Ajith Sominanda Department of Anatomy

Lecture outline Why a circulatory system ? Arrangement of the CVS Vascular tree-Gross Anatomy CVS histology

Circulatory system; Why? Amoeba in motion

Circulatory system; Why?

Functions of circulatory system Transport of materials and cells by continuous movement of blood Gases Nutrients Waste products Components of immune and endocrine system Thermoregulation

Components of human circulatory system Blood vascular system (closed) Heart Arteries and arterioles (conduction / distributing vessels) Capillaries (exchange vessels) Venules and veins (capacitance vessels) Lymph vascular system (open ) Lymphatics Lymph nodes Pulmonary circulation Heart: left chambers (oxygenated blood) Heart: right chamber s (De-oxygenated blood) Conducting vessels Arterioles Exchange vessels (Capillaries) Venules Lymph nodes Lymphatics Capacitance vessels (Veins) Distributing vessels

Overall arrangement Aorta (2-2.5 cm) Large and medium size arteries ( ) Arterioles (4 * 10 6 ) (<300 µm) Capillaries (16 * 10 6 ) (7 µm)

LV RV RA Arch of aorta Superior vena cava Pulmona ry artery Intercostal vessels Inferior vena cava Heart, great vessels and circulation in thorax Heart, great vessels and circulation in thorax

Heart, great vessels Circulation in axilla and upper arm Heart, great vessels Circulation in axilla and upper arm Pulmonary artery Left bronchus Subclavian artery & vein Axillary artery & vein Brachial artery & vein

Common carotid arteries External & internal carotid arteries Arch of aorta Circulation in head & neck

Circulation in abdomen, upper and lower limbs Circulation in abdomen, upper and lower limbs Abdominal aorta Common iliac artery External & internal iliac arteries Femoral artery Radial & ulnar arteries

Branching patterns of arterial tree 1. Terminal branches 2. Co-lateral branches

1. End-to-end anastomosis 1. Vaginal artery-ovarian artery 2. Left gastro epiploic arteries 3. Ulnar artery and superficial palmar branch of radial artery 2. Anastomosis by convergence Vertebral arteries forming basilar artery 3. Transversal anastomosis 1. Between anterior cerebral arteries 2. Between radial and ulnar at wrist 3. Between posterior tibial and peroneal arteries Anastomosis of arteries

Venous system Superficial veins Deep veins Venae comitantes Valves & Venous drainage

Venous system: problems Failed superficial veins: ’’Varicosities’’ Obstructed deep veins: ’’Deep vein thrombosis (DVT)’’

General arrangement of cardio-vascular tissues (CARDIO VASCULAR TUBE) ’’ Tunic = coat ’’ 1.Tunica externa / adventitia 2.Tunica media 3.Tunica intima Vasa vasorum (Vessels of vessels) Nervi vasorum (Nerves of vessels) Has three-layered structure

General arrangement of cardio-vascular tissues HeartArteriesCapillaries Veins Note the changes occurring in the wall of the structures

Structure for Function ! The heart is a (muscular) pump !

Heart 1. Endocardium (Tunica intima) 2. Myocardium (Tunica media) 3. Epicardium / viceral pericardium (Tunica adventitia) Cardiac wall consists of three layers:

1. Endothelium (single layer of flattened epithelial cells) 2. Sub-endothelial connective tissue Heart Endocardium Tunica intima

1. Consists of cardiac muscle fibers (Cardiocytes) arranged in a network ’’ Syncytium’’ 2. Cardiocytes have central nucleus and are connected by junctional complexes ’’intercalated discs’’ 3. Mitochondria and sarcoplasmic reticulum are abundant in cytoplasm 4. Muscle contractions are Strong, continuous and inherent Heart Myocardium

Heart Cardiocyte-Ultra structure Transverse junctional complexes (Intercalated discs) Striations Longitudinal junctional complexes (GAP junctions)

Heart Epicardium 1. Consists of flattened epithelium (Mesothelium) that secretes serous fluid into pericardial space 2. Epithelium is supported by Sub- endothelial connective tissues 3. Contains coronary vasculature

HeartArteriesCapillaries Veins Arterial tree Arteries conduct and distribute blood to periphery

Blood pressure Vascular anatomy High pressure tubal system for conduction of blood to periphery Low pressure tubal system for drainage of blood Exchange system Structural adaptation for Function !

Conform to the three-layered tissue arrangement Main types of vessels in arterial system 1. Large elastic arteries (Aorta, Brachiocephalic, common carotid, subclavian & common iliac arteries) 1. Medium-sized muscular arteries (Intercostal, axillary, radial arteries) 1. Arterioles Arterial tree

Elastic arteries 1. Tunica media contains large amounts of fenestrated sheaths of elastin and lesser amounts of collagen and smooth muscle cells 2. Tunica adventitia contains collagen tissues Arterial tree

Muscular arteries 1. Tunica intima has three layers: 1. Endothelium 2. Sub endothelial connective tissues 3. Internal elastic lamina (sheath of elastin) 2. Tunica media has thick layer of smooth muscle cells 3. Larger vessels have external elastic lamina Arterial tree

Arterioles 1. Arterioles are final branches of arterial system that regulate blood flow to capillary bed 2. Tunica media has concentric layers of smooth muscles 3. Innervated by sympathetic nerves and control the vascular tone Arterial tree

Arterioles and micro circulation Arterial tree Arteriloes Venule Sympathetic nerve Pre-capillary spincters

1. Continuation of endothelium 2. No smooth muscle and adventitial layers 3. Occasion pericytes are found Capillaries: the exchange compartment

Capillaries: different types 1.Continuous 2.Fenestrated 3.Discontinuous Q: List the sites where different capillary types are found

Venous system Veins & venules Venules (Post capillary, Muscular & Collecting venules) Capillaries Veins Has relatively Large lumen & thinner wall Elastic and muscular components are much less prominent compared to arteries Acts as reservoirs of blood; Capacitance vessels

Lymph vascular system Reuptake excess tissue fluid that accumulates in ECS Similar to venous system

Things that are good to read (know) ! Formation of Edema Thickening of arterial walls i.e. Arteriosclerosis & Atherosclerosis Endothelium and inflammation Endothelium and blood coagulation Biology of vessel formation and tumors (tumor angiogenesis )

References 1. Wheaters functional histology 2. Histology and cellbiology by Abraham L Kierszenbaum 3. Grays Anatomy 4. WWW.

The END Thank you