Download Circulatory System 2

Investigation #3:
Examining the direction of blood
flow in the veins of the forearm
Procedure
Capillaries
• The finest type of
blood vessels connecting
the arterioles and
venules
• They reach all parts
of the body
• Very thin walls–
only one cell-thick
• Allow materials to be
• Lumen is only big
exchanged between the
enough for one RBC
blood and body tissues,
to pass through at
e.g. oxygen, glucose, etc.
a time
Exchange of substances between
blood and body cells (Video)
Adaptations of capillaries
for the exchange of materials
In order for the diffusion of substances
between blood and body cells to occur
more efficiently:
• The capillary wall is only one-cell thick
• The cross-sectional area is very large
and thus blood flow is slow
• Large branching of the capillaries
Investigation #4:
Examining the capillary
flow in a fish’s tail fin
Procedure
Arteries
Veins
Capillaries
Thickness of
wall
Away from Towards
heart
heart
Thick
Thinner
Presence of
pulse?
Yes
No
From arteries
to veins
Only one-cell
thick
No
Rate of blood
pressure
Highest
Lowest
Low
Presence of
valves?
No
Yes
No
Size of lumen
Sm
Large
Very small
all
Near art.: Ox
Oxygenated Deoxygenated
Near vein: Deo
Deep under Near surfaceNear all cells
skin
Direction of
flow
Condition of
blood
Location of
vessel
Varicose Veins
Varicose Veins
• The result of
problems with valves
within the veins of
the leg
• Blood is conducted
back into the leg
instead of up to the
heart, causing blood
to accumulate
• Pressure causes the
veins to bulge and
become visible
Varicose Veins
Arteriosclerosis
• The hardening and/or thickening of
the blood vessel walls
• Cholesterol and other fatty materials
harden the walls by producing plaque
along the inner core of the vessels
• As the vessel walls become
increasingly thicker, the passageways
through the vessels narrow
• Result in decreased blood supply and
increased blood pressure
Arteriosclerosis
• Due to the arterial walls becoming
weaker and less elastic, the high
blood pressure may cause the
arteries to burst
• If the arteries are in the brain,
the brain cells will lack nutrients
and oxygen, resulting in death of
the cells – this condition is referred
to as a stroke
Arteriosclerosis
Bruise
• Blood vessels are
damaged or
broken as the
result of a blow to
the skin
• The raised area
of a bump or
bruise results
from blood leaking
from these injured
blood vessels into
the tissues
The Human Heart
• Muscular organ
inside thorax
(between lungs)
• Weighs about 300g
• Protected by
pericardium
• Contracts and
relaxes to pump
blood around the
body
Answers:
• Aorta
• Pulmonary
artery
• Left atrium
• Left ventricle
• Septum
• Inferior venae
cavae
• Right ventricle
• Right artrium
• Semilunar valve
• Superior venae
cavae
External Structure of
Heart
1
1
2
2
Structures of the Heart
• The heart is made up of 4 chambers –
2 atria (singular: atrium) and 2
ventricles
• The atria have thinner walls than the
ventricles, whereas the right
chambers have thinner walls than the
left chambers
• The left chambers and the right
chambers are separated by a septum
to prevent the mixing of blood
3
3
Structures of the Heart
• The right atrium receives
DEOXYGENATED BLOOD via the
superior vena cava (blood from
upper part of body such as head
and arms) and inferior vena cava
(blood from lower part of body such
as legs)
• It receives blood from all parts of
the body except for the lungs
4
Structures of the Heart
• The blood is pumped from the right
atrium into the right ventricle
• The right ventricle then pumps the
DEOXYGENATED BLOOD to the
lungs via the pulmonary artery
(remember: artery = away from
heart)
5
Structures of the Heart
• The left atrium receives
OXYGENATED BLOOD from the
lungs via the pulmonary veins
6
Structures of the Heart
• The blood is pumped from the left
atrium into the left ventricle
• The left ventricle then pumps the
OXYGENATED BLOOD to all parts of
the body via the aorta
• A huge pressure is needed to pump
blood all over the body, and
therefore the left ventricle and aorta
must be able to withstand the
greatest pressure
7
7
7
Heart Valves
Heart valves ensure that blood only
flows in one direction:
• Tricuspid valve – between the right
atrium and right ventricle; it is called
“tricuspid” because it is made up of
three flaps
• Bicuspid valve – between the left
atrium and left ventricle; it is called
“bicuspid because it is made up of
only two flaps
Heart Valves
Heart valves ensure that blood only
flows in one direction:
3) Semilunar valve – found at the base
of the aorta and the pulmonary
arteries; it is called “semilunar”
because it looks like a half-moon
Heart Valves
Valve opened –
Valve closed –
blood flows through
Blood flow is blocked
Heart Valves
Opened valve Closed valve
Heart Valves
Chordae Tendineae
• The valves are
attached to
chordae tendineae
(heart tendons)
which are
attached to
papillary muscles
• The strings
prevent the valves
