Zusammenfassung der Ressource
Biology B1
- Fitness and Health
- Blood Pressure
- Measured
in
millimetres
of mercury
(mmHg)
- Stylostic pressure is the maximum pressure the heart produces
Diastolic pressure is the blood pressure between heartbeats
- Can be increased by:
stress, high alcohol
intake, smoking and
being overweight
- Can be decreased by:
regular exercise and
eating a balanced diet
- High blood pressure can
cause blood vessels to burst.
It can cause damage to the
brain (stroke) and to the
kidneys
- Low blood pressure can cause dizziness, fainting (because the blood
supply to the brain is reduced) and poor circulation to other areas such
as the fingers and toes.
- Fitness and Health
- Fitness is the ability to do
physical activity
- Health is being free from
diseases such as those caused
by bacteria and viruses.
- General level of fitness can be measured by your cardiovascular efficiency
- Fitness can be measured for different activities
- Strength - by the amount of weights lifted
- Flexibility - by the amount of joint movement
- Stamina - by the time of sustained exercise
- Agility - by changing direction many times
- Speed - by a sprint race
- Therefore, you can
be very fit for a sprint
race but not perform
well in a marathon
(stamina)
- Ways of measuring fitness should be evaluated to
check effectiveness in particular situations
- Smoking
- Smoking can increase blood
pressure in a number of ways
- Carbon monoxide in smoke causes blood to carry less oxygen.
This means the heart rate increases so that the tissues receive
enough oxygen
- Carbon monoxide decreases the oxygen-carrying capacity of blood
- It combines with haemoglobin, preventing it from
combining with oxygen, so less oxygen is carried
- Nicotine in cigarette smoke directly increases heart rate
- Diet and Heart Disease
- Heart disease is caused by a restricted
blood flow to the heart muscle
- The risk is increased by having a high level of saturated fat in the diet,
which leads up to a build-up of cholesterol (a plaque) in arteries
- Also increased by having high
levels of salt, which can
increase blood pressure
- It is essential to be able to interpret data showing links between the
amount of saturated fat eaten ,the build-up of cholesterol and the
incidence of heart disease
- The narrowing of the arteries (caused by plaques in the coronary arteries)
can reduce blood flow to the heart
- The plaques also make blood clots or thrombosis more
likely to happen, which will also block the artery
- Remember: It is the blood vessel into the heart muscle that is blocked,
not the blood flowing into the heart!
- Human Health and Diet
- A Balanced Diet
- It is important for good
health to eat a balanced
diet
- A balanced diet contains the correct
amounts of chemicals found in food
- Three of these are:
carbohydrates (made of
simple sugars such as
glucose), proteins
(made up of amino
acids), fats (made up of
fatty acids and glycerol
- A balanced diet varies according to factors including age,
gender, level of activity, religion, being vegetarian or vegan,
or because of medical issues such as food allergies
- If you eat too much fat or carbohydrates they are stored in the body
- Carbohydrates are stored in the liver as glycogen or converted into fats
- Fats are stored under the skin and around the organs as adipose tissue
- Although proteins are essential for growth and repair, they cannot be stored in the body
- Although proteins cannot be stored in the body,
some amino acids can be converted by the body
into other amino acids
- Protein Intake
- Proteins are needed for growth and so it
is important to eat the correct amount
- This is called the estimated average daily requirement (EAR)
- It can be calculated using this formula:
EAR in g = 0.6 x body mass in kg
- Example: Sue has a mass of 72.5kg.
Her EAR is 0.6 x 72.5 = 43.5 g/day
- The EAR is only an estimated figure based on an average person
- It may be affected by factors such as body mass, age, pregnancy or breast-feeding
- Too little protein in the diet causes kwashiorkor.
This is more common in developing countries due
to overpopulation and lack of money to improve
agriculture
- Proteins from meat and fish are called first-class proteins
- They contain all the essential
amino acids that cannot be made
by the human body
- Plant proteins are called second-class proteins as they do not contain all the essential amino acids
- Overweight or Underweight?
- To work out if a person is overweight or underweight you calculate their body mass index (BMI)
- BMI = mass in kg / (height in m)2
- Example: Tom is 170cm tall and has a mass of 80kg.
170cm = 1.7 m. BMI = 80 / 1.7 squared = 27.7
- A BMI of more than 30 means the person is obese,
25-30 is overweight, 20-25 is normal, less than 20 is
underweight
- Some people may become ill as they choose to eat less than they need.
