Year 8 Revision questions on Respiratory, Circulatory and Excretory Systems 2014
Name: Mr. Hung 2014 ANSWERS
Circulatory System
1. What are the 2 main function of the circulatory system?
To transport
oxygen
from lungs to all cells for respiration.
To transport metabolic wastes including
urea and Carbon dioxide
(a gas) for excretion.
2. The 3 main parts of the circulatory system are Heart, Blood & Blood vessels.
3. Blood consists of 55% of plasma ( the liquid part) and 45% of blood cells, including the
Red blood cells, White blood cells & platelets.
4. The red blood cells consist of a red pigment called Haemoglobin ( a protein with iron), which is
responsible to carry Oxygen ( a gas).
5. White blood cells are colourless and can change shapes, they are responsible to protect us from infection,
by
killing
germs.
6. Blood platelets are responsible for blood clotting when the skin is wounded.
7. The following are the chemicals found in the blood:
A. nutrients: glucose, amino acids, vitamins, minerals
B. useful chemicals: hormones, proteins, antibodies, oxygen, heat
C. wastes: carbon dioxide, urea, ammonia, heat
8. All of these chemicals are carried by Plasma except oxygen, which is carried by
Red blood cells.
9. Glucose and oxygen are delivered by blood vessels to the living cells where respiration takes place.
What is the main product of the reaction and the 2 metabolic wastes?
Main product Energy
Metabolic wastes
Water + Carbon dioxide
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10. How would you describe our heart?
It is a muscular organ with 4 chambers. There are 2 atria and 2 ventricles.
The left side and right side of the heart are separated by septum.
11. There are 3 main types of blood vessels: arteries, veins and blood capillaries
12. Both veins and arteries are larger blood vessels for delivery of blood to different organs.
Artery is a blood vessel always carries blood AWAY from the heart.
Vein is a blood vessel always carries blood TOWARD the heart.
13. Capillaries are very fine blood vessels, which are only one-cell thick. This allows the exchange of
substances between the cells and blood.
Glucose and Oxygen enter the cells from the capillaries whereas wastes such
as Urea
and Carbon dioxide
leave the cell and enter the capillaries.
14. Valves can be found in the heart as well as all the veins. Arteries are normally under high blood
pressure and do not require valves. The main function of the valves is
to prevent the blood from backflow or allow blood to flow in one direction.
15. Label all these parts in the diagram:
Left ventricle
Pulmonary artery
Valve
Right ventricle
Pulmonary vein
septum
Left auricle
Vena cava
16. Blood full of oxygen is known as oxygenated blood (left side of the
heart). What do you think about the colour of oxygenated blood?
Bright Red
Deoxygenated blood is found in Right side of the heart and carries
little oxygen and is dull or dark red in colour.
17. Draw arrows to show the blood flow throughout the heart. Using red pen
for oxygenated blood and blue pen for deoxygenated blood.
18. There are 2 main circulations in the body:
Pulmonary (lung) circulation in which blood circulates between the
heart and the lung.
Systemic (body) circulation in which blood circulates between the heart
and the Body.
Right auricle
Aorta
Respiratory System
19. The main purpose of Respiratory system is for breathing – Breathing is taken in Oxygen and
Carbon dioxide is given out.
20. The Life Process so called “RESPIRATION” is, in fact, not the same as “BREATHING”.
Respiration is the process in which Glucose is broken down by Oxygen to release
ENERGY inside all living cells.
Glucose + Oxygen ------- > ENERGY + Carbon dioxide + Water
21. Label the diagram of the Respiratory System:
22. Special features of Respiration system:
a) C-ring cartilage found in trachea is important to keep it open at all times.
b) Cilia (tiny hairs) and mucus in nasal cavity and trachea sweep dust and germs upward to be
swallowed or split out.
c) There are 600 millions alveoli in 2 lungs, equivalent to a 70 square m of a tennis court.
23. Composition of atmospheric air and breathed out air:
Gas
Air in the atmosphere
Breathed out air
1.
Oxygen
21%
16%
Carbon dioxide
0.03%
4%
Nitrogen
78%
78%
Water vapour
Small amount
1% (saturated)
a)
b)
c)
d)
Which gas consists of about ¾ of the air? Nitrogen
Which gas is used up by the body? How many percentage is used up?
What percentage of carbon dioxide is in the breathed out air? 4%
Which gas is not been used by our body at all? Nitrogen
Oxygen 5%
24. Name all the words for:
Breathing in air = Inspiration, Inhalation
Breathing out air = Expiration, Exhalation
25. Arrange the following steps in order during Inhalation:
A. This reduce the pressure inside the thorax
B. The intercostal muscles in the ribs also contract, making the ribcage move upward and outward.
Deoxygenated
C. Air moves through the air way of the respiratory system and
eventually reaches the alveoli, filling Lungs with air
bronchiole
D. The contraction of both the diaphragm and intercostal muscles
increase the volume of the thorax (chest cavity)
E. Air is rushed in from a higher air pressure to a lower one in the
thorax (chest cavity).
F. This inflates the lungs.
G. Diaphragm is contracted and change the shape from Dome-shaped
to flattened shape.
G  B  D  A E  C F
capillary
Oxygenated
26. What happens at the Alveoli?
Gas exchanges take place in which Oxygen diffuses from alveoli to blood capillaries and
Carbon dioxide diffuses from blood capillaries to alveoli.
Excretory System
27. Excretion is the removal of metabolic wastes from the body.
28. There are 3 main parts involved in Excretion:
a) The SKIN is used to remove sweat, salt, urea and heat from the body surface.
b) The Lungs are used to remove carbon dioxide and water vapour.
c) The KIDNEYS being part of the Urinary system are responsible to remove metabolic
wastes including urea, ammonia, excess salts and water.
29. Blood vessels of the Kidneys:
a)
b)
c)
d)
The Aorta has a branch given to the kidney called Renal artery.
This blood is filtered by the kidney and forms Urine - about 2L per day.
160 L of blood is filtered per day from 5 L of blood in the body,
The rest of the blood will be collected to the renal vein (clean blood) and then go to Vena Cava.
30. Urine is actually formed from blood: It is different from blood in chemical composition:
Blood cells
Colour
Protein
Urea (metabolic waste)
Blood
Red blood cells, white
blood cells and platelets
Red because of Red blood
cells or Haemoglobin
Lots of different proteins
Relatively small amount
Urine
No blood cells at all
Not red, slightly
yellow like the plasma
of blood
No proteins
More concentrated
31. Each kidney consists of microscopic units called nephrons; about 1 millions each.
32. The kidney actually form urine every second, it is transported by the ureter and is stored in the urinary
bladder to be emptied when it is full.
33. The Urethra is a narrow tube from the bladder for the urine to pass out. It is a lot longer in male, found in
the middle of the penis.