Circulatory System Objectives Understand the roles of the cardiovascular and lymphatic systems and their relationship to each other Know the tissue layers that characterize blood vessels Know the anatomical and functional differences between arteries, veins and capillaries Distinguish systemic and pulmonary circulation and portal circulation Describe differences in adult and fetal circulation with respect to the hepatic portal and pulmonary systems Know the cellular components of blood Know where hematopoeisis occurs and where blood cells are removed from circulation Know the relationship of cerebrospinal fluid (CSF) to blood Relate the function of the following organs to the circulatory system: spleen, thymus, lymph nodes, tonsils, carotid bodies, hypothalamus, brown fat, lungs, kidneys, liver, bone marrow, endocrine glands, choroid plexus

Major divisions of the circulatory system Cardiovascular system functions distributes nutrients, wastes, O2, CO2, hormones thermoregulation, osmoregulation, physiological homeostasis components heart, arteries, veins, capillaries blood Lymphatic system

Major divisions of the circulatory system Lymphatic system functions immune response, lipid absorption, returns fluids from tissues to venous cardiovascular system components Lymph Capillaries, Vessels, Ducts Lymph Organs Lymph Nodes Thymus Spleen Tonsils Peyer’s Patches Vermiform Appendix Lymph

Layers of the cardiovascular system listed from luminal to superficial: Vessels Endothelium Tunica Intima Muscle and CT Tunica Media Covering Tunica Adventitia

General terms Collateral Circulation Anastomosis

Heart Endocardium Myocardium Pericardium

Arteries by definition: conduct blood away from heart typically conduct O2-rich blood exceptions are pulmonary arteries and umbilical arteries narrow diameter (than veins) thicker wall (than veins) Tunica Intima maybe Stratified Squamous Epithelium Tunica Media alternating bands of Smooth Muscle and Elastic CT high pressure located deep (not merely subcutaneous) except to pass joints typically co-occur with veins and nerves of same name

Veins by definition: conduct blood towards the heart typically conduct O2-depleted blood exceptions are pulmonary veins and umbilical vein large diameter thin wall low pressure passive valves two tier system of both superficial (subcutaneous) and deep vessels

Capillaries leaky vessels consist only of Tunica Intima only

Blood Plasma – extracellular matrix water, dissolved salts, proteins, nutrients, urea, hormones, CO2 Albumin – osmolarity Fibrinogen – clotting Globulins – immune response Formed elements of blood – cellular Hematopoeisis from pleuripotent stem or progenitor cells Red Bone Marrow in adults Yolk Sac, Spleen, Liver, Kidneys in embryo and fetus

Erythrocytes or Red Blood Cells (RBC’s) carry hemoglobin, four-ringed protein that binds iron (hence O2) most numerous blood cell type biconcave anucleate 7.5 µm in diameter Rollo formation ~120 day lifespan unlike leucocytes, RBC’s cannot escape capillaries

Leucocytes or White Blood Cells (WBC’s)

Granulocytes or Polymorphonuclear Cells extracellular digestion by release of lytic enzymes innate immune response types distinguished by hemotoxylin and eosin (H&E) staining Neutrophils – neutral pH, red and blue most numerous granulocyte, major constituent of pus Eosinophils – acid, red Basophils – basic, blue produce edema, release heparin and histamine Agranulocytes Monocytes or Macrophages (mature) amoeboid cells, internal digestion by phagocytosis Lymphocytes many types: t-lymphocytes, b-lymphocytes, natural killer-lymphocytes recognize, target, and kill antigens adaptive immune response Thrombocytes or blood platelets small pieces of cells involved in clotting

Heart Pericardial cavity – middle mediastinum Parietal Pericardium Serous Pericardium Fibrous Pericardium Heart suspended by great vessels superiorly (anterior and posterior) tissue layers of heart Visceral pericardium (or simply “pericardium”) – serosa Myocardium – cardiac striated muscle Endocardium – simple squamous epithelium

margins of the heart superior – sternal angle to 4th thoracic intervertebral disc right – ½ inch parasternal apex – left midclavicular line or ½ inch medial to areola in males inferior – xiphisternal joint to 8th thoracic intervertebral disc

Pulmonary circulation – to and from lungs Systemic circulation – to and from body Intrinsic circulation of the heart Hepatic Portal circulation separated as right and left chambers of the heart

