Download Circulatory System

How much do you know?
1. How many blood cells are destroyed
in the human body in one second?
a) 150,000
b) 15,000,000
c) 150,000,000
2. A man’s heartbeat is faster than a
women’s. True or False?
a) True
b) False
How much do you know?
3. The adult's heart pumps about
15,140 litres of blood in what
amount of time?
a) One day
b) One hour
c) One week
How much do you know?
• 4. How long (on average) does it
take for blood to circulate around
the WHOLE body?
a) 23 seconds
b) 23 minutes
c) 23 hours
How much do you know?
7. Human blood on its own is clear in colour.
Haemoglobin, a pigment in the red blood
cells, is responsible for the red colouring
of the blood.
8. The average adult body contains
and an infant has about 1 litre.
5-6 litres of blood
The Circulatory System
The Circulatory System
• The function of a circulatory system is to carry blood
or hemolymph into close contact with every cell in
the body.
• The most sophisticated circulatory systems consist
of:
– one or more pumps called hearts
– arteries (tough, thick-walled tubes) that carry
blood away from the heart under high pressure;
– small vessels called capillaries whose walls are
just one cell thick, allows the exchange of gases
and other molecules with tissues in networks
called capillary beds; and
– vessels called veins that return blood to the
heart under low pressure
Functions of the Circulatory
System
• Transport oxygen to cells
• Transport nutrients from the
digestive system to body cells
• Transport hormones to body cells
• Transport waste from body cells to
excretory organs
• Distribute body heat
How Are Oxygen and Carbon Dioxide Transported
in Blood?
•Blood : connective tissue that consists of
cells in a watery extracellular matrix called
plasma
•Remainder of the blood is made up of
formed elements: platelets, red blood
cells, and several types of white blood
cells:
•Platelets : Cell fragments that minimize
blood loss from ruptured blood vessels by
releasing material that assists in the
formation of clots
•White blood cells: which are part of the
immune system fight infections
RBCs
• Red blood cells (RBCs):
– transport oxygen from the lungs to
tissues throughout the body
– critical role in transporting carbon
dioxide from tissues to lungs
• In humans, red blood cells make up
99.9% of the formed elements.
– contain an oxygen-carrying molecule
called hemoglobin
Circulation
Pulmonary Circuit
Systemic Circuit
How Does the Heart Work?
• In animals with closed circulatory systems,
the heart contains at least two chambers.
• the atrium receives blood returning from
circulation
• the ventricle generates force to propel the
blood through the system.
• Atria are separated from ventricles by
atrioventricular valves.
• The number of distinct heart chambers has
increased as vertebrates diversified.
How Does the Heart Work?
• Vertebrates evolved two separate pumping
circuits:
– The pulmonary circulation is a lowerpressure circuit to the lungs.
– The systemic circulation is a higherpressure circuit to the rest of the body.
pulmonary vein
pulmonary artery
lungs
head & arms
aorta
main vein
Right
Left
liver
digestive system
kidneys
legs
Our circulatory system is a double circulatory system.
This means it has two parts parts.
Lungs
the right side of
the left side of
the system
the system
deals with
deals with
deoxygenated
oxygenated
blood.
Body cells
blood.
Components of the Human Circulatory System
The Heart
Blood Vessels
Blood
Lymphatic Vessels
Lymph
The Heart
This is a vein. It
brings blood from
the body, except
the lungs.
These are
arteries. They
carry blood away
from the heart.
2 atria
Coronary
arteries, the
hearts own
blood supply
2 ventricles
The heart has four
chambers
now lets look inside the heart
The Path of Blood
1. The heart pumps blood to the lungs
2. The blood gets oxygen in the lungs
3. The blood returns to the heart
4. The heart pumps the oxygenated blood to the cells in the body
5. The blood delivers oxygen to the body cells
6. The deoxygenated blood travels back to the heart
The Heart
Artery to Lungs
Vein from Head and Body
Right Atrium
valve
Right Ventricle
Artery to Head and Body
Vein from Lungs
Left Atrium
valve
Left Ventricle
How does the Heart work?
STEP ONE
blood
from the
body
blood
from
the
lungs
The heart beat begins when
the heart muscles relax and
blood flows into the atria.
How does the Heart work?
STEP TWO
The atria then contract and
the valves open to allow blood
into the ventricles.
How does the Heart work?
STEP THREE
The valves close to stop blood
flowing backwards.
The ventricles contract forcing
the blood to leave the heart.
At the same time, the atria are
relaxing and once again filling
with blood.
The cycle then repeats itself.
Structure of the heart
You need to be able
to label all parts of
the heart
Blood from
?
Blood from lungs
?
right atrium
valve
Right ventricle
RIGHT SIDE
Left ventricle – has a
thicker muscle wall
than right side – why?
LEFT SIDE
Body
organs
Blood to the ?
Blood from ?
right atrium
Blood to the ?
Blood from lungs
Left atrium
valve
Right ventricle
RIGHT SIDE
Left ventricle
LEFT SIDE
Beating heart – blood flow
The valves prevent
the backflow of blood.
How do the
valves work?
How many can
you see?
out
Can you
see the 4
valves?
in
Atrium and ventricle muscles
force the blood through and out
of the heart
in
blood from the heart gets around
the body through blood vessels
There are 3 types of blood vessels
a.
