Cardiovascular System Flashcards
The heart
It is an organ – a muscle that pumps blood around
body
When looking at the heart – the left side is actually
the right side!
Blood enters the atria and into the ventricles
The heart also contains valves, so blood can only
flow in one direction – bicuspid (mitral) valve,
tricuspid valve, and the semi-lunar valves
The thick muscle walls of the heart allows for
muscle contraction to pump blood around the body
– left side is thicker and stronger due to needing
to pump blood around whole body, whereas the
right ventricle needs to just pump blood to the lungs
The heart #2
It is a double circulatory system with one
circuit pumping the deoxygenated blood to the
lungs
The other circuit pumps the oxygenated blood all
around the body
The pacemaker
The body’s natural pacemaker sends an
electrical signal to the heart muscle cells,
telling them to contract at the same time.
Arteries
Carry blood away from the heart
• Largest artery is the Aorta
• Aorta divides into smaller arteries
• Smallest arteries are called arterioles
• Arteries have an outer layer of connective
tissue to provide strength and support
• Have a thick layer of muscle and elastic
tissue – the muscle for constriction and
dilation, to allow for blood flow regulation,
and elastic tissue to allow for the artery to
expand and to withstand blood flow pressure from the pumping heart
Capillaries
The arterioles lead to the
capillaries
The smallest vessels in the
cardiovascular system
Single cell thick wall
Veins
The capillaries come together to form venules
• Venules merge to form larger veins
• Blood flow through the vein is a lower pressure
• The lumen is larger than arteries
• The veins have thinner walls, due to the lower pressure
• The veins also have valves, to prevent back-flow
Plasma
Straw-coloured fluid
• Carries blood cells around the body
• Contains plasma proteins, hormones and small molecules (e.g. carbon dioxide, glucose, amino acids) and
ions transported in the blood
Platelets
• Small and disc-shaped
• Cell fragments without nuclei
• Also called thrombocytes
• Present in large numbers in the blood
• Important role in blood clotting
Red blood cells
• Also known as erythrocytes
• Differentiated cells without a nucleus or majority of organelles
• Filled with haemoglobin
• Transport oxygen from lungs to tissues
White blood cells
• Also known as leucocytes
• Mostly involved in protection against infection – immune response
Normal blood pressure
120/80
Low blood pressure
90/60
High blood pressure
140/90
What is the cardiac cycle
The cardiac cycle is when the heart pumps blood by a series of muscle contractions and relaxations
Stages in the cardiac cycle
• The blood enters the heart via the vena cava into the Right Atrium (RA)
• Then through the tricuspid valve into the Right Ventricle (RV)
• From the RV through the Pulmonary Artery to the lungs and then back to the heart via the pulmonary vein
• From the pulmonary vein into the Left Atrium (LA)
• The through the bicuspid valve into the Left
Ventricle (LV)
• From the LV out through the Aorta to the body
