Circulatory System Flashcards
Circulatory system
Transport system for the body. It carries the following:
»Oxygen »Nutrients »Carbon dioxide »Waste
Glucose
From digestive system
Necessary for respiration / cell functions
Oxygen
From inhaled air in the lungs
Necessary for respiration
Carbon Dioxide
From Cellular respiration
Needs to be exhaled via the lungs
Waste
From bodily processes
Needs to be excreted via the lungs, skin, kidneys…
Components of Blood
Plasma
Red blood cells
White blood cells
Platelets
System of tubes
Arteries
Veins
Capillaries
THE HEART
Plasma
• Liquid part of the blood
• Pale yellow – mostly water
Plasma function
to transport chemicals and heat
Also carries the red blood cells, white blood cells, and platelets.
Red Blood Cells
Round, flattened discs, curve inward near centre
• Small, no nucleus, formed in bone marrow
• Very numerous – approx 5million per drop bloo
Red Blood Cells function
transport oxygen to cells
White Blood Cells
• Larger than Red Blood Cells but fewer in number
• No definite shape – shape can change
• They are also made in the bone marrow
White Blood Cells function
to fight infection
Platelets
• Smaller than red or white blood cells
• They are formed in the bone marrow
• They are formed from larger cells breaking down into pieces
Platelets function
help to form blood clots
System of Tubes + Pump (pump= heart)
• These tubes are called blood vessels
• They come in three main types:
– Arteries
– Veins
– Capillaries
Arteries
• Carry blood AWAY from the heart
• Flow of blood is strong and at high pressure
• Artery walls are thick and strong to withstand this pressure
All arteries (except pulmonary artery) carry oxygenated blood
Veins
• Carry blood BACK to the heart
• Flow of blood is weaker and pressure is low
• Vein walls are thinner and weaker than artery walls
• Pressure is low, so there is a danger of backward flow of blood, especially when flow direction is against gravity
The Heart
• Is an organ about the size of a clenched fist
• Function: pumps blood around the body
• It pumps blood by contracting periodically
• Cardiac muscle provides the contraction
Pulse Rates
• When the heart contracts, it squeezes blood into the arteries under pressure.
• As blood flows down the arteries, surges of pressure can be felt where the arteries are close to the surface
Two Blood Circuits
• The human circulatory system has what is known as Double Circulation
• Blood passes through the heart twice on its journey around the body
• 1: Pulmonary Circulation
– Blood leaves the heart
– goes to the lungs to become oxygenated
– returns to the heart
• 2: Systemic Circulation
– Blood leaves the heart
– travels to other parts of the body – returns to the heart
Structure of the Heart
• The heart is split down the middle into two sides by the septum
• Each side has an upper chamber called an atrium (plural atria)
• Each side also has a lower chamber called a ventricle.
• This makes a total of 4 chambers
• Valves between the upper and lower chambers ensure that blood only flows in one direction
Left versus Right Of the Heart
• Heart diagrams are always shown as if facing the person
• The left side of the heart appears on the right of the diagram, and vice versa
• The left side of the heart always pumps oxygenated blood (shown in red), received from the lungs, and pumps it to the body.
• The right side always pumps deoxygenated blood (shown in blue), received from the body, and pumps it to the lungs
Blood Vessels of The Heart
• The vena cava (veins) bring blood from the body into the right atrium.
• The right ventricle pumps blood into the pulmonary artery, which leads to the lungs.
• The pulmonary vein returns blood from the lungs to the left atrium.
• The left ventricle pumps blood into the aorta (an artery) which leads to all other parts of the body.
• Both the pulmonary artery and the aorta have valves at the base to prevent blood flowing back into the heart.
