B2.2.3 - Heart And Blood Flashcards
What muscle is your heart made of?
Cardiac muscle
How many times does a typical heart beat per minute?
70 times
Why are cardiac muscle cells strange?
They contract without receiving a nerve impulse from your brain.
What is your heart beat?
Your heart muscle cells contracting together
How many chambers does your heart contain?
4
What are the smaller chambers at the top of your heart called?
Atrium (atria)
What are the bigger chambers at the bottom of your heart called?
Ventricles
What separates the chambers in a heart?
Valves
Describe the heart pumping and blood flowing around your body.
Deoxygenated blood enters your right atrium, and is then pumped through your right ventricle when the heart beats. From here it is pumped to the lungs (through the pulmonary artery) to collect oxygen. The blood returns to the heart (via the pulmonary vein) into the left atrium. It is then pumped into the left ventricle, so the muscle in the left ventricle has to be very thick to withstand high pressures of blood (through the aorta).
How many litres of blood do you have in your body?
5 litres
What is blood made up of?
Red blood cells
White blood cells
Plasma
Platelets
Describe the red blood cells.
Small biconcave cells that have no nucleus and contain haemoglobin. They carry oxygen. They fit through the lumen of a capillary 1 cell at a time.
Describe white blood cells.
Large cells that have a nucleus. They fight diseases by having antibodies, or by changing shape to engulf microorganisms.
Describe plasma.
Straw coloured liquid that blood cells float in. Many materials are transported by dissolving in plasma. These include digested foods, waste, hormones and antibodies. Excess water is taken from the large intestine to the kidneys where it is removed.
What percent of plasma is water?
90%
