Transcript Circulatory System PPT

Circulatory System
Functions of the Circulatory System:
1. Transports nutrients from
intestines to all cells of the body
• some cells require more
nutrients than others
(ex. brain cells, liver cells,
active muscle cells)
2. Transports nitrogenous wastes
from cells of the body to the
kidneys
• your cells produce
nitrogenous wastes when
they break down proteins
3. Transports oxygen from your
lungs to cells of the body
• cells need O2 to produce ATP
(energy)
This process is called
aerobic respiration
4. Transport carbon dioxide from
your cells to the lungs to be
exhaled
• CO2 is a by product of
aerobic respiration
5. Transports hormones from the
endocrine gland that produce
them to their target cells
• insulin is produced in your
pancreas
• it is transported in your
bloodstream to cells in
muscles and liver
6. Distributes heat throughout the
body
• if you are too hot, blood is
brought to your skin so the
heat can be removed as
sweat evaporates
• if you are too cold, blood
flow to the skin is restricted,
allowing you to conserve
heat in the body
Components of the circulatory system
A. Blood vessels – function to
transport blood throughout
the body
5 major types of blood vessels
1. Arteries – vessels that
transport blood away
from the heart
• they usually carry
oxygenated blood
2. Arterioles – small arteries
• important because the
smooth muscle in their
walls can constrict and
relax
• constricting arterioles to
one area of the body
reduces blood flow to
that area
• example – when you are
cold, you constrict the
arterioles that send
blood to your skin
3. Capillaries – the smallest of all
blood vessels (some are
slightly larger than a single
red blood cell)
• capillaries are important
because their walls are
thin enough to allow the
exchange of materials
(O2, CO2, wastes,
nutrients, and hormones)
• you have several
thousand miles of
capillaries
4. Veins – vessels that return
blood to the heart
• they usually carry
deoxygenated blood
• the largest veins in the
body are the inferior and
superior vena cavae (~
1.2 inches in diameter)
• the vena cavae empty
blood returning from the
body into the heart
• veins differ in structure
from arteries in that
veins:
are often larger in diameter
have thinner walls because blood
pressure in the veins is much
less than that in the arteries
have one-way valves that prevent the
back flow of blood (keeps blood
moving toward the heart)
5. Venules – (= “little vein”) – tiny
vessels that transport blood
from the capillaries to the
veins
heart  arteries  arterioles 
capillaries  venules  veins 
back to the heart
Blood pressure varies as it flows
through each type of vessel
• blood pressure is highest in the
artery leaving the heart (aorta)
• blood leaving the heart must
be pumped under great
pressure so that it can travel
through the body
• blood pressure falls steadily
as it moves through the
circulatory system
It is lowest in the veins
emptying into the heart (vena
cavae)
B. Lymphatic vessels – function to
collect fluid that leaks from
the capillaries and return it
to the circulatory system
• about 3 liters of fluid leak from
your capillaries each day
• this could be harmful to your
health because you have only 5 –
6 liters of blood
• capillaries leak because they are
so thin (only 1 cell layer thick)
• every time your heart beats, fluid
is forced out of the capillaries
and into the surrounding tissues
• this fluid enters lymphatic
capillaries where it is now called
lymph
• lymph flows into larger and
larger lymphatic vessels, in a 1way direction toward the heart
• lymph is cleaned by tiny
structures called lymph nodes as
it makes its way toward the heart
• some lymph nodes are scattered
along lymphatic vessels, while
others are concentrated in
specific areas (armpit, neck)
• If you have an infection in your
hand, lymph nodes in the armpit
on that side of the body become
painfully swollen (filled with
dead bacteria that have been
filtered out of lymph returning
from the hand)
• clean lymph is dumped into 2
large veins that enter the heart –
returning this fluid to the
circulatory system
C. Blood – is made up of liquid
(plasma) and 3 kinds of
solids
1. Plasma makes up 55% of the total
blood volume
Plasma contains:
• a large amount of water
• metabolites (ex. glucose,
vitamins, and hormones)
• nitrogenous wastes (ex. urea)
• salts and ions (ex. sodium ions,
chloride ions, and bicarbonate
ions)
• proteins
2. Solids make up 45% of the total
blood volume
The 3 major solids found in
blood are red blood cells,
white blood cells, and
platelets
Red blood cells (erythrocytes) are
flattened disks that function
to transport oxygen
• they are able to transport oxygen
because they are packed with
hemoglobin – a protein that
binds to O2 in the lungs and
releases it to the cells in the
body
• RBCs differ from all other cells in
the body in what they lose their
nucleus when they start
transporting O2
