Cystic fibrosis and sickle cell disease
Cystic fibrosis affects the movement of fluid in the lungs and causes thick, sticky mucus to form, particularly in the lungs and digestive tract.
Symptoms include:
- mucus blocking airways of the lungs and causing breathing difficulties
- lung infections because of bacteria becoming trapped in the mucus
- problems digesting food, which can lead to malnutrition
- bone disease
Treatments for cystic fibrosis include: nourishing diet, physiotherapy and massage.
Sickle cell disease:
Sickle Cell caused by a mutation that alters hemoglobin molecules and causes them to absorb less oxygen. This also results in the red bloody cells becoming sickle shaped.
Symptoms of sickle cell disease:
- feeling week and tired
- sudden pain, known as a sickle cell crisis, caused by sickled red blood cells forming clumps in the bloodstream, blocking blood flow to organs and causing organ damage
Treatments include: Medication, lots of fluids and blood transfusion.
Inheriting genetic disorders
If a mutated allele is dominating or if the person inherits two copies of the recessive mutation then the individual will be affected by the genetic disorder.
The risk of someone inheriting a particular disorder can be predicted using pedigree analysis. This looks at the disorder’s inheritance pattern and predicts the risk for future generations.
In pedigree charts, the generations are indicated from the top using Roman numbered, and members of each generation are numbered from the left.
Homeostasis and body temperature
Living things keep their body’s internal environment stable using homeostasis.
Regulating body water content and body temperature are examples of this. The water content is leveled with osmoregulation.
Signals to the brain send information about the water content of the blood.
The brain sends signals – hormones – to the kidneys, to regulate the amount of water they remove in urine.
All examples of homeostasis are self-regulating - that is, the body adjusts automatically to keep the internal environment stable.
The triggers for these responses are called stimuli. Having a natural body temperature of 37ºc means those stimuli for us could be getting too hot or cold.
Thermoregulation
Thermoregulation is the controlling of temperature. Body temperature is controlled in the hypothalamus.
Responses to increased body temperature include:
Vasodilation – widening of blood vessels to allow more blood flow and ensure more heat is lost through the skin.
Sweat that evaporates the water in sweat off the skins surface
Hairs that stand on end to release air through the small gaps
When too cold - Vasoconstriction
Hairs lie down to protect body heat and air from escaping
Shivering cause muscles to contract very quickly and therefore muscles to release heat
Body hair rises away from the skin, trapping a layer of air next to it to insulate the body.
The thermoregulatory center detects the temperature of the blood, processes the information and sends nerve impulses to sweat glands and hair erector muscles, which control shivering and blood flow through the skin.
Senses and the nervous system
A neurone is a nerve cell that consists of a cell body with thin fibers stretching out from it. The fibres carry electrical impulses.
Bundles of neurons from nerves and these nerves form the nervous system:
- Central nervous system is brain and spine
- The peripheral nervous system consists of the nerves connecting the sense organs with the central nervous system
Nerves consist of different types of neurone, which send electrical impulses in particular directions:
- Sensory neurons send impulses from receptors in the sense organs and the CNS
- Motor neurons send impulses from the central nervous system to muscles and glands.
Stimulus receptor Sensory neurone CNS motor neurone effector response
- Nerve impulses are sent to the effectors. Muslces are effectors and the impulses cause them to contract.
- Receptions are linked to effectors by a chain of neurons
- The fibres at the end of one neurone are separated from the beginning of the next neurone by tiny gaps called synapses
- Neurotransmitters are chemical messengers that carry information across the synaptic gaps
- The myelin sheath is a fatty substance surrounding dendrons and axons that speed up the nerve impulses along neurons.
The Reflex Arc
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The involuntary behavior of the person pulling their foot away after stepping on a pin is known as a reflex response.
- Reflex responses are automatic and usually fast. They help to protect the body from damage.
- A reflex response is brought about by a chain of nerves called the reflex arc.
Hormones and diabetes
Hormones are chemicals produced by endocrine glands in the body and released into the blood. They circulate in the bloodstream and affect different tissues and organs.
Hormones help to regulate the body’s activities and maintain homeostasis.
The pancreas produces two hormones: insulin and glucagon.
Types of diabetes
Type 1: Occurs when the pancreas does not produce enough insulin – usually in youth
The treatment to this s a daily injection of insulin into the body’s subcutaneous to reduce blood glucose levels
Type 1 diabetes is a result of: an auto-immune disease (when a person’s immune system destroys the pancreatic cells that produce insulin). It can lead to obesity and development of type two.
