Transcript B1 - ME School of Excellence

Core Biology (B1)
Topics:
•Fitness and Blood Pressure
•Respiration
•Eating Healthily
•Diet Problems
•Digestion
•Infectious Disease
•Preventing and Treating Infectious Disease
• Other Health Conditions
•Drugs; Use and Harm
•Smoking and Alcohol
•Receptors; The Eye
•Neurones and Nervous System
•Reflex Actions
•Homeostasis
•Controlling Blood sugar
Fitness and Blood Pressure
Healthy = being free from any infections or disease
Fit = measure of how well you can perform physical tasks
* STRENGTH, SPEED, FLEXABILTY, STAMINA, CARDIOVASCULAR ENDURANCE
Blood is pumped around your body under pressure…
The blood is pumped around the body by contractions of the heart, these contractions increase the pressure
of the blood. The blood leaves the heart and flows through the arteries, these split into many tiny
capillaries which take blood to every cell in the body. The blood then flows back to the heart through the
vein, the pressure gets lower as the blood flows through the system. The blood pressure is at its highest
when the heart contracts - systolic pressure. When the heart relaxes its pressure is at its lowest –
diastolic pressure.
A healthy person shouldn’t be higher than about 135 (systolic pressure) and 85 (diastolic pressure). Factors
that contribute to high blood pressure:
• A diet with too much salt in
• Being overweight
• Drinking too much alcohol
• Being under lots of stress for a long time
• Not doing enough exercise
• Old age (as people get older, their blood pressure tends to get higher)
If the pressure of the blood is too high is can cause blood vessels to burst.
Respiration
• Respiration is the process of releasing energy from glucose which happens
constantly in every cell
There are two types of respiration;
- Aerobic
- Anaerobic
Aerobic respiration happens when there is a lot of oxygen available
Glucose + Oxygen
Carbon Dioxide + Water (+energy)
C₆H₁₂O₆ + 6O₂
6C0₂ + 6H₂O (+energy)
Anaerobic respiration doesn’t use oxygen at all
Glucose
Lactic Acid (+energy)
•
•
Anaerobic respiration the glucose is only partially broken down and only lactic acid is
produced
When you do really vigorous exercise your body cannot supply enough oxygen to your
muscles for aerobic respiration so your muscles have to start respiring anaerobically.
Eating Healthily
You need to eat a balanced diet to supply all your essential nutrients…
Carbohydrates – e.g. glucose, provide energy
Fats – provide energy, act as an energy store and provide insulation
Proteins – needed for growth and repair of tissue, provide energy in emergencies
Vitamins – Various functions e.g. vitamin C is used to prevent scurvy
Minerals – Various functions e.g. iron is used to make haemoglobin for healthy blood
Water – we need a constant supply of water to replace water lost through urinating, breathing and sweating
* Carbohydrates are made up of simple sugars like glucose
* Fats are made up of fatty acids and glycerol
*Proteins are made from amino acids
Energy and nutrition vary between different ages and types of people…
AGE: children and teenagers need more protein for growth. Older people need more calcium to
protect against degenerative bone diseases like osteoporosis
GENDER: females need more iron to replace the iron lost in menstrual blood
PHYSICAL ACTIVITY: active people need more protein for muscle development and more
carbohydrates for energy
Diet Problems
• Eating too much can lead to obesity…
Obesity can lead to many risks including diabetes, high blood pressure, coronary heart
disease and sometimes even forms of cancer e.g. breast cancer
• Eating too little can cause problems..
Eating too little protein can cause a condition called Kwashiorkor. A common symptom
of this is a swollen stomach. Some psychological disorders cause under-nutrition
e.g. anorexia or bulimia.
To calculate the recommended daily allowance of protein you do;
RDA(g) = 0.75 x body mass (kg)
To calculate body mass index (BMI) you do;
BMI = body mass (kg)
height²
You use this to help decide whether someone is underweight, normal, overweight or obese.
Digestion
First the big lumps of food are physically digested so they can pass easily through the
digestive system (chewing in the mouth and churning in the stomach). Then chemical
digestion is used to break the big molecules that are too big to pass through the cell
membrane. this involve using enzymes – biological catalysts that break big molecules
into small ones.
There are three types of main digestion enzymes:
1) Carbohydrases – break down big carbohydrates such as starch into simple sugars.
They are present in the mouth and the small intestine.
2) Proteases – convert proteins into amino acid. They are present in the stomach(where
it is referred to as the pepsin) and the small intestine.
3) Lipases – convert fats into fatty acids and glycerol. They are present in the small
intestine.
Glucose and amino acids are small enough to diffuse into the blood plasma. The
products of fat digestion cant get into the blood plasma so they diffuse out of the gut
(intestines) and into a fluid called lymph. From here they are emptied into the blood/
the nutrients then travel to where they’re needed and diffuse out again. E.g. glucose
travels to muscles for respiration during exercise.
Infectious Disease
Pathogens are micro-organisms that cause disease. There are four types:
1) Fungi e.g. athletes foot
2) Bacteria e.g. cholera
3) Viruses e.g. flu
4) Protozoa e.g. dysentery
Malaria is an example of an infectious disease. It is caused by a protozoan and is carried by
mosquitoes which are insects that feed on the blood of animals including humans. The
protozoan is the parasite and the animal it affects is the host.