This may be caused by low self-esteem, poor self-image or a desire for
what they think is perfection
- Staying Healthy
- Malaria
- Malaria is caused by a protozoan called Plasmodium
which feeds on human red blood cells
- Plasmodium is carried by mosquitoes, which are vectors
- Vectors are not affected by the disease
- It is transmitted to humans by mosquito bites
- Plasmodium is a parasite and humans are its host.
A parasite is an organism that feeds on another
living organism, causing it harm
- Knowledge of the mosquito's life cycle has helped stop the spread of malaria (by
draining stagnant water, putting oil on the water surface and spraying insecticide).
This knowledge has also helped to develop new treatments
- Cancers
- Change in lifestyle and diet can
reduce the risk of some cancers
- Not smoking reduces the risk of lung cancer
- Using sunscreen reduces the risk of skin cancer
- Benign tumour cells such as warts divide slowly and are harmless
- Cancers are malignant tumours:
the cells display uncontrolled
growth and may spread
- Ways of interpreting data on cancer and
survival/mortality rates should be considered
- The Fight Against Illness
- Pathogens (disease causing organisms) produce the symptoms of an infectious disease
by damaging the body's cells or producing waste products called toxins
- The body protects itself by producing antibodies
- These lock onto antigens on the surface of pathogens such as a bacterium.
This kills the pathogen
- White blood cells produce antibodies resulting in
active immunity. This can be a slow process but has a
long-lasting effect
- Vaccinations using
antibodies from
another human or
animal result in
passive immunity,
which has a quick
but short-term
effect
- Each pathogen has its own antigens so a
specific antibody is needed for each pathogen
- The process of
immunisation is
also called
vaccination
- It starts with
injecting a
harmless
pathogen carrying
antigens
- The antigens trigger a response by white
blood cells, producing the correct antibodies
- Memory cells (a type of T-lymphocyte cell) remain in the body,
providing long-lasting immunity to that disease
- Immunisation carries a small risk to the
individual, but it avoids the potentially
lethal effect of the pathogen, as well as
decreasing the risk of spreading the
disease
- Treatments and trials
- Antibiotics (against bacteria and fungi) and
antiviral drug are specific in their action
- Antibiotics destroy pathogens, antiviral
drugs slow down pathogen's development
- New treatments are tested using animals, human
tissue and computer models before human trials.
Some people object to causing suffering in animals
in such tests
- The Nervous System
- How Do Eyes Work
- Light rays are refracted (bent) by the cornea and lens
- The retina contains light receptors. Some are sensitive to different colours
- Binocular vision helps to judge distance by comparing the images from each eye;
the more different they are, the nearer the object
- Accommodation is where the eye can focus light from
distant or near objects by altering the shape of the lens
- The ciliary
muscles relax and
the suspensory
ligaments tighten
(so the lens has a
less rounded
shape) to focus
on distant objects
- The ciliary muscles contract and the suspensory ligaments slacken
(so the lens regains a more rounded shape due to its elasticity) to
focus on near objects
- Faults In Vision
- Red-green colour blindness is
caused by a lack of specialised
cells in the retina
- Long or short sight are caused by the eyeball or lens being the wrong shape
- In long sight, the eyeball is too short or the lens is too thin,
so the image is focused behind the retina
- In short sight, the eyeball is too long or the lens is too rounded so the lens refracts light too much,
so the image would be focused in front of the retina
- Corneal surgery or a lens in glasses or contact lenses corrects long and short sight.
A convex lens is used to correct long sight, a concave lens to correct short sight
- Nerve Cells
- Nerve cells are called neurones.
Nerve impulses pass along the axon
- What happens in a reflex action is shown by a reflex arc. The links in a reflex arc are:
stimulus-->receptor-->sensory neurone-->central nervous system-->motor
neurone-->effector-->response
- The pathway for a spinal reflex is:
receptor-->sensory neurone-->relay
neurone-->motor neurone-->effector
- Neurones are adapted by being long, having branched endings
(dendrites) to pick up impulses and having an insulator sheath
- The gap between neurones is called a synapse.
- The arrival of an impulse
triggers the release of a
transmitter substance, which
diffuses across the synapse.
The transmitter substance
binds with receptor
molecules in the membrane
of the next neurone causing
the impulse to continue