ARTERY
b.
VEIN
c.
CAPILLARY
The ARTERY
Arteries carry blood away from the heart.
the elastic fibres allow
the artery to stretch
under pressure
thick muscle
and elastic
fibres
the thick muscle
can contract to
push the blood
along.
The VEIN
Veins carry blood towards the heart.
veins have valves
which act to stop
the blood from
going in the wrong
direction.
thin muscle and
elastic fibres
body muscles surround the veins
so that when they contract to move
the body, they also squeeze the
veins and push the blood along the
vessel.
The CAPILLARY
Capillaries link Arteries with Veins
they exchange materials
between the blood and
other body cells.
the wall of a capillary
is only one cell thick
The exchange of materials
between the blood and the
body can only occur through
capillaries.
The CAPILLARY
A collection of capillaries is known as a
capillary bed.
artery
vein
capillaries
body cell
what’s in
digested food
red blood cells
white blood cells
oxygen
waste (urea)
platelets
carbon dioxide
plasma
hormones
The Blood
red blood cell
platelets
white blood cell
plasma
Red Blood Cells
a biconcave disc that is round
and flat without a nucleus
contain haemoglobin, a
molecule specially designed
to hold oxygen and carry it to
cells that need it.
can change shape to an
amazing extent, without
breaking, as it squeezes
single file through the
capillaries.
White Blood Cells
there are many different types and all
contain a big nucleus.
the two main ones are the
lymphocytes and the macrophages.
macrophages ‘eat’ and digest microorganisms .
some lymphocytes fight disease by making antibodies to destroy
invaders by dissolving them.
other lymphocytes make antitoxins to break down poisons.
Platelets
Platelets are bits of cell
broken off larger cells.
Platelets produce tiny
fibrinogen fibres to
form a net. This net
traps other blood
cells to form a blood
clot.
Plasma
It also contains useful
things like;
• carbon dioxide
• glucose
A strawcoloured
liquid that
carries the
cells and the
platelets
which help
blood clot.
• amino acids
• proteins
• minerals
• vitamins
• hormones
• waste materials
like urea.
Types of Blood Vessels
• Capillaries:
– smallest vessels
– the site where gases, nutrients, and
wastes are exchanged between the
blood and other tissues
• The smallest veins are venules;
– carry blood back to the heart after it
passes through the capillaries
– veins have much thinner walls and
much larger interior diameters than
arteries
Location of Heart
Pericardial Cavity
Layers of Cardiac Tissue
Visceral pericardium
• Outer protective layer composed of a
serous membrane
• Includes blood capillaries, lymph
capillaries, and nerve fibers.
Myocardium
• Relatively thick.
• Consists largely of cardiac muscle tissue
responsible for forcing blood out of the
heart chambers.
• Muscle fibers are arranged in planes,
separated by connective tissues that are
richly supplied with blood capillaries, and
nerve fibers.
•
•
•
•
Endocardium
Consists of epithelial and
connective tissue that contains
many elastic and collagenous
fibers.
Connective tissue also contains
blood vessels and some
specialized cardiac muscle fibers
called Purkinje fibers.
Lines all of the heart chambers
and covers heart valves.
The Human Heart
• The human circulatory system returns oxygendepleted blood from the body to the right atrium of
the heart through two large veins
– the inferior and superior venae cavae.
• When the right atrium contracts:
– deoxygenated blood is sent to the right ventricle
– it contracts and sends blood out to the lungs via
the pulmonary artery
• One-way valves ensure that blood follows only this
path. After blood has circulated through the capillary
beds in the lung’s alveoli:
• it becomes oxygenated
– returns to the heart through the pulmonary veins
The Human Heart
• The oxygenated blood enters the left atrium:
– it contracts and pushes the blood into the left
ventricle
• The contraction of the left ventricle sends
oxygenated blood at high pressure out the aorta
and into:
– the arteries
– capillaries
– veins
• forms the systemic circulation
Heart Anatomy
Heart Anatomy
VALVES
pulmonary
semilunar valve
aortic
semilunar valve
bicuspid valve
tricuspid valve
Heart valves
The Cardiac Cycle
• The contraction phase of the atria and the
ventricles:
– called systole
• is coordinated with their relaxation phase
– called diastole
• A cardiac cycle:
– consists of one complete systole and one
complete diastole
• systolic blood pressure :
– blood pressure measured in the systemic
arterial circulation at the peak of ventricular
ejection into the aorta
• diastolic blood pressure:
– blood pressure measured just prior to
ventricular ejection
Contraction cycle of the heart
Contraction
Cycle of the
Heart
Contraction Cycle of the Heart
Circulatory System -Gross and Cool Facts!
•The body of an adult contains over 60,000 miles
of blood vessels!
•An adult's heart pumps nearly 4000 gallons of
blood each day!
•Your heart beats some 30 million times a year!
•The average three-year-old has two pints of
blood in their body; the average adult at least five
times more!
•A "heartbeat" is really the sound of the valves in
the heart closing as they push blood through its
chambers.
References
 AP Biology Textbook
 Addison and Wesley Biology 11
 Vijay Aswathy and S Morris
 www.worldofteaching.com