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A net movement of water particles from an region of high water concentration to a region of low water concentration through a partially permeable membrane

Animal cells:  If the solution outside the cell is more dilute than the cell contents then water will enter the cell by osmosis and swell and burst. If the solution is more concetrated water will move out of the cell by osmosis and will shrivel up


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Active transport

The net movement of mineral ions from a region of low concentration to a region of high concentration against a concentration gradient.

- Anywhere where active transport happens a lot of mitochondria are present for energy

Nitrogen: Proteins for growth

Magnesium: chlorophyll for photosynthesis

Phosphurous: Enzymes, respiration and photosynthesis

Pottasium: DNA and cell membrane

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Sports drinks

Sports drinks contain sugars ions an water to replace the water and ions lost during sweatind and the sugar when exercising

For day-to-day exercise, evidence suggests that water is more effective than sports drinks.

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Adaptations for exchanging materials

- Large surface area: To make exchange efficient

- Thin: short diffusion path

- Efficient blood supply: So substances are exchanged quickly

- Ventilated: Differences in concentration maintains the gradient and speeds up the rate of reaction

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Ventilating the lungs

Inhaling: Diaphragm flattens and intercostal muscles contract, pulling ribcage up and out, increasing the volume for the lungs to expand. Thus pressure outside is higher than inside so air is drawn in.

Exhaling: Diaghragm domes up and intercostal muscles relax, ribs drop down and in so volume of thorax gets smallerso lungs contract. Thus pressure inside is higher than outside and air is forced out.


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Iron lung

1. Air is pumped out of the iron lung, creating a very low pressure

2. This low pressure causes the thorax to expand causing air to flow into the lungs

3. when air is pumped back into the iron lung the pressure inside increases causing air to move out of the lungs

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Modern Ventilators

1. Modern ventilators increase the pressure in the patients airway using a tube put into the trachea

2. The increase of pressure in the patients airway causes air to flow into the patients lungs

3. Then the ventilator causes the pressure patients' airway to drop to zero and the patient breathes out

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Villi are small finger-like projections in the small intestine that increases the surface area of absorption

They have:

- A large surface area

- A thin wall

- A rich blood supply

They also use active transport to move glucose and other food molecules from the small intestine into the blood stream

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Exchange in plants (Part 1)

- The carbon dioxide level outside is higher outside than inside the leaf. So it moves in by diffusion. As soon as it gets in photosynthesis takes place and reduces the concentration level again

- There are more water particles in the soil than in the roots so it moves in by osmosis. The roots act as a partially permeable membrane.

- There are less mineral ions in the soil than in the roots so they move in using the energy from the mitochondria by active transport.  

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Exchange in plants (Part 2)

- The root hair cells are small and thin giving them a smaller distance to travel making the process faster. They also have a large surface area to help absorb lots of water and thin walls for a short difussion path

- Leaves have waxy cuticles to reflect light and have minimum hair loss

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The lower epidermis of a leaf has more stomata than the upper epidermis due to the upper epidermis being in direct light so the stomata would open more often and a lot of water would be lost.

Open: Guard cells are swolen, due to lots of water

Cose: Guard cells lose water and become flaccid and close. This happens when the plant has a lost a lot of water.

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- The loss of water vapour through the stomata by evaporation

- Transpiration stream: The movement of water from the roots via the xylem to the leaves and then evaporates through the stomata

Light: Stomata opens more to allow carbon dioxide into the leaf by photosythesis

Temp: Evaporataion and diffusion happens faster at higher temperatures

Wind: As soon as water reaches the stomata it gets blown away maintaining the gradient

Humidity: Concentration gradient isn't speed so transpiration is slower

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The heart (part 1)

Double circulation: one transport stream carries blood from your heart to your lungs and back. The other carries blood around your body and back.

The heart is divided into 4 chambers. Tops are atriums, bottoms are ventricles.

The muscle on the left ventricle has more thickness because the left side is pumuping blood to the whole body so the pushing action has to be harder

Coronary: to do with the heart

Pulmonary: to do with the lungs

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The heart (Part 2)

The blood coming into the right atriumm from the vena cava is deoxygenated blood from your body.

