Blood, the Cardiac Cycle and Respiration Flashcards
Explain the structure of Red Blood Cells (Erythrocytes)
They have a biconcave shape (flattened disc shape) to maximise their surface area for oxygen absorption. They are small and flexible so that they can fit through narrow blood vessels.
Oxygen deliverers. They also carry back waste gases or carbon dioxide. They contain a protein called haemoglobin. They have no nucleus so that they can contain more haemoglobin; this contains iron, which combines with oxygen to give blood its red colour.
Explain the structure of White Blood Cells (Leukocytes)
Various structures of white blood cells can be found. Typically a granular cytoplasm, large nucleus and a lobed nucleus.
They defend the body against disease. Consist of B Lymphocytes responsible for making antibodies and T Lymphocytes which initiate the immune response.
Explain the structure of Platelets.
Fragments of cells with proteins attached to their surface; These allow them to stick together during clotting.
Make up the rest of the blood. These cells help your body repair by stopping bleeding after illness or injury.
Explain the structure of Plasma
A clear, pale straw coloured liquid which makes up the fluid component of blood.
Is a liquid part of the blood and involved with material transport like hormones, carbon dioxide and waste. Plasma makes up 55% of the blood volume.
What is the main function of the blood?
Transport materials and heart around the body, and also help to protect against disease.
Why is the Circulatory system necessary?
It allows blood to circulate around the body, and transports nutrients, oxygen, carbon dioxide, hormones, waste and blood cells to and from each cell in the body.
Explain the Circulatory system.
It involves the circulation of blood and is important for delivering oxygen and nutrients and also removing waste products. It is made up of the heart, blood and blood vessels. The heart pumps blood around the body by contracting and relaxing. Blood is pumped around the heart and body via a network of vessels: arteries, veins and capillaries.
Mammals have a double circulatory system. This means that blood travels through two circuits: the pulmonary and systemic.
What are arteries?
Arteries carry oxygenated blood at a higher pressure from the heart to parts of the body so that they have a thick layer of elastic tissue in the wall.
What are veins?
Veins carry deoxygenated blood at lower pressure from the body back to the heart so they have less elastic tissue than arteries. Valves stop the blood from flowing backwards.
What are capillaries?
Capillaries have thin walls that allow exchange of compounds like nutrients, glucose, oxygen and carbon dioxide between blood and tissues.
What is the structure of the heart in mammals and birds?
They have four-chambered hearts. This system is very efficient and does not allow oxygenated (red) and deoxygenated (blue) blood to mix.
The aorta is the largest artery, which is very elastic and thick as it has to withstand large pressures as it carries oxygenated blood away from the heart.
The Vena Cava transporting deoxygenated blood to the heart is made up of the superior and inferior vena cava, and is not as thick as it is not under as much pressure.
Explain the heart chambers.
There are two types of heart chamber: the atria and ventricles. Both have muscular walls which help them pump blood. The ventricles are more muscular than the atria, as the blood must be forced out of the heart at a higher pressure and around the body. The left side side of the heart is more muscular as it pumps blood around the body, while the right side just pumps blood to the lungs.
Heart valves open and close allowing blood to flow due to pressure changes in the chambers. They are important in preventing backflow of blood.
What is the Cardiac Cycle?
A series of mechanical and electrical events that repeats every time the heart beats. It is split into two phases: Diastole and Systole. This circulates blood through the pulmonary and systemic circuits that make up the double circulatory system.
Why are double circulatory systems more effective than single systems?
They are more efficient in transporting oxygenated blood around the body because the deoxygenated and oxygenated blood are kept separate.
What is the pulmonary circuit?
The pulmonary circuit carries blood to the lungs to be oxygenated and then back to the heart.
In the lungs, carbon dioxide is removed from the blood and oxygen is taken up by the haemoglobin in the erythrocytes.
