Cardiovascular system Heart The size of persons fist Less than 500gm in weight. Apex at the level of 5th intercostals space Base is where great vessels emerge, beneath 2nd rib Receive 5% of cardiac output.

Pericardium Serous membrane, formed of two layers Visceral layer: on external surface of the heart. Parietal thick layer, protect heart, anchor it to surrounding structures like diaphragm, reinforced superficially by dense connective tissue Lubricating serous fluid secreted by visceral layer is present pericardial membrane

Is formed by three layers The wall of the heart Is formed by three layers Outer layer epicardium (visceral pericardium) Middle layer myocardium which is thick bundle of cardiac muscle twisted into ring like arrangements It is reinforced internally by dense fibrous connective tissue called skeleton of the heart Deep layer endocardium thin glistening sheet of endothelium enclose the heart and continuous with great vessels in and out

Chambers of the heart Two atria, receiving chambers, thin wall. Two ventricles are discharging chambers, thick wall The left ventricle form the apex The right ventricle form anterior surface. Septum divides heart to RT, lt halves. Interatrial, interventricular septum.

Heart is double pump RT is the pulmonary circuit. It receives oxygen poor blood by superior and inferior vena cava, and pumps it through pulmonary trunk, which divides into RT, lt pulmonary arteries. The four pulmonary veins return blood to the heart.

Aorta: pump blood through systemic circulation to the body. Heart Body Heart A left ventricle is thicker than right ventricles. Atrioventricular valves Tricuspid between RT atrium, and RT ventricle Mitral between lt atrium and ventricle They prevent back flow of blood to atria as they are one way valve,mitral valve have two cusps (bicuspid) Chordae tendineae (heart strings) anchor the heart to wall of ventricles Semilunar valves: guard the arteries which leave the heart

Pulmonary valve: guard pulmonary artery which leave RT ventricle Aortic valve: guard the aortic artery which leave lt ventricle Each valve has three cusps  

Blood supply to the heart The right and left coronary arteries They arise from ascending aorta The right coronary give posterior interventricular, and marginal The left coronary give anterior interventricular and circumflex arteries Angina pectoris Myocardial infarction  

Major arteries of systemic circulation Aorta Arise from the left ventricle. It is the largest artery in the body. Start as the ascending aorta, then continue as aortic arch, curve downward as descending aorta, ends in the diaphragmatic opening by becoming abdominal aorta.

Branches of the thoracic aorta Branches of ascending aorta: Rt and left coronary arteries Branches from aortic arch Brachicephalic, lt common carotid, lt subclavian arteries Brachiocephalic artery divides in to RT common carotid, RT Subclavian arteries behind Rt sternoclavicular joint.

Common carotid artery divides into: External, and internal carotid arteries at level of thyroid cartilage C4 External carotid artery is the artery to the neck, supply face tongue, thyroid. Internal carotid artery supplies the brain.  

Subclavian artery gives vertebral artery to the brain. Continue as axillary artery in axilla, then brachial artery in the arm, divide into radial and ulnar arteries at elbow joint.

Abdominal aorta give Celiac trunk to supply liver, spleen, stomach Superior and inferior mesenteric arteries to large and small bowel RT,and LT renal arteries to kidneys Gonadal arteries to ovaries and testes

Abdominal aorta ends at level of L3-L4 by dividing into RT and lt common iliac arteries. Common iliac artery divides into external and internal iliac arteries. Internal iliac artery supply pelvic organs. External iliac artery continue as femoral artery in thigh, then popliteal artery in back of knee, then divide into anterior and posterior tibial arteries in the leg.

Major veins of systemic circulation Superior vena cava for upper part of the body, head neck, and upper limb Inferior vena cava for lower part of the body, abdomen pelvis and lower limb.

Veins of clinical importance Cephalic, and basilic veins, at lateral and medial aspect of fore arm, median cubital vein at elbow region connect the two; deep to it is the brachial artery. External and internal jugular veins from head and neck Great saphenous vein begins at in front the medial malleolus, and end in femoral vein. Hepatic portal vein drain the digestive system to liver

Circle of Willis Arterial blood supply to the brain 15% of cardiac output The grey matter contain more capillaries than white matter Formed by Internal carotid artery Vertebral artery

Internal carotid artery, of common carotid artery inter the skull through temporal bone (carotid canal) ICA divides into Anterior cerebral artery Middle cerebral artery Vertebral arteries, enter skull through foramen magnum

Right and left vertebral arteries, which are branches of subclavian arteries, join to form basilar artery, which divide into two posterior cerebral arteries Basilar artery supply blood to cerebellum, and brain stem The anterior and posterior blood supply are united by small communicating arteries

Circle of Willis

Posterior cerebral artery supply, center of vision, smell, thalamus, and mid brain Anterior cerebral artery supply motor and sensory areas of lower limbs Middle cerebral artery supply motor and sensory areas of rest of the body

Hepatic portal circulation Portal vein Is formed by union of Superior mesenteric vein and Splenic vein behind neck of pancreas Portal vein blood contain nutrients from digestion in the gut, and deliver them to liver, some of nutrients are stored or processed Blood leave the liver through hepatic veins which drain into inferior vena cava.

Hepatic portal circulation

Superior mesenteric vein drain blood from small bowel Inferior mesenteric vein drain the colon in to Splenic vein.

STRUCTURE OF BLOOD VESSELS Endothelium Smooth muscle Connective tissue Collagen fibers Elastic fibres Tunica intima Tunica media Tunica adventitia

MUSCULAR ARTERY

ARTERIOLE

CAPILLARIES

STRUCTURE OF VEINS