The Human Cardiovascular System * In preparation for a pig’s heart dissection Larry M. Frolich, Ph.D.,Human Anatomy

Cardiovascular/Circulatory System: Principles Structures Two circuits Pulmonary Systemic Heart Details Other Details

CV System Function:  Circulate blood through entire body for Transport of oxygen to cells Transport of CO2 away from cells Transport of nutrients (glucose) to cells Movement of immune system components (cells, antibodies) Transport of hormones

How? Heart is pump Diffusion in capillaries Arteries = Away Veins = Return

Heart/Great Vessels--1 Route Smaller arteries & veins --many routes -collateral circulation Overall Organization

Walls of Arteries and Veins Tunica externa –Outermost layer –Strengthens, Anchors Tunica media –Middle layer –Vaso-constriction/dilation Tunica intima –Innermost layer –Minimize friction Lumen

Artery/Vein Differences ArteriesVeins Direction of flow Blood Away from Heart Blood to Heart PressureHigherLower WallsTHICKER: Tunica media thicker than tunica externa THINNER: Tunica externa thicker than tunica media LumenSmallerLarger ValvesNo valvesValves (see next)

Capillaries Microscopic: 1 cell thick Network Entire goal of C-V system is to get blood into capillaries where diffusion takes place

GREAT VESSELS Aorta IVC, SVC Pulmonary Trunk Pulmonary Veins

2 Circulatory Paths Pulmonary Systemic heart  arteries  arterioles   veins  venules  capillaries

Larry M. Frolich, Ph.D.,Human Anatomy Heart Chambers and Valves

Right Heart Chambers: Pulmonary Circuit Right Atrium (forms most of posterior of heart) –Receives O 2 -poor blood from body via IVC, SVC, Coronary sinus Right Ventricle –Receives O 2 -poor blood from right atrium through tricuspid valve –Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk –Septum

Left Heart Chambers: Systemic Circuit Left Atrium –Receives O 2 -rich blood from 4 Pulmonary Veins Left Ventricle (forms apex of heart) –Receives blood from Left Atrium via bicuspid valve –Pumps blood into aorta via Aortic Semilunar Valve to body

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 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 Lft. Ventricle by chordae tendinae –Functions same as Rt. AV valve **Semilunar valves: prevents backflow in large arteries –Pulmonary Semilunar Valve: Rt 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)

Location of Heart in Thorax

Heart Wall Epicardium (most superficial) – Visceral pleura Myocardium (middle layer) –Cardiac muscle –Contracts Endocardium (inner) –Lines the heart

Blood supply to heart wall Rt and Lft Coronary Arteries –Branch from Ascending Aorta –Have multiple branches along heart –Coronary Heart Disease Cardiac Veins –Coronary Sinus (largest) –Many branches feed into sinus

Chamber contraction/relaxation