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Transport in Mammals (The Circulatory System (network of tubes, called…
Transport in Mammals
The Circulatory System
- network of tubes, called blood vessels
- the heart keeps the blood flowing
- valves in the heart make sure the blood is flowing in the right direction
- blood on the left hand side come from the lungs and is oxygenated
- this is then sent around the body and taken up by body cells that need oxygen for respiration
- the blood then becomes deoxygenated and is brought back to the heart through the right side
- the blood is then sent back to the lungs where it becomes oxygenated again
- this is called the double circulatory system
- the double circulatory system is made up of two parts
- the vessels that take the blood to the lungs and back are called the pulmonary system
- the vessels that take blood to the rest of the body are called the systemic system
- there is also another type of circulatory system valled the single circulatory system
- this is when blood only passes through the heart once
- a double circulatory system transports blood faster than a single circulatory system
- the double circulatory system is much more effective
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The Heart
- function of the heart is to pump blood around the body
- made of cardiac muscle
- contracts and relaxes regularly
- there are four chambers
- two upper chambers are called the atria
- two lower chambers are called the ventricles
- there are two chambers on the left and two on the right and these are separated by a septum
- blood flows from the top, into the atria
- left atrium receives blood from the pulmonary veins
- the right atrium receives blood from the rest of the body, arriving through the vena cava
- the blood then flows into the ventricles and then the ventricles pump it out of the heart
- blood in the left ventricle is pumped to the aorta which then circulates to the whole body
- blood in the right ventrile is pumped into the pulmonary artery which goes to the lungs
- the atria receive blood and supply it to the ventricles
- the ventricles pump blood out of the heart to other parts of the body
- the ventricles have much more thicker walls than the atria because of this
- the left ventricle has an especially thick wall so that it can pump blood all around the body
- a good way to measure the rate of your heart beat is to take your pulse rate
- pulse is caused by the expansion and relaxation of an artery
- when a person exercises, their heart beats faster
- their muscles are using up oxygen more quickly to supply energy needed for the movement
- the rate of heart beats is controlled by a patch of muscle in the right atrium called the pacemaker
- the pacemaker's rate changes according to the needs of the body
- the signal for this is an increase in the pH of the blood
- one way valves between the left atrium and ventricle and between the right atrium and ventricle are called atrioventricular valves
- these valves stop blood from flowing back to the atria from the ventricle
- when the ventricles contract, the blood will be pushed to the arteries and not into the atria
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Coronary Heart Disease
- coronary arteries supply the heart muscles with nutrients and oxygen so it can keep contracting
- if a coronary artery gets blocked, the cardiac muscle runs short of oxygen
- they cannot respire thus they cannot obtain the energy for them to contract
- the heart stops beating, this is called a heart attack or cardiac arrest
- this blockage is called the coronary heart disease
- smoking cigarettes causes damage to the circulatory system because of components in the cigarette
- foods that are high in salt have higher risks in getting coronary heart disease
- being overweight increases the risk of coronary heart disease
- unmanageable or long term stress appears to increase risk of developing heart disease
- genes could also play a factor in getting coronary heart disease
Blood Vessels
- arteries have very strong walls to withstand the high pressure of the blood flowing through them
- blood does not flow smoothly through the arteries
- they have elastic tissue which can stretch and recoil with the force of the blood
- there are no valves in the arteries because the force of the heart beat keeps the blood moving
- capillaries are arteries that gradually divide into smaller and smaller vessels
- the capillaries reach to every part of our body
the capillaries take nutrients, oxygen and other materials to all the cells in the body
- they also take away waste materials
- their walls are very thin so that it is easier for substances to pass in and out
- veins are capillaries that gradually join up again
- blood in the veins are at a much lower pressure than in the arteries
- blood flows more slower and smoother
- veins don,t have walls as thick or strong as arteries
- the space inside the vein is much wider than in an artery to help keep blood moving easily
- veins also have valves to stop blood moving backwards
- the contraction of skeletal muscles also helps keep blood moving
Types of Blood Cells
- liquid part of blood is called plasma
- mostly water with many substances dissolved into it
- also carries soluble nutrients such as glucose, amino acids and mineral ions
- transports hormones and carbon dioxide
- red blood cells are made in the bone marrow of some bones
- produced at a very fast rate because they do not live for very long
- each red cell only lives for 4 months
- red because they contain the pigment haemoglobin, which carries oxygen
- haemoglobin is a protein and contains iron
- the lack of a nucleus in a red cell means there is more space to pack in haemoglobin
- the shape of red cells are biconcave discs
- their shape and size give them a large surface area compared to their volume
- this speeds up the rate at which oxygen can diffuse in and out of the red blood cell
- the small size of the red blood cell also means that it can squeeze through all the capillaries
- oxygen can then be taken very close to every cell int he body
- white blood cells have a nucleus, which is often quite large and lobed
- can move round and squeeze out through blood capillaries and into all parts of the body
- they fight pathogens (disease causing bacteria and viruses) and clear up any dead body cells
- some (phagocyte) take in and digest bacteria (phagocytosis)
- others (lymphocyte) create antibodies
- platelets are small fragments of cells with no nucleus
- involved in blood clotting
- blood clotting stops pathogens from getting into our body through breaks in the skin
- blood clotting also prevents blood loss