The blood coming into the left atrium from the pulmonary vein is deoxygenated blood from your lungs.

The atria contract together and force blood down into the ventricles.

Valves close to stop the blood flowing backwards out of the heart

pulmonary vein -> aorta -> vena cava -> pulmonary artery

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Lumen: holes in which things pass through

Arteries: Small lumen (high pressure); thick layer of muscle (so it doesn't burst); carries blood away from heart (oxygenated)

Veins: Big lumen (low pressure); have valves (prevents backflow); carries blood to the heart (low oxygen)

Capillaries: small to fit in tight places (short diffusion path) links arteries to veins.

veins -> atria -> ventricles -> arteries

Pulmonary veins/arteries carry oposite blood.

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When a blood vessel is clogged with fat or is narrowed with age, a stent is inserted into the blood vessel via the groin or arm. The stent is inserted and the balloon is inflated, pushing the fat into the wall of the vessel when the wire mesh   is opened. Blood flows easily.

Immunosuppressents is taken for the rest of your life when you have a transplant

Adv: No anaesthetic, cheap, effective. Prevents heart attacks, pain or death./ Dis: Cant open most arteries 

Bypass adv: Effective against severe blockages./ Dis: anaesthetic needed

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Mechanical Valve

Pro: Lasts long, works well

Con: Medication for the rest of your life, open heart surgery

Biological Valve

Pro: works well, no medication

Con: Replaced after 15 years

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Blood transport

Red blood cells contain haemoglobin and iron (which makes it red), are biconcave (which makes the surface area larger) and have no nucleus (More space for haemoglobin)

Platelets are small fragments with no nucleus. When you get a cut they produce a network of protein threads that capture blood cells and form a clot.

Haemoglobin + oxygen <-> oxyhaemoglobin

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Artificial blood


Pro: Can match everyone and can be stored for a long time/ Con: carries very little oxygen

Blood from others

Pro: has everything                                        Con: might not match, can pass diseases


Pro: Replaces the blood volume to buy time for the body to make more blood                                            Con: Doesn't carry oxygen

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Controlling internal conditions

Carbon dioxide: Produced during respiration (If disolved produces acidic solution) (Acidic solution can affect enzymes)leaves the body via lungs when breathing out

Urea: Liver removes amino acid and converts it into urea (poisonous) 

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Nephron (kidney tubule)

Renal: To do with Kidneys

Convoluted: Long and coiled

The unfiltered blood from the body is taken to the kidney via the renal artery. It seperates into capilaries called the glomerous. The sugar, amino acids, mineral ions and urea move out of the blood and into the bowmans capsule by diffusion, down a concentration gradient. The blood carrying the waste moves through the convoluted tubes, then the loop of henle to the collecting duct which does to the bladder. If the body lacks water (dehydrated), the water moves out of the loop of henle tothe renal vein by osmosis, down a concentration gradient. If the body isn't lacking in water it is passed through the urine

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Dialysis: artificially carries out the funtion of Kidneys

A Dialysis machine removes the blood from the arm and filters waste products out using a dialysis fluid. This fluid contains the same concentration of every useful product as the blood and has low concentrations of the waste products and none of the urea. This removes most of the waste products and all of the urea.


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Controlling body temperature

When you are hot, the blood vessels that supply your skin capillaries dilate. This lets more blood flow through the capillaries. Your skin flushes, so you lose more energy by raditaion. Your rate of sweating goes up. This extra sweat cools your body down as it evaporates. In humid weather when sweat doesn't evaporate as much it is harder to cool down.

When you are cold, the blood vessels that supply your skin capillaries constrict to reduce the flow of bloodthrough the capilaries. This reduces the energy released by radiation through the surface of the skin. Sweat production is reduced. You may shiver - your muscles contract and relax rapidly. These muscle contractiona need a lot of respiration, which releases more energy. This raises your body temperature 

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Controlling blood glucose

When the blood sugar level is high: Insulin is released which triggers glucose to be changed to glucagon which lowers the sugar level.

When the blood sugar level is low: Glucagon is released which triggers glycogon to be converted back to glucose which raises the blood sugar level.

The blood glucose concentration of the body is monitored and controlled by the pancreas releasing insulin and glucagon


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