Biology Revision Notes
Circulatory systems
Closed circulatory systems:
• Blood leaves heart under pressure to arteries then arterioles then capillaries.
• Capillaries come in large numbers. They exchange substances between the blood and cells.
• After passing through capillaries, blood goes back to the heart via veins.
• Valves in the veins ensure that blood only flows in one direction.
Single circulatory system:
• Heart pumps deoxygenated blood.
• Gaseous exchange (diffusion of CO2 from blood to H2O and diffusion of O2 from H2O into the blood)
• Blood leaves, then goes to rest of body then heart
Double circulatory system:
• Right ventricle pumps deoxygenated blood to the lungs where it receives oxygen.
• The oxygenated blood then returns to the heart to be pumped a second time ( by the left ventricle) out to the rest of the body.
Circulation
In the circulatory system all the particles it contains are transported in one direction in a process known as mass flow. properties of water that make it a good transport medium:
• Water is liquid at room temperature.
• The hydrogen's in the water push away from each other making the molecule V shaped.
• Many water molecules can bond together forming hydrogen bonds, as the negatively charged oxygen of one molecule bonds to the positively charged hydrogen of another.
• The hydrogen bonding holds them together and results in many of the properties of water.
• Many chemicals dissolve easily in water.
• Polar molecules (hydrophilic) dissolve easily in water.
• Non-polar (hydrophobic) substances, e.g. lipids, do not dissolve in water.
• Water has a high boiling point because the hydrogen bonds require a lot of energy to break as they are very strong.
The heart and blood vessels.
The heart consists of:
• Aorta (to body).
• Pulmonary artery (to lungs).
• Pulmonary veins (from lungs).
• Left and right atrium.
• Left and right ventricle.
• Atrioventricular valves (separates the ventricles and atrium).
• Semi-lunar valve
Closed circulatory systems:
• Blood leaves heart under pressure to arteries then arterioles then capillaries.
• Capillaries come in large numbers. They exchange substances between the blood and cells.
• After passing through capillaries, blood goes back to the heart via veins.
• Valves in the veins ensure that blood only flows in one direction.
Single circulatory system:
• Heart pumps deoxygenated blood.
• Gaseous exchange (diffusion of CO2 from blood to H2O and diffusion of O2 from H2O into the blood)
• Blood leaves, then goes to rest of body then heart
Double circulatory system:
• Right ventricle pumps deoxygenated blood to the lungs where it receives oxygen.
• The oxygenated blood then returns to the heart to be pumped a second time ( by the left ventricle) out to the rest of the body.
Circulation
In the circulatory system all the particles it contains are transported in one direction in a process known as mass flow. properties of water that make it a good transport medium:
• Water is liquid at room temperature.
• The hydrogen's in the water push away from each other making the molecule V shaped.
• Many water molecules can bond together forming hydrogen bonds, as the negatively charged oxygen of one molecule bonds to the positively charged hydrogen of another.
• The hydrogen bonding holds them together and results in many of the properties of water.
• Many chemicals dissolve easily in water.
• Polar molecules (hydrophilic) dissolve easily in water.
• Non-polar (hydrophobic) substances, e.g. lipids, do not dissolve in water.
• Water has a high boiling point because the hydrogen bonds require a lot of energy to break as they are very strong.
The heart and blood vessels.
The heart consists of:
• Aorta (to body).
• Pulmonary artery (to lungs).
• Pulmonary veins (from lungs).
• Left and right atrium.
• Left and right ventricle.
• Atrioventricular valves (separates the ventricles and atrium).
• Semi-lunar valve