human heart and its function
DESCRIPTION
This is about human heart and its function suitable to teach school biologyTRANSCRIPT
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