The Circulatory System

Report
The Circulatory and
Lymphatic systems
Blood

Blood is a fluid that circulates throughout the body.

It carries nutrients from digestive system to body
cells.

It carries oxygen taken up by respiratory system

It removes wastes produced by cell metabolism. *

The human body contains approx 5-6L of
blood.

*
Blood consists of:

A fluid component called plasma.

And formed elements :
– Red blood cells
– White blood cells
– Platelets
Function of blood components
Plasma :
–Makes up 55% of whole blood
–Is a yellowish liquid (mainly water)
in which red blood cells, white
blood cells and platelets are in
suspension.
–Also contains nutrients, antibodies,
hormones and metabolic waste .*
Red blood cells:
– Are concave on both sides and lack a nucleus
– Contain Hemoglobin (red pigment that
carries oxygen)
– Are produced in the bone marrow
– 45% of blood volume
*
 Oxygenated blood carries oxygen and is
bright red
 Deoxygenated blood depleted of
oxygen, carrying carbon dioxide and is
dark red (not blue).
*
White blood cells:
– Also called Leucocytes
– Are colourless
– Larger than red blood cells
 White blood cells protect the body by:
– Engulfing and digesting dead or damaged cells, old RBC’s,
and microorganisms
– Produce antibodies to neutralize invading organisms
*
Platelets:
 are red blood cell fragments
 Important in the clotting of blood
(clotting –the process
where the platelets
clump together and start
the formation of fibrin
filaments to form a solid
mass (a clot) and stop
the bleeding)
Fibrin filaments
Blood groups
 Red blood cells have proteins on their surface,
called antigens that provoke a clotting reaction
when they are introduced into another body.
 Blood is grouped according to the type of antigen it
contains and by the Rhesus factor.
 Blood typing is important for blood transfusions
 A blood transfusion is the injection blood products
(usually red blood cells) from one person to
another.

Blood type A
-has the A antigen (protein)
on its surface

Blood type B
-has the B antigen on its
surface

Blood type AB
-has both A and B antigen
on its surface

Blood type O
-has NO antigen on its
surface
Rhesus (Rh)factor

This Rh factor is another antigen determining
the compatibility for blood transfusions
– Rh+ means the antigen is present
– Rh - means the antigen is not present
Blood
can donate to
Type
+
+
+
+
can receive from
Rh-
A+, A-, AB+, AB-
A-, O-
Rh+
A+, AB+
A+, A-, O+, O-
B-, B+, AB-, AB+
B-, O-
Rh-
Rh+
B+, AB+
B+, B-, O+, O-
AB-, AB+
AB-, A-, B-, O-
Rh-
Rh+
AB+
Universal recipient
Rh-
Universal donor
O-
Rh+
O+, A+, B+, AB+
O+, O-
The anatomy of the
Circulatory System
The Heart

the heart has 4 chambers:
– Right and left atrium (1st chambers that blood
enters in heart)
– Right and left ventricle (last chamber before blood
leaves heart)
Left atrium
Right atrium
ri
Right ventricle
Left ventricle
(very muscular)
Heart Valve movie
Major blood vessels of the heart

Blood vessels are the plumbing of
body that assure the distribution
blood to the entire body.
 Two vessels leave the ventricles:
 The Pulmonary artery –blood is pumped
to the lungs.
 The Aorta – blood is pumped throughout
the body.

Two vessels enter the atria:
 The Pulmonary veins – bring blood back
from the lungs.
 The Venae Cavae – bring blood back from
the body.
the
of
Main blood vessels
Aorta
(blood to body)
Superior vena cava
(blood from the
upper body)
Pulmonary
artery
(blood to the
lungs)
ri
Inferior vena cava
(blood from the
lower body)
Pulmonary
vein
(blood from
the lungs)
Septum
Blood Vessels
Arteries

Arteries carry blood away from the heart to the
organs of the body

have thick, muscular,
walls to withstand high pressure.

The Aorta is the largest artery
in the body.

These large arteries progressively branch and get
smaller and smaller, becoming- arterioles, then
capillaries.
*
elastic
Capillaries

Capillaries are minute branches at the ends of
the arteries and veins.

They are permeable allowing the diffusion of
substances into all body cells which are within
50µm of a capillary.
*
Veins

Veins –go to the heart and have
thinner walls and are less elastic
than the arteries because there
is less pressure.

to help the blood to flow up from the extremities (e.g.
legs), veins have one way valves that prevent
backflow.

Leg muscle contractions help “pump”
blood back to the heart.

Capillaries turn into venules enlarging into
veins
returning to left atrium via the large Vena Cava.
the
*
How it works
When a heart beats it first
contracts the atria and then
the ventricles
1.
Deoxygenated blood returns
under pressure via the Vena
Cava into the relaxed right
atrium.
2.
Contraction of right atrium
forces blood into the right
ventricle.
*
3.
Ventricular contraction forces
blood through the Pulmonary
artery into the lungs.
Blood travels through smaller
arteries then arterioles and
finally the capillaries in single file.
The capillaries surround the minute air sacks
(alveoli) and allow the exchange of gases
(O2,CO2) between blood and inhaled air.
*

Oxygenated blood leaves the
capillaries of the lungs, first
through the venules, then
veins returning to the left
atrium via the pulmonary vein.

Contraction of the left atrium
forces the blood into the left
ventricle.
*
4.

Contraction of the left ventricle
forces the blood through the Aorta
throughout the body.
Arteries branch off the aorta and supply various organs and
tissues with oxygenated blood. The blood follows this path:
 Arterioles
 Capillaries – exchange of gases
 Venules
 Veins
 Vena cava
*
Blood pressure





Blood pressure is the force with which the blood
is pushing against the arterial walls.
Bp is measured in mm of mercury (mm Hg)
The systolic pressure is when the ventricular
pressure is at its maximum and the vessels are
expanded.
The diastolic pressure is when the heart is at
rest ( no contraction).
The pressure is given as a ratio of systolic 120
diastolic 80
(for adolescents normal bp is 113 mm Hg)
65
*
The lymphatic system
 Carries dissolved O2 and nutrients to the cells
 Collects cellular waste products
 plays an important role in the immune system
Lymph is:
 A fluid that fills the spaces between the blood
vessels and the body cells
 A fluid derived from the blood
*

Lymphatic vessels resemble blood vessels and
are close to them

The lymph returns to the circulatory system via
two veins near the heart.

The lymph relies on muscle movement for
circulation.
*
The lymphatic system comprises of the following
organs :
 The thymus- found underneath the heart
 The bone marrow- found in long bones
(femur)
 The spleen- found left of stomach under
diaphragm
 The tonsils- found in mouth bordering the
pharynx
*


The lymphatic vessels have lymph nodes
throughout the body.
When an infection occurs these nodes
swell and harden (e.g. A cold or tonsillitis)
*
Tonsils
The immune system

The ability of the body to protect itself against
antigens is called immunity.

Antigens are viruses, bacteria, abnormal cells
or other substances that produce an immune
reaction.

*


An antibody is a substance produced by
certain white blood cells that can neutralize
specific antigens.
*

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