IGCSE Revision- Biology
Chapter 9- Transport in animals
9.1 Circulatory systems
- Circulatory system: A system of blood vessels with a pump and valves to ensure
one-way flow of blood
- Valves: Structures that allow a liquid to flow in one direction only
OXYGENATING THE BLOOD
- The blood in the left-hand side of the heart has come from the lungs. It contains
oxygen, which was picked up in the capillaries surrounding the alveoli. It is called
oxygenated blood
- This oxygenated blood is then sent around the body. Some of the oxygen is
taken up by the body cells, which need oxygen for respiration. When this
happens, the blood becomes deoxygenated. This deoxygenated blood is brought
back to the heart on the right-hand side.
DOUBLE AND SINGLE CIRCULATORY SYSTEMS
- Double circulatory system: A system in which blood passes through the heart
twice on one complete circuit of the body
- This is made of two parts. The blood vessels that take the blood to the lungs and
back, called the pulmonary system, and the blood vessels that take the blood to
the rest of the body and back, called the systemic system
- Double circulatory systems are found in all mammals, and in birds and reptiles
- Single circulatory system is when blood passes through the heart one on one
complete circuit of the body
9.2 The heart
- The heart is divided into four spaces, called chambers
- The two upper chambers are called atria (singular: atrium). The two lower
chambers are called ventricles. The chambers on the left-hand side are
completely separated from the right-hand side by a septum
- Blood flows into the heart at the top, into the atria. Both of the atria receive blood.
The left atria receives blood from the pulmonary veins, which come from the
lungs. The right atrium receives blood from the rest of the body, arriving through
big veins called the venae cavae
- From the atria, the blood flows into the ventricles. The muscle in the walls of the
ventricles contract. This pumps the blood out of the heart. The muscle contracts
strongly, producing a large force that squeezes inwards on the blood inside the
heart and pushes it out. The blood in the left ventricle is pumped into the aorta.
This is a big artery that takes blood around the body. The right ventricle pumps
blood into the pulmonary artery, which takes it to the lungs
, VALVES
- The valves between the atria and the ventricles are called atrioventricular valves.
They allow blood to flow from the atria into the ventricles, but prevent it from
going into opposite direction
- The valves in the entrances to the aorta and the pulmonary artery are called
semilunar valves. These valves allow the blood to flow from the ventricles into
the arteries, but stops it from going the wrong way
DIFFERENCES IN MUSCLE WALL THICKNESS
- The function of the ventricles is different from the function of the atria
- The atria simply receive blood, from either the longs or the body, and supply it to
the ventricles
- The ventricles pump blood out of the heart and all around the body , to help them
do this, the ventricles have much thicker, more muscular walls than the atria
- There is also a difference between the thickness of the left and right ventricles
- The right ventricles pumps blood to the lungs, which are very close to the heart.
The left ventricles, pumps blood to the rest of the body. The left ventricle has a
really thick wall of muscle to do this. The blood flowing to the lungs in the
pulmonary artery has a much lower pressure than the blood in the aorta
CORONARY ARTERIES
- Coronary arteries are the vessels that deliver oxygenated blood to the heart
muscle
- The muscle of the heart is so thick that the nutrients and oxygen in the blood
inside the heart would not be able to diffuse to all the muscle quickly enough
- The heart muscle needs a constant supply of nutrients and oxygen, so it can
undergo aerobic respiration
- This releases energy that the muscle uses to contract. The coronary arteries
supply the nutrients and oxygen that the muscle needs
- Coronary arteries can get blocked. In some people, cholesterol deposits build
inside the walls of the arteries including the coronary arteries. Because of this,
blood clots can form. When this happens the heart stops beating.