2 Atria (s. atrium) 2 Ventricles Interatrial Septum Interventricular Septum Atrioventricular Septum

Systemic circulation Superior vena cava – from upper ½ body Inferior vena cava – from lower ½ body Coronary sinus – intrinsic circulation of heart

↓ Right atrium ↓ Right ventricle ↓ Pulmonary circuit Pulmonary trunk to pulmonary arteries Lungs Pulmonary veins

↓ Left atrium ↓ Left ventricle ↓ Systemic circulation Ascending Aorta – to everything

General features of Atria smaller and thinner walled than ventricles Musculi Pectinati Auricles Atria separated from one another by Interatrial Septum Atria separated from ventricles by Atrioventricular Septum contains Atrioventricular (AV) Node – beginning of Moderator Band

Right Atrium Sinus Venosus posterior right, smooth surface receives Superior and Inferior Venae Cavae and Coronary Sinus Crista Terminalis Sinoatrial (SA) Node – the “pacemaker” Fossa Ovalis – vestige of Foramen Ovale (fetal interatrial bypass)

Left Atrium

receives Upper and Lower Right and Upper and Lower Left Pulmonary Veins

General Features of Ventricles larger and thicker walled than atria Trabeculae Carnae Atrioventricular (AV) Valves – active, muscular Cusps Chordae Tendinae Papillary muscles Semilunar Valves – passive Ventricles separated from one another by interventricular septum contains Moderator Band or Purkinje Fibers

Right Ventricle Right AV or Tricuspid Valve – three cusps opening of Pulmonary Trunk – anterior superior left Pulmonary Semilunar Valve

Left Ventricle Left AV or Bicuspid or Mitral Valve – two cusps opening of Ascending Aorta – anterior superior right Aortic Semilunar Valve

Electrical conduction of the heart Sinoatrial Node – pacemaker Atrioventricular Node Moderator Band or Bundle of HIS or Purkinje Fibers

Locations to listen to heart valves Aortic Semilunar – Right 2nd intercostal space parasternal Pulmonary Semilunar – Left 2nd intercostal space parasternal

Tricuspid – Right 5th intercostal space parasternal Bicuspid or Mitral – Left 5th intercostal space midclavicular

Fetal circulation fetal structure

fate

R&L Umbilical Arteries Umbilical Vein Ductus Venosus (also Portal Sinus Foramen Ovale Ductus Arteriosus

Vesical Arteries and Median Umbilical Ligament Ligamentum Teres in Falciform Ligament Ligamentum Venosus Hepatic Portal Vein) Fossa Ovalis Ligamentum Arteriosum

Fetal

Definitive

Branches of the Thoracic Aorta listed in order of branching Ascending Aorta Right and Left Coronary Arteries Aortic Arch Brachiocephalic Artery branches: Right Common Carotid and Right Subclavian Arteries Left Common Carotid Artery Left Subclavian Artery Descending Aorta segmental Esophageal and Intercostal arteries

Superior Vena Cava venous counterpart to the Thoracic Aorta drains entire upper half of body located to right side of Aortic Arch, on mediastinal surface of right lung begins with the union of Right and Left Brachiocephalic Veins terminates in Sinus Venosus of Right Atrium Tributaries Left Brachiocephalic or Left Innominate Vein long, horizontal, anterior to branches of aortic arch begins with union of Subclavian and Internal Jugular Veins Right Brachiocephalic or Right Innominate Vein short, vertical begins with union of Subclavian and Internal Jugular Veins Azygos Vein drains right Intercostal Veins drains left Intercostal Veins via Hemiazygos Veins

Branches of the Abdominal Aorta listed in order of branching Coeliac Trunk – to superior abdominal organs Superior Mesenteric Artery – to Jejunum, Ileum, Large Intestine up to and includingTransverse Colon Right and Left Renal Arteries Right and Left Gonadal (Testicular or Ovarian) Arteries Inferior Mesenteric Artery – to Descending and Sigmoid Colons and superior Rectum Right and Left Common Iliac Arteries – to pelvic region and lower limbs

Inferior Vena Cava venous counterpart to the Abdominal Aorta drains entire lower half of body its main tributaries are those corresponding only to paired arterial branches of the Abdominal Aorta, except the Hepatic vein located to right side of Abdominal Aorta, anterior to lumbar vertebrae begins with the union of the Right and Left Common Iliac veins terminates in Sinus Venosus of Right Atrium