Once microorganisms enter your body they reproduce rapidly unless they’re destroyed; this is
the job for your immune system. White blood cells travel around your body and when they
come across a microorganism they do three different things:
•
Consuming them – white blood cells engulf the cells and ingest them
•
Producing antitoxins – these counter the effect of any poisons produced by the bacteria
•
Producing antibodies – when your WBC come across an antigen they start to produce
proteins called antibodies which lock onto and kill the new invading bacteria. The
antibodies produced are specific to the pathogen and wont lock onto any other ones.
Antibodies are then produced rapidly and flow around the body to kill all similar bacteria
or viruses. If the person is infected with the same pathogen again the WBC can quickly
produce the antibodies to kill it meaning the person is naturally immune to that pathogen
and won’t get ill.
Preventing and Treating Disease
Immunisation
• When you’re infected with a new microorganism it can take your WBCs a while to produce the
antibodies needed to deal with them. In that time you can become very ill or maybe even die. To avoid
this you can become immunised against some diseases e.g. measles. Immunisation involves injecting
dead/inactive microorganisms into the body. These carry antigens so even though they’re harmless to
your body the antigens attack them. T
Here are two types of immunity;
1) Active – where the immune system makes its own antibodies, usually permanent
2) Passive – where you use antibodies made by another organism, temporary
There are both benefits and risks associated with immunisation…
•
Can stop you from getting ill
•
If most people are immunised the disease won’t be able to spread as easily
•
Short term side effects e.g. swelling/ redness by injection, feeling ‘under the weather’
•
Can cause other disorders (some think) e.g. MMR vaccine and autism
•
You can’t have some vaccines if you are already ill
Antibiotics:
•
Drugs that kill bacteria and fungi without killing your own body cells.
•
They don’t kill viruses. Some bacteria are naturally resistant to some antibiotics, which is why you
should always finish of a course of antibiotics once you’ve started giving it an oppurtunity to kill all the
bacteria. Otherwise you risk leaving the resistant ones to thrive and multiply and get passed on to
other people. MRSA is an example of an antibiotic resistant strain.
Other Health Conditions
Health disorders can be caused in different ways…
• Vitamin deficiency – e.g. you can get scurvy if you don’t get enough vitamin C
• Mineral deficiency- e.g. lack of iron can lead to anaemia
• Genetic inheritance – e.g. red-green colour blindness or haemophilia
• Body disorders – body cells not working properly e.g. cancer, diabetes
Cancer – caused by cells growing out of control
Benign – where the tumour grows until there is no more room, and the cells stay where they are
(usually not dangerous)
Malignant – the tumour grows and can spread to other sites in the body (dangerous may be
fatal)
Testing Disease Treatments..
Clinical Trial: two groups of patients, one is given the real drug and the other are given a
placebo(sugar pill, looks like the real drug but doesn’t do anything). This allows the scientist
to see it actually works. The placebo effect is where patients expect to feel better so think
they feel better even though the pill has done nothing. Clinical trials are blind so the patient
doesn’t know which drug they are getting, the scientist also doesn’t know.
Drugs; Use and Harm
Drugs can be both beneficial or harmful
Drugs are substances that alter the way the body works. Some are medically useful such as antibiotics e.g.
penicillin but many drugs are dangerous is misused.
There are different types of drugs, all having different types of effects on the body…
1) Depressants: e.g. alcohol. Decreases the activity of the brain, slow reactions, poor judgment of speed
and distances, slows down the responses of the nervous system
2) Stimulants: e.g. nicotine. Increase the activity of the brain by increasing the amount of neurone
transmitters released, you feel more alert/awake
3) Painkillers: e.g. aspirin. Works by reducing the number of the number of painful stimuli at the nerve
endings, the pain stimuli still happen but the nerve impulses are blocked.
4) Performance Enhancers: e.g. anabolic steroids. Sometimes taken by athletes, to help build muscle and
allow the athletes to train harder (banned by most sport organisations).
5) Hallucinogens: e.g. cannabis and LSD. Distort what is seen/heard by altering the pathways nerve
impulses normally travel along.
Some drugs are illegal.. They are put into three main categories A,B and C (class A being most dangerous)
CLASS A: heroine, ecstasy, LSD and cocaine, lengthy prison sentence
CLASS B: cannabis and amphetamines
CLASS C: anabolic steroids and tranquillisers, warning, possibly short prison sentence
In all cases, supplying drugs to others usually results in a greater punishment
than actually doing them yourself.
Smoking and Alcohol
Alcohol is a depressant drug. Its main effect is to reduce the activity of the nervous system. Alcohol is
poisonous. Normally, the liver breaks down the toxic alcohol into harmless products. Drinking too much
causes death of the liver cells forming scar tissue that stops blood reaching the liver . If the liver cannot
do its normal job of cleaning the blood, dangerous substances start to build up and damage the rest of
the body. Being drunk leads to impaired judgment, poor balance, poor coordination, slurred speech,
blurred vision and sleepiness.
