Lifestyle and Influence - Topic 1 Flashcards
What is diffusion?
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration. Particles are always moving and net movement is the sum of all movement of particles. In diffusion, particles move down a concentration gradient.
Describe the flow of blood through the heart
Great veins receive deoxygenated blood from the body, the superior vena cava brings deoxygenated blood from the heads and arms and the inferior vena cava brings blood from the rest of the lower body.
Blood enters the right atrium from the vena cava at relatively low pressure and once pressure builds up in the atrium then the atrioventricular valve (tricuspid valve) opens up.
Blood enters the ventricle following the contraction of the atrium.
Blood re-enters the heart through the pulmonary veins at low pressure due to the long capillary journey. The atrium fills with blood first and contracts which forces blood through the atrioventricular valve which causes blood to enter the ventricle. The contraction of the ventricle provides sufficient force to move and take the blood to all of the body extremities via the aorta.
What do valves do?
Valves prevent the back flow of blood. Valves allow the unidirectional flow as tendinous cords stop inverting under high pressure.
Why is the left ventricle wall thicker than the right ventricle?
The left ventricle wall is thicker than the right ventricle wall because the left side of the heart has to pump blood around he body to all of the body extremities, whereas the right side of the heart only has to pump blood to the lungs
Describe the structure of an artery
“Arteries have thick walls made up of collagen and elastic fibres, collagen is a tough fibrous protein, this makes the artery walls strong and durable. The arteries need such thick walls in order to withstand the high pressure of the blood as it enters from the heart when it contracts (systole) and is forced against the walls.
Due to the thick walls of arteries, the lumen is very narrow.
The heart has a large effect on the flow of blood in the arteries, blood flows at high pressure with constant pulses due to systole.
Smooth muscle surrounds the lumen to allow the flow of blood at such a high pressure to be as efficient as possible.
During diastole (relaxation of the heart), the elastic fibres of the artery walls causes them to recoil behind the blood, this helps to push the blood forward.
There are no valves in the arteries.”
Describe the structure of a vein
“The vein wall is also made up of collagen and elastic fibres but there are much less of them, this is because blood in veins is under relatively low pressure and the flow of blood is more continuous
As a result of thinner walls, veins have a much larger lumen which helps in the assist of blood flow return to the heart.
Smooth muscle surrounds the lumen to allow the flow of blood to be as efficient as possible
The flow of blood in veins is assisted by the contraction of skeletal muscles during the movement of limbs and breathing. The skeletal muscles contract which push blood forwards, it’s the valves that prevent the backward flow of blood by closing.
The heart has little effect on the flow of blood in the veins, where it flows steadily and without pulses.”
Describe the structure of a capillary
“By the time blood reaches the capillaries there is already a steady flow of blood (low pressure).
Blood flows through capillaries relatively slowly, this is due to the very narrow lumen. The flow of blood is slowed down due to friction with the wall of the capillary.
The slow flow of blood allows exchange of materials between the blood and surrounding cells though the endothelium (one-cell thick wall).
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Why is water a polar molecule?
Water (H20) has an unevenly distributed electrical charge, the hydrogen end of the molecule is slightly positive whilst the oxygen end of the molecule is slightly negative. This is because the electrons are more concentrated to that end. WATER IS A DIPOLE (electrically neutral molecule)
Water molecules
The slightly positive charged end of a water molecule is attracted to the slightly negative ends of surrounding water molecules - hydrogen bonds old the water molecules together and results in many of waters properties including being a liquid at room temperature.
POLAR MOLECULES
Polar molecules dissolve in water because they’re hydrophilic (water loving), they become surrounded by water and go into solution.
NON-POLAR MOLECULES
Non-polar molecules such as lipids (fats) don’t dissolve in water because they have both a non polar end and polar end, meaning one end of a lipid is hydrophilic and the other end is hydrophobic. to be able to dissolve in water, lipids need to combine with proteins to form lipoproteins.
Ionic substances in water
Sodium chloride dissolves easily in water, this is because the negative Chlorine ions are attracted to the positive ends of the water molecules and the positive sodium ions are attracted to the negative ends of the water molecule. The chlorine and sodium ions become hydrated in an aqueous solution and become surrounded by the water molecules.
Why is the amount of energy required to raise the temperature of water very high?
It takes a lot of energy to increase the temperature of water because in order to do this you have to break the hydrogen bonds which takes a lot of energy to do this. A large input of energy causes only a small increase in temperature. Therefore water also has a high boiling point
LOOK AT BLOOD IN NOTES
LOOK IN NOTES
ATRIAL SYSTOLE (CONTRACTION)
Blood re-enters the heart due to the movement of skeletal muscles and stuff. Blood under low pressure flows into the atria from the vena cava and pulmonary veins. As the atria fill, the increasing pressure in the atria causes the atrioventricular valves to open and blood flows into the ventricles. The atria walls then contract simultaneously forcing any remaining blood into the ventricles.
