Paper 1 organisation 8 Flashcards
List the 3 parts of the circulatory system?
- the blood
- the blood vessels
- the heart
What is the purpose of the circulatory system?
To transport materials required by the cells (eg. Glucose and oxygen) and remove waste (eg. Carbon dioxide)
List 4 things found in blood
- plasma
- red blood cells
- white blood cells
- platelets
Plasma
- Plasma is a yellow liquid formed mostly of water.
- in your blood
- it transports the products from the intestines to cells
- carbon dioxide from the dissolves in it to be taken back to the lungs
- carries urea, which is formed by the liver in the breakdown of proteins. It is taken to the kidneys to be extracted in the urine
Red blood cells
- carry the oxygen from the lungs to the respiring cells
- they are a biconcave disc shape, increasing the surface area to volume ratio for oxygen to diffuse in and out
- they have no nucleus, more space for oxygen
- they have haemoglobin, which can bond to oxygen to form a bright red oxyhemoglobin
- in the low oxygen concentrations of the tissues it breaks down again, and releases the oxygen (turns a purply-red colour)
What is the equation for oxyhemoglobin?
Hb + O_2 ———> HbO_2
White blood cells
- are larger and there are less of them than red blood cells
- they have a nucleus and form part of the immune system, defending the body against pathogens
- some engulf and destroy invading microbes, other produce antibodies or antitoxins phagocyte
Platelets
- are small fragments of cells without a nucleus
- They form a clot at the site of a wound by forming a mesh of protein fibres that trap other blood cells to form a scab
- This prevents further blood loss and prevents infection
Name the 3 types of blood vessels
- arteries
- veins
- capillaries
Arteries
- carries blood away from the heart
- As they are close to the heart, they experience pulses of high pressure
- They therefore have thick muscular and elastic walls that can stretch
- The lumen is relatively small to maintain the pressure
Define lumen
hole down the middle
Veins
- carry blood towards the heart
- have much thinner walls as the pressure is a lot less
- lumen is usually large
- have valves within them to prevent backflow of the blood under this low pressure
- Contractions of the skeletal muscles also helps to keep the blood flowing back towards the heart
Capillaries
- are the only blood vessels that allow materials to enter or leave the blood
- They form a huge network of narrow, thin-walled vessels, giving a large surface area for exchange
- It is here that glucose and oxygen leave the blood to reach the cells and waste carbon dioxide passes back
A Double circulatory system
- Humans have a double-circulatory system
- meaning that the blood flows through the heart twice during each full circuit
- One loop takes the blood through the lungs to be oxygenated
- then the second loop carries it to the cells of the body
- It is very efficient, as it can be pumped at high pressure to increase its speed of delivery
The heart
- The heart is muscle that contracts in a coordinated sequence to move the blood around the body
- It is supplied with oxygen and glucose by coronary arteries
Pacemaker
Pacemaker cells in the right atrium coordinate the muscle cells to contract together
Explain the full transportation of blood
- Deoxygenated blood arrives through the vena cava from the body into the right atrium
- The atrium contracts and forces the blood into the right ventricle
- The ventricle contracts and forces the blood up the pulmonary artery towards the lungs.
- Valves stop the blood from moving back into the right atrium
- Oxygenated blood arrives through the pulmonary vein from the lungs into the left atrium
- The atrium contracts and forces the blood into the left ventricle
- The ventricle contracts and forces the blood up the aorta to the body.
- Valves stop the blood from moving back into the left atrium
List 4 artificial devices that help with blood circulation
- stents
- valve replacement
- artificial hearts
- pacemaker
Stents
- are metal mesh sleeves that can be inserted into an artery and inflated with a ballon
- They are used to widen blood vessels such as the coronary arteries that supply the heart, if they have been narrowed by fatty deposits over time
- it doesn’t require general anaesthetics
What is the alternative to stents?
- bypass surgery
- which involves replacing narrow or blocked arteries with veins from another part of the body
- This is more expensive and requires a general anaesthetic
What would someone with cardiovascular disease be prescribed with?
- statins
- which lowers blood cholesterol and reduce the fatty deposits in the artery
Valve replacement
-are used if a person’s natural heart valves begin to fail under the constant high pressure
(Valve replacement) Mechanical valves
-Can be made of titanium and polymers will last forever, but require the patient to take drugs to prevent blood clots forming
(Valve replacement) Biological valves
-from human donors or other animals (pigs or cows) do not require medication, but will only last for 15 years
Artificial hearts
- can save many lives, as there are never enough hearts to use in transplants
- are primarily used as a temporary fix until a replacement human heart can be provided
- require lots of machinery so the patient must stay in hospital
- Mobile artificial hearts are still being experimented with for the future
Electrical pacemaker
- If the natural pacemaker cells in the right atrium becomes damaged, the heart can beat irregularly, or at the wrong speed
- electrical pacemaker can be implanted in the chest, connected to the heart muscle, that stimulates contractions at the correct rate
Non-communicable diseases
- are not infectious
- rarely caused by a single agent
Communicable diseases
- are those that can be passed from one person to another
- These are caused by pathogens (bacteria, fungi, virus)
A disease
Absent of good health
What 4 factors cause non-communicable diseases?
- inherited genes
- lifestyle
- environmental substances
- mental
