Anatomy and Physiology of Farm Animals

Anna Dee Fails, DVM, PhD, is an Assistant Professor in the Department of Biomedical Sciences at Colorado State University in Fort Collins, Colorado, USA.

Christianne Magee, DVM, PhD, Dip ACT, is an Assistant Professor in the Department of Biomedical Sciences at Colorado State University in Fort Collins, Colorado, USA.

Dedication xii

About the Companion Website xiii

Chapter 1: Introduction to Anatomy and Physiology 1

Anatomical Nomenclature, Directional Terms, and Planes of Section 3

Microscopic Anatomy: Animal Cells and Tissues 5

Epithelial Tissues 6

Connective Tissues 11

Muscle Tissue 13

Nervous Tissue 15

The General Plan of the Animal Body 15

Chapter 2: Anatomy and Physiology of the Cell 21

Properties of Life 22

Chemical Composition of the Cell 24

Water 24

Proteins 25

Lipids 26

Carbohydrates 28

Inorganic Substances 29

Acids, Bases, and pH 29

Microscopic Study of the Cell 29

Light Microscopy 30

Electron Microscopy 32

The Cell Membrane 33

Structure of the Membrane 33

Intercellular Contact and Adhesion 35

Transport Across Cell Membranes 36

Simple and Facilitated Diffusion 36

Osmosis 38

Active Transport 40

Membrane Potentials and Excitable Cells 41

Resting Membrane Potential 41

Excitable Cells and Action Potentials 42

Membrane Receptors and Intracellular Signaling 43

Cytoplasm and Cytoplasmic Organelles 47

Cytoplasm 47

The Golgi Apparatus 47

The Endoplasmic Reticulum and Ribosomes 47

Mitochondria 47

Lysosomes 48

Other Structures 48

Nucleus 49

Structure of the Nucleus 49

DNA and DNA Replication 50

RNA: Transcription and Translation 51

Biotechnology 53

Cell Division 55

Mitosis 55

Meiosis 56

Regulation of Cell Growth and Replication 57

Chapter 3: Embryology 59

Development of Germ Layers 60

Principles of Differentiation 63

Neurulation 63

Mesodermal Differentiation 64

Teratogenesis 66

Chapter 4: The Skeletal System 69

Functions of Bones 70

Terminology 70

Classification of Bones According to Gross Appearance 73

Axial Skeleton 75

Skull 75

Vertebral Column 79

Sternum and Ribs 82

Appendicular Skeleton 83

Thoracic Limbs 83

Pelvic Limbs 87

Chapter 5: Microscopic Anatomy and Growth and Development of Bone 91

Microscopic Anatomy and Formation of Bone 92

Ossification 94

Endochondral (Intracartilaginous) Ossification 94

Intramembranous Ossification 96

Physiology of Bone 96

Bone Mechanics and Remodeling 96

Calcium of Bone 97

Fractures and Fracture Healing 97

Other Pathologic Conditions 99

Chapter 6 Joints 101

Classification of Joints 102

Fibrous Joints 102

Cartilaginous Joints 103

Synovial Joints 103

Other Synovial Structures 104

Movements of Joints 104

Types of Synovial Joints 106

Joints of the Axial Skeleton 107

Joints of the Appendicular Skeleton 108

Joints of the Thoracic Limb 108

Joints of the Pelvic Limb 111

Pathology of Joints and Related Structures 117

Chapter 7 Anatomy of the Muscular System 121

Anatomical Nomenclature of Muscles 122

Types of Muscle Tissue 122

Skeletal Muscle Organization 122

Muscle Attachments 123

Functional Grouping of Muscles 124

Synovial Structures 126

Muscles of the Thoracic Limb 127

Extrinsic Muscles of the Thoracic Limb 130

Muscles Acting on the Shoulder Joint 131

Muscles Acting on the Elbow 132

Muscles Acting on the Distal Limb 133

Muscles of the Pelvic Limb 135

Muscles Acting on the Hip Joint 135

Muscles Acting on the Stifle 141

Muscles Acting on the Hock 142

Muscles Acting on the Digit 142

Muscles of the Head 143

Muscles of Mastication 143

Muscles of Facial Expression 144

Other Muscles of the Head 144

