B4: The Circulatory System

Question 1

What is the blood plasma, what does it so, what is in it?

Answer 1

The plasma is a yellow liquid that transports all blood cells and and other substances around the body.
* Waste CO2 carried to lungs
* Urea formed by the liver is carried to the kidney where it’s removed from the blood to form urine
* The small soluble products of digestion pass into the plasma from the small intestine, to individual cells

Question 2

What are red blood cells, what do they do?

Answer 2

Red blood cells pick up oxygen from the lings and carry it to cells where it is needed. Red blood cells have adaptation for efficiency such as:
* Biconcave discs, giving them an increases surface area for diffusion
* Packed with haemoglonim that binds to oxygen
* No nucleus, allowing for more space for haemoglobin

Question 3

What are white blood cells, what do they do?

Answer 3

• White blood cells are much largee than eed blood cells and there are fewer of them within the human body.
• They have a nucleus and are used for the body’s defence system against harmful microprganisms.
• Some (lymphocytes) form antibodies whilst others form antitoxins against poisons produced by microorgansims. Others (phagocytes) engulf and digest bacteria and viruses

Question 4

What are platelets, what do they do?

Answer 4

• Platelets are small fragments of the cell
• They have no nucleus and are important in helping the blood to clot at a wound
• This protects the new skin as it grows and stops bacteria entering the bidy through the wound

Question 5

What are blood clots?

Answer 5

Blood clotting is a series of enzyme-controlled reactions, coverting fibrinogen into fibrin. This peoduces a network of protein fibres that capture red blood cells and form a clot, stopping you from bleeding, forming a scab

Question 6

What are arteries?

Answer 6

• Arteries carry blood away from the heart to the organs
• This blood is usually bright red oxygenated blood
• Arteries have thick walls containing muscle and elastic fibres for high blood pressure as blood is pumped from the heart
• They stretch as blood is forced through them

Question 7

What are veins?

Answer 7

• The veins carry blood away from the organs towards your heart.
• This blood is usually low in oxygen and a deep purple-red colour
• Have much thinner walls than arteries and often have valves to prevent the backflow of blood
• The valves open as blood flows through them towards the heart and close if the blood flows backwards
• The blood is squeezed back towards the heart by the action of skeletal muscles

Question 8

What are capillaries?

Answer 8

• Capillaries form a huge network of tiny vessels linking the arteries and veins
• They are narrow with very thin walls of one cell thick
• This allows substances such as oxygen and glucose to easily diffuse out of the blood and into cells

Question 9

Label the heart

Question 10

Label the structure of the respiratory system

Question 11

What are adaptations of the alveoli?

Answer 11

Very thin alveolus walls give a short distance betwene air and the blood to make diffusion easy- only 1 cell thick

# Spherical shape of the alveoli gives relatively large surface area for diffusion
# Good blood supply maintains concentration gradient for diffusion by removing oxygen and bringing lots of carbon dioxide
# Ventilation moves air in and out through the bronchioles help maintain a steep diffusion gradient
# Alveoli surfaces are moist, allowing gasses to dissolve, increasing rate of diffusion

Question 12

What are coronary arteries?

Answer 12

Arteries that supply blood to the heart muscle

Question 13

In coronary heart disease, what happens to coronary arteries?

Answer 13

They become narrow

Question 14

Why does coronary heart disease occur?

Answer 14

Commonly due to a a buildup of fatty material on the lining of the vessels. The supply of oxygen to the heart muscle is also reduced, causing pain, a heart attack or even death

Question 15

What is a stent?

Answer 15

A stent is a metal mesh that is placed in the artery. They can be used to open up a blocked artery almost anywhere in the body, reducing the effects of coronary heart disease. The can also release drugs to prevent blood from clotting

Question 16

What are other options for someone with badly blocked arteries?

Answer 16

Bypass surgery, replacing the narrow or blocked coronary arteries with bits of veins from other parts of the body.

Question 17

What do statins do, who would use them?

Answer 17

They reduce blood cholesterol levels, slowing down the rate at which fatty material is deposited in the coronary arteries. These can be provided to anyone at risk from cardiovascular disease

Question 18

What are mechanical heart valves

Answer 18

These valves are made of lightweight, strong, and durable materials, such as titanium which replaced damaged heart valves. They will last 20–30 years before a replacement is needed.

Question 19

What are the advantages of a mechanical heart valve?

Answer 19

• Made of lightweight, strong and durable materials, such as titanium
• Will last 20-30 years
• Cheaper

Question 20

What are disadvantages of mechanical heart valves?