Tributaries of the Inferior Vena Cava listed in order of union Right and Left Common Iliac Veins Right Gonadal (Testicular or Ovarian) Vein simultaneously because they are paired: Right Renal Vein Left Renal Vein Left Renal Vein - long, crosses anterior to Abdominal Aorta tributary of Left Renal Vein: Left Gonadal (Testicular or Ovarian) Vein Hepatic Vein

Arterial Branches

Intrinsic circulation of the heart “Coronary” Arteries vs “Cardiac” Veins

Branches of Right Coronary Artery Marginal (coronary) Artery on right margin of heart Circumflex (Coronary) Artery (right side) at Atrioventricular Septum

Branches of Left Coronary Artery Anterior Interventricular or Descending Artery at anterior interventricular septum anastomoses with Posterior Interventricular Artery

Circumflex (Coronary) Artery (left side) branch: Posterior Interventricular or Descending Artery at posterior interventricular septum anastomoses with Anterior Interventricular Artery

Cardiac veins Small Cardiac Vein corresponds to Marginal Artery on right margin of heart Great Cardiac Vein corresponds to Anterior Interventricular Artery at anterior interventricular septum Middle Cardiac Vein corresponds to Posterior Interventricular Artery at Posterior Interventricular Septum Coronary Sinus alongside Circumflex Artery at Atrioventricular Septum receives Cardiac Veins and drains into Sinus Venosus of Right Atrium

Branches of the Common Carotid Arteries and their ends in two terminal branches at level of laryngeal eminence in carotid triangle

branches Internal Carotid Artery major branches of the Internal Carotid Artery: Middle Cerebral Artery – to majority of Cerebrum via Carotid Canal passes through the Cavernous Sinus (a venous “dural sinus” surrounding the sella turcica) Ophthalmic Artery – to orbit via optic canal select branches of Ophthalmic Artery: Central Artery – enters eye within optic nerve branches of the Central Artery Superior and Inferior Temporal Arteries – to retina Superior and Inferior Nasal Arteries – to retina Supraorbital Artery External Carotid Artery

(continued)

Branches of the External Carotid Artery and its branches Lingual Artery – to tongue Facial Artery – crosses face from mandibular ramus to medial orbit Superficial Temporal Artery – to temporal fossa, scalp Occipital Artery Maxillary Artery – to muscles of mastication, palate, teeth, and infraorbital region select branches: Sphenopalatine Artery – to nasal cavity and palate Middle Meningeal Artery – to cranial cavity via foramen spinosum Alveolar Arteries (3) – to teeth Infraorbital Artery – to middle face

Branches of the Subclavian Arteries and their branches Vertebral Artery – to cranial cavity via foramen magnum Thyrocervical Trunk – to scapular and cervical regions Internal Thoracic Artery Costocervical Trunk Dorsal Scapular Artery Axillary Artery (terminal branch) Subclavian Artery → Axillary Artery at first rib to anterior and lateral thoracic regions branches: Thoracoacromial Artery (travels with Lateral Pectoral nerve) Subscapular Artery Lateral Thoracic artery (travels with Long Thoracic nerve) Circumflex Humeral Artery Brachial Artery (terminal branch) Axillary Artery → Brachial Artery at Teres Major muscle (continued)

Location of the Brachial Artery Proximally: on medial side of brachium between anterior and posterior compartments but within anterior compartment Distally: medial to tendon of biceps brachii in antecubital region

Major Branches of the Brachial Artery Profunda Brachii Artery Superior and Inferior Ulnar Collateral Arteries Radial Artery (terminal branch) Deep Palmar Arch – anastomoses with Ulnar Artery Ulnar Artery (terminal branch) Common Interosseous Artery Anterior Interosseous Artery Posterior Interosseous Artery Superficial Palmar Arch – anastomoses with Radial Artery

Circulation of the cranial cavity 1) Internal Carotid Artery → Middle Cerebral Artery (at carotid canal) serves frontal, parietal, and temporal lobes of the cerebrum passes through Cavernous Sinus (a venous plexus of the dural sinuses) four levels from deep to superficial emerges through Central Sulcus or Fissure between frontal and parietal lobes of cerebrum emerges through Sylvian or Lateral Sulcus or Fissure between frontal and temporal lobes of cerebrum branches: Anterior Cerebral Artery - to anterior inferior frontal lobe Right and Left Anterior Cerebral Arteries anastomose via: Anterior Communicating Artery Posterior Communicating Artery – an anastomosis with posterior cerebral artery (continued)