Muscles of the Trunk and Neck 145

Extensors of the Vertebral Column 145

Flexors of the Vertebral Column 150

Abdominal Muscles 150

Muscles of Respiration 151

Chapter 8: The Equine Foot and Passive Stay Apparatus 153

Structure of the Foot 154

Bones and Cartilages 154

Cornified Tissues 155

Tendons 159

Ligaments 160

Synovial Structures 162

Function 163

Concussion and Storage of Energy 163

Stay Apparatus 163

Thoracic Limb 164

Pelvic Limb 166

Chapter 9: Microscopic Anatomy and Physiology of Muscle 171

Skeletal Muscle 172

Structure 172

Excitation, Contraction, and Relaxation 175

Strength of Contraction 179

Drugs That Affect Skeletal Muscle Function 181

Types of Muscle Contraction 182

Smooth Muscle 182

Structure 183

Stress–Relaxation 183

Contraction and Relaxation 184

Role and Sources of Calcium 184

Action Potentials and Slow Waves 185

Autonomic Innervation 186

Cardiac Muscle 187

Excitation and Contraction 187

Cardiac Hypertrophy 188

Chapter 10: Anatomy of the Nervous System 189

Microscopic Neuroanatomy 192

Embryology 194

Central Nervous System 197

Brain 197

Meninges 200

Spinal Cord 202

Peripheral Nervous System 205

Spinal Nerves 205

Cranial Nerves 206

Autonomic Nervous System 206

Sympathetic Nervous System 208

Parasympathetic Nervous System 211

Enteric Nervous System 212

Chapter 11:Physiology of the Nervous System 213

Functional Regions of the Neuron 214

Physiology of the Nerve Impulse 214

Conduction Velocity and Myelination 216

Synaptic Transmission 217

Neurotransmitters 220

Neural Control of Skeletal Muscle 221

Reflexes Involving Skeletal Muscle Contraction 222

Voluntary Movement 223

Physiology of the Autonomic Nervous System 224

Regulation of Autonomic Nervous System Activity 224

Autonomic Neurotransmitters and Their Receptors 226

Regeneration and Repair in the Nervous System 227

Chapter 12: Sense Organs 229

Sensory Receptors 230

Somatosensation 232

Pain 232

Proprioception 233

Touch 234

Visceral Sensations 234

Chemical Senses 234

Gustation 234

Olfaction 235

Hearing and Balance 236

External Ear 236

Middle Ear 238

Internal Ear 238

Physiology of Hearing 239

Mechanisms of Balance 242

Vision 245

Ocular Adnexa 245

Globe 247

Lens 250

Visual Field and Light Path 251

Visual Pathways of the Brain 251

Chapter 13: Endocrinology 253

Hormones and Their Receptors 254

Chemical Classes of Hormones 254

Eicosanoids 255

Hormone Receptors 256

Cellular Effects of Peptide

Hormones 256

Cellular Effects of Steroid and Thyroid Hormones 259

Negative and Positive Feedback Regulation 259

Hypothalamopituitary Axis 260

Hormones of the Neurohypophysis 262

Hormones of the Adenohypophysis 263

Growth Hormone 263

Adrenocorticotropic Hormone 264

Thyroid‐Stimulating Hormone 265

Other Endocrine Glands 268

Parathyroid Glands 268

Pancreatic Islets 270

Epiphysis (Pineal Gland) 271

Chapter 14: The Integument 273

Integument 274

Skin 274

Epidermis 274

Dermis 275

Hypodermis 276

Adnexa of the Skin 276

Hair 276

Glands 278

Modified Epidermis 279

Hooves 280

Horns 282

Dewclaws 283

Chestnuts and Ergots 283

Coat Color in Horses 283

Wool 285

Chapter 15: Blood and Other Body Fluids 287

Blood 288

Formed Elements of Blood and Hematopoiesis 289

Erythrocytes 290

Platelets 293

Leukocytes 294

Plasma and Serum 295

Blood pH 296

Hemostasis and Coagulation 296

Platelets and the Endothelium 297

Intrinsic and Extrinsic Coagulation Pathways 297

Lymph 300

Serous Fluids 300

Chapter 16: Body Defenses and the Immune System 301

Nonspecific Defenses 302

Specific Immune Response 304

B Lymphocytes 304

