BloodThere are four main blood groups. Other than antigens and antibodies, there is a third antigen, Rhesus, which can make blood Rh+ or Rh-. Group A, AB, and B can all donate to AB and receive from O, and group O can give to all three others and receive from O.

Donating bloodDonating blood

•You must be over the age of 18

•Haemoglobin levels are checked to ensure that the donator does not become anaemic after giving blood.

•Blood pressure and blood type are recorded.

•An anticoagulant is added after the blood is taken, to stop it from clotting.

•In a blood transfusion, blood of the correct type is slowly introduced intravenously, ensuring there are no air bubbles, which could cause a blockage.

If blood from two different types is mixed, it often causes agglutination – when blood clumps together. The groups of blood depend on the presence or absence of two agglutinins; protein antigen A or B on the surface of red blood cells; two antibodies A or B in blood plasma.

The cascade process is the process in which blood clots. It results in a network of fibrin fibres being formed, which is a blood clot. Blood clots stop us losing too much blood, and provides a barrier to infection. Chemicals effect the blood; Warfarin, heparin and aspirin thin the blood, preventing clotting. Vitamin K helps blood clotting, cranberries and green vegetables are a good source of this.

Blood is the transport system for moving substances around the body. Parts of the blood…

PlasmaPlasmaPale yellow liquid in blood

Carries everything needed by the body; red and white blood cells, platelets, glucose, amino acids and other digested food products, CO2 from cells to

lungs, urea from liver to kidneys, hormones, antibodies

and antitoxins produced by white blood cells.

PlateletsPlateletsIrregular shaped colourless bodies in

blood.Used in clotting.

Have a sticky surface which allows them to clot to stop bleeding. When bleeding occurs, platelets gather at

the wound. Calcium, Vitamin K and a protein called Fibrinogen help to form the clot. When platelets sense air they begin to break apart. They react with

the fibrinogen to form fibrin which creates threads to mesh, forming a

scab.

Red Blood CellsRed Blood CellsCarry oxygen from lungs to cells in

rest of body.Adapted for their function; small

and biconcave to give large surface area fro absorbing and

releasing oxygen. Haemoglobin in red blood cells

give blood its colour and contain lots of iron. In lungs, reacts with oxygen to form oxyhaemoglobin. In tissue, the reverse happens to release the oxygen to the cells.

White Blood CellsWhite Blood CellsDefence against Disease; produce antibodies to fight microbes, and antitoxins to

neutralise toxins produced by microbes.

They have a flexible shape, allowing them to engulf

microorganisms; the white blood cell would surround the microorganism and digest it

using enzymes.

Breathing in the Animal KingdomBreathing in the Animal Kingdom

An earthworm relies on its skin to absorb oxygen. Its skin is thin and moist and is supplied with a network of capillaries which absorb oxygen, and delivers it, via the circulatory system, to the rest of the body.

In a frog, thin wet skin allows for the absorption of oxygen. Frogs also have lungs to supplement oxygen supply when necessary. Gas exchange happens through a film of mucus above the epidermal cells, and capillaries lie beneath in a circular muscular layer.

A fish absorbs oxygen through gills. The filaments are branched, presenting a large surface area to the water to allow oxygen and carbon dioxide to be exchanged in the network of capillaries. A fish takes in water from its mouth, forces it between the gills, and out through a gap between its body and the gill cover.

Human Respiratory SystemHuman Respiratory System

The diaphragm moves down so the volume of lungs is larger forcing air into the lungs. It moves up, making the lungs smaller in volume, so air ruches out. The air travels in through the mouth and nose, down the trachea, into the bronchi, bronchioles, eventually reaching the alveoli.

The alveoli have a large surface area for gas exchange, and are moist, and have a close network of capillaries. Inside the alveoli oxygen from the bronchiole diffuses into the red blood cells, and carbon dioxide diffuses from the red blood cells back into the bronchioles to be taken back to the lungs.

BreathingBreathingA Spirometer measures the changes in your breathing rate and lung capacity. It measures the volume of air you can breathe out in one breath. A nose clip is used so that no exhaled air escapes through the nose.

•Tidal Air – volume of air breathed in and out at rest.

•Vital Capacity – Breathing out as hard as you can.

•Residual air – air remaining in lungs after you have forced as much out as possible.

< A SPIROGRAM

Total air volume in lungs = vital capacity + residual volume

•Asthma is a restrictive disorder.

•It limits the amount of oxygen available for gas exchange in the lungs.

•The airways are sensitive, and when in contact with a trigger, the muscles of the airways constrict, and mucus is produced which lines the bronchioles, making it difficult for air to get to the lungs.

Cystic Fibrosis – recessive genetic disorder. Asbestosis – exposure to asbestos in insulation materials. Lung cancer – exposure to ionising radiation.

The Menstrual CycleThe Menstrual Cycle

Oestrogen

The Menstrual CycleThe Menstrual CycleDays 1-5 – menstruation, uterus lining shed.

Days 13-15 – egg released from ovary.

Day 19 – egg dies if not fertilised.

Day 20-23 – uterus lining continues to thicken.

Day 28 End of cycle, beginning of next.

A hormone is a chemical messenger. It is released by a gland and travels through the blood to a target audience.

•The menstrual cycle is triggered by receptors in the hypothalamus in the brain which cause the pituitary gland to produce two hormones.

•Follicle Stimulating Hormone (FSH) stimulates the development of a follicle in an ovary.

•Luteinising Hormone (LH) controls the release of eggs.

FSH is released

Follicle in ovary develops nutritional cells, migrates to edge, releases

Oestrogen.

Pituitary gland in brain connected to hypothalamus receptors

Womb lining builds up

LH is released

Pituitary gland in brain connected to hypothalamus receptors

Ovulation – egg released into fallopian tube. Yellow body, empty follicle left produces progesterone.

Follicle dissolves. Progesterone level decreases. Uterus lining decreases. If

egg fertilised, it itself produces progesterone to maintain thickness of

uterus wall.

Oestrogen makes the uterus wall thicken. Progesterone maintains this thickness.

Infertility

Reasons for InfertilityReasons for Infertility

Problem Solution

Not enough FSH being produced, so ovary follicles do not develop eggs.

Hormone injections containing FSH. Straight forward, used for many years without side effects.

Inability to carry foetus until birth Surrogate mother – can become emotionally attached to the baby and find it difficult to give to the parents.

Cannot naturally conceive In Vitro Fertilisation – IVF has a low success rate and is very expensive. Multiple births possible if more than one egg takes.

Ovaries stopped producing eggs Egg donation – means baby will have only the husband’s genetic material.

Low sperm count or blockage of fallopian tubes

Artificial insemination – fertilised egg cell is placed inside the woman’s cervix. No guarantee however that fertilised egg will develop in the uterus.

Preimplantation Genetic Diagnosis (PGD)

•Used in combination with IVF

•Used to screen for genetic disorders such as Huntington’s disease, Downs syndrome, and cystic fibrosis.

•Stage 1 – Create embryos using IVF

•Stage 2 – Remove a cell from each to identify which may have diseases

•Stage 3 – Good embryos implanted in mother

•This could be used to find tissue matches for an existing child who needs a tissue donor. There is a 98% chance that the embryo would be a match for the diseased child. If the baby was a match, cells could be taken from the umbilical chord to create stem cells for child’s treatment.

•Human Fertilisation and Embryo Authority (HFEA) allows embryos to be screened for genetic disease – health of unborn child is only concern. It is currently illegal to pick out embryos which could donate tissue to a sick sibling. This is because they fear it may lead to parents becoming more selective about the sex, hair colour etc. of the baby.