Circulation of the cranial cavity 2) Right and Left Vertebral arteries anastomose to form: Basilar artery (unpaired) branches: Cerebellar arteries Posterior cerebral artery – terminal paired branches anastomoses with middle cerebral artery via posterior communicating artery 3) Middle meningeal Artery – to meninges and calvarium

Branches of the coeliac trunk and their major branches Left Gastric Artery branches to lesser curvature of stomach and esophagus Common Hepatic Artery branches: Hepatic Artery Gastroduodenal Artery branches to (right side of) greater curvature of stomach, duodenum, and head and neck of pancreas Splenic Artery branches to fundus and (left side of) greater curvature of stomach, and body and tail of pancreas

Branches of Common Iliac arteries and their major branches Internal iliac Artery branches: Iliolumbar Artery (serves iliopsoas muscle) Lateral Sacral Artery Superior and Inferior Gluteal Arteries Umbilical Artery of fetus… or Superior Vesical Artery of adult Uterine and Vaginal Arteries of female… or Inferior Vesical Artery of male Middle Rectal (“Middle Hemorrhoidal”) Artery Obturator artery – to obturator muscles Internal Pudendal Artery - to perineum Branch (one among many): Inferior Rectal (“Inferior Hemorrhoidal”) Artery External Iliac artery (continued)

Branches of Internal Iliac artery

Branches of Internal Iliac artery

Branches of External Iliac Artery and its branches Inferior Epigastric artery Circumflex Iliac artery Femoral Artery (terminal branch) external iliac Artery → femoral artery at inguinal ligament

Branches of Femoral Artery: External Pudendal arteries – to external genitalia, i.e., scrotum in males or labia majora in females Profunda Femoris Artery – to muscles of medial and posterior compartments Medial and Lateral Circumflex Femoral Arteries – branches descend medial and lateral thigh Popliteal Artery (terminal branch) Femoral Artery → Popliteal Artery at adductor hiatus (continued)

Branches of Popliteal Artery and their major branches Genicular arteries (superior medial and lateral, inferior medial and lateral) Sural Arteries Anterior Tibial Artery (terminal branch of Popliteal Artery) branch (terminal): Dorsalis Pedis Artery Posterior Tibial Artery (terminal branch of Popliteal Artery) branches: Peroneal Artery Medial and Lateral Plantar Arteries (terminal branches of Posterior Tibial Artery)

Pulse Superficial Temporal Artery temporal fossa Carotid Artery (Common or External) anterior to sternocleidomastoid at level of laryngeal eminence Brachial Artery antecubital fossa medial to tendon of biceps brachii Radial Artery anterior distal radius Femoral Artery femoral triangle Popliteal Artery popliteal fossa Posterior Tibial Artery posterior to medial malleolus Dorsalis Pedis Artery between tendons of extensor hallucis longus and extensor digitorum longus

Venous drainage of the Head and Neck for most arteries there are corresponding veins of the same name except: Internal, External, and Common Carotid arteries veins with no corresponding arteries: Internal Jugular vein drains cranial cavity, anterior face, tongue and pharynx Sigmoid Dural Sinus → Internal Jugular vein at jugular foramen major tributaries: Facial Vein Lingual Vein External Jugular Vein drains lateral and posterior scalp, posterior face, infratemporal fossa major tributaries: Maxillary Vein Superficial Temporal Vein Anterior Jugular Vein drains superficial thyroid region

Brain Ventricles, Cerebrospinal Fluid, Meninges, Dural Sinuses Choroid Plexus – a capillary-like structure within some ventricles Cerebrospinal Fluid (CSF) – blood filtrate produced by choroid plexus that bathes the central nervous system from within and without Structures filled with CSF: Subarachnoid Space Brain Ventricles - derivatives of the embryological neural tube (CNS) Lateral Ventricles – in paired cerebral hemispheres of forebrain Third Ventricle – between right and left thalami and within hypothalamus of forebrain Cerebral Aqueduct – narrow tube in midbrain Fourth Ventricle – between cerebellum and pons of hindbrain Central Canal of the spinal cord

