Download 17.1 Notes

CIRCULATORY SYSTEM
CH 17 LESSON 1
FUNCTIONS
1.
Maintains internal environment in which all cells of your body are nourished.
2.
As your heart beats (pumps blood) blood vessels carry oxygen & nutrients to body
cells.
3.
Carbon dioxide is carried along with waste matter from your cells and delivered to
your lungs & kidneys for removal from body.
STRUCTURE OF CIRCULATORY SYSTEM
• Heart
• Blood
• Network of branching vessels (arteries, veins, and capillaries).
• These carry blood throughout the body.
HEART
• Never rests.
• Beats continuously to send blood to lungs and rest of body.
• Much of heart consists of a special type of muscle called myocardium.
• When given sufficient oxygen & nutrients, the myocardium contracts rhythmically &
automatically.
CHAMBERS OF THE HEART
• Septum – divides the interior of the heart into right & left halves.
• Each half has two chambers
• Upper chambers – atrium
• Lower (larger) chambers – ventricle
• One way valves are at the exit of each heart chamber guaranteeing that blood can only
flow one direction.
CHAMBERS OF THE HEART
• Right atrium serves as a natural pacemaker, controlling the rate at which the heart beats.
• This area sends an electrical impulse through the heart causing it to contract.
• This contraction forces blood forward into the ventricles.
• Within milliseconds, the same electric charge causes ventricles to contact, increasing the
pressure of blood in the heart. This increased pressure causes the valves to close,
preventing backflow.
CIRCULATION IN THE HEART
• Blood that has been depleted of oxygen but contains carbon dioxide and waste matter is
carried to the heart by two large blood vessels called the vena cava.
• This blood enters the right atrium, is transferred to the right ventricle, and is then
pumped to the lungs.
• In the lungs, the blood picks up oxygen from inhaled air and releases carbon dioxide.
• The newly oxygenated blood returns to the heart.
• Newly oxygenated blood enters the left atrium, is transferred to the left ventricle, and is
then pumped to all the tissues of the body.
BLOOD
• Fluid that transports all of the substances your body needs to sustain life.
• Oxygen, hormones, and nutrients.
• It also carries away waste that cells produce.
• 55% of the total volume of blood is made up of plasma (fluid in which other parts of the blood
are suspended). Plasma is most water, contains many important nutrients, salts, proteins, and blood
cells. Blood cells include white & red blood cells.
RED BLOOD CELLS
• Carry oxygen from the lungs to the body tissues, where oxygen is exchanged for carbon
dioxide.
• Each red blood cell contains hemoglobin (oxygen carrying part of blood).
• Rich in iron
• Binds with oxygen in lungs and releases oxygen in tissues
• Is the pigment that gives blood its red color
WHITE BLOOD CELLS
• Principle role is to protect body
against infection and to fight
infection when it occurs.
• Larger than red blood cells, but few
of them.
• Production increases when there is
infection in the body.
PLATELETS
• Platelets are the smallest type of
blood cell. They prevent the body’s
loss of blood.
• Initiate a chain reaction that causes
blood to clot.
BLOOD VESSELS
• Blood is distributed throughout the body through a network of vessels.
• More than 60,000 miles of blood vessels in your body!
• They are divided into 3 groups:
• ARTERIES
• CAPILLARIES
• VEINS
ARTERIES
• Vessels that carry blood away from the heart.
• Pulmonary arteries carry blood from right ventricle (RV) to
lungs.
• Systemic arteries carry blood from left ventricle (LV)
through aorta.
• Arteries are flexible tubes with a smooth inner lining and thick
walls so it can withstand the high blood pressure it is subjected to
every time the heart beats.
• Arteries branch off into smaller vessels called arterioles
(arterioles then break off into capillaries).
CAPILLARIES
• The smallest blood vessels.
• Carry blood between arterioles and
small vessels called venules.
• Form a network throughout the body’s
organ and tissues.
• Some are 50 times thinner than a single
strand of hair.
• Can open & close in response to body’s
needs.
• Play a role in regulating body temperature.
VEINS
• Capillaries lead into tine vessels called
venules. The venules join to form veins.
• Veins are vessels that return deoxygenated
blood toward the heart from the body’s
organs and tissues.
• 2 main exceptions: pulmonary veins (carry
O blood from lungs to left side of heart) &
portal vein.
• Blood pressure in veins is lower than it is
in arteries.
YOUR BLOOD IS NOT
BLUE
• A common myth is that your
deoxygenated blood is blue but
when it hits oxygen (wound) it turns
red.
• Your blood is AWLAYS red.
Oxygenated or deoxygenated.
• Light wavelengths (specifically
red/blue) and their absorption into
skin give it the bluish look.
LYMPHATIC SYSTEM
• Supports the circulatory system.
• All body tissues are bathed in a watery fluid that comes
from blood. Much of this fluid returns to the blood
through walls of capillaries. The remainder is carried to
the heart though the lymphatic system.
• Serves 2 functions:
• Drains tissue fluid back into bloodstream
• Fights against infection.
• Lymphatic fluid is circulated by movement for the body’s
muscles.
LYMPH
• A clear yellow fluid that fills the
spaces around body cells.
• Made up of proteins, fats, and
lymphocytes (white blood cells that
protect against pathogens).
• 2 main types of lymphocytes:
• B CELLS
• T CELLS
• - killer cells
• - helper cells