HUMANCIRCULATORY

SYSTEM

• Is a muscle about the size of your fist

•Weighs approximately one pound• Is located behind and slightly to the

left of the breastbone•Pumps about 4.7 liters of blood

every minute

Heart size - about 14

cm long by 9 cm wide

Cardiovascular system

1) pericardium =

double-layer serous membrane

2) endocardium -

squamous epithelial inner

lining of the heart

coverings

c. chambers1) atria - receive

blood from the vesselsa) pectinate

muscles - ridges of muscle in anterior wall

2) auricles - small expandable

attachments to the atria

a) pectinate muscles (Latin pecten =

comb)

4) ventricles - pump blood to body by contraction of myocardium.

a) walls are thicker than atria, left side thickest

ventricles - pump

blood to body by

contraction of

myocardium.

a) walls

are thicker than

atria, left side

thickest

interventricular septum - parallels a groove in the outer surface of the heart (the interventricular sulcus).

valves - allow only one direction of flow1) atrioventricular (AV)

valves

a) tricuspid - 3 folded valve between right A and V

b) biscuspid - mitral valve - 2 folded on left side

c) made of dense connective tissue

Semilunar valves - between ventricle and the first major artery.

a) Right ventricle and pulmonary trunk - pulmonary

b) Left ventricle and aorta - aortic valve

chordae tendineae = attach cusps to papi l lary muscles.

c) 3 half-moon shaped cusps

a) Thinner walls and smaller lumen.

3) Capillariesa) Single layer of epithelium

onlyb) lumen diameter .01 mm

2. Blood Vesselsa. Structure

1) Arteries and veins

2 1) s. Blood Vessels

a. Structure

2. Blood Vessels 1) Arteries and veins

c) form vast branching networks

a) Arteries have thicker smooth muscle layer while veins have larger

lumen and also have valves.2) Arteriloe and

venules

a. Cardiac cycle - the

contraction of both atria and then both ventricles.

Cardiac cycle - the contraction of both atria and then both ventricles. 1) systole = state of

contraction (blood forced out)2) diastole = state of

relaxation (blood drawn in)

3) both ventricles at the relax or contract at the same time

4) likewise atria are simultaneous

Heart sounds - results from valves

shutting lub = AV valves

dup = Semilunar valves