Transcript Circulatory System 1

Why do organisms
need a transport system?
• In large organisms, the distance over which
oxygen, carbon dioxide, nutrients and
wastes have to move is too L-O-N-G for
food absorption and gaseous exchange to
occur efficiently
Transport Systems in Humans
Circulatory System Lymphatic System
Circulatory System
BLOOD
Human Circulatory System
BLOOD VESSELS
HEART
Blood
• Blood is a LIQUID TISSUE consisting
of blood cells which float in a liquid
• Blood acts as a TRANSPORT MEDIUM
to carry various substances in the
forms of solution and suspension
Blood
• The various
components in blood
can be separated
by a machine called
a CENTRIFUGE
• After
centrifugation,
blood is divided into
two portions
Blood
Plasma
(55% by
volume)
Blood Cells
(45% by volume)
(red colour)
(straw colour)
What is blood made up of?
BLOOD CELLS
250 000/mm3
7 000/mm3
5 000 000/mm3
Blood Cells
White Blood Cell
Red Blood Cell
Platelet
Where are blood cells made?
Red Blood Cells (Erythrocytes )
Red Blood Cells
• RBC’s are formed in BONE MARROW
• They have a short life-span: about
120 days only
• Old RBC’s are destroyed in the liver
and the spleen
• Matured RBC’s in mammals do not
possess a nucleus
Red Blood Cells
• They are shaped like biconcave discs
in order to provide a large surface
area for diffusion of gases
• Their red colour comes from
haemoglobin which is responsible for
carrying oxygen from the lungs to all
parts of the body
Transport of Oxygen
Transport of Oxygen
Transport of Oxygen
Transport of Oxygen
Haemoglobin + Oxygen
(Purplish Red)
In Lungs
In Tissues
Oxyhaemoglobin
(Bright Red)
Transport of Carbon Dioxide
• Most of the carbon dioxide is carried in
the blood in the form of hydrogencarbonate
ions (HCO3-). An enzyme inside the RBC
helps to convert the CO2 into HCO3- and
vice versa
Investigation #1:
To investigate the effects of
oxygen and carbon dioxide
on chicken’s blood
Procedure
White Blood Cells (Leukocytes)
•
•
•
•
Irregularly-shaped
Possess nucleus
Kill pathogens
Number of WBC’s in
body can vary
• Different WBC’s
have different
lifespans: ranging
from 10 hours to
over 1 year
White Blood Cells
1) Phagocytes
• They are made in the bone marrow
• They have a lobed nucleus
• They can move like an Amoeba out of
blood capillaries to engulf germs and
dead cells
Phagocytes
Bacteria
Phagocyte
White Blood Cells
2) Lymphocytes
• They have a large nucleus
• They are made in the bone marrow
and then migrate to lymph nodes
• Some lymphocytes produce antibodies;
others kill invading cells directly
• They also produce antitoxins to
neutralize toxins produced by germs
When the lymphocyte encounters a matching
antigen, the antibody interlocks with
the antigen and marks it for destruction
Leukaemia
• Leukaemia is a cancer of the tissues which
produce blood
• Large numbers of abnormal white cells are
produced, which are unable to carry out
their normal function of fighting infection
• The abnormal cells also displace the normal
production of red cells and platelets
• Can be treated with chemotherapy,
radiotherapy or bone marrow transplant
Platelets (Thrombocytes)
• Tiny fragments
formed from
specialized cells in
the bone marrow
• They have no nucleus
• They have a short
life span: less than
10 days
• They are involved in
the process of blood
clotting
Platelets
After the clot is formed, bleeding is stopped.
The clot hardens to form a scab and the wound gradually heals
Blood Clotting
RBC’s trapped
in a network of
fibrin threads
Platelet plug
Blood vessel
constricts to
slow down
blood loss
Blood Clotting
A Comparison of RBC’s, WBC’s and Platelets
Red blood cells
Site of production
Bone marrow
White blood cells
Platelets
Bone marrow,
Bone marrow
lymph nodes
Number
Size
Shape
Structure
Function
5 000 000/mm3
8m diameter
Biconcave
disc-shaped
No nucleus
Haemogloblin
7 000/mm3
250,000/mm3
Lym:8-10m
Tiny cell
Phag:12m
fragments
Irregular
Irregular
Nucleus
No nucleus
No haemoglobin No haemoglobin
Transport of oxygen Body defence
Blood clotting
PLASMA
Dissolved
Substances
(10%)
Water
(90%)
Plasma – Dissolved Substances
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•
•
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•
•
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Plasma proteins – antibodies, fibrinogen
Lipids
Nutrients
Glucose
Amino acids
Hormones – coordinate body activities
Mineral salts
Urea
Wastes
Carbon dioxide
Investigation #2:
Detecting the presence
of glucose in a blood sample
Procedure
Functions of Blood
Transportation of:
1. Oxygen – in the form of oxyhaemoglobin
2. Carbon dioxide – in the form of HCO33. Food – from ileum to all parts of body
4. Urea – from liver to kidneys
5. Hormones – from endocrine glands
6. Antibodies – to all parts of body
7. Heat – to keep uniform temperature
Functions of Blood
Defence against infection:
1. Phagocytes engulf germs
2. Lymphocytes produce antibodies to
destroy germs or antitoxins to
neutralize toxins
3. Blood clotting prevents excess blood
loss and entrance of bacteria
Blood Vessels
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A system of tubes for distributing blood
around the body:
Artery – carry blood AWAY from the heart
Vein – carry blood TOWARDS the heart
Capillary – narrow vessel connecting arteries
and veins
Arteries branch into smaller vessels called
arterioles
Small vessels called venules join into veins
16
(kPa)
Blood pressure
Changes in blood pressure in
different types of blood vessels
8
With pulse
No pulse
Arteries Capillaries
Arterioles Venules
Veins
Arteries
• Carry blood AWAY
from the heart
• Contain oxygenated
blood (exception:
pulmonary artery)
• Thick walls of muscles
• Elastic fibres allow
arterial wall to
withstand pressure
• Lumen is small and
appeared to be round
• No valves
• Need to withstand
high pressure
• The muscles around
the artery can
contract or relax to
allow the vessel to
constrict or dilate
Arteries
Veins
• Carry blood TOWARDS
the heart
• Contain deoxygenated
blood (exception:
pulmonary vein)
• Thinner walls compared
to those of arteries
• Walls are less elastic •
and muscular
• Lumen is larger and
appeared flattened
•
Contain valves that are
surrounded by skeletal
muscles
Pressure of blood is low
Veins