Excellent page William, well maintained. The information is clear and to the point and the diagrams illustrate the information perfectly. Great effort on this page, well done!

Lymphatic Systemexternal image swollen-lymph-node-picture.jpg

  • The liquid which contains dissolved substances such as glucose, respiratory gases and proteins is called tissue fluid. It is at high pressure and filters through thin capillary walls to the surrounding tissue. Excess fluid is absorbed by lymphatic vessels. This excess fluid is called lymph and is transported around the body, through the lymphatic system by muscular contraction, until it reaches a lymphatic duct where it is filtered back into the blood stream.
  • Villi, in the small intestine, contain a lymphatic vessel, called a lacteal. The products of fat digestion are absorbed and the droplets of fat enter the lymphatic system via the lacteal and eventually in to the bloodstream.
  • Lymph Nodes - Found in clusters located in the underarms, groin, neck, chest and abdomen. These act as filters, removing micro organisms and other materials. Macrophages destroy bacteria and viruses. The nodes can swell up if there is an infection since the nodes themselves are infected. The lymph nodes are the site of lymphocyte and antibody production which is essential for the body to stay well.
  • Oedema - When the tissue fluid builds up between the spaces between the cells and blood capillaries, causing the tissue to swell up.
  • Elephantiasis - Larvae of the Filarial worm is transmitted by mosquitos. Once inside, they attack the lymphatic system and the mature worms block the vessels.
References: PowerPoint

Blood Pressure
Blood pressure
Blood pressure

  • High Blood Pressure (Hypertension): Dependant on a combination of two factors - How forcefully the blood is pumped by the heart, and how narrowed or relaxed the arteries are. High blood pressure is classed as having a blood pressure of 160/100 mmHg. Hypertension hardly ever causes symptoms early on but later it may cause a stroke or a heart attack. It also increases the risk of atherosclerosis, a stroke, heart failure, kidney failure, eye damage and more. Obesity, smoking, a family history to suffer hypertension, high alcohol intake and high salt intake all increase the risk of suffering from hypertension.
  • Low Blood Pressure (Hypotension): A blood pressure of 90/60 or less means that the person has low blood pressure. On its own, low blood pressure does not always cause symptoms. However, since the necessary blood may not reach the vital organs, dizziness, blurred vision, fainting and general weakness can all be symptoms.

References: http://www.netdoctor.co.uk/diseases/facts/hypertension.htm

Heart Disease

Heart disease occurs when the blood vessels supplying the heart, the coronary arteries, become blocked and fail to supply the heart with the glucose and oxygen needed for respiration.
  • Myocardial Infarction: This is the restriction or blockage of the coronary artery. Due to the blockage, the heart cannot receive nutrients and oxygen and therefore cannot respire, which causes the death of muscle cells. This is sudden, irreverible damage and if it affects a large part of the heart then the person may insantly die.
  • Atherosclerosis: The hardening of the arteries due to the build up of fatty materials called artheromas. These artheromas build up on the inner layer of thexternal image 7799W.jpge artery and decrease the volume of blood that can easily pass through the artery. Cholesterol and lipids promote the build up and further decreases the volume of blood that can flow.
  • Angina: A crushing pain across the chest often experienced by sufferers of atherosclerosis. Coronary arteries affected by this can allow blood flow when at rest. During exercise, the heart beats faster which means more oxygen is required but the blood cannot meet this increased demand which causes angina.
  • Coronary Thrombosis: The artheromas present in the arteries result in an uneven surface. This uneven surface is a prime location for a blood clot (thrombus) to develop. The blood clot again decreases the volume of blood which can pass and if it travels through the blood and reaches a smaller blood vessel, it can completely halt the blood flow.


  • Coronary Angioplasty: A small balloon is inserted into the affected artery and is used to push the fatty tissue out and widen the artery to allow more blood to flow. A metal stent is used to hold the artery open.external image 19136.jpg
  • Coronary Artery Bypass Graft: Performed when arteries become narrowed or blocked. A blood vessel in inserted (grafted) between the aorta and just past the blockage point in the coronary artery. This allows blood to bypass the affected sections of the coronary artery and continue to supply the heart.
  • Heart Transplant: If the heart is severely damaged and medicine has no effect on the heart, or when the heart cannot efficiently pump blood around the body, a heart transplant may be required. The damaged heart is replaced by a healthy, donor heart.

References: http://catalog.nucleusinc.com/generateexhibit.php?ID=7799

Chapter 15 Essay Question

Give an account of the hormonal control of a menstrual cycle that does not involve fertilisation under the headings:
  1. Follicular Phase (5)
  2. Luteal Phase (5)
Follicular Phase: This is when the gonadotrophic follicle stimulating hormone (FSH) produced in the pituitary is present(1). FSH promotes the development of the Graafian Follicle in the ovaries(1) . During this phase, oestrogen (an ovarian hormone) is secreted from the ovarian tissue (1) which promotes the build up of the endometrium which was lost after menstruation (1). These hormones are controlled by negative feedback control which is where an increase in a hormone will be recognised which means that if too much is being produced, then the hypothalamus will signal the pituitary to decrease production. When the oestrogen concentration peaks, lutenising hormone (LH) is released which causes ovulation (on day 14) (1). (5)
Luteal Phase: The luteal phase occurs when LH causes the follicle to break down to become the corpus luteum after ovulation (1). The corpus luteum then produces the hormone progesterone (1) which maintains the endometrium in case fertilisation occurs in order to nourish the embryo. This hormone inhibits FSH and LH to prevent more follicles being produced if the egg becomes fertilised (1). However, due to the lack of LH, the corpus luteum degenerates, causing a decrease in progesterone (1). This means that the endometrium is no longer maintained which results in menstruation. FSH then becomes present again, and the cycle repeats (1). (5)

You have met the high standard you set for yourself. Excellent essay William! Full marks.

