Transcript The Circulatory System

The Circulatory System (also called
the cardiovascular system)
Objectives
• To be able to compare and contrast the
three types of blood vessels
• To understand the function of valves in
veins
• Many invertebrates don’t have a
circulatory system
• Their cells are close enough to their
environment for oxygen, wastes, nutrients,
and other gases to simply diffuse into and
out of their cells
• In many multi-cellular animals, especially
land animals, this won’t work. Their cells
are not close enough to the external
environment for diffusion and osmosis to
function quickly enough in exchanging
needed gases
Closed Circulatory System
Components of the Circulatory
System
• Heart
• Blood vessels
• Blood
Functions of the Cardiovascular
System
• Picks up needed oxygen from the lungs
and transports it to all the cells in the body
• Rids the body of the waste product,
carbon dioxide, by delivering it to the lungs
to be removed
• Helps keep the body healthy with its
“germ- fighting” white blood cells
• Delivers nutrients from food to all body
cells
Anatomy of the Heart
Four chambers of the heart
• The two upper chambers are the atriathey collect blood from incoming blood
vessels and transfer it to the ventricles
• The two lower chambers, the ventricles
are the pumping components of the heart;
responsible for pumping blood to the lungs
and to the rest of the body
Valves
• Valves prevent the back flow of blood in
the veins
• They are also found in the heart and keep
blood flowing from atria to the ventricles
• The “lub dub” sound you hear in the
heart is caused by the opening and closing
of the valves
HEART
The right side of the
heart contains
deoxygenated blood
(blood low in oxygen and
high in carbon dioxide
(CO2)).
The left side of the heart
contains oxygen rich
blood.
The right side of the heart contains
deoxygenated blood and the left side
contains oxygen rich blood
• You have about 100,000 km of blood
vessels laid out in your body. Laid
end -to -end that is enough to circle Earth
2.5 times!
Arteries verses Veins
• Thicker walls than
veins
• Blood carried here is
under high pressure
• Usually carries blood
away from the heart
to the body cells
• Walls made three
layers of smooth
muscle
• Walls of veins thinner
than arteries
• Blood carried here is
under lower pressure
• Usually carries blood
towards the heart
• Walls made of three
layers of smooth
muscle
• Most contain valves
Only Veins Have Valves,
Arteries Do Not Have Valves
Valves prevent the backflow of
blood
How Does Blood go from your legs to your
heart?
• Contraction of skeletal muscles when you walk
or run help push blood towards the heart
• One way valves help keep blood moving in one
direction
• Breathing causes contraction of chest muscles
which also squeeze blood forward
Capillaries
• These are the tiniest of
the blood vessels
• They connect veins to
arteries
• Their job is to distribute
oxygenated blood coming
from arteries to all body
tissues, and then move
deoxygenated blood from
tissues to the veins
(through diffusion)
Capillaries
• Walls of capillaries are made of flattened
endothelial cells
• These cells are permeable, enabling
substances to quickly diffuse through the
capillary walls
• When the arteriole branches into the
capillaries, the total cross- sectional area
increases, slowing down blood flow, giving
more time for the exchange of substances
Capillaries
• Capillaries are so
narrow that many red
blood cells travel
single file through
them!
• Each cell in the body is very close to a
capillary- no further apart than the
thickness of 4 sheets of paper.
• Most tissues have a rich supply of blood,
but some are poorly vascularized, such as
tendons and ligaments, and the cornea
and lens in the eyes have no capillaries at
all
• In places where activity is higher, there is
a rich supply of capillaries: heart,
digestion, bone, skeletal muscles, lungs,
liver, brain, etc
Interesting Fact..
• Capillaries may be flooded with blood at times,
or completely bypassed depending on the need
of the body at that time. Here is an example:
• Between meals, when digestion isn’t taking
place, blood bypasses most of the capillaries in
the digestive tract
• After a meal, much of the blood is directed to the
capillaries in the digestive tract in order to power
digestion
• Why might it be a bad idea to engage in
vigorous exercise just after eating a meal?
• The body may not have enough blood to
supply both the digestive tract and the
skeletal muscles, resulting in abdominal
cramps
What is blood?
• Blood is a little thicker than water, has a
little bit of a salty taste
• In the adult body there is about 10 pints of
blood circulating around
• If you took a machine, called a centrifuge,
and placed blood in it, you would see the
layers of blood
• This machine spins things around, and the
heavier parts sink to the bottom. Red
blood cells are heaviest, plasma lightest
Composition of Blood
• Plasma- makes up 55% of total blood
volume
• Red blood cells- make up 40% of total
blood volume
• Platelets- make up 4% of total blood
volume
• White blood cells-make up 1% of total
blood volume
Composition of Blood
Amazing!
Plasma
• The liquid portion of the blood
• It is 90% water and contains nutrients,
proteins, salts, hormones, and waste
products
• Transports red blood cells and white blood
cells through out the body
Red Blood Cells
• Also called erythrocytes
• They do not have a nucleus;
survive about 120 days
• RBC’s are the only cells in
the body that lack
mitochondria
• They have a characteristic
flattened-disc shape, or
donut shape
• They are soft and flexible
• They contain an iron- rich
pigment called hemoglobin
which binds very well to
oxygen and gives red blood
cells their color
• For this reason, RBC’s are
the main transport system for
oxygen in the blood
White Blood Cells
• Also called leukocytes
• Tend to be larger than red
blood cells
• They are colorless because
they lack hemoglobin
• Their job is to fight infections
when microorganisms enter
the body
• RBC’s, WBC’s, and platelets
are produced in the bone
marrow
• The body can produce more
white blood cells in response
to an infection
Platelets
• Irregularly-shaped, colorless bodies that
have a sticky surface to stop bleeding
• Also called thrombocytes, they are the
blood clotting agents in the blood
• Only survive about 9 days and are being
constantly replaced by the bone marrow
How do Platelets Work?
