Chapter 15

Cardiovascular System

Organs

• Heart - begins beating in the 4th week of development.– Pumps 7,000 liters of blood each day.– Contracts 2.5 million times in a lifetime.

• Closed Vessel System– Arteries - carry blood away from the

heart.– Veins - carry blood toward the heart.– Capillaries - attach arteries and veins.

Function

• Circulates blood to every cell in the body and removes waste.

The Heart

• Location and Size– Size of a man’s fist

(14 cm long and 9 cm wide)

– Lies within the mediastinum - behind sternum (rests on diaphragm).

– 2/3 of the heart is on the left side of the body.

– Apex is the lower, left “point” of the heart.

• Stethoscope is placed here to count the beats.

The Heart • Coverings

– Pericardium - sac around the heart - loose-fitting• Fibrous - tough white outer

covering, • Serous parietal - smooth

lining of the fibrous sac.– Epicardium - covers

surface of the heart - smooth• Also called serous visceral

pericardium– Pericardial space - area

between pericardium and epicardium• Contains fluid - pericardial

fluid• Lubricates beating heart• Pericarditis -

inflammation of pericardium due to infection - linings stick together, very painful.

The Structure of the Heart

• The wall of the heart:– Epicardium –

reduces friction.– Myocardium – thick

contractile middle layer, high in mitochondria.

– Endocardium – delicate inner layer.

The Structure of the Heart Continued

• Cavities– Upper – atria– Lower – ventricles

• Larger and thicker walled

• Carry heavier pumping burden

• Left is thickest – has to pump blood to all parts of the body

The Structure of the Heart Continued

• Valves and Openings• Blood flows in one

direction.– Cuspid valves – between

cavities(atria and ventricles)

• Bicuspid (mitral) valve - left cavities.

Valve has 2 cusps or leaflets. Also called the leftatrioventricular valve. • Tricuspid valve - right

cavities. Valve has 3 cusps or leaflets.Also called the rightatrioventricular valve.

The semi-lunar valve moves blood out of the heart to the aorta and pulmonary artery.

i.Cusps of valve are half moon shaped (‘lunar’)Found at the base of thepulmonary arteries (called thepulmonary valve) and at thebase of the aorta (called theaortic valve)

•Attached by fibrousstrings called chordaetendineae to the papillarymuscles.

Tricuspid valve repair

A murmer is an abnormal sound that identifies the leakage of blood though valves in the wrong direction

4 2

5

6

10

89 - Apex

12

11 – left coronary artery

13

14

15

16

(auricle)

(auricle)

Left auricle

Right auricle

Auricle = A small, earlike projectionthat extends anteriorly from the atrium.

18

1. Aortic arch

2 . SuperiorVena cava

3.RightPulmonaryArtery

4. Pulmonary trunk

5. Right Pulmonary Veins

6. PulmonaryValve

7. RightAtrium

8. Tricuspid valve

9. Right ventricle 10. InferiorVena cava

11. Aorta

12. InterventricularSeptum

13. Left ventricle

14. Bicuspid valve (Mitral valve)

15. Aortic valve

16. Left atrium

17. Left pulmonaryVeins18. Left pulmonaryartery12

13

45

67

89

10

11

13

14

15

16

172

The Structure of the Heart Continued

• Blood Supply– Ventricles get blood from the right and

left coronary arteries. – Atria get blood from the small branch

coronary artery. – Anastomosis is branching of the main

arteries (“detours”)– Myocardial infarction - death of the heart

muscles due to a clot (heart attack).

Blood Vessels

• Structure– Outer – fibrous tissue,

keeps firm– Middle – muscle,

constriction, and dilation.

– Inner – endothelium - capillaries

Blood Vessels Continued

• Function– Transportation of nutrients to cells

• Capillaries perform this function• Arteries = distributors arterioles

capillaries venules veins • Veins = carry and pool blood

Blood Vessels Continued

• Main Blood Vessels– ascending aorta– aortic arch– subclavian– common carotid – common iliac

Ascending

Aorta

Blood Vessels Continued

Blood Vessels Continued

• Portal Circulation– Organs that do not pour blood into

inferior vena cava.– Blood sent to the liver by the portal

vein.

Blood Vessels Continued

• Fetal Circulation– Gets oxygen and food from mother, not

own lungs and digestive tract.– Additional vessels

•Umbilical arteries (2) – carry fetal blood to placenta

•Placenta – exchanges oxygen and other substances between mother and fetus

•Umbilical vein – returns oxygenated blood to liver of fetus

•Foramen ovale – opening between right and left atria bypass lungs, closes with first breath.

Shed at birth