《IGCSE BIOLOGY》Topic 9
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{Topic 9]: Transport in Animals
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Transport in animals require the . The function of the circulatory system is to:
to the cells
from the cells
the body from
In mammals, the circulatory system consists of:
> The heart, blood vessels, and blood
> The lymphoid organs (spleen, thymus, tonsils, lymph nodes), lymphatic vessels and lymph
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- It is a system made up of and a
Blood is by the heart
Blood is from the heart in an
Blood is to the heart in a
- are present in the and in to ensure of blood
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- In single circulation, the blood only goes through the heart for each complete circulation of the body
- When blood passes through the , is
- However, the blood still needs to before returning to the heart to increase blood pressure
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- In double circulation, the blood passes through the heart in one complete circuit:
The circulation through the lungs (Pulmonary circulation)
The circulation around the rest of the body (Systemic circulation)
- Maintaining a to all major organs of the body
- Collect blood from the body, sends it to the lungs to be .
- Receives the from the lungs, proceeds to pump the blood to the rest of the body.
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(Please refer to a diagram from the internet)
- The vein that carries from the body into the heart ()
- Blood enters the from the and then enters the
- Blood enters the from the and then leaves through the
- The artery that carries from the to the
- The vein that carries from the to the
- Blood enters the from the and then enters the
- Blood enters the from the then leaves through the
- The largest artery in the body that carries from the heart () to the body (except the lungs)
- The muscle that separates the left and right sides of the heart
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- are supplied with and by the , which are present on the surface of the heart
- The than the walls of the atria. This is because atria only pump blood into ventricles, while ventricles have to pump blood out of the heart.
- The is than the . This is because the only has to pump blood to the while the has to pump blood to the . The has to create a higher blood pressure, and therefore has to withstand the pressure.
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**When the blood pressure in the right ventricle is too high, it forces blood into the lungs, which can cause (Infection of the lungs).**
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- The purpose of valves are to ensure one-way flow of blood and to prevent back-flow
- Valves that are between the and the
- Prevent blood in ventricles from flowing back into the atria
- Located at the , where theand leaves the heart
- Prevent blood from flowing back into the
**Veins also have valves in them to prevent back-flow. The pulmonary artery and aorta are the only two arteries that have valves in them.**
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There are three ways to monitor heart activity:
using stethoscopes (there will lup-dup sounds, which result from the opening and closing of the valves)
(ECG)
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- The heart rate at rest is around
- During increased physical activity, the pulse rate may increase
- This is because the muscles need to and therefore need more and , and the heart pumps faster to deliver the nutrients cells require
- If the muscle does get enough oxygen, it will respire (without oxygen), which produces as one of its' byproducts
- causes and leads to
- , the pulse rate gradually drops and returns to the rate at rest
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(otherwise known as heart attack)
- The is due to the deposits of (or ) in the lining of the coronary arteries
- If atheroma forms in the (which deliver nutrients to the heart and are around the cardiac muscle), the blood supply to part of the heart muscle is cut off
- The atheroma the of arteries
- The part of the heart cannot continue to contract, which then causes a
Lack of exercise
Diet high in fat and cholesterol
Genetics
Stress
Smoking
Age (risk increases with age)
Gender (males are more at risk than females)
- Less chance of becoming
- of results in the chances of forming in the coronary arteries
- Increases muscle tone ()
- Leads to an , so the heart requires to keep pumping
Regular, low dose of (a pain-killer)
- To prevent the formation of blood clots in the arteries
Surgery ()
- A long, thin tube () is inserted with a into the
- The balloon is then to widen the artery wall
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- The (made from aluminium) along with the balloon
- The balloon is removed from the expanded stent, which holds the artery open
Surgery ()
- A section of a from a different part of the body (such as the leg) is removed
- The blood vessel is then around the of the artery to it
- This allows the blood to
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- divide into smaller vessels called , which eventually join to even smaller vessels called
- join into larger vessels called , which eventually join to eve larger vessels called
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Function: To carry blood from the heart (All arteries the carry )
Wall: to withstand high blood pressure
Size of lumen:
Adaptation: to withstand as the blood leaves the heart
Function: Allow of from blood into the body cells
Wall: Very thin, specifically to allow shorter diffusion distance
Size of lumen:
Adaptation: Walls contain to allow between body cells and blood
Function: Carry blood the heart (All veins the carry ) ]
Wall: than the '
Size of lumen:
Adaptation: Contain to of blood
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- In , the and become to to the capillaries
- Blood flow also slows down, and blood pressure reduces to prevent capillaries from bursting
- The (vessels that directly link the arterioles to the venules) to allow blood to the capillaries
- This helps to as the blood doesn't gain more surface area by going through the capillaries
**By-passing of the capillaries leads do skin becoming paler because there isn't much blood flow to the skin surface.**
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From liver to the heart:
From heart to the liver:
From kidneys to the heart:
From heart to the kidneys:
From lungs to the heart:
From heart to the lung:
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(in order of concentration in blood)
-
-
-
-
**The concentration of white blood cells are higher in the blood of someone who has an infection/leukemia.**
: Spinning blood at a high speed to separate the blood cells from the plasma. The plasma settles as a yellow liquid at the top while all the cells sink to the bottom.
(RBC)
- Made in the
- RBC contains , which is a red-coloured protein that combines with to form
- They have to contain more haemoglobin
- They have a to maximise their for oxygen transport
(WBC)
- Made in the and sometimes the
- All WBC have a
- There are of WBCs
> Contains a
> Function:
> Contains an
> Function: () and . The process is called .
- of cells with
Function:
too much
to the
Platelets reach the edges of the cut and release a
Meanwhile, the blood vessel to lessen blood loss
The chemical released causes the conversion of (a soluble protein) in the blood to convert into (insoluble protein)
The forms a across the wound, trapping blood cells and forming a blood clot
- The liquid part of blood
- Plasma is only found in blood because once it gets pushed out of the blood vessels it becomes
- Functions: of , , , , and
**When centrifuging, the cap of the test tube is coated in , which prevents the blood from clotting.**
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- carried in the blood must leave the blood vessels and
- produced by the tissues need to to be carried away
- The movement of nutrients and wastes between the tissues and the blood vessels is done via , down concentration gradient (The concentration of nutrients are higher inside the blood vessels, so they diffuse out into the tissues. On the other hand, the concentration of wastes are higher in the tissues compared to inside the blood vessels, so they diffuse into the blood vessels)
- , while carrying nutrients, diffuses out of capillaries and becomes .
**Tissue fluid does NOT contain any blood cells or proteins, because both are too big to pass through the capillary walls.**
- is a for dissolved substances
- The extend through every body tissues
- , , , and diffuse of the capillaries into the tissues
- and diffuse the capillaries from the tissues
Walls of capillaries:
- This makes diffusion more efficient as the diffusing distance is little
- They cover a lot of surface area, which makes more space for diffusion to occur
- The blood is constantly being supplied by the arteries, so the steep concentration gradient is maintained in order for diffusion to happen
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- Not all the tissue fluid returns to the capillaries (When wastes of metabolism diffuse back into the capillaries). Some of it enters the .
Destroys old red blood cells
Largest in size by age 6 and reduces with age
Contain to fight infections
**After tissue fluid enters the lymphatic vessels, it becomes .**
- Filters , , and any
- Drains to of the
- to protect the body against
- to fight bacteria
- (by ) from the intestine and transports it to the liver
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Leave a vote and a comment if this helped you! Disclaimer: I cannot guarantee that all the information is correct. I an NOT a professional teacher.
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