Circulation In Humans Flashcards
Explain the double circulatory system
- the left and right side of the heart is flipped
The heart has 4 chambers, at the top are the right and left atriums
At the bottom at right and left ventricles
The first loop:
The vena cava brings deoxygenated blood into right atrium into the right ventricle
The right ventricle pumps the deoxygenated blood out of the heart through the pulmonary artery
- the blood goes to the lungs to take in oxygen and return black to the heart, but this time through the pulmonary vein on the left side
Second loop:
The left ventricle pumps the oxygenated blood out of the heart through the aorta
- the oxygenated blood travels around all the other organs of the body and gives up its oxygen to body cells
- the blood becomes deoxygenated and enters the right side of the heart to repeat the first loop
The structure of the heart
- it’s wall is made out of muscle tissue
- has 4 chambers, left and right atria, left and right ventricles
- resting heart rate is controlled by pace maker cells in the right atrium
(Artificial pace are electric devices used to correct irregularities in heart rate due to fault pace maker cells)
- has valves to stop backflow of blood
- the heart needs its own supply of oxygenated blood, coronary arteries branch around the aorta making sure the heart gets enough oxygen
What is coronary heart disease
- layers of fatty material build up inside the coronary arteries, reducing the flow of blood and oxygen reaching the heart.
- stents are used to keep coronary arteries open
What happens when someone has a faulty heart valve
Some people’s heart valves may become faulty, there are 2 main faults:
- the heart valve tissue may stiffen, preventing the valve from opening fully
- the heart valve might develop a leak
This can be fixed by:
- biological valves ( from humans or other mammals)
- mechanical valves
What are the 3 blood vessels and their jobs
Arteries- carry blood away from the heart
Capillaries- involved in the exchange of materials at the tissues + connect veins to arteries
Veins- carry blood into the heart
Adaptations of arteries
- walls made of thick muscles and elastic fibers, as blood is pumped out at high pressures
(Allows them to stretch and spring back) - walls are thick compared to size of the lumen
Adaptations of veins
- have thin walls but a bit lumen to help blood flow despite low pressure
- have valvaes to stop blood backflow
Adaptation of capillaries
- walls one cell thick to reduce diffusion distance
- permeable walls to allow diffusion
- carries blood very close to every cell, to allow exchange of substances
What is blood and what are its components
A tissue:
- rbc
- wbc
- platelets
- plasma
What is the job of blood plasma
- carries nutrients and waste products in the bloodstream
Transports: - carbon dioxide from organs to lungs
- soluble products of digestion from the small intestine to other organs
- urea from liver to kidneys
- hormones
- proteins
- antibodies and antitoxins produced by wbc
What is the job of rbc
- have no nucleus
- have a biconcave shape to increase sa for absorbing oxygen
- packed with a red pigment called haemoglobin which binds to oxygen to form oxyhaemolglobin, in other organs it’s splits back up into oxygen and haemoglobin
What is the job of wbc
- have a nucleus
- part of the body’s immune system:
- Englulf pathogens by phagocytosis
- Produces antibodies to bind to antigens of pathogens and destroy them
- produces antitoxin to neutralise toxins produced by pathogens
What is the job of platelets
- small fragments of cells
- have no nucleus
- helps clot blood at wounds to stop excess blood flow and harmful microorganisms entering
( enzymes convert fibrinogen into fibrin, which forms a network of fibers trapping blood cells and forming a clot)
What are antigens
- every cell has proteins called antigens on its surface
- the combination of antigens on your cells is unique to you
- the antigens on microorganisms that enter our body are different than ours, our immune system recognises these different antigens
How are antigens linked to blood groups
- the antigens found on the surface of our rbc give us different human blood groups
- the ABO system has these blood groups:
A, B, AB, O
In this system, there are 2 possible antigens on the rbcs, antigen A and antigen B
There are also 2 possible antibodies in your plasma, antibody A and antibody B
(These antibodies are always there)
- if blood from different groups are mixed, there may be a reaction between the antigen and the complimentary antibody, causing the red blood cells to agglutinate (stick together)
- this can cause rbc to clog up the capillaries and larger vessels