Answer 20

• Likely a blood clot will form on it, preventing it from working
• Patients will need to take blood thinning drugs every day for the rest of their lives
• Risk that a blood clot will form and then move to block a blood vessel, potentially causing a stroke or heart attack
• Expensive use of long term drugs

Question 21

What are biological heart valves?

Answer 21

Biological valves are created from animal valves or other animal tissue that is strong and flexible, usually from pigs. They can last 10–20 years. The risk of blood clotting is very small, so patients don’t usually require the long-term use of medication.

Question 22

A 76-year-old man needs a replacement heart valve. He lives alone and cares for himself. What would be the most suitable type of heart valve replacement for him: mechanical or biological?

Answer 22

The most suitable type of heart valve replacement for him would be a biological heart valave. This is because there is a decreased risk of blood clots and therefore heart attacks or strokes. Furthermore, it is likely it will be uneccessary to be used for up to 30 years so one kasting 10-20 years would be more suitable. It may also be better to not have to take blood thinning drugs every day, particularly as they would be increasingly likely to forget.

Question 23

What is the natural pacemaker?

Answer 23

The resting rhythm of a healthy heart of 70bpm is controlled by a group of cells found in the right atrium of the heart, acting as a ‘natural pacemaker’.

Question 24

What are the effects of the natural pacemaker stopping?

Answer 24

If the natural pacemaker stops working properly, this can cause serious problems. If the heart beats too slowly, the person won’t get enough oxygen. Id too fast, it cannot pump blood to organs properly

Question 25

What is an artificial pacemaker

Answer 25

An artificial pacemaker is an electrical device used to correct irregularitites in the heart rate, which is implanted into the chest. They are attached to the heart by 2 wires and sends strong, regular electrical signals to the heart, stimulating it to beat properly.

Question 26

What are some of the disadvantages of having an artificial heart?

Answer 26

* They have to wait for a donor heatt that is a tissue match. As a result of this wait, many die before they get a chance to have a trasnplant * Need a lot of machinery to keep them working * Most patients have to stay in hospital until they have their transplant * Always a risk of blood clotting in an artificial heart, which can lead to death * Resources and costs mean they are not yet widely used

Question 27

What are advantages of having an artificial heart?

Answer 27

* New technology gives people a chance to live a relatively normal life while they wait for a heart transplant * Can be used to give a diseased heart a rest, so that it can recover * Patients have a part or whole artifical heart implanted that removes the strain of keeping the blood circulating for a few weeks or months.

Question 28

In what situation may a person need an artificial heart?

Answer 28

When the heart fails completely

Question 29

What is the process of inhaling?

Answer 29

* Rib cage moves up and out as the external intercostal muscles contract * Diaphragm contracts and flattens * Volume of the thorax increases * Pressure in the thorax drops below atmospheric pressure * Air rushes in to fill the decreased pressure

Question 30

What is the process of exhaling

Answer 30

* Rib cage moves down and in as the external intercostal muscles relax * Diaphragm relaxes and moves upwards * Volume of the thorax decreases * Pressure in the thorax rises above atmospheric pressure * Air rushes out

Question 31

What is translocation?

Answer 31

* Sugary sap is transported uo and down in phloem vessels * This is called translocation

Question 32

What us transpiration?

Answer 32

Water leaves the plant by evaporation: - As vapour - Through the stomata

Question 33

What is the upper epidermis?

Answer 33

* One cell thick and covers the leaf like skin. The cuticle is a waxy layer which protects the leaf against diseased organsims, such as parasitic fungi * The cuticle is waterproof and helps prevent water loss by evaporation

Question 34

What is the pallisade mesophyll layer?

Answer 34

* Pallisade cells have a cylindrical shape, helping light to penetrate the leaf * Chlorophyll contained in the chloroplasts. Pallisade cells have more chloroplasts than other cells in the leaf * Chloroplasts can move within the cell to areas where light intensity is greatest

Question 35

What is the spongy mesophyll layer?

Answer 35

* Consists of irregular shaped cells with large air spaces between them and looks like a sponge under a microscope * Cells have fewer chloroplast than the pallisade cells since the light intensity is less

Question 36

What is the lower epidermis?

Answer 36

* One layer thick, like the upper upidermis * Contains pores called stomata (singular stoma), each made up of a pair of guard cells * Stomata allows gases and water vapour to diffuse in and out of the leaf

Question 37

What are the guard cells?

Answer 37

* Stomata open and close in response to changing conditions, such as light intensity, humidity, and carbon dioxide concentration

Question 38

What is the 'leaf vein'?

Answer 38

* Water and salts enter via the xylem. * Sugar sap (sucrose) made by photosynthesis passes out of the leaf via the phloem

Question 39

How do the stomata open?