Male Infertility


  • Obstructive problems: Groin surgery, trauma to the scrotum or infection could all lead to a bloackage in the sperm ducts. The sperm ducts can even be blocked from birth since some have a congenital absence of the sperm ducts on one or both sides of the testes.external image 19471.jpg
  • Sperm Disorders: Problems with the sperm can also lead to infertility. The average concentration of sperm in semen is 20 million per millilitre, at least 75% of sperm should be alive, at least 30% should be of normal shape and size, and 25% should be rapidly swimming forward.
  • Genetic Disorders: Chromosome disorders can affect the development of the testes. The disorders are often sex-linked (such as klinefelters syndrome where an extra X chromosome is present (XXY)).
  • Hormonal Problems: A problem with testosterone production can cause infertilty - this can be caused in either in the pituitary gland or the testes. Over production of prolactin from the pituitary can also cause increase the chance of infertility.
  • Varicocele: A dilation of the testicular veins in the cord that leads from the testes to thexternal image 19472.jpge abdomen. It isn't certain what role this condition has on infertility and is highly controversial. Some experts have suggested that the condition could heat up the testes or it could cause a build up of waste products since it could impair blood flow.
  • Medical disorders that affect fertility: A fever, diabetes, high blood pressure and kidney disease can all affect fertility.
  • Other causes include smoking over 20 cigarettes a day, taking in a lot of alchohol, stress, heat, obesity and very frequent intercourse..


  • If it is a hormone deficiency, then some medications could treat the infertility (however this is case is rare).
  • It is often not possible to give any treatment if the infertility is due to a low sperm count since this is often due to genetics.
  • If a varicocele is present then it could be corrected through surgery.
  • Clomiphene citrate can be given to men with mild sperm abnormalities in order to improve the semen. Sometimes this can improve motility or sperm count but many medical studies have shown no increase in pregnancy rates after this medication is given.
  • If the infertility is due to infection, then antibiotics can be used.
  • IVF could be used when the sperm count and/or motility is severely low.

References: http://www.netdoctor.co.uk/menshealth/facts/malefertility.htm

Female Infertility


Hormonal Problems:
  • The ovaries can produce abnormal follicles, so therefore the egg cannot mature. This syndrome is characterised by a reduced production of FSH, normal or increased levels of LH and oestrogen
  • The hypothalamus can fail to trigger and control the negative feedback control of FSH and LH which results in immature eggs being produced.
  • The pituitary gland produces and secretes FSH and LH. If the balance isn't correct, then the ovaries cannot ovulate. If there is a chemical imbalance, a tumour or some physical injury to the pituitary, infertility can result due to the hormonal problems which will result.
Scarred Ovaries
  • Physical damage to ovaries can result in failed ovulation. This could be caused by repeated surgeries which may result in the capsule of the ovary to become damaged or scarred, meaning follicles cannot mature properly. Infection could have a similar effect.
Infection to Oviduct:
  • Caused by bacteria and viruses, and is generally sexually transmitted. The infections cause inflammation which can lead to scarring and blockage.
Abdominal Problems:
  • Conditions such as appendicitis and colitis can cause inflammation leading to scarring and blockage in the oviduct.
  • This is the excessive growth of the endometrium. It doesn't just occur in the uterus, but also in the oviduct and ovaries. Cysts can be formed on the ovaries. The endometriosis tissue cannot leave the body and is trapped which can sometimes damage the fallopian tubes or ovaries, which could result in infertility.
Other factors:
  • Diet and exercise, smoking, alchohol, drugs and exposure to various toxins and chemicals (such as lead and dibromochloropropane) can all have an effect on fertility.
external image ivf.gif


  • Intrauterine insemination (IUI) - A small volume of concentrated sperm inserted into the uterus. This is usually used with a fertility drug to stimulate ovulation.
  • In Vitro Fetilisation (IVF) - Mature eggs removed from uterus and are fertilised in a laboratory dish and are then implanted into the uterus. This is used to treat any women with any problems to their oviducts.
  • Fertility Drugs - Used to "trick" the ovaries to produce eggs by stimulating the woman's hormone to do their jobs or by replacing them with "outside" hormones. For example, clomiphene is an agent which increases the production of FSH from the pituitary. The FSH stimulates ovulation which can release two or more eggs due to the drugs, increasing the chance of carrying twins by 10%.



Contraception is used to prevent fertilisation or implantation. There are mechanical methods (such as a condom) and chemical methods (such as spemicidal cream that kills sperm). There are also biological methods: The rhythm method and the contraceptive pill.

The rhythm method is where the women's ferile period is figured out by observing any changes in body temperature or the consistency of cervical mucus. Before ovulation, body temperature rises by about 0.5 degrees celsius and cervical mucus becomes thinner. If the couple do not wish to have a baby, then they would not have sexual intercourse for a few days before and after the fertile period. Also, a couple who do want to have a child would have intercourse in this fertile period to increase the chance of fertilisation.
external image contraceptive-pill.jpg
The contraceptive pill is taken orally over three weeks (a placebo is taken on the fourth week). The pill contains synthetic progesterone and sometime oestrogen. This increases the levels of pregesterone which inhibits the pituitary from secreting FSH and LH. This means the woman does not ovulate and pregnancy cannot occur. The placebo pill is to allow progesterone to drop which allows menstruation to occur.