- Blockage of coronary arteries is called coronary heart disease, or CHD
PREVENTING CHD
- No smoking
- Taking care of diet
- Regular exercise
HEARTBEAT
- A good way to measure your heartbeat is to take your pulse rate
- A pulse is the expansion and relaxation of an artery, caused by the heart pushing
blood through it
- Your pulse rate is therefore the same as your heart rate
Chapter 9- Transport in animals
9.1 Circulatory systems
- Circulatory system: A system of blood vessels with a pump and valves to ensure
one-way flow of blood
- Valves: Structures that allow a liquid to flow in one direction only
OXYGENATING THE BLOOD
- The blood in the left-hand side of the heart has come from the lungs. It contains
oxygen, which was picked up in the capillaries surrounding the alveoli. It is called
oxygenated blood
- This oxygenated blood is then sent around the body. Some of the oxygen is
taken up by the body cells, which need oxygen for respiration. When this
happens, the blood becomes deoxygenated. This deoxygenated blood is brought
back to the heart on the right-hand side.
DOUBLE AND SINGLE CIRCULATORY SYSTEMS
- Double circulatory system: A system in which blood passes through the heart
twice on one complete circuit of the body
- This is made of two parts. The blood vessels that take the blood to the lungs and
back, called the pulmonary system, and the blood vessels that take the blood to
the rest of the body and back, called the systemic system
- Double circulatory systems are found in all mammals, and in birds and reptiles
- Single circulatory system is when blood passes through the heart one on one
complete circuit of the body
9.2 The heart
- The heart is divided into four spaces, called chambers
- The two upper chambers are called atria (singular: atrium). The two lower
chambers are called ventricles. The chambers on the left-hand side are
completely separated from the right-hand side by a septum
- Blood flows into the heart at the top, into the atria. Both of the atria receive blood.
The left atria receives blood from the pulmonary veins, which come from the
lungs. The right atrium receives blood from the rest of the body, arriving through
big veins called the venae cavae
- From the atria, the blood flows into the ventricles. The muscle in the walls of the
ventricles contract. This pumps the blood out of the heart. The muscle contracts
strongly, producing a large force that squeezes inwards on the blood inside the
heart and pushes it out. The blood in the left ventricle is pumped into the aorta.
This is a big artery that takes blood around the body. The right ventricle pumps
blood into the pulmonary artery, which takes it to the lungs
, VALVES
- The valves between the atria and the ventricles are called atrioventricular valves.
They allow blood to flow from the atria into the ventricles, but prevent it from
going into opposite direction
- The valves in the entrances to the aorta and the pulmonary artery are called
semilunar valves. These valves allow the blood to flow from the ventricles into
the arteries, but stops it from going the wrong way
DIFFERENCES IN MUSCLE WALL THICKNESS
- The function of the ventricles is different from the function of the atria
- The atria simply receive blood, from either the longs or the body, and supply it to
the ventricles
- The ventricles pump blood out of the heart and all around the body , to help them
do this, the ventricles have much thicker, more muscular walls than the atria
- There is also a difference between the thickness of the left and right ventricles
- The right ventricles pumps blood to the lungs, which are very close to the heart.
The left ventricles, pumps blood to the rest of the body. The left ventricle has a
really thick wall of muscle to do this. The blood flowing to the lungs in the
pulmonary artery has a much lower pressure than the blood in the aorta
CORONARY ARTERIES
- Coronary arteries are the vessels that deliver oxygenated blood to the heart
muscle
- The muscle of the heart is so thick that the nutrients and oxygen in the blood
inside the heart would not be able to diffuse to all the muscle quickly enough
- The heart muscle needs a constant supply of nutrients and oxygen, so it can
undergo aerobic respiration
- This releases energy that the muscle uses to contract. The coronary arteries
supply the nutrients and oxygen that the muscle needs
- Coronary arteries can get blocked. In some people, cholesterol deposits build
inside the walls of the arteries including the coronary arteries. Because of this,
blood clots can form. When this happens the heart stops beating.
- Blockage of coronary arteries is called coronary heart disease, or CHD
PREVENTING CHD
- No smoking
- Taking care of diet
- Regular exercise
HEARTBEAT
- A good way to measure your heartbeat is to take your pulse rate
- A pulse is the expansion and relaxation of an artery, caused by the heart pushing
blood through it
- Your pulse rate is therefore the same as your heart rate