Type 2: Occurs when the pancreas still produces insulin but the garget tissues (liver and muscles) and insensitive to it – usually enhanced by age
The treatment to this is regulating their bloody glucose level by careful eating. Regular exercise and losing weight. However, drugs are sometimes needed to help control blood glucose levels.
To test if someone is overweight you should measure their body mass index (BMI = Kg/m2)
Plant hormones
Plants move as a resort of stimuli, the response is called a ‘tropism.’
Auxin
Plant hormones such as auxin are responsible for this tropisms.
- Phototropism refers to the response of plants to the stimulus of light.
- Geotropism refers to the response of plants to the stimulus of gravity
Phototropism can be investigated using cress seeds in the dark (and some in the light)
In shoots, auxin Is more concentrated in tissues on the side where light is least intense. The cells here grow more quickly than those on the brightly lit side. In this way, the shoot grows towards the brightest side.
In roots where the concentration of auxin is high, the cells of the tissues grow more slowly. Auxin is more concentrated on the underside of roots so the cells of tissues of the underside grow more slowly than those on the upper-side, causing the roots to grow down.
Plant hormones in food production
Copies of plants can be made by taking cuttings and dipping the end in rooting powder. This contains plant hormones that encourages cut stems to develop roots.
Fruit that can be picked unripe are subjected to ‘ethane’ gas to ripen them.
Because some herbicides contain plant hormones that stimulate the growth of plant stems, the rate of root growth does not keep pace with stem, the roots are not able to absorb enough water to support the growing plant and it dies.
Herbicides only affect the weeds because they are broad-leaved and absorb more herbicides than narrow-leaved crop plants.
Growers can produce seedless fruits by smearing the plants’ female sex organs with auxin paste, to stimulate the development of the fruit. However, the egg cells within the female sex organs have not been fertilized so seeds are not produced. (Fertilisers can be given to not produce seeded fruit.)
Drugs Smoking and alcohol abuse
Types of drugs:
- Morphine which will deaden pain or affect the way we think about it. Pain is very psychological
- Cannabis, LSD, Solvents – produce sensations of false reality
- Caffeine which increases the speed of our reaction time
- Alcohol, slows the activity of the brain and reaction time
A person can be addicted to a drug because it gives a false sense of well-being which the person craves when it goes away. Or The body gets used to a change taking place within its tissues and craves this change more.
Painkillers
Block the release of neurotransmitters into the synapses, which separate the neurons
Stimulants enhance the release of neurotransmitters
Reaction time – How long it takes for a person to respond to a stimulus. This depends on how quickly and how much neurotransmitter is released.
Legal drugs
Cigarette smoke contains many chemicals such as carbon monoxide (which reduces the amount of oxygen that red blood cells can carry), Nicotine which is an addictive stimulant that raises blood pressure and risk of heart disease and Tar which contains substances that can cause cancer and emphysema.
Alcoholic drinks contain ethanol, which can lower inhibitions, slowed reaction times, blurred vision and difficulty controlling limbs.
Alcohol abuse
Usually refers to heavy drinking over a long period of time or large volumes in a short time.
Can cause:
- Liver damage
- Brain disease
- Heart disease
- Cancer
- Raised blood pressure
And the effects can be enhanced by:
- Sex
- Age
- Body mass
- How quickly the body’s cells break down the alcohol affect
The recommended limit is four units of alcohol a day (three for women.)
A pregnant female can cause abnormalities to the child of drinking regularly when.
- Smoking can burn away at the Cillia which is part of your digestive system. Cillia are small hairs that filter out negative substances and bacteria
Transplanting organs:
Transplant surgery replaces a diseased organ with a healthy one. There is always a ‘donor’ and a ‘recipient’ involved. Donors can be dead or alive.
Organ rejection is less likely to happen is the donor is related to the recipient. This is where the immune system senses the changes in an organ and the unusuality of it and rejects it. Cyclosporine is a drug that prevents this happening.
Supply and demand for organs
Alternative organ sources have led to research into:
- Animal donors (tried with a kidney from a chimp but rejected)
- Genetically engineering the organs of animals to stop them being rejected by the recipient. Not widely used but it could be a powerful solution in the future.
