Transport in Humans

Question 1

What is the word that describes the movement of molecules from areas of high concentration to low concentration in liquids and gases?

Answer 1

Diffusion

Question 2

How is diffusion one of the processes responsible for the movement of substances in living things?

Answer 2

Small molecules can pass through cell membranes, so diffusion occurs between the cytoplasm and surrounding environment.

Diffusion moves oxygen and glucose into cells for respiration and removes carbon dioxide and other waste substances.

Question 3

What are the four main factors that affect the rate of diffusion?

Answer 3

1) Temperature. At higher temperatures molecules have more kinetic energy and move faster, therefore diffusion is faster
2) Concentration gradient. If there is a large difference in the concⁿ gradient between two areas, molecules will move from the higher to the lower concentration quicker
3) Surface area. A larger surface area speeds up diffusion as there is more space for the molecules to move
4) Volume. Diffusion is slower if it has to fill a larger volume
5) Distance. Diffusion happens faster over shorter distances

Question 4

What system transports substances around the body?

Answer 4

The circulatory system

Question 5

What substances are transported by the circulatory system?

Answer 5

Oxygen and nutrients are transported to all the cells and waste products from the cells to the lungs and kidneys

Question 6

What are the two circulatory circuits, and what do they do?

Answer 6

Blood returning from the body is deoxygenated. It is pumped to the lungs where oxygen is gained and carbon dioxide is lost and then returned to the heart. This is the pulmonary circulation.

Blood is then pumped around the rest of the body where cells absorb the oxygen and releases carbon dioxide, before being returned to the heart. This is the system circulation.

Question 7

Some animals have a single circulatory system. How does this work?

Answer 7

Blood is pumped from the heart to the gas exchange organ and then directly onto the rest of the body

Question 8

Define ‘metabolic rate’

Answer 8

The rate of chemical reactions in the body. It is higher in more active organisms, especially those which maintain their own body temperature

Question 9

Blood is a complex tissue. What are the components?

Answer 9

Plasma

Platelets

Red blood cells

White blood cells

Question 10

What is plasma?

Answer 10

A straw coloured liquid, mainly made of water, containing a wide range of dissolved and suspended molecules

Question 11

What does plasma do?

Answer 11

Plasma transports the blood cells

It also transports dissolved nutrients, dissolved waste products and a wide range of proteins

Question 12

What are platelets?

Answer 12

Platelets are small cell fragments which help to form clots, which prevents blood loss and infection

Question 13

What do white blood cells do?

Answer 13

White blood cells help destroy pathogens which are infecting our body. They are an essential part of the immune system.

Question 14

What are red blood cells?

Answer 14

Highly specialised cells which live in the bone marrow, and only survive for about 100 days before being destroyed by the liver or spleen

Question 15

In what blood cells will you find haemoglobin?

Answer 15

Red blood cells

Question 16

What shape are red blood cells and why?

Answer 16

Red blood cells are biconcave - they are discs with a dip in the middle.

This increases the surface area to volume ratio and decreases the distance to the centre of the cell. This allows for a higher rate of diffusion of oxygen in and out of the cell

Question 17

Do red blood cells have a nucleus? Why?

Answer 17

No, so more haemoglobin can be stored in each cell

Question 18

What is the function of the heart?

Answer 18

The heart pumps blood around the body via the blood vessels

Question 19

Where is the heart found?

Answer 19

The heart is found in the centre of the thorax, partially surrounded by the lungs and protected by the rib cage

Question 20

The heart is divided into left and right sides. What does each side do?

Answer 20

1. The right side of the heart pumps blood to the lungs where it takes up oxygen and loses carbon dioxide.
2. The oxygenated blood then passes back to the left side of the heart.
3. The left side of the heart pumps blood to the rest of the body.
4. Cells throughout the body absorb the oxygen from the blood and deoxygenated blood returns to the right side of the heart.
   (5. The blood passes through the heart twice for every complete circuit of the body.)

Question 21

The heart is divided into four chambers, describe them.

Answer 21

The two atria are located at the top of the heart. They are the smaller of the chambers and have thin muscular walls.

Below each atriaum is a ventricle, a larger chamber with a thicker muscular wall.

The left atrium and ventricle are separated from the right atrium and ventricle and by thick muscular wall called teh septum

Question 22

Why does the left ventricle have a much thicker muscular wall than the right ventricle?

Answer 22

A much higher pressure is required to pump blood to the entire body then to the lungs. The left ventricle has a much thicker muscular wall than the right ventricle, allowing it to pump blood at a higher pressure

Question 23

In the cardiac cycle, where does blood flow into the two atria from?

Answer 23

Blood flows into the two atria from either the Vena Cava or pulmonary veins

Question 24

Why are the valves essential in the cardiac cycle?

Answer 24

The valves are essential in preventing blood from flowing in the wrong direction through the heart. Valves do not open by themselves, but are forced open or closed by changes in blood pressure.

Question 25

For an artery, describe the outer wall, lumen, intercostal muscles and elastic fibres

Answer 25

An artery has a thick outer wall, small lumen, and thick layer of muscles and elastic fibres

Question 26

Which way do arteries and veins carry blood?

Answer 26

Arteries transport blood away from the heart to all regions of the body.

Veins carry blood from the organs back to the heart.

Question 27

For a vein, describe the outer wall, lumen, intercostal muscles and elastic fibres

Answer 27

A vein has a thin layer of muscles and elastic fibres, a thin outer wall, and a large lumen

Question 28

Describe the blood pressure in arteries and veins

Answer 28

Arterial/artery blood is high-pressure, and venous/vein blood is low pressure

Question 29

In the human circulatory system, where will you find one way pocket valves?

Answer 29

Veins contain one way pocket valves

Question 30

What do capillaries do?

Answer 30

Capillaries carry blood through organs

Question 31

When does our heart rate increase?

Answer 31

It increases when we are stressed or when we exercise

Question 32

What happens to our muscles when our heart rate increases?

Answer 32

The faster blood flow provides extra oxygen and glucose to the muscles, allowing for a faster rate of aerobic respiration

Question 33

What part of the brain controls changes in heart rate?

Answer 33

Changes in heart rate are controlled by nerve impulses from the medulla

Question 34

Label this diagram of the heart

Answer 34