Answer 39

This is because the guaed cells have areas of of cell wall which are thickened. As a result, when the cells become turgid, they bend and create an opening: the stomata.

Question 40

When do the stomata close?

Answer 40

During periods of lower water availbality, stomato close

Question 41

When do the stomata open?

Answer 41

When a plant is able to absorb enough water from the soil, the stomata open

Question 42

What is key information about the phloem cells?

Answer 42

* Transports the sugars (sucrose) made from photosynethesis from the leaves to the rest of the plant (growing areas of the roots and stem- meristem tissue) * Living tissue * Sap moving between cells through tiny pores * Movement of dissolved sugar from the leaves to other areas of th plant is called translocation * In woody plant such as trees, the phloem vessels are found in the ring under the bark. If destroyed, the tree will die

Question 43

What is key information about the xylem?

Answer 43

* Carries water and mineral ions from the soil around the plant to the stem and the leaves * Mature xylem cells are dead * In woody plant such as trees, the xylem vessels male up the bulk of the wood * Dead cells that form hollow tubes * Dead cells strengthened with lignin

Question 44

Where are the phloem found?

Answer 44

Further from the centre, whilst the xylem is found closest to the centre

Question 45

How does light intensity effect the rate of transpiration?

Answer 45

If light intensity increases, rate if transpiration will increase. When there is more light, the plant will photosynthesise more. This means the stomata will open to let carbon dioxide in. This also means more water will be lost out of the stomata.

Question 46

How does temperature affect the rate of transpiration?

Answer 46

If temperature increases, the rate of transpiration will increase. The molecules have more kinetic energy as temperature increases, resulting in quicker diffusion. The rate of photosynthesis also increases, so more stomata will be open for gas exchange, increasing rate of transpiration.

Question 47

How does humidity affect the rate of transpiration?

Answer 47

Rate of transpiration decreases. Water vapour diffuses more rapidly into dry air than into humid air as the concentratin gradient is steeper, thus, reducing the rate of transpiration as himidity increases.

Question 48

How does air movement/ windy conditions affect rate of transpiration?

Answer 48

Transpiration will increase. Windy conditions both increase the rate of evaporation and maintain a steep concentration gradient from the inside of the leaf to the outside by removing water vapour as it diffuses out.

Question 49

What are two features of a leaf that help plants to reduce water loss in normal conditions?

Answer 49

- One feature of a leaf that helps plants tonreduce water loss in normal comditions is the cuticle, a waxy waterproof layer to prevent uncontrolled waterloss through the upper epidermis. - Another feature of a leaf reducing water loss is the stomata, found on the underside of the leaves to protect them from the direct light and enegry of the sun, to control water loss as they open and close

Question 50

How does a plant try to protect itself in times of extreme or rapid water loss? Give two measures the plant may take and explain how they help the plant survive

Answer 50

- One measure the plant may take during times of rapid water loss is wilting, a protection mechanism as the leaves collapse and hang down, reducing rhe surface area available for water loss by evaporation. - Another measure a plant may take is the stomata closing, which stops photosynthesis and risks overheating however prevents most water loss and any further wilting.

Question 51

If you were to coat the bottom surface of a leaf with petroleum jelly (Vaseline), what effect would this have on the water loss from the leaf?

Answer 51

Coating the bottom surface of a leaf with petroleum jelly would significantly reduce any water loss from the leaf. The primary job of the stomata is to facilitate gas exchange, including the release of water vapour during transpiration. Since the stomata is covered with a hydrophobic substance such as petroleum jelly, water loss through the diffusion of water vapour will be significantly reduced.

Question 53

Where does blood go from the pulmonary artery?

Answer 53

When the right ventricle contracts, blood is forced through the pulmonary semilunar valve into the pulmonary artery. Then it travels to the lungs. In the lungs, the blood receives oxygen then leaves through the pulmonary veins. It returns to the heart and enters the left atrium.

Question 54

What occurs on the left side of the heart?

Answer 54

Oxygenated blood enters from the lungs through the pulmonary vein where it enters the left atrium. It is then pushed through by the bicuspid valves into the left ventricle, where it then moves through the semilunar valves into the aorta where it is pumped to organs around the body through arteries.

Question 55

What occurs on the right side of the heart?

Answer 55

Deoxygenated blood is carried through the vena cava into the right atrium, where it is pushed through the tricuspid valves into the right ventricle. The blood is then carried through the semilunar valves through the pulmonary artery where it is pushed by contraptions to the lungs to pick up oxygen.

Question 56

How is carbon dioxide carried around the circulatory system to be diffused into the alveoli?

Answer 56

Within the blood plasma