from turning
inside-out
Cardiac Muscles
• Make up the wall of the heart
• Muscles that are never tired
• Throughout life, the muscles contract some
70 times per minute, pumping about 5 liters
of blood each minute
• The cells are joined end-to-end
• Each cell has a single nucleus
• Cardiac muscles are controlled involuntarily
(contract on their own rhythmically)
Cardiac Cycle
• Sequence of events taking place in
the heart during ONE heartbeat
• One cycle lasts for about 0.8
second
• The pumping action of the heart is
carried out by the contraction and
the relaxation of the atria and
ventricles
• Contraction of the heart –
SYSTOLE
3 Stages of Cardiac Cycle
•
•
•
Atrial systole (0.1 second)
Ventricular systole (0.3 second)
Diastole (0.4 second)
Total cardiac cycle: 0.8 second
Atrial Systole
• Just prior to atrial contraction, both the
atria and ventricles are relaxed
• The semilunar valves connecting the
ventricles to the major arteries are closed
• The valves in the venae cavae and
pulmonary veins are forced to close by the
high blood pressure in the atria
• However, the atrioventricular
(bicuspid/tricuspid) valves that connect the
atria to the ventricles are open
Atrial Systole
• Blood flows continually from the veins into
the atria, filling these chambers
• Some of this blood passes through the open
atrioventricular valves to the ventricles
• When the atria contract, they force the
remaining blood contained in them to flow
into the ventricles
• By the end of atrial contraction, the
ventricles contain a full supply of blood
while the atria contain virtually none
Ventricular Systole
• The ventricles begin to contract, the
pressure within them quickly exceeds
that within the atria, forcing the
atrioventricular valves to close
(First heart sound: “lub”)
• As ventricular contraction continues, the
pressure within the ventricles reaches a
point where it exceeds that in the aorta
and the pulmonary arteries
Ventricular Systole
• At this point, the semilunar valves open,
and the blood from the ventricles is
ejected through these valves into the aorta
and pulmonary artery
• At about the same time that the ventricles
enter systole, the atria begin to relax
• Blood flows into the left atrium from the
pulmonary veins and into the right atrium
from the superior and inferior vena cavae
Diastole
• The ventricles start to relax and the
pressure within the ventricles decreases
• Once the ventricular pressure becomes
lower than the pressure in the aorta and
the pulmonary artery, the semilunar valves
close (Second heart sound: “dup”)
• As the ventricles fully relax, the
ventricular pressure becomes lower than
the pressure in the atria. This allows the
atrioventricular valves to open
Diastole
• Because the ventricles are now in
diastole and the atrioventricular
valves are open, some of the blood
that has been flowing into the atria
flows through the open valves into
the ventricles. The ventricles
reach about 80% of their capacity
before the atria begin to contract
and the cardiac cycle is repeated
Cardiac Cycle
Blood Pressure
• Blood pressure is a
measurement of the
force applied to the
walls of the arteries
as the heart pumps
blood through the
body. The pressure
is determined by the
force and the amount
of blood pumped, and
the size and flexibility
of the arteries
Blood Pressure
• Systolic blood pressure - the maximum
pressure exerted when the heart
contracts
• Diastolic blood pressure - the pressure
in the arteries when the heart is at rest
• Generally, in adults, the systolic
pressure is approximately 120 mmHg,
and the diastolic pressure is
approximately 70 to 80 mmHg
• The contraction
of the atria
causes a rise in
pressure
• The pressure
pushes any blood
left in the atria
into the
ventricles
• As the ventricles
contract the
ventricular pressure
begins to rise
• As soon as the
ventricular pressure
surpasses the atrial
pressure the A-V
valves close (1)
• The rapid closing of
the valves causes a
rise in pressure in
the atria
• The pressure in
the ventricle
continue to
increase rapidly
• The pressure
quickly rises to a
point above that
of in the
aorta/pulmonary
artery (2)
• The aortic and
pulmonary valves are
forced open and
blood flows into the
aorta and pulmonary
artery
• When the
ventricular pressure
becomes lower than
the aortic/pulmonary
pressure, the aortic
and pulmonary valves
are forced to close
(3)
• When the ventricular
pressure drops below
that of the atrial
pressure, the A-V
valves open (4)
• The blood pressure
which has slowly
built up in the atria
causes blood to
quickly flow into the
ventricles
• Cycle is repeated
Effects of exercise on pulse rate
•
•
•
•
Increased blood flow to skeletal muscles
Increased blood flow to heart muscles
Increased blood flow to skin
In other words, pulse rate will increase
when we exercise
• The more vigorous the exercise, the
faster the pulse rate (why?)
• A greater pulse rate leads to a longer
recovery time (why?)
