The Heart and Circulation Cardiovascular System = Heart, Blood and Vessels Lymphatic System = Lymph nodes, Organs and Vessels

The Heart External Innervation –Vagus (parasympathetic) – C + T sympathetic chain ganglion Pericardium (3 layers) 1) Outer-fibrous pericardium –Serous pericardium 2) parietal 3) visceral (epicardium) Pericardial Cavity –between layers of serous pericardium –serous fluid –lubricate heart while beating pg 502

Location of Heart in Chest Oblique Position Apex = Left of Midline (5th ICS), Anterior to rest of heart Base (posterior surface) sits on vertebral column Superior Right = 3rd Costal Cartilage, 1” right midsternum Superior Left = 2nd Costal Cartilage, 1” left midsternum Inferior Right = 6th Costal Cartilage, 1” right midsternum Inferior Left = 5th Intercostal Space at Midclavicular line

Location of Heart in Thorax pg 501

External Features of Heart Interventricular sulcus Coronal/Coronary sulcus Auricles of atria Apex Base Coronary vessels Ligamentum Arteriosum pg 504

The Great Vessels and major branches Aorta (from Left Ventricle) Ascending – Coronary arteries Aortic Arch –Brachiocephalic trunk –Left Common Carotid –Left Subclavian Descending (Thoracic/Abdominal) –Many small branches to organs Pulmonary Trunk (from Rt Ventricle) --2 Pulmonary Arteries into lungs Inferior/Superior Vena Cava - Coronary sinus Pg 504, 532

Layers of Heart Epicardium (most superficial) – Visceral pleura Myocardium (middle layer) –Cardiac muscle –Contracts Endocardium (inner) –Endothelium on CT –Lines the heart –Creates the valves pg 502

Right Heart Chambers: Pulmonary Pump Right Atrium (forms most of base of heart) –Receives O 2 -poor blood from body via IVC, SVC, Coronary sinus –Ventral wall = rough Pectinate muscle –Fossa Ovalis- on interatrial septum, remnant of Foramen Ovale Right Ventricle –Receives O 2 -poor blood from right atrium through tricuspid valve –Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk –Trabeculae Carnae muscle ridges along ventral surface –Papillary Muscle-cone-shaped muscle to which chordae tendinae are anchored –Moderator Band-muscular band connecting anterior papillary muscle to interventricular septum

Left Heart Chambers: Systemic Pump Left Atrium –Receives O 2 -rich blood from 4 Pulmonary Veins –Pectinate Muscles line only auricle Left Ventricle (forms apex of heart) –Receives blood from Left Atrium via bicuspid valve –Pumps blood into aorta via Aortic Semilunar Valve to body –Same structures as Rt Ventricle: Trabeculae carnae, Papillary muscles, Chordae tendinae –No Moderator Band

Chambers of Heart

Heart Valves: Lub*-Dub** *Tricuspid Valve: Right AV valve –3 Cusps (flaps) made of endocardium and CT –Cusps anchored in Rt. Ventricle by Chordae Tendinae –Chordae Tendinae prevent inversion of cusps into atrium –Flow of blood pushes cusps open –When ventricle is in diastole (relaxed), cusps hang limp in ventricle –Ventricular contraction increases pressure and forces cusps closed *Bicuspid (Mitral) Valve: Left AV valve –2 cusps anchored in Left Ventricle by chordae tendinae –Functions same as Rt. AV valve **Semilunar valves: prevents backflow in large arteries –Pulmonary Semilunar Valve: Right Ventricle and Pulmonary Trunk –Aortic Semilunar Valve: Left Ventricle and Aorta –3 cusps: blood rushes past they’re flattened, as it settles they’re pushed down (valve closed)

Heart Valves pg 506

Flow of Blood O 2 -poor blood (S+I VC, Coronary Sinus) enters Rt Atrium Travels through Tricuspid Valve into Rt Ventricle Pumped out through Pulmonary Semilunar Valve into Pulmonary trunk (branches into Pulmonary Arteries) and to lungs After circulating through lungs, O 2 -rich blood returns to the heart through 4 Pulmonary veins The O 2 -rich blood enters the Left Atrium Travels through Bicuspid/Mitral Valve into Left Ventricle Pumped out through Aortic Semilunar Valve into Aorta to be distributed to rest of body by descending aorta and branches of aortic arch

Cardiovascular Circuits pg 500

Circuits Pulmonary Circuit –Vessels carrying blood to and from lungs –Pulmonary arteries and veins Systemic Circuit –Vessels carrying blood to and from the rest of the body –All other vessels

Blood Flow to Supply the Heart Muscle Heart wall too thick for diffusion of nutrients Rt and Lft Coronary Arteries –Branch from Ascending Aorta –Have multiple branches along heart –Sit in Coronary Sulcus –Coronary Heart Disease Cardiac Veins –Coronary Sinus (largest) –Many branches feed into sinus –Sits in Coronary Sulcus

