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IGCSE Biology > Chapter 9: Transport in humans > Flashcards

Chapter 9: Transport in humans Flashcards

1
Q

What does the circulatory system consist of?

A

The circulatory system consists of blood vessels connected to a pump (heart).

These blood vessels contain a series of valves which ensure that the blood flows in a single direction.

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2
Q

Describe single circulation in fish.

A

A fish’s circulatory system consists of a heart with one atrium and one ventricle, connected to blood vessels that allow blood to flow in a single loop.

Deoxygenated blood is pumped from the heart to the gills to obtain oxygen and then to the rest of the body before returning back to the heart.

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3
Q

State the disadvantages of single circulation.

A

Blood pressure is very low.

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4
Q

Describe double circulation in mammals.

A

Mammals have two atria and ventricles connected to blood vessels allowing blood to flow in two distinct loops.

Blood is first pumped through the heart to the lungs to become oxygenated. From here, it returns to the heart and is then pumped to the body carrying the oxygen to the body cells.

The blood travels through the heart twice in a cardiac circuit.

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5
Q

State the advantages of double circulation.

A
  1. Allows blood pressure to be maintained in the systemic circuit allowing it to reach all organs rapidly.
  2. It also ensure that deoxygenated blood and oxygenated blood is kept separate.
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6
Q

Name parts of the heart.

A
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7
Q

What blood vessel is the right atrium connected to?

A

Vena cava

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8
Q

What blood vessel is the right ventricle connected to?

A

Pulmonary artery

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9
Q

What blood vessel is the left atrium connected to?

A

Pulmonary vein

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10
Q

What blood vessel is the right ventricle connected to?

A

Aorta

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11
Q

State the function of valves.

A

They ensure that blood flows in a single direction.

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12
Q

State the two types of valves in the heart.

A

A.V valves - ensures blood flows from atrium to ventricle.
Semilunar valves - ensures blood flows from the ventricle into the arteries.

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13
Q

Why is the muscles of the left ventricle thicker than the right?

A

Because it need to build up sufficient pressure to send the blood to the whole body.

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14
Q

How does the heart function?

A
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15
Q

How can we measure the activity of the heart?

A

Using:

An ECG - measures the electrical impulses that causes the heart to contract and relax

Pulse rate - gives an idea of the strength and speed of the heartbeat

Stethoscope - to listen to the sounds of the heart ‘lub-dub’

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16
Q

Why do children have a higher pulse rate?

A

Because of their size.

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17
Q

Why do men have a lower pulse than women?

A

Because the female heart is smaller than the male so pumps less blood each minute.

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18
Q

Why id the heart rate of a fit person lower than an unfit person?

A

Because the heart does not have to work as hard to pump blood around the body.

19
Q

Why does an increase in physical activity cause the pulse rate to increase?

A

Because the heart must work harder to provide oxygen and nutrients to the muscle cells through aerobic respiration.

More CO2 is produced as a result which needs to be removed from the body.

If there is insufficient oxygen , lactic acid is produced leading to muscle fatigue and cramps.

20
Q

What is recovery time?

A

How fast a person’s pulse returns to normal.

21
Q

What causes coronary artery disease?

A

When the coronary arteries become blocked by a buildup of fatty plaques containing cholesterol.

22
Q

What does coronary artery disease lead to?

A

Heart attack. Because essential nutrients and oxygen cannot reach the heart tissue causing it to die.

23
Q

What causes CHD?

A

Stress
Gender
Age
Smoking
High Blood Pressure
Lifestyle diseases
Genetics
Poor diet

24
Q

How do you prevent CHD?

A
  1. Maintain a healthy diet -> decreases the chance that plaques will form and ensures that the person will remain within a healthy weight range for their age.
  2. Regular exercise -> makes the heart muscle stronger and encourages blood flow. Exercise ensure that energy is burned than stored as fat, helping the person maintain a healthy weight.
25
Q

Name the types of blood vessels.

A

Arteries
Veins
Capillaries

26
Q

List the characteristics of arteries.

A
  1. Moves blood away from the heart
  2. Blood moves in pulses as high pressure
  3. Has thick muscular walls
  4. Has narrow lumen
  5. Has no valves
  6. Carries oxygenated blood
27
Q

List the characteristics of veins.

A
  1. Moves blood towards the heart
  2. Blood flows smoothly at low pressure
  3. Has thin walls
  4. Has a wide lumen
  5. Semi-lunar valves are present
  6. Carried deoxygenated blood.
28
Q

List the characteristics of capillaries.

A
  1. Takes blood from arteries to veins
  2. Blood moves at very low pressure and pulse gradually disappears
  3. Very thin, permeable walls that are one cell thick.
  4. Narrow lumen
  5. No valves present
  6. Blood loses its oxygen (or gains it in the lungs)
29
Q

What do arteries have a narrow lumen?

A

To help maintain blood pressure

30
Q

Why does the artery not have valves?

A

High pressure prevents blood from flowing backwards.

31
Q

Why do veins have a large lumen?

A

To reduce resistance to blood flow.

32
Q

What are the four main components of blood?

A

Red blood cells
White blood cells
Platelets
Plasma

33
Q

How are RBCs adapted for their function?

A
  1. They are biconcave (to maximise the amount of haemoglobin they contain)
  2. They have no nucleus
  3. They conatin oxygen-binding pigment (haemoglobin)
34
Q

State the function of RBCs.

A

To transport oxygen

35
Q

State the functions of white blood cells.

A

Fight infection.

36
Q

Name the types of WBCs.

A

phagocytes
lymphocytes

37
Q

State the function of phagocytes.

A

Engulfs and digests harmful bacteria through the process of phagocytosis

38
Q

State the function of lymphocytes.

A

They produce antibodies.

39
Q

What are platelets.

A

Cell fragments

40
Q

State the function of platelets.

A

Causes clotting.

41
Q

State the process of blood clotting.

A

Platelets and damaged cells at the wound produces a substance that acts through a series of enzymes on the protein, fibrinogen (soluble) this changes to fibrin (insoluble)

This creates a network of fibres across the wound trapping the red blood cells and preventing further bleeding.

42
Q

Why is clotting important?

A

Prevents harmful microbes from entering the wound and causing infection.

43
Q

What is plasma?

A

A pale yellowish fluid where blood cells and platelets are suspended.

44
Q

State the function of plasma.

A

To carry cells and other important substances around the body including CO2, antibodies, hormones, urea and nutrients.

IGCSE Biology (21 decks)

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