Immunoglobulins 305

T Cells and Cell‐Mediated Immunity 306

Lymphocyte Origin, Development, and Residence 308

Active and Passive Immunities 308

Immunological Surveillance 308

Lymphatic System 309

Lymphatic Vessels 309

Lymph Nodes 309

Spleen 312

Thymus 313

Tonsils 314

Chapter 17: Anatomy of the Cardiovascular System 315

Heart 316

Pericardium 316

Cardiac Anatomy 317

Vessels 320

Blood Vessels 320

Lymphatic Vessels 320

Pulmonary Circulation 320

Systemic Circulation 321

Aorta 322

Arterial Distribution to the Head 323

Arterial Distribution to the

Thoracic Limb 323

Arterial Distribution to the Pelvic Limb 324

Veins 325

Cranial Vena Cava 326

Caudal Vena Cava 327

Portal System 327

Fetal Circulation 327

Chapter 18: Physiology of the Heart and

Circulation 331

Basic Design and Function of the Cardiovascular System 332

Cardiac Cycle 333

Systole 336

Diastole 336

Heart Sounds and Murmurs 336

Imaging the Heart 337

Electrical Activity of the Heart 337

Sinoatrial Node and Heart Rate 337

Atrioventricular Node and Other Specialized Conductive Cells in the Heart 339

Electrocardiography and Arrhythmias 339

Cardiac Output and Its Regulation 340

Ventricular Filling and Stroke Volume 340

Cardiac Contractility and Stroke Volume 341

Structure and Function of Blood Vessels 341

Microscopic Structure of Blood Vessels 341

Function of Blood Vessels 342

Regulation of Arterial Blood Pressure and Blood Volume 344

Neural Reflexes 345

Humoral Agents 345

Paracrine Agents 346

Cardiovascular Function During Exercise and Hypovolemia 346

Chapter 19 The Respiratory System 349

Upper Respiratory Tract 350

Nose 350

Paranasal Sinuses 352

Pharynx 354

Larynx 354

Trachea and Bronchi 357

Thorax 357

Lungs 358

Pleura 360

Physiology of Respiration 360

Ventilation 360

Gas Exchange 363

Gas Transport in Blood 365

Control of Ventilation 366

Chapter 20: Anatomy of the Digestive System 369

Organization of the Digestive System 370

Mouth 371

Teeth 372

Tongue 377

Pharynx 378

Tonsils 378

Esophagus 380

Simple Stomach 380

Ruminant Stomach 381

Ruminoreticulum 384

Omasum 385

Abomasum 385

Small Intestine 385

Large Intestine 387

Ruminants 387

Pig 387

Horse 388

Peritoneal Features 388

Accessory Digestive Organs 389

Salivary Glands 389

Pancreas 389

Liver 391

Chapter 21: Physiology of Digestion 395

Pregastric Physiology 397

Prehension and Chewing 397

Saliva and Salivary Glands 397

Swallowing 398

Ruminant Forestomach 398

Fermentative Digestion 398

Forestomach Motility 400

Reticular, or Esophageal, Groove 400

Omasum 401

Gastric Physiology 401

Gastric Glands and Secretions 401

Gastric Motility 402

Physiology of the Small Intestine, Exocrine Pancreas, and Liver 403

Small Intestine Secretions and Motility 403

Exocrine Pancreas 404

Liver Digestive Function and Secretion of Bile 406

Nutrient Absorption in the Small Intestine 407

Physiology of the Cecum and Colon 409

Cecum and Colon of the Horse 410

Rectum and Defecation 410

Neuroendocrine Control of Feeding 411

Chapter 22: Nutrition and Metabolism 413

Nutrition 414

Metabolism 414

Absorptive State: Anabolism 415

Postabsorptive State: Catabolism 417

Energy Needs During Exercise 418

Blood Glucose in Ruminants 419

Ketosis 419

Chapter 23: The Urinary System 421

Anatomy of the Kidney 422

Blood and Nerve Supply 424

Ureters, Urinary Bladder, and Urethra 424

Micturition 426

Overview of Function and Histology

of the Kidneys 426

Glomerular Filtration 429

Proximal Tubule Transport 430

Concentration and Dilution of Urine: Role of the Loop of Henle and Collecting Duct Transport 431