Effects of exercise on pulse rate
• We can use a data logger to
measure a person’s pulse rate
• A pulse rate sensor is clipped to
the person’s ear lobe or the tip of
the index finger
• The pulse rate will be shown on a
computer
Control of Heart Beat
• The heartbeat (heart rate) is normally
governed by the frequency of electrical
signals which are generated by the heart's
natural pacemaker
• Electrical signal from the pacemaker
stimulate the cardiac muscles to contract
• The rate of heart rate can be changed by
the action of nerves and hormones
• If the natural pacemaker fails to work,
artificial pacemaker may be inserted into
the heart
Blood Circulation
The blood circulation in humans is
a double circulation. It consists
of:
• Pulmonary circulation – circulation
through the lungs and the heart
• Systemic circulation – circulation
through the heart and the rest of
the body
The Double Circulation
Questions
•
•
•
What happens during the
pulmonary circulation?
What happens during the systemic
circulation?
What is the advantage of having a
double circulation?
Pulmonary Circulation
• Deoxygenated blood is carried from
the body cells to the right side of
the heart via the venae cavae
• Blood is pumped from the heart to
the lungs via the pulmonary artery
• Blood drops off carbon dioxide and
picks up oxygen at the lungs
• Oxygenated blood is returned to the
left side of the heart via the
pulmonary vein
Systemic Circulation
• Oxygenated blood is pumped from the
left side of the heart to all parts of the
body (except the lungs) via the aorta
• When the blood reaches a particular
organ, oxygen and nutrients are dropped
off whereas carbon dioxide and other
wastes are picked up
• The venae cavae carries deoxygenated
blood back to the right side of the heart
Advantage of a Double Circulation
• Since the oxygenated blood is
returned to the heart first, it can
be pumped to the rest of the body
under a high pressure
• The high pressure allows blood
(containing oxygen/nutrients and
carbon dioxide/wastes) to be
transported rapidly
Coronary Heart Disease
• Coronary heart disease develops when
one or more of the coronary arteries
that supply blood to the heart become
narrower than they used to be
• This happens because of a buildup of
cholesterol and other substances in the
wall of the blood vessel, affecting the
blood flow to the heart muscle
• Many people experience chest pain or
discomfort from inadequate blood flow to
the heart
Coronary Heart Disease
As coronary heart disease develops,
more damage to the heart occurs and
the following conditions may develop:
• If the heart is not getting enough
oxygen, a person may experience pain or
discomfort in the chest known as angina
• If blood flow to any part of the heart is
completely blocked, the cells in that part
of the heart begin to die, causing a
heart attack
Coronary Heart Disease
Treatments:
• Coronary bypass operation rerouting the blood flow around
the obstructed part of the artery
• Angioplasty - widen narrowed or
blocked arteries using an inflated
balloon
Lymphatic System
Lymphatic System
Tissue fluid
Lymph
Lymph vessels Lymph nodes
Lymphatic System
Tissue Fluid
• Tissue cells are bathed in tissue fluid
• Serves as the medium for the
exchange of materials between the
blood and the cells
• Its composition is similar to that of
plasma (contains glucose, amino acids,
minerals, etc.)
• However, plasma proteins and RBC’s
are too big to pass into the tissue
fluid
Tissue Fluid
• Due to the high pressure of blood
at the arterial end, some plasma in
the blood is forced out through the
capillary wall into the spaces among
the tissue cells, forming tissue fluid
Tissue Fluid
• At the venous end, blood pressure
has greatly decreased. Also, water
potential of the tissue fluid is
higher than that of blood because
of the lack of plasma proteins
• Therefore most of the tissue fluid
will return back to the blood
Tissue Fluid
• Tissue fluid also helps to regulate
blood pressure
• If blood pressure is too high, more
fluid will be moved out of the
capillaries
• If blood pressure is too low, less
fluid will be moved out of the
capillaries
Lymph Vessels
• Thin-walled
• Blind-ended
• Small lymph capillaries join into larger
lymph vessels
• Fluid inside the lymph vessels (lymph)
moves forward due to the contraction
of surrounding skeletal muscles
• Lymph vessels, like veins, contain
valves to prevent backflowing of lymph
Lymph Vessels
• Tissue fluid that is not returned to
the capillaries are collected into
the lymph vessels
• Lymph in lymph vessels is drained
into the lymphatic duct and then
into a large vein near the neck
region. Thus all the tissue fluid is
eventually returned to the
circulatory system
Lymph Nodes
• Swellings/filters along lymph vessels
that produce and store white blood
cells
• Viruses, bacteria, cancer cells and
other unwanted substances are
trapped and killed by the white
blood cells at the lymph nodes
•
•
What are the functions
of lymphatic system?
Collects and carries excess tissue
fluid back to the blood stream
(What happen if the lymph vessels
in an organ are blocked?)
It consists of lymph nodes for
filtering unwanted substances.
Lymph nodes also produce white
blood cells (What type of WBC’s
are produced by the lymph nodes?)
What are the functions
of lymphatic system?
3) It transports absorbed fats from
lacteals in the small intestine to the
blood stream
Blocking of Lymph Vessels
• Blocking of lymph vessels and leading
to the swelling in tissues – edema
• Due to the accumulation of tissue fluid
• Reasons causing lymph vessels blockage
– injury, inflammation, infection, etc.
• Elephantitis – lymph vessels are
blocked by roundworms that are
transmitted by mosquitoes