Paper 1 organisation 8 Flashcards
1
Q
List the 3 parts of the circulatory system?
A
- the blood
- the blood vessels
- the heart
2
Q
What is the purpose of the circulatory system?
A
To transport materials required by the cells (eg. Glucose and oxygen) and remove waste (eg. Carbon dioxide)
3
Q
List 4 things found in blood
A
- plasma
- red blood cells
- white blood cells
- platelets
4
Q
Plasma
A
- 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
5
Q
Red blood cells
A
- 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)
6
Q
What is the equation for oxyhemoglobin?
A
Hb + O_2 ———> HbO_2
7
Q
White blood cells
A
- 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
8
Q
Platelets
A
- 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
9
Q
Name the 3 types of blood vessels
A
- arteries
- veins
- capillaries
10
Q
Arteries
A
- 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
11
Q
Define lumen
A
hole down the middle
12
Q
Veins
A
- 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
13
Q
Capillaries
A
- 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
14
Q
A Double circulatory system
A
- 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
15
Q
The heart
A
- 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