Session 1 Flashcards
Describe the critical importance of adequate blood flow for the maintenance of capillary exchange
Unless blood is supplied at an appropriate rate, the gradients driving exchange will dissipate and nutrients will not be supplied at the right rate.
The supply of nutrient to a tissue depends most critically on maintaining the right flow of blood for the prevailing metabolic activity.
Describe the factors influencing the exchange of substances between the blood in capillaries and the surrounding tissues
Diffusion is affected by the area available (capillary density), diffusion resistance and gradient.
State the normal cardiac output for an average adult male at rest and during exercise
Deliver 5 - 25 l/min to the body.
0.75 l/min to the brain.
Maintain flow to heart and kidney at all times.
Explain why blood flow changes in some organs and remains constant in others
Organs such as the brain, heart and kidneys require a constant flow to perform their function.
Organs such as gut and liver can tolerate short term flow reduction.
Describe the distribution of cardiac output over major organs of the body, at rest
Brain - 750 ml Heart - 300 ml Kidneys - 1200 ml Gut/liver - 1400 ml Skin - 200 ml Rest of body - 200 ml
Describe the major components of the circulation and explain their function
Pump - heart
Distribution vessels - arteries
Flow control - resistance vessels e.g. arterioles, pre capillary sphincters
Capacitance - veins store blood
Describe the distribution of blood volume over the major parts of the circulation
Veins - 67%
Heart and lungs - 17%
Arteries and arterioles - 11%
Capillaries - 5%
Describe the position of the heart in situ and indicate the surface anatomy of the heart on a subject
The heart lies in the middle mediastinum (thoracic cavity between the right and left pleural cavities)
Describe the structure and function of the pericardium and its relationship with the phrenic nerves
The pericardium is a fibroserous, fluid filled sack that surrounds the muscular body of the heart.
It has two layers - tough, fibrous outside and a thin, serous inside
The serous layer itself has an outside parietal layer and an inside visceral layer.
It is innervated by the phrenic nerve (C3-C5).
Understand the problems associated with pericarditis and the assimilation of fluid in the pericardial sac
Pericarditis - inflammation of the pericardium may be due to infection or MI. Symptoms include chest pain. It may lead to acute cardiac tamponade due to accumulation of fluid.
Cardiac tamponade - an accumulation of fluid in the pericardium leading to increased pressure and compressed heart chambers.
Pneumopericardium - filled with air
Haemopericardium - filled with blood
Describe the major vessels entering and leaving the heart and the course of blood flow through the heart
Pulmonary arteries, pulmonary veins
Aorta –> brachiocephalic trunk, left common carotid, left subclavian –> descending aorta
Inferior vena cava, superior vena cava
Blood flow: pulmonary veins –> left atrium –> left ventricles –> aorta
Vena cavae –> right atrium –> right ventricles –> pulmonary arteries
Describe the blood supply to the heart itself and be able to identify the right and left coronary arteries, their origins and major branches
Left and right coronary arteries arise from the left and right coronary sinuses within the aorta.
The coronary sinuses are small openings within the aorta behind the flaps of the aortic valve. They are filled when the heart relaxes.
Left coronary artery branches to left anterior descending branch, left marginal artery and left circumflex artery.
Right coronary artery branches to right marginal artery and posterior interventricular artery.
Describe the venous drainage of the heart and be able to identify the coronary sinus and great cardiac vein
The great cardiac vein originates at the apex of the heart and follows the anterior interventricular groove into the coronary sulcus and joins the coronary sinus. Other veins that drain into the coronary sinus include the small cardiac vein, middle cardiac vein, left marginal vein and left posterior ventricular vein.
Identify the major arteries and veins in the body
Arteries:
Aorta, brachiocephalic, left common carotid, left subclavian, facial, maxillary, internal carotid, subclavian, axillary, brachial, radial, ulnar
Descending aorta and intercostal branches, abdominal aorta, suprarenal, renal, ovarian/testicular, celiac, superior mesenteric, inferior mesenteric, common iliac, external iliac, internal iliac, femoral, popliteal, anterior and posterior tibial
Veins:
Superior vena cava, internal jugular, external jugular, right and left brachiocephalic, subclavian, cephalic, basilic, median cubital
Inferior vena cava, hepatic, renal, ovarian/testicular, common iliac, external iliac, internal iliac, femoral, long saphenous, short saphenous, popliteal
Describe the structure of cardiac muscle
Myocardium - striated, involuntary, intercalated discs, branching, T tubules run along Z discs, gap junctions
