Biology Unit 1 AQA

REVISION CARDS- BIOLOGY UNIT 1

A stimli is a change in your environment.

A receptor is a specialised cell which are sensitive to stimli and can detect stimli.

Receptors clustered together in special sense organs like the eyes.

Eyes contain light receptors. skin contains, temperature, pressure and touch receptors. mouth/ tongue contains, taste receptors.

The central nervous system or CNS consists of the spinal cord and the brain. This is where the receptors send messages along the nerves to the CNS, to get the right response to the certain stimli. The messages can also be called the nerve impulses, where they come back along the neurone to the effectors: normally muscle which bring about movement or a gland which secrete a hormone.

Sensory neurone: receives the information from the receptors and sends them to the CNS. 

motor neurone: receives the right response from the CNS and sends it to the effector.

A reflex action is an instant response. Something which you do not have to think about. Its used to prevent various injuries, which could happen if it was not an instant response. The reflec arc goes through the unconscious part of the brain, so that its a fast reaction.

For example: a person placing his hand on a hot pan, instantly that person know it is hot and quickly removes his hand, to prevent further damage.

A synapse is a junction between two neurones. when an impulse reaches the end of the axon ( the long line, in a neurone) then chemicals are released, so that it can diffuse across the gap to start off another impulse in the next neurone.

As the information is sent from the recepetors to the sensory neurone, and as the sensory neurone reaches the CNS, in the CNS there is the relay neurone, but between the sensory and relay there is a synapse and the chemicles diffuse to the relay and then the motor, but again between the relay and motor there is a synapse and the chemicals diffuse across and start the impuse again. This is why the relay neurone is said to connect the sensory and motor neurone and the relay neurone is found in the CNS.

Stimulus>receptor>sensory neurone>relay neurone>motor neurone>effector>response

Hormones control the functions of the body organs. The womans menstral cycle is a good example. The average length is 28 days and each month the lining of the womb gets thicker so that it is ready to support a baby. At the same time, an egg starts to maturing in the ovaries.

if the egg is not fertillised, the lining of the womb and the dead egg are shed from the body causes the bleeding known as the period.

Ovulation: 14 days after the egg starts maturing it is released from the ovary. the lining of the womb starts stays thick for several days.

stage 1, day 1: the bleeding starts and the uterus breaks down for about 4 days.

stage : the lining of the uterus builds up again from day 4- day 14 into thick spongy layer of blood vessels, ready to recieve fertilised egg.

stage 3, day 14: an egg is developed and released from the ovary.

stage 4: the wall is maintained until day 28 and if no fertillised egg the lining breaks down and cycle starts again.

FSH( follice stimulating hormone) produced in the pituitary gland, causes an egg to mature in one of the ovaries and stimulates the ovaries to produce oestrogen.

Oestrogen produced in the ovaries. Causes the pituitary gland to produce the hormone LH. inhibits ( stops)  the production of FSH.

LH( luteinising hormone) produced by pituitary gland. stimulates the release of an egg at around about the middle of the menstral cycle.

progesterone. produced in the ovaries and is used to maintain the lining of the uterus.

Homeostasis ( keeping a constant internal environment)

ion content: excess ions (sodium) are removed by the kidneys in the urine.

water content: water is removed by sweat, urine, breath and feaces. water can be taken in by food. water content needs to be not to high and not to low. but drinking is very important for the kidneys to fuctions properly.

glucose level: glucose is a type of carbohydrate, obtained through digestion of the food we eat.

Body temperature : the body needs to be kept at a constant temperature, for the enzyems to work properly.

IVF- in vitro fertilisation. causes women to have babies. involes collecting eggs from the womans ovaries and fertilising them with the mans sperm outside the body and grown into embryos and implanted into womans womb (bypasses the fallopain tube) hormones given before egg collection- fsh and LH to stimulate eggs and collect more than one.

lack of FSH, can not stimulate the eggs in the ovaries.

Damaged fallopian tube, eggs can not reach the womb.

disad: can be expensive, sometimes needed more than once. side effects.

advan: gets you pregnant.

Contraception pill. prevents pregnacy. birth control pill contains lower amounts  of oestrogen and more progesterone. leads to fewer side effects. inhibits fsh no eggs mature. disad: not 100% effcient. advan: more than 99% effcient.

Healthy diet: carbohydrates, proteins, fats, vitamins, minerals, fibre and water.

The metabolic: rate of chemical reactions in the cells of your body. The proportion of muscle to fat in your body affects metabolic rate and the amount of activity you do.

Different people need different amounts of energy.

losing weight

reduce the amount of energy by cutting down fast foods.

increase the energy by exercising.

slimming programmes.

starvation

thin and muscles waste away.

irregular periods

immune system don't work properly.

Carbohydrates, fats and proteins are used by the body to release energy and to build
cells. Mineral ions and vitamins are needed in small amounts for healthy functioning of the body is not required.

bmi= body mass in kg/ (height in metres)2 this formula is very important and tells you the body mass index.

obesity: is when a person eats too much, more then they require and this can lead to other serious problems such as: ' arthritis , diabetes , high blood pressure and heart disease and more likely to die than slimmer people.'

A person is malnourished if their diet is not balanced. This may lead to a person being overweight or underweight.

is made in the liver. it gets carried around the body in the blood. high levels is bad for you and can increase the risk of getting heart disease or diseased blood vessels.

LDL- lipoprotein bad cholesterol.

HDL-high- density liproproteins. good cholesterol.

saturated fats- increases blood cholesterol levels. ( meat, butter and cheese)

mono-unsaturated fats- (no c=c double bond) Reduce overall blood cholesterol levels and improve balance between LDLs-HDLs in the blood. (olive oil, olives, peanuts)

polyunsaturated fats- (c=c double bond) better at reducing blood cholesterol and balancing LDLs and HDLs. ( corn oil, sunflower oil)

is a substance which alters the way in which the body works. It can affect your mind, body or both.

Still doing the revision cards....but hope the revision cards which i have already completed, help!