Anatomy of Arteries and Veins Tunica externa –Outermost layer –CT w/elastin and collagen –Protects, Strengthens, Anchors Tunica media –Middle layer –Circular Smooth Muscle –Collagen & Elastic Fibers –Vaso-constriction/dilation Tunica intima –Innermost layer –Endothelium –Minimize friction Lumen pg 525

Vessels of Cardiovascular System: Arteries Carry blood AWAY from heart Systemic Circuit: carry O 2 blood Pulmonary Circuit: carry de-O 2 blood Walls thicker than Veins –Tunica media > Tunica externa 3 Types –Conducting (elastic) large, elastin, high pressure –Distributing (muscular) medium size, to organs –Arterioles smallest pg 532

Vessels of Cardiovascular System: Capillaries Smallest blood vessels Single layer of endothelium surrounded by basal lamina Deliver O 2 and nutrients to cells and remove waste Capillary Beds: networks of caps. Regulating amount of blood going to cells throughout tissues Tendons, Ligaments poorly vascularized Epithelium, cartilage has no capillaries

Vessels of Cardiovascular System: Veins Carry blood from capillaries INTO the heart Systemic Circuit: O 2 poor blood Pulmonary Circuit: O 2 –rich blood Thinner walls than arteries –Tunica externa > tunica media, Less elastin Larger lumen than arteries Contain valves (made of T. intima) Normal movement, Muscular contraction push blood through Venules- smallest veins

Movement through Veins Pg 529

Cardiovascular Blood Flow Heart  Arteries  (conducting-distributing)  Arterioles  Capillaries of tissues At Capillaries O 2 is delivered and CO 2 picked up Capillaries  Venules  Veins  Heart Portal System: Special vascular circulation where blood goes through 2 capillary beds before returning to the heart to achieve 2 nd function –(eg) Hepatic Portal System: aids digestion by picking up digestive nutrients from stomach + intestines and delivers to liver for processing/storage –Pick-up occurs at capillaries of stomach and intestine –Via Hepatic Portal Vein goes to capillaries of liver –Via Hepatic Vein blood goes back to heart

Hepatic Portal System pg 548

Vascular Anastomoses Vessels unite and connect Arteriole Anastomoses –Communication between arteries –Joints, Abdominal Organs, Brain, Heart Venous Anastomoses –Communication between veins –More common –(eg) back of hand Vaso Vasorum –Tiny arteries, veins, capillaries in tunica externa of vessels to nourish them (outer half)

Fetal Circulation: 2 main differences 1) Fetus must transport blood to and from the placenta 2) Lungs are not functional, and do not need much blood All major vessels are in place by 3 rd month Blood flows in same direction as in adults

Fetal Circulation: Blood to Placenta Fetus must supply placenta w/blood Umbilical Vessels: carries blood to/from placenta –2 Umbilical Arteries = bring blood that contains waste & little O 2 from fetus to placenta –1 Umbilical Vein = brings blood w/O 2 and nutrients to fetus from placenta (some goes to portal vein to process in liver) Ductus Venosus = shunt taking blood returning from placenta to fetus directly to heart, largely bypassing liver –Too much blood for liver to handle –Results in highly O 2 blood going to heart

Fetal Circulation: Bypassing the Lungs Fetal Lungs are not functional and do not need large amounts of blood Foramen Ovale (becomes Fossa Ovalis) –Small hole in inter-atrial septum allows blood to flow directly from Rt. Atrium to Lft. Atrium –This largely bypasses the Rt. Ventricle  Pulmonary trunk that would bring blood to lungs Ductus Arteriosus (becomes Ligamentum Arteriosum) –Shunt directs blood from Pulmonary Trunk to Aortic arch, largely bypassing lungs

Bypassing the Lungs Pg 555

Remnants of Fetal Circulation Ligamentum teres = Round ligament –Remnant of the umbilical vein –Anterior abdominal wall Ligamentum venosum –Remnant of ductus venosum –On liver’s inferior surface Medial Umbilical Ligaments –Remnant of umbilical arteries –Anterior abdominal wall below navel –Also gives branch to urinary bladder

The Lymphatic System Function: to collect excess tissue fluid collecting at arteriole end of capillary beds, and return leaked blood proteins to blood (maintain osmotic pressure needed to take up water into bloodstream) Lymph is moved through vessels –Pulse of nearby arteries –Contraction of surrounding skeletal muscle –Regular movement of body (wiggling legs) –Muscle in Tunica Media Lacteals-lymphatic capillaries w/unique function –In mucosa of small intestine, receive digested fat from intestine –Fatty lymph becomes milky = Chyle –Chyle goes to bloodstream

Lymphatic System…The Players: Lymph- clear fluid from loose CT at capillaries Lymphatic capillaries (near blood capillaries)  Lymph collecting vessels (small, 3 tunicas, # valves)  Lymph nodes (sit along collecting vessels)-clean lymph of pathogens, they are NOT glands Lymphatic trunks  (convergence large collecting vessels) –Lumbar, intestinal, bronchomediastinal, subclavian, jugular Lymphatic ducts  empty into veins of neck