Post on 16-Jan-2016
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Circulatory System heart, blood, and blood vessels transport oxygen and nutrients
to organs and tissues throughout the body
carry away waste products
I. Functions Increases blood flow
meet increased energy demands during exercise
regulates body temperature conveys disease-fighting elements of
immune system to regions under attack white blood cells and antibodies
sends clotting cells and proteins to the affected site stop bleeding and promote healing
II.Circulatory System Components Heart - divided into four chambers
right atrium, right ventricle, left atrium, left ventricle
Pumping action of the heart -two stages for each heart beat
Diastole-when the heart is at rest
Systole-when the heart contracts to pump deoxygenated blood toward the lungs and oxygenated blood to the body.
During each heartbeat, typically about 60 to 90 ml (about 2 to 3 oz) of blood are pumped out of the heart.
If the heart stops pumping, death usually occurs within four to five minutes.
Three types of blood cells oxygen-bearing red blood cells disease-fighting white blood cells blood-clotting platelets, all of which
are carried through blood vessels in plasma plasma is yellowish, consists of water, salts,
proteins, vitamins, minerals, hormones, dissolved gases, and fats.
Three types of blood vessels arteries carry blood away
thicker walls to withstand the pressure of blood being pumped from heart
veins - toward heart lower pressure one-way valves to prevent blood from flowing
backwards away from heart
capillaries tiny links b/w arteries and veins where oxygen
and nutrients diffuse to body tissues smallest of blood vessels, are only visible by
microscope ten capillaries lying side by side are barely as thick as a human hair.
Inner layer of blood vessels lined with endothelial cells - create
a smooth passage for blood transit surrounded by connective tissue
and smooth muscle for: Expansion - during exercise to meet demand
for blood and to cool body Contraction - after injury to reduce bleeding
and/or conserve body heat
If all the arteries, veins, and capillaries in the human body were placed end to end, the total length would equal more than 100,000 km (more than 60,000 mi)—they could stretch around the earth nearly two and a half times.
Arteries, veins, and capillaries - divided into two systems: Systemic - carries oxygenated blood from heart to
all tissues in body except lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to heart. oxygen-rich blood ejected under high pressure out of heart's main pumping chamber (L. ventricle) through largest artery (aorta) smaller arteries branch off from aorta to various parts of the body smaller arteries in turn branch out into even smaller arteries
(arterioles) arterioles become progressively smaller eventually forming
capillaries - blood pressure is greatly reduced
interstitial fluid fills the gaps between the cells of tissues or organs dissolved oxygen and nutrients then enter the cells from interstitial fluid
by diffusion carbon dioxide and other wastes leave the cell via interstitial fluid, cross
capillary walls, and enter blood. after delivering oxygen to tissues and absorbing wastes,
deoxygenated blood in capillaries then starts the return trip to heart
capillaries merge to form tiny veins, called venules
venules join together to form progressively larger veins
veins converge into two large veins: inferior vena cava-brings blood from the lower half of
body superior vena cava-brings blood from upper half Both join at the right atrium of heart
FYI Varicose Veins
pressure is dissipated in arterioles and capillaries blood in veins flows back to heart at very low
pressure, often running uphill when a person is standing
Flow against gravity allowed by one-way valves several centimeters apart in veins
Veins with defective valves (allow the blood to flow backward) become enlarged or dilated to form varicose veins
Pulmonary Circulation deoxygenated blood returning from organs and tissues travel
from R. atrium to R. ventricle. pushed through pulmonary artery to lung pulmonary artery divides forming pulmonary capillary region microscopic vessels pass adjacent to alveoli (air sacs) - gases
are exchanged across thin membrane oxygen crosses membrane into blood while carbon dioxide
leaves blood through same membrane newly oxygenated blood then flows into pulmonary veins and is
collected by L. atrium of the heart (collecting pool for L.ventricle)
contraction of L. ventricle sends blood into aortacompleting circulatory loop
On average, a single blood cell takes roughly 30 seconds to complete a full circuit through both the pulmonary and systemic circulation.
III. Additional Functions & Features Transports nutrients and removes toxins
Absorbed through intestine wall via network of capillaries and veins that drain the intestine - hepatic portal circulation (HPC)
HPC – carries nutrients/toxins to the liver for further metabolic processing.
Liver stores sugars, fats, and vitamins & releases to the blood as needed
Liver also cleans blood by removing waste product and toxins. After hepatic portal blood has crossed the liver cells veins converge to form the large hepatic vein that joins the vena cava near the right atrium.
Body Temperature
Regulation exercise = muscles
generate heat blood supplying muscles
with oxygen and nutrients absorbs much heat and carries to other parts of body
If body gets too warm, vessels near skin enlarge = disperse excess heat outward through skin
If cold, blood vessels constrict to retain heat.
Hormone Transportation Endocrine system = collection of hormone-
producing glands Regulates rate of metabolism, growth, sexual
development, and other functions. chemical messengers (hormones) released
directly into bloodstream transported to specific organs and tissues
WBC & Antibody Transport and Clotting WBC and antibodies circulate in blood transported to infection sites coagulation system - composed of
Platelets and clotting factors circulate in blood Damaged blood vessels are repaired by forming
clots
Supporting Organs Brain/nervous system
monitor blood circulation send signals to heart or blood vessels to maintain constant blood
pressure. Bone Marrow
Site of new blood cell manufacture Spleen
Old blood cells are broken down valuable constituents, such as iron, are recycled
Kidneys metabolic waste products removed from blood also screens for excess salt maintains blood pressure balance of minerals and fluids