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system (Royal College of Physicians, 2017) and her total score was calculated as 11. Any score of 7 or above should trigger an emergency response by a clinical team with experience in caring for critically ill patients.

      Mary was seen by the critical care outreach team and transferred to the High-Dependency Unit where the Sepsis Six Pathway (Sepsis Trust, 2019) was initiated: oxygen was administered, blood cultures were taken, intravenous antibiotics were commenced and a urinary catheter was inserted to measure Mary’s urine output accurately. Serial lactates were checked. A raised serum lactate (> 4 mmol/L) is associated with a significantly increased mortality rate. Lactate levels rise during sepsis from both aerobic and anaerobic sources as well as reduced lactate clearance. Mary gradually recovered and was able to return home two weeks after her admission.

      Mary’s case study highlights that although sepsis is immediately life-threatening, if it is recognised early and treatment initiated quickly, even elderly patients can recover.

      Not all bacteria are pathogenic or harmful; indeed, some are essential to human survival and health. Bacteria are found in huge numbers within and on the surface of the human body where, together with other microorganisms, they form the microbial biome. It has been estimated that there are around 23 times more bacterial cells associated with the human body than human cells, and although it has been known for a long time that certain bacteria such as those found in the colon play key roles such as synthesising vitamin K (a key clotting factor), the complex roles of the microbial biome are still poorly understood.

      Cells as targets for drugs

      Virtually all drugs used by nurses exert their effects at a cellular level. A good example would be synthetic insulin that is used to control the blood sugar levels of patients with diabetes mellitus. Synthetic insulin mimics the naturally produced insulin of the pancreas, stimulating human cells to take up glucose from the blood. Human cells are able to recognise each other using the glycoproteins embedded in their cell membranes; these protein markers can also allow drugs to target specific cell types within the body. To conclude this chapter, we will return to Josie who was recently diagnosed with breast cancer.

      Case study: Josie revisited – breast cancer evidence-based practice

      Josie was fortunate to detect the lump in her breast while the tumour mass was small and quickly underwent surgery (lumpectomy) to remove the cancerous tissue. Following histological examination it was determined that the malignant cells forming Josie’s tumour expressed the human epidermal growth factor receptor 2 (HER2). Drugs that block this receptor such as Herceptin have recently become available, which provide a new tool for treating breast cancer.

      Herceptin can slow the growth of breast tumour cells and when used in early breast cancer can reduce the risk of recurrence. Josie was relieved to be told by her consultant that since her tumour mass was small, chemotherapy would not be required and since beginning her Herceptin treatment six months ago tests have revealed that Josie is currently free of the disease.

      Targeted drugs such as Herceptin are revolutionising the treatment of many forms of cancer, with new targeted therapies continually being developed and made available.

      Now that you have completed the chapter, attempt the multiple-choice questions in Activity 1.5 to assess your knowledge.

      Activity 1.5 Multiple-choice questions

      1 DNA is found wrapped arounda) Histamineb) Histone proteinc) Myosin proteind) Keratin protein

      2 The region of a cell primarily involved in protein synthesis isa) The smooth endoplasmic reticulumb) The lysosomesc) The plasma membraned) The rough endoplasmic reticulum

      3 The diploid number of human chromosomes isa) 46b) 23c) 48d) 52

      4 Release of energy within the mitochondria in the presence of adequate oxygen is referred to asa) Anaerobic respirationb) Aerobic respirationc) Glycosylationd) Gluconeogenesis

      5 Which of the following is not a function of the Golgi apparatus?a) Production of lysosomesb) Preparing material for export out of the cellsc) Refining of crude proteins from the rough endoplasmic reticulumd) Production of mitochondria

      6 Which of the following commonly results in dehydration?a) Vomitingb) Poorly controlled diabetesc) Not drinking enough fluidd) All of the above

      7 Cells will show crenation when placed in aa) Hypertonic solutionb) Isotonic solutionc) Hypotonic solutiond) All of the above

      8 Water intoxication can cause death becausea) Soft organs will rapidly become dehydratedb) Swelling of the brain raises the intracranial pressure, reducing blood flowc) Excess water increases movement of water into the bloodd) Blood pressure will rise rapidly

      9 The elastic tissue found lining the bladder isa) Simple columnar epitheliumb) Simple cuboidal epitheliumc) Pseudostratified epitheliumd) Transitional epithelium

      10 Which of the following tissues forms the walls of each alveolar air sac?a) Stratified columnar epitheliumb) Stratified cuboidal epitheliumc) Simple squamous epitheliumd) Simple cuboidal epithelium

      Chapter summary

      Human cells have three major regions called the nucleus, the cytoplasm and the plasma membrane. The nucleus is the control centre of the cell and is the location of DNA. When cells divide the DNA condenses to form chromosomes, which can be visualised and counted. Human cells (with the exception of sperm and ova) have the diploid number of chromosomes (46). Deviations from this diploid number can result in chromosomal disorders such as Down’s syndrome.

      The cytoplasm of the cell consists of the rough endoplasmic reticulum which is an area of protein synthesis and the smooth endoplasmic reticulum which is responsible for the synthesis of lipids (fats). The cytoplasm is also the location of organelles including: mitochondria which release energy from molecules such as glucose and the Golgi apparatus which prepares and packages material for export.

      The plasma membrane which surrounds the cell is composed predominantly of a phospholipid bilayer in which there are a variety of proteins which function as channels and receptors. The plasma membrane holds the cell together, controls what enters and leaves the cell and plays key roles in signalling and recognition between cells.

      Cells are grouped together in organised collections termed tissues; these include epithelial, connective, muscle and nervous tissue which are used to construct the internal and external organs. The human body also hosts a diverse community of microorganisms which are collectively referred to as the microbial biome.

      Activities: Brief outline answers

      Activity 1.1: Reflection (page 8)

      As you wind the elastic up tighter and tighter it will begin to fold and loop over itself and progressively become thicker. This process is termed ‘supercoiling’ and a similar thing happens to DNA as cells begin to divide.

      Activity 1.2: Team working (page 14)

      Eventually the whole room will start to smell of the aroma as the material evaporates into the room and begins to diffuse in the air from a region of high concentration (the tissue) to a region of low concentration (the room), until an even distribution occurs.

      You may have noticed a similar phenomenon when somebody boards a bus with strong-smelling deodorant and eventually everyone on the bus becomes aware of the smell as the deodorant diffuses through the air.

      Activity 1.3: Evidence-based practice and research (page 18)

      Most saline drips will state 0.9 per cent NaCl which is isotonic to human cells.

      Activity 1.4: Evidence-based practice and research (page 19)

      Effective infection prevention and control measures include:

       Hand washing with soap and water following the World

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