• When there is an injury, platelets sense
the presence of air and break apart
• They react with the presence of fibrinogen
and form fibrin, a protein which resembles
tiny threads
• The fibrin then forms a web-like mesh that
traps in red blood cells
• This mesh of red blood cells hardens as it
dries it, forming a clot, or a “scab”
Platelets rushing to the site of
an injury
Fibrin forms a net that traps in red
blood cells and helps stop bleeding.
• Vitamin K and calcium must be present in
the blood for normal blood clotting- can
bleed to death if missing from blood
• A bruise in an internal clot, a scab is an
external clot- both lead to healing
• A clot in the artery sometimes occurs and
can be serious- it can prevent the flow of
blood, can result in a stroke or a heart
attack
Tips for taking care of your heart…
• Do not smoke, and avoid being around
second hand smoke
• Eat less foods with saturated fat and
cholesterol
• Eat low sodium foods
• Engage in regular physical activity for 30
minutes everyday
• Maintain a healthy weight
• Maintain a blood pressure around or under
120/80
• Keep total cholesterol under 200
Aerobic-Type Exercise
Strengthen the Heart Muscle
Blood pressure
• Blood pressure is the force exerted on the
walls of your blood vessels (artery) as
blood flows through them
• Normal blood pressure is 120/80
• A reading of 140/90 is borderline
hypertensive (high blood pressure)
• Blood pressure is measured by a device
called a sphygmomanometer
• Your heart is a like pump. When it
contracts, or beats, it sends a surge of
blood through the blood vessels. This is
called your systolic pressure
• When the heart relaxes between beats,
your pressure decreases. This is called
your diastolic pressure.
120
___
Systolic pressure (lub) load phase
80
Diastolic pressure (dub) reload
Hypertension (high blood pressure)
• Hypertension is known as the “silent killer”
because it can creep up on people.
• It adds to the workload of your heart and arteries
• The heart must work harder and the arteries
carry blood under higher pressure
• If high blood pressure continues for a long time,
your heart and arteries may not work as well
• Combined with obesity, high cholesterol,
diabetes, and smoking, the risk of heart attack or
stroke increases dramatically
• Would you rather exercise 1 hour a day, or
be dead 24 hours a day?
• Aerobic exercises, such as fast walking,
running, soccer, biking, skating, and roller
blading, are good for your heart!
Cholesterol
• Normal cholesterol levels should be under
200
• HDL-high density lipoproteins (good
cholesterol)
• LDL- low density lipoproteins (bad
cholesterol)
Cholesterol…not so bad
•
•
•
•
Cholesterol occurs naturally in our bodies
It is manufactured normally by the liver
It helps keep the brain healthy
The liver uses cholesterol to make sex
hormones and the hormone, adrenaline
• It also uses cholesterol to make bile
• It is a main component of our cell membranes
• Cholesterol is not bad unless we have too much
of it in our bodies
HDL and LDL in the Body
• Cholesterol can’t dissolve in blood so it is
carried by lipoproteins
• When too much LDL cholesterol circulates
the blood it can slowly build up in the walls
of the arteries, leading to atherosclerosis
• HDL is thought to carry cholesterol back to
the liver so that it may be passes from the
body, thus protecting against heart attacks
Which type of foods contain
cholesterol?
• Meats and dairy products
Diseases
Atherosclerosis
• A condition that leads to hardening of the
inside walls of arteries (due to plaque)and
can lead to coronary artery disease
• Plaque deposits build up inside the
arteries; some normally as we age
• Plaque is made up mainly of fat
cholesterol, and calcium
• Plaque build up begins in childhood and
continues through life
Atherosclerosis
• Over time plaque build up
leads to narrowing of the
arteries which reduces
the amount of blood and
oxygen that reaches the
heart muscle
• If it completely blocks the
flow, can cause a heart
attack
• It can also cause a blood
clot, which also impedes
blood flow to the heart
Angioplasty
A treatment for
atherosclerosis-here
a thin catheter with a
deflated balloon is
inserted in the
blocked vessel. Once
inside it the balloon is
inflated, crushing the
plaque build up and
opening up the
pathway for blood
flow.
Heart Failure
• Failure of the heart
muscle to pump
enough blood through
the body
• As a result, some
organs, such as the
kidney, liver, and
lungs may not get
enough oxygen and
nutrients
Heart Attack
• A part of the heart
muscle dies as a
result of a blocked
blood vessel that
supplies the heart
with blood
• Heart cells do not go
through mitosis, so
when they are lost
they can not be
replaced
Stroke-caused by a blocked blood vessel in the brain;
afflicted area is deprived of oxygen and nutrients which
results in a variety of symptoms, like speech problems, or
the inability to move an arm
Deep Vein Thrombosis (DVT)
• DVT is a clot in the vein, usually in the
lower leg, or the thigh
• Sometimes they can break apart and
move to the lungs
• This is called a pulmonary embolism, if
the clot is large enough or if there are
many,this can be life threatening
• Show students the animation (favorites)
Varicose
Veins
• To return blood back to the
heart, veins in your legs
must work against gravity
• As you get older veins lose
their elasticity, causing them
to stretch
• The valves in your legs may
become weak, allowing
blood that should be moving
towards your heart to flow
backwords
• This results in pooling of the
blood. It appears blue
because it contains
Varicose Veins