Cardiovascular system:

• Pericardium = serous membrane creates a closed cavity (pericardial space) with limited fluid to allow frictionless movement of the heart.
• 2 layer of the pericardium = visceral - inner layer that's adhered to the outer heart and parietal - continuous to the visceral layer at the heart base and reinforced by the fibrous pericardium.
• Pericardial sac = parietal pericardium, fibrous pericardium and mediastinal pleura which is thin but tough tissue surrounding the heart.
• 3 layers of the heart = epicardium - outer/serous, endocardium - thin/endothelial and myocardium - thick/muscular.
• Auricle = atria appendages.
• Conus arteriosus = funnel shape as the right ventricle wraps around the cranial side of the heart.
• Capillaries are made of simple squamous epithelium.
• Lymphatic vessels resemble veins with many valves and are emptied into the vena cava.
• Tracheal trunks = 2 large lymph vessels draining the head and neck.
• Thoracic duct = lymph from the caudal body half empties into the vena cava.
• Lymph nodes = filter lymph.
• Blood supply to the thoracic limbs is via the subclavian arteries and costocervical trunks.
• Aortic hiatus = opening through the diaphragm.
• Common carotid arteries supply the face, head and cranial neck.
• Inner carotid artery is the primary source to the brain.
• External carotid artery supplies the face, tongue, oral and nasal cavities.
• Saphenous artery = plantar dorsal pedal supply.
• Venipuncture = needle into the vein.
• Portal system = vessel divides into a capillary bed, recombines to form another vessel and then redivides into a 2nd capillary bed.
• The heart is located between 2nd-6th ribs just behind the elbow.
• Sinus node = pacemaker.
• Systole = contraction phase.
• Diastole = relaxation phase.
• Maximal HR = 250 beats.
• Stroke volume = 1-1.5 litres of blood.
• Cardiac output = rest - 30-50 litres and maximal - 300 litres.
• Endothelium = thin, inner blood vessel layer.
• Coronary vessels = blood vessels supplying the heart which branch off the aorta.
• The pulmonary artery is the only artery to carry de-oxygenated blood.
• Blood pressure = (standing horse) 120/70 mmHg.
• Blood pressure is regulated by = cardiac output, blood volume and blood vessel diameter.
• Circulatory shock = sudden, dramatic decrease in bp caused by a reduction in the volume of circulating blood/vasodilation.
• Circulatory health checks = assess pulse, assess mucous membrane colours, assess capillary refill, assess bp and assess jugular vein.
• Ductus thoracicus = main thoracic lymph duct.
• Haematocrit = percentage of cellular components of blood as a proportion of the overall volume.
• Haematocrit = 32-46% at rest and 60+% during exercise.
• Blood volume = 7-8% of body weight, a 500kg horse has around 35-40 litres.
• 1 ml of blood contains 6.5-10.5 thousand million erythrocytes and 5-11 million leucytes/WBCs.
• Granulocytes = neutrophils, basophils and eosinophils.
• Coagulation = blood clotting.