B2 Keeping Healthy

What are the symptoms of an infectious disease caused by?

Damage done to cells by microorganisms, or by the toxins they produce.

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Why do microorganisms reproduce quickly inside the human body?

Ideal conditions- warm, moist, source of nutrients so that the chemical reactions can take place.

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What are the two ways white blood cells defend the body from foreign microbes?

1) Phagocytosis- white blood cells detect anything 'foreign' to the body and enulgf and digest the microorganism. 2) Producing antibodies

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Describe how antibodies defend the body.

Specific white blood cells recognise foreign microbes by their antigen markers, protein molecules on the surface of a microorganism cell.

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Describe how antibodies defend the body (2).

Antibodies latch onto invading organisms and mark it so other white blood cells can engulf and digest it, neutralise viruses/toxins or latch on and kill the bacteria directly.

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What is immunity?

Some white blood cells stay in the blood after an infection has been fought off- memory cells. These can reproduce very quickly if faced with a repeating microorganism before you become ill.

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How do vaccinations provide protection from microoganisms?

Vaccination/Immunisation involed injecting dead or inactive microorganisms which, when your body produces the antibodies, establishes memory cells.

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What is needed to prevent epidemics of infectious diseases?

A large percentage of the population needs to be vaccinated. If a significant amount of people are not vaccinated, disease can spread rapidly but if most people are vaccinated, even those who aren't are unlikely to catch a disease.

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Why can vaccinations and drugs never be completely safe for everyone?

People experience varying side-effects, which can be more serious for some than others. Genetic differences mean people will react differently to drugs.

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What are antimicrobials?

Chemicals that inhibit the growth of microorganisms, or kill them, without damaging your own body cells.

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Explain how microorganisms can become restistant to antimicrobials.

Random mutations in DNA lead to changed in characteristic which could mean an organism is less affected by an antimicrobial. This means it is more likely to survive and reproduce.

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How can we reduce antibiotic resistance?

1) Only use antibiotics if completely necessary- they create a situation where naturally resistant bacteria have an advantage to reproduce. 2) Finish a course- increase risk of resistance.

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Why are drugs tested on human cells and what is a disadvantage?

Effectiveness. Disadvantages- cannot recreate the conditions of a whole organism

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Why is animal testing useful?

Many mammals have systems similar to those of humans.

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What do human trials test for and on who?

Healthy volunteers to test for safety and people with the illness to test for safety and effectiveness.

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Describe open-label trials.

Both the patient and the scientists are aware of the treatments being used. They are used when you cannot mask the treatment being tested

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Describe blind trials.

Patients do not know if they are being given the drug or a placeo because a patient who knows their being treated may feel better for psychological reasons, blind trials eliminate this.

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Describe double-blind trials.

Neither the scientist nor patient know which patients were given real drugs and which got placebos. This is so the scientists are not subconsciously influenced by their knowledge.

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What is the importance of long-term trials and why can placebos have ethical implications?

Long-term trials are important to observe any harmful long-term side effects. Placebos aren't used in some trials because it's unethical not to allow all patients to get benefits of the new drug.

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Describe the role of the heart as a double pump.

The right side pumps blood to the lungs to collect oxygen and remove carbon dioxide, the left side pump the oxygenated blood around the body.

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Why do the heart muscle cells need their own blood supply and where do they receieve it from?

To deliver the nutrients and oxygen needed to keep the heart beating continually. Blood is supplied to the heart by two coronary arteries which branch from the base of the aorta.

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How are arteries structured for their function?

Strong and elastic walls because the blood comes out of the heart at such a high pressure.

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How are veins structured for their function?

Valves to keep the blood flowing in the right direction. Bigger lumen and thinner walls than arteries to help the blood flow more easily as the blood is at a lower pressure.

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How are capillaries structured for their function?

Permeable 'one cell thick' walls so substances can diffuse in and out very quickly.

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Why can your pulse rate be used to measure heart rate?

The pulsation of an artery is caused by blood being pumped through it by a heart beat.

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How is blood pressure measured?

Blood pressure records the pressure of the blood on the walls of the artery. They have two values: 1)when the heart contracts and blood is forced out of the heart 2) when the heart relaxes and the heart fills with blood.

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Why are 'normal' heart and blood pressure rate measurements given within a range?

Because individuals vary.

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How can high blood pressure increase the risk of heart disease?

The inner lining of an arter is usually smooth/unbroken but high bp can damage it. Fatty deposits can build up in damaged areas of arteries which restrict blood flow. If a fatty deposit breaks through the inner lining, a blood clot may form.

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What is a heart attack?

If a coronary artery becomes completely blocked, an area of the heart muscle will be totally cut off from its blood supply receiving no oxygen.

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Name and describe lifestyle factors which can increase the risk of heart disease.

1)Poor diet- cholesterol(saturated fat)makes up a large part of the fatty deposits which can block arteries. A diet high in salt can increase blood pressure. 2)Smoking- CO reduces the amount of oxygen blood can transport (heart attack)

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What can epidemiological studies identify?

Epidemiology is the study of patterns of diseases and the factors that affect them. They can be used to identify the factors that increase the risk of heart disease.

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Define homeostasis and why it is important.

Homeostasis is balacing inputs and outputs to maintain a constant internal environment. The conditions inside your body need to be kept steady because cells need the right conditions to function.

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How does negative feedback counteract changes?

Receptors detect a change in the environment, the processing centre receives the information and coordinates a response, the effector produces a response.

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What role do the kidneys play in the body?

Balance substances- fiter small molecules from the blood including water, sugar, salt and waste and then reabsorb all the sugar, and as muuch salt and water is required.

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Describe ADH.

Anti-diuretic hormone is released into the blood stream by the pituitary gland, the brain monitors the water content of the blood. If the water content of blood is too high, less ADH will be released so the kidneys reabsorb less water.

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What effect does alcohol and ecstasy have on ADH production?

Alcohol suppresses ADH, the kidneys reabsorb less water which results in a larger amount of more dilute urine (risk of dehydration). Ecstasy increases ADH production, a smaller amount of more concentrated urine is produced.

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B2 Keeping Healthy

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