Circulatory System Flashcards
What is the function of circulatory system?
Carries food and oxygen to every cell in body & carries waste products
What does the right side do?
- Right ventricle pumps deoxygenated blood to lungs to take in oxygen
- Blood returns to heart
What does the left side do?
- Left ventricle pumps oxygenated blood around other
organs of body - Blood gives up its oxygen at body cells and deoxygenated blood returns to heart to be pumped out to lungs again
What is your resting heart rate controlled by?
Pacemaker cells
Where are pacemaker cells found?
Right atrium wall
What do pacemaker cells do?
Produce a small electric impulse → spread to surrounding muscle cells = causing them to contract
If you pacemakers cells stop working, what can you do?
Can use an artificial pacemaker to control heartbeat
What is an artificial pacemaker?
Little device implanted under skin and has wire going to heart
How does an artificial pacemaker work?
Produces electrical current to keep heart beating regularly
What is a heart and what does it do?
Pumping organ that keeps blood flowing around body & exchange substances
What are walls of heart mainly made out of?
Muscle tissue
Why does the heart have valves?
Prevent blood flowing backwards (in wrong direction)
How heart uses its four chambers to pump blood around? (5 steps, name arteries, ventricles, etc.)
- Blood flows into two atria from vena cava and pulmonary vein
- Atria contract pushing blood into ventricles
- Ventricles contract forming blood into pulmonary artery and aorta → out of heart
- Blood then flows to organs through arteries and returns through veins
- Atria fill again and whole cycle starts over
How does the heart gets its own supply of oxygenated blood?
Via coronary arteries (branch off aorta and surround heart)
What do arteries do?
Carry blood AWAY from heat
What do veins do?
Carry blood TO the heart
What do capillaries do?
Carry blood really close to every cell in body to exchange substances with them
Why are artery walls strong and elastic?
Heart pumps blood out at high pressure
What are walls of artery like?
Thick compared to size of hole down middle (lumen)
What do arteries contain that makes them strong?
Thick layers of muscle
What do elastic fibres in arteries allow them to do?
Allow them to stretch and spring back
e.g. Less blood pressure = recoils
What allows arteries to stretch/recoil?
Its folded endothelium
What kind of walls do capillaries have?
Permeable walls that are usually one cell thick
Why do capillaries have permeable walls?
So substances can diffuse in and out
Why do capillaries have one cell thick walls?
Increases rate of diffusion by decreasing distance over which it occurs
Why are vein’s walls not as thick as arteries’?
Blood is at lower pressure in veins
Why do veins have a bigger lumen than arteries?
To help blood flow (lower pressure)
Why do veins have valves?
To prevent back flow of blood
What is blood?
A tissue → huge part of transport system
What is job of RBCs?
To carry oxygen from lungs to all cells in body
Name 5 features of RBCs?
- Shape is biconcave disc (like doughnut)
- Don’t have nucleus
- Contain haemoglobin
- Vast number of them
- Have large surface area to volume ratio
Why is the shape of RBCs a biconcave disc?
Gives large surface area for absorbing oxygen
Why don’t RBCs have a nucleus?
Allows more room to carry (bind to) oxygen
Why does RBCs have haemoglobin?
- In lungs, haemoglobin binds to oxygen to become oxyhemoglobin
- In body tissues, reverse happens → oxyhemoglobin splits up into haemoglobin and oxygen to release oxygen to cells
What do platelets do?
Help blood clot at wound
Do platelets have nuclei?
No
What are platelets?
Small fragments of cells
Why do you need your blood to clot? (name 3 reasons)
- Stop microorganisms getting in
- Stop blood pouring out
- Protects new skin forming underneath
What is blood clotting?
Series of enzyme controlled reactions that change fibrinogen into fibrin
What can a lack of platelets cause?
Excessive bleeding and bruising
What do WBCs do?
Defend against infection
What is phagocytosis?
When WBCs (phagocytes) change shape to engulf pathogens
What do other WBCs do that are not phagocytes?
Others (lymphocytes) produce antibodies to fight pathogen & antitoxins to neutralise any toxins produced by pathogen
What are 3 features of white blood cells ( that RBCs do not have)?
- Have multi-lobed nucleus
- Larger in size than red blood cells
- Fewer in number compare to red blood cells
What is plasma?
(Pale straw-coloured) liquid which carries everything in the blood
What is coronary heart disease?
Coronary arteries get blocked by layers of fatty material building up ∴ arteries become narrow
= blood flow is restricted and there’s a lack of oxygen to heart muscle = heart attack
What can be used to lower the risk of a heart attack in people with coronary heart disease?
Stents
What are stents?
Tubes inserted inside arteries
What do stents do?
Keeps arteries open (pushes artery walls out & squashes deposited fat) = blood can pass through to heart muscles (keeps the person’s heart beating)
What are 2 advantages of using stents?
- Effective for a long time
2. Recovery time from surgery is relatively quick
What is thrombosis?
Blood clotting near a stent
What are 3 disadvantages of using stents?
- Risk of complications during operation (e.g. Heart attack)
- Risk of infection from surgery
- Risk of patients developing a blood colt near the stent
How are faulty heart valves caused? (name 3 things)
Heart attacks, infection or old age
What are the two main heart valve faults?
- Valve tissue may stiffen
2. Valve may become leaky
What happens if heart valve tissue stiffens?
Valve won’t open properly
What happens if heart valves become leaky?
Allows blood to flow in both directions = blood doesn’t circulate as effectively as normal
What can faulty valves be replaced with?
- Biological Valves
2. Mechanic Valves
What is the good thing about replacing faulty valves?
Less drastic procedure than whole heart transplant
What are the downsides about replacing faulty valves?
Fitting artificial valves = still major surgery & can be problems with blood clots
If a patient has heart failure, what can they do? (name 2 options)
- Donor organs from people who recently died
2. Artificial heart (if donor organs aren’t available or not best option)
What are artificial hearts?
Mechanical devices that pump blood for person whose heart has failed
Why would someone have an artificial heart as temporary fix?
- Help person recover by allowing heart to rest & heal
- Keep person alive until donor heart found
What are the advantage of having an artificial heart?
- Reduces need for donor hearts
- Less likely to be rejected
What are the disadvantage of having an artificial heart? Name 3
- Don’t work as well as healthy natural ones (e.g. electrical motor could fail & parts could wear out)
- Surgery to fit artificial heart (& transplant surgery) = leads to bleeding & infection
- Blood doesn’t flow through artificial hearts as smoothly = cause blood clots & lead to strokes
When a patient has an artificial heart they have to take drugs, why? And what may be the problem with this?
Patient has to take drugs to thin blood = make sure blood clots & strokes don’t happen BUT this can cause bleeding problems if they’re hurt in accident
What are antigens?
Proteins on surface of cells
What are 4 ABO blood groups?
A, B, AB, O
What ABO blood groups based on?
On type of antigens on surface of RBC & type of antibodies in blood plasma
Why does no one react to O blood?
O has no antigens
What is the disadvantage of having donor organs?
Recipient’s antibodies may attack antigens on donor organ since doesn’t recognise them
How can we prevent the rejection of transplanted organ? Name 2 methods
- Recipient treated with drugs = suppress immune system
2. Donor organ with ‘tissue-type’ similar recipient
Draw the ABO Compatibility Table
See mind map
What happens when a fatty despot in an artery breaks off?
Can form a blood clot = lead to blood vessel bursting
Before stents, what was used?
Bypass (vessel taken from leg)
