Transcript Functions of The Human Circulatory System

Functions of
The Human Circulatory System
• The human circulatory system, or cardiovascular system, has the great
job of transporting oxygen and nutrients to the organs and tissues of
the body, and to carry away waste products.
• It regulates the body’s temperature and increases blood flow to meet
demands during exercise.
• This system also sends parts of the immune system (white blood cells
and antibodies) to fight off foreign substances upon their invasion.
• Should injury or bleeding occur, it sends clotting cells and proteins to
help stop bleeding and promote healing.
Bluish, deoxygenated blood enters the heart at the right atrium,
through the vena cava. It then drops down to the right ventricle
through a valve that opens only in one direction. Entering the
A single
of blood
longwhere
wayit is
pulmonary
artery, drop
the blood
next goesgoes
to thealungs,
“reimbursed”
with
oxygen,
becoming
brightInred
again.ifItall
goes
back
through
the
human
body.
fact,
the
to the heart through the pulmonary veins to the left atrium. This
arteries,
veins,
capillaries
adultis to
voyage
through the
lungs isand
pulmonary
circulation.inItsan
function
fill the
blood with
oxygenwere
from the
lungs. Next,
to the
left
human’s
body
placed
endit’stodown
end,
the
ventricle, the most powerful chamber of the heart. From here it
total
length
would
stretch
nearly
two
and a
enters
the aorta,
to the
body’s arteries,
then
arterioles,
to veinioles,
to veins,
finallyaround
back to the
vena
cava. Thisequator.
journey throughout
half and
times
the
earth’s
This
the body is called systemic circulation. Its mission is to bring oxygen
is over
(60,000
miles).
to the organs
and 100,000
tissues of thekm
body,
and to carry
away waste
materials back to the lungs, where they are exhaled. When blood is
being transmitted through the heart, that is coronary circulation.
Follow me!
Blood on the right side of the heart is
bluish and the oxygen has all been
used up. Blood on the left side,
however, is bright red and full of
oxygen to take to the body.
BLOOD
• Blood is made up of red and white blood cells, and
platelets, all carried in plasma:
– Red blood cells: bear oxygen
• Hemoglobin: bears iron (inside the red b.c.’s)
– White blood cells: fight disease (a part of the
immune system)
– Platelets: clot blood--this slows, stops bleeding
– Plasma: yellowish, it consists of water, salts,
proteins, vitamins, minerals, hormones, dissolved
gases, and fats.
BLOOD PRESSURE
• Blood pressure is the pressure generated when the pumping action of the
heart propels blood to the arteries.
• It’s measured using a sphygmomanometer, wrapped around the upper arm.
This is displayed as a ratio--average is 120/80.
• Blood pressure is measured during systole and diastole.
– Systole: active pumping phase of the heart.
– Diastole: resting phase between heartbeats.
Heartbeats are triggered by myocardium, the muscle forming the walls of the heart’s four
chambers. This muscle rhythmically and continuously contracts to pump blood. The pumping
phase of the heartbeat consists of two cycles: systole, the pumping of the heart; and diastole, the
resting in between pumps.
DISEASES OF THE HEART
• Hypertension
- High blood pressure: blood vessels narrow, making heart pump harder.
- Eventually the heart will need more oxygen. This can lead to heart failure or
brain stroke.
• Atherosclerosis
- High concentrations of cholesterol lead to plaque, which deposits on the sides
of arteries, reducing blood flow.
- Blood clots can form where plaque roughens artery walls.
- This causes damage to organs.
* When a brain artery is blocked--stroke.
* When a coronary artery is blocked--heart attack, and
heart muscle is destroyed.