Equine Science

Preface xxiii Acknowledgement xxv 1 The Biochemical Nature of Cells 1 Metabolism 1 Water 1 Important Properties ofWater 4 Proteins 4 Basic Structure of Amino Acids 4 Polypeptides 5 Levels of Protein Structure 5 Primary Structure of Proteins (Amino Acid Sequence) 6 Secondary Structure of Proteins (Alpha Helix or Beta Pleated Sheet) 6 Tertiary Structure of Proteins (3D Shape/Folding) 7 Quaternary Structure of Proteins (Aggregations of Polypeptide Chains) 7 Classification of Proteins 7 Structure of Collagen 8 Modification of Proteins 8 Denaturation of Proteins 8 Carbohydrates 8 Fructans 9 Starch 10 Cellulose 11 Glycogen 11 Lipids/Fats 11 Triglycerides 12 Essential Fatty Acids 12 Phospholipids 13 Cholesterol 15 Nucleic Acids 15 Deoxyribonucleic Acid (DNA) 15 Ribonucleic Acid (RNA) 16 Messenger RNA (mRNA) 17 Transfer RNA (tRNA) 18 Ribosomal RNA (rRNA) 18 Protein Synthesis 18 Transcription 18 Translation 20 The Genetic Code 21 Reading the Genetic Code 23 Enzymes 23 Factors that Affect the Activity of Enzymes 25 Temperature 25 pH 25 Enzyme Concentration 25 Substrate Concentration 25 Cofactors and Coenzymes 25 Enzyme Inhibitors 25 Metabolic Poisons 26 Drugs 26 Summary Points 26 Q + A 27 2 Cells, Tissues and Organs 29 Cells Building Blocks of Life 29 Prokaryotic Cells 29 Eukaryotic Cells 31 Cell Function 31 Cytoplasm 32 Cytosol 32 Movement of Substances in and around Cells 32 Cell Organelles 32 Cytoskeleton 32 Cell or Plasma Membrane 33 The Fluid Mosaic Model of Cell Membrane Structure 34 The Role of Membranes in Cell Organelles 34 Nucleus 37 Endoplasmic Reticulum and Ribosomes 38 Golgi Body (Dictyosome) 38 Mitochondria 38 Lysosomes 38 Peroxisomes (Microbodies) 39 Centrosomes 39 Apoptosis (Programmed Cell Death) 39 Cell Turnover 40 Cell Division (Mitosis and Meiosis) 40 The Cell Cycle 40 Mitosis 41 Key Events 41 Cytokinesis or Cytoplasmic Division 43 Meiosis 44 Key Events 45 First Meiotic Division 46 Second Meiotic Division 46 Cell Signalling 46 Cell Differentiation and Stem Cells 46 Blood Cell Production from Stem Cells 47 Tissues and Organs 47 Epithelium/Epithelial Tissue 48 Epithelial Cell Shapes 50 Epithelial Arrangement of Cells 50 Connective Tissue 51 Connective Tissue Cells 52 Connective Tissue Fibres 52 Tissue Repair 53 The Four Stages ofWound Healing 54 Stage 1 Traumatic Inflammatory Phase 54 Stage 2 Destructive Phase (0 3 Days) 54 Stage 3 Proliferative Phase (3 24 Days) 55 Stage 4 Maturation Phase (24 Days to 2 Years) 56 Ageing Tissue 56 Stem Cell Therapy 56 Summary Points 57 Q + A 58 3 Equine Support and Movement 59 Points of the Horse 59 The Skeletal System 59 Bone 59 Classification of Bone Tissue 60 Dense or Compact Bone 60 Spongy or Cancellous Bone 61 Types of Bones 61 Microscopic Bone Structure 64 Bone Formation and Growth 64 Developmental Orthopaedic Disease 67 Bone Remodelling 68 Hormones and their Effect on Bone Growth 68 Effect of Exercise on Bone Tissue 69 Calcium Homeostasis 69 Bone Fracture and Repair 69 The Skeleton 70 The Axial Skeleton 70 The Skull 70 The Vertebral Column or Spine 71 The Appendicular Skeleton 75 Forelimb 76 Hindlimb 79 Stay Apparatus 80 The Mechanics of Movement 80 Joints 80 Types of Joints 81 Movement of Joints 83 Ageing of Joints 83 Muscles 83 CardiacMuscle 84 Smooth Muscle 84 Skeletal Muscle (Voluntary or Striated Muscle) 85 The Sliding FilamentModel 87 Muscle Anatomy 87 Muscles of the Neck and Shoulder 91 Brachiocephalic 91 Sternocephalic 91 Splenius 91 Trapezius 91 Rhomboideus 95 Deltoideus 95 Triceps 95 Muscles of the Trunk 95 Latissimus Dorsi 95 Pectorals 95 Muscles of the Forearm 95 Digital Extensor 95 Digital Flexor 95 Muscles of the Abdomen 97 Intercostal Muscles 97 Longissimus Dorsi 97 Muscles of the Hindlimb 97 Gluteal 97 Biceps Femoris 97 Semitendinosus 97 Digital Extensor 97 Gastrocnemius 99 The Importance of Muscle Fibres in Equine Performance 99 Muscle Fibre Types 99 Muscle Fibre Recruitment 100 Fatigue 101 Causes of Fatigue 101 Lactic Acid