviour. The science of classification is known as taxonomy.

If organisms have certain basic features in common they are grouped together into a kingdom. For example, if an organism is composed of more than one cell (i.e., it is multicellular) and obtains its food by ingestion, it is placed in the animal kingdom. Other kingdoms include plants and fungi. The animal kingdom is then further subdivided, based upon similarities of organisms, into a hierarchical system (Table 1.1). This narrows the classification down until we eventually reach a particular genus and species. Most living organisms are identified by a genus and species – a method known as the binomial system, invented by the Swedish scientist Carl Linnaeus.

Table 1.1. Classification of the domestic dog and cat

Taxonomic group	Dog	Cat
Kingdom	Animal	Animal
Phylum	Chordata (vertebrate)	Chordata (vertebrate)
Class	Mammalia (mammal)	Mammalia (mammal)
Order	Carnivora	Carnivora
Family	Canidae	Felidae
Genus	Canis	Felis
Species	familiaris	catus
Common name	Domestic dog	Domestic cat

All the species within the animal kingdom are divided into those with backbones – the vertebrates – and those that do not have backbones – the invertebrates (e.g., insects, worms, etc.). The vertebrates are divided into eight classes. The classes that are of the most veterinary importance are:

• Amphibia – approximately 3080 species

• Reptilia – approximately 6600 species

• Aves or birds – approximately 8500 species

• Fish – approximately 30,000 species

• Mammalia – approximately 4070 species.

These classes are then further divided into orders, and so on, until a species is identified, as in Table 1.1.

Most of this section of the book concerns the mammals, because the majority of animals seen in veterinary practice will be from this class. The distinctive features of mammals are the production of milk by the mammary glands and the possession of hair as a body covering. Examples of mammalian orders include:

• Insectivores (e.g., shrews, moles)

• Rodents (e.g., mice, rats)

• Lagomorphs (e.g., rabbits, hares)

• Carnivores (e.g., cats, dogs, bears, seals)

• Ungulates (e.g., cows, sheep, horses)

• Cetaceans (e.g., whales, dolphins)

• Primates (e.g., monkeys, apes)

Generally speaking, all mammals have a similar basic structural plan in terms of anatomy and physiology, but each species has been modified to suit its specific lifestyle. In other words, mammals have become specialised for activities such as running, digging, gnawing, jumping and eating specific foods.

Anatomical definitions

When studying anatomy and physiology it is important to understand the terms that are used to describe where structures lie in relation to one another. These are illustrated in Fig. 1.1 and named as follows:

• Median plane – divides the body longitudinally into symmetrical right and left halves; can be described as ‘the line down the middle of the animal’ from nose to tail

• Superficial – near to the surface of the body

• Deep – closer to the centre of the body

• Cranial/anterior – towards the front of the animal (i.e., towards the head)

• Caudal/posterior – towards the rear end or tail of the animal (i.e., away from the head)

• Medial – structures that lie towards or near the median plane (i.e., closer to the middle of the animal)

• Lateral – structures that lie towards the side of the animal (i.e., away from the median plane)

• Dorsal – towards or near the back or vertebral column of the animal and the corresponding surfaces of the he...