Meninges Pia Mater Arachnoid Mater Subarchnoid Space – location of CSF between pia and arachnoid maters Arachnoid Villi – drain CSF from subarachnoid space to dural sinuses Dura Mater continuous with periosteum of calvarium and vertebral canal extensions of dura extending into fissures of brain: Falx Cerebri – midsagittal septum between cerebral hemispheres Falx Cerebelli – midsagittal septum between cerebellar hemispheres Tentorium Cerebelli – horizontal septum between occipital lobes of cerebrum and cerebellum

Dural Sinuses Superior Sagittal Sinus – superior margin of falx cerebri inferior to sagittal suture Inferior Sagittal Sinus – along inferior margin of falx cerebri Straight Sinus – along union of falx cerebri and tentorium cerebelli Transverse Sinuses – along lateral margin of tentorium cerebelli Superior Sagittal Sinus → Right Transverse Sinus at internal occipital protuberance Straight Sinus → Left Transverse Sinus at internal occipital protuberance Sigmoid Sinuses continuation of Transverse Sinuses sigmoid sinus → Internal Jugular Vein at jugular foramen (continued)

Dural Sinuses Cavernous Sinus venous plexus surrounding Sella Turcica passed through by Internal Carotid Artery, nIII, nIV, nV1, nV2, nVI receives Ophthalmic Vein* drains indirectly to Transverse and Sigmoid sinuses * Facial Vein anastomoses with Ophthalmic Vein, unlike arteries of same names – this is a superficial venous pathway into the cranial cavity and potential source of infection

Hepatic Portal Vein terminates in liver tributaries: Splenic Vein Superior Mesenteric Vein Inferior Mesenteric Vein

Venous drainage of the upper extremity and girdle for every artery there are corresponding veins of the same name Superficial veins with no corresponding arteries: Cephalic Vein drains dorsum of hand, lateral antebrachium and brachium ends in Axillary Vein at Deltopectoral Triangle Basilic Vein Anterior medial antebrachium and medial brachium ends in Brachial Vein Median Cubital Vein Antecubital anastomosis of Cephalic and Basilic Veins

Venous drainage of the lower extremity and pelvic region for every artery there are corresponding veins of the same name Superficial veins with no corresponding arteries: Great or Long Saphenous Vein drains medial crus and thigh ends in Femoral Vein in femoral triangle Short Saphenous Vein drains sural region ends in Popliteal Vein in popliteal region

Lymphatic system Functions Immune response lipid absorption removes dead blood cells from circulation, produces bilirubin returns fluids and mobile leucocytes from extracellular tissues to venous cardiovascular system

Terminal lymph vessels Right Lymphatic duct drains upper right ¼ of body terminates in right subclavian vein Thoracic duct drains all but upper right ¼ of body terminates in left subclavian vein Cysterna Chyli – bulb-like expansion of inferior end of thoracic duct

Lymph Nodes scattered and concentrated in locations throughout body, especially major joints, the cervical region, and digestive organs Leucocytes within nodes attack antigens and impede them from circulating Afferent and Efferent lymph vessels - lead to and from nodes parts of the node: Capsule Trabeculae Nodules Germinal Centers site of maturation and acquisition of new antibodies by b-lymphocytes and their clonal proliferation Reticular fibers Macrophages and Lymphocytes

Distribution of Select Major Groups of Lymph Nodes of head: Parotid Submaxillary or Submandibular Occipital of neck: Cervical superior and inferior deep – surround internal jugular veins Superficial – superior anterior triangle (continued)

Distribution of Select Major Groups of Lymph Nodes of upper limb and girdle: Axillary Pectoral, Subclavicular, Subscapular, Brachial of lower limb and girdle (including genitals and perineum): Inguinal – femoral triangle of thoracic cavity: Tracheobronchial, Intercostal Mediastinal – mostly concentrated around arteries of abdominal Cavity: Lumbar – efferents to cisterna chyli many groups, mostly concentrated around and named after all arteries and their branches, as well as viscera of pelvic cavity (e.g., rectum)

Thymus site of maturation of t-lymphocytes primarily in youth located posterior to manubrium in superior mediastinum size at age 2 (maximal): from laryngeal eminence to mid-sternal body size at adolescence (replaced by adipose): jugular notch to sternal angle

Spleen blood filter removes dead erythrocytes from circulation populated by monocytes and macrophages degrades hemoglobin to bilirubin (subsequently excreted by liver) located in left hypochondriac region, to left of stomach Capsule Cords of Billroth – reticular fibers