- Transplantation tourism, wealthy people can pay for organs from poor people in less developing countries, even if it is illegal to do so.
Moral and ethical issues are obvious. These include:
- The right of a human to use an animal as a source of organ donation
- Whether money should be an incentive to donate organs
- Wider human rights concerning transplant tourism (exploitation of the poor people in developed countries)
- Increased risk of transplanting diseased organs into receptions because poor donors do not received regular health care.
The biggest ethical issue is why should someone that needs (for example) a new liver due to alcoholism get a transplant over someone that is suddenly ill.
Infectious diseases
Pathogens = organisms that causes infectious diseases. We often call them microbes because they’re often only visible under a microscope.
A human body is the ideal place for the spread of microbes. Warm, moist etc. Infectious diseases are those caused by pathogens that spread form person to person.
Choloera bacteria is found in contaminated water in the sewage – many people that do not have access to clean drinking water have to deal with this and get this infection.
Different ways of catching a disease
- Airborne, such as colds and flu.
- Food – such as Salmonella, a type of food poisoning that comes from chickens.
- Body fluid exchange – HIV destroys white blood cells that fight off pathogens and effectively destroy your immune system.
- Fungal – Athletes food thrives in warm, moist environment of sweaty feet.
Bacteria that causes diarrhea produces endotoxins (poisons) that stimulate the small intestine wall to contract violently and more frequently then usual. This prevent water form being absorbed and can lead, eventually, to dehydration.
Insect-borne diseases
An animal vector can transfer bacteria, which cause dysentery on food, via their feet.
Anopheles mosquitoes are vectors for malaria. They feed on the victim and suck in the pathogen before biting another person and passing it on.
These can be stopped by:
- Antiseptics – chemicals that stop microbes multiplying
- Antibacterial – substances that interfere with the growth of bacteria
- Antibiotic drugs – control infection caused by bacteria. Some kill bacteria and others stop multiplication
- Antifungal drugs – used to treat infections by killing the fungal cells but not human.
Resistance arises because of the high mutation rates of bacterial genes and ongoing exposure of bacteria to antibiotics. Treating cystic fibrosis with antibacterial means constantly changing because the mutated bacteria (the ones that survive) multiply.
Defenses and interdependency
Physical
The most obvious and helpful physical barrier protecting pathogens is your skin.
Lungs contain mucus which traps bacteria and other particles and is swept away by hair-like cilia until lit reaches the throat, where it swallowed and digested. Plant surfaces are also a physical barrier. They may have thorns as a defense against plant-chewing animals or hair-like structure that secrete sticky substances to trap insects.
Chemical
- Glands in the skin produce sebum (a type of oily substance) which kills bacteria and fungi. Hydrochloric acid in the stomach also kills bacteria on food.
- Tears contain enzymes, which destroy bacteria.
- Some white blood cells bind to substances on pathogens and use antibodies to destroy them.
- Platelets in the blood form scabs over cuts and skin
New medicines
Plants use chemical defenses. Animals avoid bitter tasting pray as they can cause vomiting. Bacterial attacks often signal the plants to produce antibody chemicals. Antibacterial such as lemon balm, garlic and tea tree are also effective against bacterial pathogens that infect humans.
Mutualism and parasitism
All living things are interdependent. Mutualism refers to where both species benefit e.g. cleaner fish on dead skin (they eat, we get clean feet!)
Parasitism one sided relationship between two species where one gains at the others expense. An example of this is a tapeworm. Mistletoe is a parasitic plant as it takes minerals and salts from the tree it grows on.
Useful bacteria
Leguminous plants such as peas, beans have swellings on their roots called nodules. These have nitrogen-fixing bacteria which convert nitrogen into proteins using bacteria.
In hydrothermic vents chemosynthesis does this using the formula:
Carbon Dioxide Hydrogen Sulfide Sugars + Sulfur
Chemosynthetic bacteria live in the bodies of giant tube worms and supply them with oxygen. They, as a result, supply them with food the worms need.
Energy, biomass and population pressures
Food chains and energy flow
Bacteria, plants or algae (at the bottom of the food chain) is a producer Animals are always consumers, they eat food
Carnivores are predators and Prey
Scavengers are carnivores that feed on dead bodies of animals (vultures)||
A food chain shows one pathway of food energy through organisms. A food web represents many pathways and is usually more accurate description of a feeding relationship.
