Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 11

Josie was showering when she noticed a small but hard lump in her right breast. Josie was quickly referred to the local breast screening clinic for further investigation where ultrasound sonography revealed a dense mass around the size of a large garden pea. The consultant immediately recommended a needle biopsy which was carried out the same day under local anaesthetic. The tissue collected was sent for histological examination and a week later Josie was diagnosed with breast cancer and her treatment options were discussed.

The collection of a tissue sample from a patient is termed a biopsy. There are many types of biopsy ranging from the collection of a peripheral blood sample from a finger prick to a more invasive needle or surgical biopsy. As we have seen in Josie’s case, study biopsies may be carried out to look for characteristic tissue changes that may be indicative of diseases such as cancer. Biopsies can also be used to check for infection or to monitor a variety of biochemical parameters in patients.

An average adult body is thought to be constructed from around 50 trillion (50 million million) cells, the majority of which have a finite lifespan, and are continually being replaced as they die. This means that most of the tissues and organs of the human body are not static but in a continual state of flux as senescent, aged cells are replaced.

This chapter will begin by examining the internal structure of a human cell. We will explore how deoxyribonucleic acid (DNA) is organised in the nucleus and the nature of human chromosomes and their use in screening for genetic disease. The individual components of the cytoplasm and structure of the plasma (cell) membrane will be described and mechanisms of transporting materials into and out of cells explored. Once you have a good grasp of cell structure, we will examine how cells are organised into the tissues which are used to construct the human body. Since microbes greatly outnumber human cells, we will examine the nature of bacterial cells which are found colonising the body as part of the microbial biome. To reinforce the key points we will explore the use of cells in detecting disease and examine how certain drugs can target specific cell types to treat disease.