Accumulation 101 Summary Points 101 Q + A 101 4 TheLowerLimb 103 Tendons and Ligaments of the Lower Limb 103 Tendons 103 Tendon Repair 104 Extensor Tendons 106 Flexor Tendons 106 Ligaments and Suspensory Apparatus 106 Check Ligament 106 Suspensory Ligament 106 Blood Supply to the Lower Leg 107 The Hoof 107 The Hoof as a Plastic Structure 107 Effect of Movement on Hoof Structure 111 Functions of the Hoof 112 Shock Absorption 112 Grip 112 Circulation 113 The External Hoof 113 Wall 113 Sole 116 Frog 116 Hoof Horn 118 Internal Structures 118 Digital or Plantar Cushion 118 Lateral (Ungual) Cartilages 119 Pedal and Navicular Bones 119 The Balanced Foot 119 Assessment of Foot Balance 119 Static Foot Balance 119 Dynamic Foot Balance 120 Adaptations of Hoof Tissue 121 Summary Points 121 Q + A 122 5 The Digestive System 123 Foregut 124 Mouth 124 Oesophagus 127 Stomach 127 Gastric Juice 128 Small Intestine 130 Pancreas 132 Endocrine Functions of the Pancreas 132 Exocrine Functions of the Pancreas 133 Liver 134 Functions of the Liver 135 Hindgut 137 Large Intestine 137 Caecum 137 Large Colon 137 Small Colon 140 Rectum 140 Digestion in the Large Intestine 140 Equine Microbiota 140 The Gut and the Immune System 142 Summary Points 142 Q + A 143 6 The Respiratory System 145 Anatomy 146 Within the Head and Neck 146 Within the Chest 148 Blood Supply 149 Pleurae 149 Diaphragm 150 Physiology of Respiration 150 Pulmonary Ventilation 150 Pressure Changes during Breathing 151 Airway Resistance 151 Lung Air Volumes and Capacities 151 Dead Space 153 Regulation of Breathing 153 Respiratory Locomotor Coupling 154 External Respiration or Pulmonary Gas Exchange 155 Internal Respiration or Systemic Gas Exchange 156 Transport of Oxygen and Carbon Dioxide Around the Body 157 Oxygen Transport 157 Carbon Dioxide Transport 157 The Oxygen Dissociation Curve 158 The Bohr Effect 158 Cellular Respiration 159 Aerobic Cellular Respiration 159 Aerobic Respiration of Glucose 161 Glycolysis 161 Link Reaction 161 Krebs Cycle 163 Electron Transport Chain 163 Aerobic Respiration of Other Fuels 166 Glycogen 166 LipidMetabolism 166 Protein Metabolism 167 Anaerobic Respiration 167 Summary Points 167 Q + A 168 7 The Circulatory System 169 Foetal Circulation 170 The Heart 171 Cardiac Output 172 Anatomy of the Heart 173 The Cardiac Cycle 175 Regulation of the Heart Beat 175 The Heart and Fittening/Training Horses 176 The Heart and VO2 Max 178 Heart Murmurs 178 Heart or Cardiac Arrhythmia 178 Second-Degree AV Block 179 Atrial Fibrillation (AF) 179 Sudden Cardiac Death 179 Blood Vessels 179 Arteries 179 Veins 180 Capillaries 182 Heart Evaluation and Examination 182 Electrocardiogram 182 Exercise Testing of Horses 183 Blood 184 Plasma 184 Red Blood Cells (Erythrocytes) 185 White Blood Cells (Leucocytes) 186 Granulocytes 188 Agranulocytes 189 Platelets (Thrombocytes) 190 Haemostasis or Blood Clotting 190 Blood Tests 191 Blood Typing 191 The Lymphatic or Lymph System 192 The Spleen 193 Summary Points 194 Q + A 194 8 The Nervous System 197 Nerves and Neurons 198 Neuroglia or Glial Cells 200 Organisation of the Nervous System 202 CNS 202 PNS 203 Action Potential 203 Resting Membrane Potential 204 Synapses 206 Transmission at the Synapse 207 Neurotransmitters 208 Endorphins and Enkephalins 208 Neuromuscular Junctions 209 The Brain 209 Forebrain 210 Hypothalamus 210 Thalamus 210 Cerebrum 210 Midbrain 210 Hindbrain 210 Spinal Cord 212 Reflex Actions or Arcs 212 Summary Points 212 Q + A 213 9 The Endocrine System 215 Hypothalamus 216 Pituitary Gland (Hypophysis) 217 Anterior Pituitary Adenophysis 217 Pars Intermedia 218 Posterior Pituitary (Neurophysis) 218 Thyroid Gland 219 Thyroid Hormones 219 Parathyroid Glands 219 Adrenal Glands 220 Adrenal Cortex 221 Mineralocorticoids 221 Glucocorticoids 222 Adrenal Medulla 222 Pancreas 222 Secretion of Glucagon and Insulin 224 Thymus 225 Ovaries 225 Equine Chorionic Gonadotropin 226 Testes 226 Pineal Gland 227 The Neuroendocrine System 2