Sodium Chloride and Water Reabsorption by the Loop of Henle 432

Collecting Duct Transport and Antidiuretic Hormone 433

Osmotic Regulation of Antidiuretic

Hormone 434

Polyuria and Polydipsia 434

Sodium, Potassium, and Aldosterone 434

Urine Acidification 436

Regulation of Acid‐Base Balance 436

Extracellular and Intracellular Buffers 436

Classification of Alkalosis and Acidosis and Compensation 438

Chapter 24: Anatomy of the Male Reproductive System 441

Testis 442

Epididymis 444

Ductus Deferens 444

Scrotum 445

Inguinal Canal 447

Descent of the Testis 447

Castration 449

Accessory Sex Glands 449

Ampullae 450

Vesicular Glands 450

Prostate Gland 450

Bulbourethral Glands 451

Penis 451

Prepuce 453

Muscles of the Male Genitalia 453

Blood and Nerve Supply of the Male Genitalia 453

Chapter 25: Physiology of Male Reproduction 455

Seminiferous Tubules and Spermatogenesis 456

Seminiferous Tubules 456

Germ Cells and Spermatogenesis 457

Spermatozoa Morphology

and Spermatogenesis 457

Rates and Timing of Spermatogenesis 460

Epididymis 460

Semen and Semen Technology 461

Hormones of Male Reproduction 462

Endocrine Regulation of Testicular Function 462

Testosterone and Its Effects 463

Erection and Ejaculation 463

Chapter 26: Anatomy of the Female Reproductive System 465

Ovaries 466

Uterine Tubes 468

Uterus 469

Vagina 471

Vestibule and Vulva 472

Blood and Nerve Supply of the Female Reproductive Tract 473

Chapter 27: The Ovary and Estrous Cycles 475

Oogenesis 476

Secondary Follicles 476

Hormones and Follicular Development 477

Ovulation 481

Luteinizing Hormone Surge 481

Spontaneous and Reflex Ovulators 481

Seasonal Transition 481

Corpus Luteum 482

Phases of the Estrous Cycle 483

Proestrus 484

Estrus 484

Metestrus 484

Diestrus and Anestrus 484

Puberty 484

Specifics of Selected Estrous Cycles 485

Mare 485

Cow 485

Ewe 486

Sow 487

Chapter 28:Pregnancy and Parturition 489

Fertilization 490

Spermatozoa Transport and Viability 490

Gamete Fusion and Early Embryonic Development 491

Implantation and Placentation 493

Hormones of Pregnancy 496

Progesterone 496

Equine Chorionic Gonadotrophin 497

Relaxin 497

Pregnancy Diagnosis 497

Parturition 498

Late Gestation 498

Initiation of Parturition 498

Oxytocin 499

Fetal Presentations and Delivery 499

Dystocia 500

Chapter 29: Anatomy and Physiology of the Mammary Glands 501

Mammary Glands of the Cow 502

Suspensory Apparatus 504

Blood Supply 504

Lymphatic Vessels 506

Microscopic Anatomy of the Mammary Gland 506

Mammary Glands of Sheep and Goats 508

Mammary Glands of Swine 508

Mammary Glands of the Horse 509

Physiology of Lactation 509

Composition of Milk 509

Milk Secretion 510

Lactogenesis 511

Galactogenesis 512

Milk Ejection or Letdown 513

Colostrum 514

Cessation of Lactation 515

Chapter 30: Poultry 517

Integument 518

Body Design 520

Skeleton and Bone 522

Musculature 524

Gastrointestinal System 524

Respiratory System 527

Ventilation and Gas Exchange 528

Cardiovascular System 530

Lymphatic System 531

Urinary System 531

Female Reproductive System 534

Egg Formation and Oviposition 535

Male Reproductive System 537

Sex Chromosomes 538

Reproduction and Photoperiods 538

Appendix: Abbreviations 539

Bibliography 545

Index 547