Circulatory System Circulatory system Three components: HUMANS –  Central pump à Heart –  Vascular system à Blood vessels –  Circula6ng fluid à Blood Blood Vessels •  Arteries •  Veins •  Capillaries Cross sec6on of artery and vein. Capillaries Location of Heart in Thorax"
Larry M. Frolich, Ph.D.,Human Anatomy The heart •  A muscular organ •  Divided into chambers –  Why? •  Relaxes and contracts regularly (cardiac cycle) Pulmonary circulation
Aorta
Superior
vena cava
Pulmonary
artery
6
3
Pulmonary
vein
4
Systemic circulation
Right
atrium
Left
atrium
1
Atrioventricular
valve
Atrioventricular
valve
5
Inferior
vena cava
2
Right
ventricle
Left
ventricle
Semilunar
valves
Double Circulatory System Heart Wall "
Larry M. Frolich, Ph.D.,Human Anatomy Larry M. Frolich, Ph.D.,Human Anatomy Control of heart rate •  Pacemaker, also called sinoatrial (SA) node, sets heart rate Control of heart rate Blood Red blood cells (erythrocytes) •  Most numerous •  Contain hemoglobin protein •  No nuclei or mitochondria White blood cells (leukocytes) •  Fight infec6ons •  Contain nuclei & organelles, but no hemoglobin Platelets (thrombocytes) •  Func6on in blood cloPng •  Ac6vate fibrin (cloPng protein)