Burning cigarettes produce FOUR main things
1) Carbon Monoxide: stops haemoglobin cells carrying as much oxygen
2) Nicotine: stimulant drug – this is what makes smoking addictive
3) Tar: covers the cilia – prevents them from moving bacteria and mucus out of your lungs
4) Particulates: accumulate in the lung tissue causing irritation
SMOKING ALSO CAUSES LOTS OF ILLNESSES;
• It causes diseases of the heart and blood vessels leading to heart attacks and strokes
• It causes lung, throat, mouth and oesopageal cancer
• Tar from the smoke collects in the lungs, it is full of toxic chemicals (some are carcinogenic; cause
cancer) carcinogenic make mutations of DNA more likely and cell division could go out of control and
malignant tumours could form
• Cilia gets destroyed on the epithelial tissue lining the trachea (windpipe). It also irritates the bronchi and
bronchioles encouraging mucus to be produced. Excess mucus cannot be cleared properly as the cilia
are damaged so it sticks to air passages. This is what causes smokers cough.
Receptors
The Eye:
1- contains light receptors
2- carries impulses from the receptors to the brain
3- controls amount of light entering the pupil
4- refracts light into the eye
5- focuses light onto the retina
5
1
4
3
2
Focusing… the eye focuses light by changing the shape of the lens, aka accommodation
Distant objects; ciliary muscles relax and suspensory ligaments pull tight, this makes the lens go thin
Close objects; ciliary muscles contract and suspensory ligaments slacken, this makes the lens become fat
Long/Short Sighted
Long sight- cant focus on near objects. Corrected by convex lenses.
Short sight- cant focus on distant objects. Corrected by concave lenses.
Binocular/ Monocular Vision
Binocular vision is what humans and some animals have; two eyes which work. It is good for judging distances
and speed.
Monocular vision is where the eyes see two separate views. This gives a wider field of view but cannot easily
judge depth or speed. Animals such as lizards have this and it is good for noticing predators.
Neurones and Reflexes
Neurones transmit information around the body…
The electrical impulse is passed along the axon
Neurones have branched endings to enable them to
connect with lots of other neurones. The sheath
Acts as an electrical insulator preventing the impulses from being lost.
The gap/connection between two neurones is called a synapse.
Nervous System
Central nervous system:
Stimulus Receptor Sensory Neurone CNS Motor neurone Effector Response
The CNS consists of the brain and the spinal cord whereas the Peripheral nervous
system is all the other neurones.
Homeostasis
maintaining a constant internal environment
*Conditions in your body need to be kept steady so cells can function properly.
*This involves balancing the inputs and the outputs…
• Levels of co₂ - respiration constantly produces co₂ which you need to get rid of
• Water content – balance between the water you gain(drink, food etc) to the water you lose (urine,
sweat breathing)
• Body temperature – need to get rid of excess body heat when you’re hot but maintain the environment
when you’re cold
Body temperature is controlled by the brain…
• The enzymes in your body work best at around 37°C.
• There is a thermoregulatory in your brain which acts as your personal thermostat
• It contains receptors that are sensitive to the blood temperature in the brain. It also receives impulses
from the skin that provide information about skin temperature;
When you’re too hot: hairs lie flat, lots of sweat is produced (it transfers heat to your environment cooling
you down), blood vessels close to the surface of the skin widen, allows more blood to flow near the
surface so it can radiate more heat into the surroundings – vasodilatation
When you’re too cold: hairs stand on end to trap an insulating layer of air which helps keep you warm, very
little sweat is produced, blood vessels near the surface constrict (vasoconstriction) so that less heat can
be transferred from the blood to the surroundings, you shiver – the movement generates heat in the
muscles.
Controlling blood sugar levels
*Insulin controls blood sugar levels
*Levels of glucose must be kept steady. Changes in blood glucose are monitored and
controlled by the pancreas using insulin
Blood glucose level = too high … insulin is ADDED
Blood glucose level = too low … insulin is NOT ADDED
*Glycogen can get stored in the lover until the blood sugar levels get low again.
Muscles have their own store.
Diabetes:
Diabetes (type 1) is a condition where the pancreas doesn’t produce enough insulin.
The result is that a person’s blood glucose level can rise to a level that can kill them.
The problem can be controlled in two ways;
• Avoiding foods rich in simple carbohydrates i.e. sugars (which cause glucose levels
to rise rapidly) it can also be helpful to take exercise after eating to try and use up
the extra glucose produced during digestion
• Injecting insulin into the blood at meal times. This makes the liver remove the
glucose as soonas it enters the blood from the gut when the food is being digested.
This stops the level of glucose getting too high. Diabetics have to make sure they
eat sensibly after injecting insulin or their blood sugar could drop dangerously.
Reflex Actions
*The nervous system uses electrical impulses to allow very quick
responses. Reflex actions are done without thinking.
*The sensory neurone joins to a relay neurone in the spinal cord (part of
the CNS) and this links directly to the motor neurone. Then this goes
to the effector which is usually a muscle, then a response.
*Reflex action responses often have a protective role for example if you
touch a boiling plate you will snatch your hand back automatically.