• since they do not have a nucleus,
they cannot reproduce
themselves and die after about 4
months – they must continually
be produced
• RBCs are produced in red bone
marrow
If more RBCs die than are produced,
you suffer from a condition
called anemia
• individuals with anemia feel
tired all the time because their
cells are not getting enough O2
White blood cells (leukocytes) are
larger than RBCs and
contain a nucleus
• they function to defend your
body against disease by
attacking and destroying
bacteria, viruses, and cancer
cells
• like RBCs, WBCs are produced
in red bone marrow
• sometimes cancer occurs among
pre-WBCs in the bone marrow –
called leukemia
Platelets are fragments that function
in blood clotting
• platelets circulating in your
blood vessels are inactive –
activated when blood vessel is
damaged
• once activated they release a
clotting protein that triggers a
series of reactions involving
about 14 other clotting proteins
If all clotting factors are present in
the blood, a fibrin net will be
formed
• this net traps other platelets,
RBCs and WBCs, forming a
clot
• this clot plugs the damaged
blood vessel, stopping
bleeding
If you are missing only 1 of the
clotting factors your blood will
not clot and you will be
suffering from a condition called
hemophilia (free-bleeders
disease)
Blood Typing:
The surface of each RBC in you
body displays about 100
different antigens
• the most important antigens
on the surface of your RBCs
are: A, B, and Rh
• the presence of the A and B
antigens determine your ABO
blood grouping, while the
presence of the Rh antigen
determines whether you are
positive or negative
1. ABO blood groupings in humans:
A, B, AB, or O
• individuals whose RBCs are
covered with A antigens (but
no B antigens) have type A
blood
If you have type A blood, you
have B antibodies (anti-B)
floating in your plasma
• individuals whose RBCs are
covered with B antigens (but
no A antigens) have type B
blood
If you have type B blood, you
have A antibodies (anti-A) floating
in your plasma
• individuals whose RBCs are
covered with both A and B
antigens have type AB blood
If you have type AB blood, you
have neither A or B antibodies in
your plasma
Knowing a person’s ABO blood type
is very important in performing
a blood transfusion
If you are given an incompatible blood
type, you will have a severe reaction
in which the antibodies in your
plasma attack the antigens on the
surface of the RBCs entering your
bloodstream, causing the RBCs to
agglutinate (clump) and rupture
• this type of reaction in called
hemolysis
• the ruptured RBCs release
hemoglobin, which may cause
kidney damage
2. Rh system
• this system is so named
because it was first worked out
in the blood of the Rhesus
monkey
• like the ABO grouping, the Rh
system is based on antigens
on the surface of your RBCs
• people whose RBCs have Rh
antigens are Rh positive
• people whose RBCs do not
have Rh antigens are Rh
negative
There are 8 possible blood types
with the ABO and Rh antigens:
A+, A-, B+, B-, AB+, AB-, O+, O-
The most common problem with Rh
incompatibility may arise during
pregnancy
• normally, there is no mixing of
the mother’s and baby’s blood
during pregnancy
• however, during the birthing
process, some of the baby’s
blood mixes with it’s
mother’s blood – if the
mother is Rh- and her child is
Rh+ she will begin producing
Rh antibodies
• fortunately this does not have
an effect on the present
pregnancy – however, if the
mother were to ever become
pregnant with another Rh+
baby, her Rh antibodies
(produced at the end of the 1st
pregnancy) would pass
through the placenta and
destroy the baby’s RBCs
Rh incompatibility is not much of a
problem presently because if an Rhwoman ever gives birth to an Rh+
child, she is immediately given a
shot of Rho-GAM, which stops her
body from producing Rh antibodies
• she must receive a shot of
Rho-GAM every time she
becomes pregnant with an Rh+
baby
Blood Groups in the U.S.
O
A
B
AB
Rh+
Whites
45% 41% 10% 4% 85%
Blacks
48% 27% 21% 4% 88%
Hawaiians 37% 61% 1.5% 0.5% 100%
Blood Types in Southeast U.S.
A+ = 1 out of 3
A- = 1 out of 16
O+ = 1 out of 3
O- = 1 out of 15
B+ = 1 out of 12
B- = 1 out of 67
AB+ = 1 out of 29
AB- = 1 out of 167
Disorders of the Blood
1. Anemia – RBC production slows
down (many different types)
2. Sickle cell anemia – inherited
condition in which abnormal
hemoglobin is produced,
causing their RBCs to
become deformed
• these deformed cells cannot
move through blood vessels
as easily as normal RBCs
• these blood clots may cut off
the blood supply to an organ
3. Mononucleosis – a contagious
disease caused by a virus
that infects the white blood
cells
• symptoms include fatigue,
headache, dizziness, sore
throat, and fever
• there is no cure, but with rest,
the individual usually suffers
no permanent ill effects
4. Leukemia – cancer of the WBCs
normal
leukemia
5. Hemorrhage – bleeding, either
internal or external