Energy is gained through mass (e.g. If a leaf has 1j of energy and an animal eats 1000 leaves) but is lost through heat, digestion, respiration etc.
Biomas
We refer to the amount of tissue in an organism as biomass
Pyramids of biomass tell us about the produers and consumers an different trophic (feeding) levels make up the pyramid. Each trophic level has less biomass then the one below it.
Population growth means that there is constantly rising demand for resources that are usually in scarce demand. Oil is running out and there are constantly new green ways to find an alternative – recycling is on the rise because of this and has many benefits when compared to landfill.
Water and air pollution
Chemicals released cause pollution. Nitrates and phosphates are pollutants in fertilizer (which are used to increase crop yield). These chemicals can pollute groundwater, ponds and rivers when they are not absorbed by crops (possibly because of excess fertilizer). Groundwater provides 1/3rd of Britain’s drinking water.
Nitrates and phosphates that are not absorbed by plants can run down (usually with rain) into local rivers. This stimulates growth in algae and water plants. When the vegetation dies, bacteria decompose to organic material that uses the oxygen up in the water. Ammonia and other substances are also released. Wildlife in the water dies through poisoning or lack of oxygen. This process is called eutrophication.
The more polluted a river is, the less oxygen there is because of eutrophication. The presence of different species can indicate how eutrophic water is. Indicator species are capable of doing this with animals like shrimps and stonefly. Bloodworms and sludge worms are polluted indicators. They can survive at low levels of oxygen because they are tolerant to pollution.
Sulfur Dioxide
Sulfur from fossil fuels + Oxygen Sulfur Dioxide
- Pollution with sulfur dioxide produces acid rain or snow which passes into lakes and rivers
- Acidic water causes fish to produce too much mucus, clogs gills and kills the fish though oxygen deprivation
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Lichens are an indicator species for air pollution. There are different types; shrubby leafy and slightly leafy.
- The number of lichen species vary according to the level of sulfur dioxide in the air.
- Black spot is a fungal disease that covers rose leaves and is an indicator of good air quality.
Recycling carbon and nitrogen
Decomposition
Decay and decomposition are caused by fungi and are natural decomposers
Nutrients such as carbon, nitrogen and compounds are released because of this – the nutrients are absorbed in solution by plants and pass to animals through feeding.
Carbon Cycle
Carbon is released through respiration and photosynthesis
- Plants absorb CO2 from the environment, photosynthesis enables sugar production. The sugars can be used to form other parts of the plants body such as proteins
- Plants eat animals, which take in the carbon. The transfer continues as each animal eats another, usually in increasing quantities.
- During respiration, organisms release carbon dioxide into the atmosphere (and it is released by fossil fuel burning)
Chalk is formed from fossilized remains of sea creatures. Explosed to rain the chalk dissolves and more CO2 is released.
Nitrogen Cycle
We can not access the nitrogen in the air. Nitrogen fixing bacteria in the root nodules of leguminous plants or in the soil can use this gaseous nitrogen to ‘fix’ nitrogen gas ammonia.
Plants absorb the compounds in solution from soil and animals obtain it from eating the plants. Proteins are major part of the remains of dead animals and animal waste. Decomposers convert these proteins into urea and ammonia.
Nitrifying bacteria convert the ammonia from decaying and waste matter to nitrates absorbed by plants. Lighting breaks apart nitrogen molecules in the atmosphere and the nitrogen reacts with atmospheric oxygen to form nitrogen oxides. These acids react with compounds in soil and form nitrates.
Nitrates not absorbed by plants are converted by denitrifying bacteria in the soil to nitrogen gas, which is released into the atmosphere.
Cause and spread of disease
Infectious diseases are called pathogens. We often call pathogens microbes.
Infectious diseases are those caused by pathogens that spread person to person.
Salmonella is a type of food poisoning that comes from chickens. Cooking thoroughly lessens this risk substantially.
HIV is a virus that causes aids. HIS is spread by body fluids.
Athlete’s food is a fungal infection that thrives in warm, sweaty and moist enviornments in the skin. It can spread through contact of contaminated surfaces.
Diarrheoa is produced by endotoxins that stimulate small intestine walls to contract violently and more frequently.
Stopping infection
Antiseptic – stop microbes from multiplying
Antibacterial – interfere with the growth
Antibiotics – stop the multiplication
Antifungal – treat fungal infections by killing fungal cells but not human cells.
