LEVELS OF ORGANIZATIONLecture 2

Levels of organization• The human body consists of basic units of life known as

cells. • Groups of cells similar in appearance, function and origin

join together to form tissues. • Different tissues then interact with each other to form

organs.• Finally groups of organs interact to form body systems.• Thus there are four levels of organization in the human

body: • cells, tissues, organs and systems.

• Let us begin by examining the first level of organization.

Cells• The cell is the basic unit of life and the bodies of all plants and animals are built up of cells.

• Your body consists of millions of very small specialized cells.

• It is interesting to note that all non-infectious disorders and diseases of the human body are really due to the abnormal behaviour of cells.

• Body cells are all built on the same basic plan.

• Most cells have the same basic components as are shown in the figure but they are all specialized to carry out particular functions within the body.

• In your studies you will come across many terms that relate to different types of cell.

• Now we will examine our first word root which refers to cells:

Root Word

•Cyt• (From a Greek word kytos, meaning cell.)

•Combining forms Cyt/o, also used as the suffix -cyte• (Remember that combining forms are made by adding a combining vowel to the word root.)

• Here we have a word that contains the root cyt:

• Reading from the suffix back, cytology means the study of cells.– (Remember when trying to understand medical

words, first split the word into its components, then think of the meaning of each component and finally write the meaning beginning with the suffix.)

• Cytology is a very important topic in medicine as many diseases can be diagnosed by studying cells.

• Cells removed from patients are sent for cytological examination to a hospital cytology laboratory where they are examined with a microscope.

• (In the word cytological, -ical is a compound suffix meaning pertaining to or dealing with.)

1

• Name the components of the word and give their meanings:

• Reading from the suffix back, the meaning of cytopathy is: ………………………………………………..

Root Word• The root -path- can be used at the beginning and in the

middle of a compound word as in the next two examples. • Write the meaning of these words:

B. path/o/logy …………………………………………..

C. cyt/o/path/o/logy ………………………………….

• write the meaning of the words below. Remember to read the meaning from the suffix back to the beginning of each word:D. cyto/lysis…………………………

E. cyto/tox/ic ……………………………..

F. cyto/logist …………………………………..

• In the above examples cyt/o was used at the beginning of words. It can also be used at the end of words in combination with other roots, its meaning remaining the same.

• Name the components of the following word and find its meaning.

• The meaning of erythrocyte is: ………………………• find the combining forms of melanin and fibre to build

words that name these cells.• A cell containing melanin……………………..• A cell that produces fibre …………………..

3• Complete the table by looking up the combining forms of the following roots and build words that refer to cell types.

Root Word• Blast

• A Greek word meaning bud or germ. • It is used to denote an immature stage in cell

development or a cell that is forming something

• Combining forms Blast/o, also used as the suffix –blast

• 4- write the meaning of:• osteo/blast ………………..• fibro/blast …………………..• haemo/cyto/blast ………………………..

Tissues• As cells become specialized, they form groups of cells known as tissues.

• Definition • A tissue is a group of cells similar in appearance,

function and origin.

• There are four basic types of tissue: • epithelial, muscle, connective and nervous tissue; • these form the second level of organization in the body.

• The study of tissues is known as histology, the combining form coming from a Greek word histos meaning web (web of cells).

• Histology is an important branch of biology and medicine because it is used to identify diseased tissues.

• The histology and cytology laboratories are usually sections of the pathology laboratory of a large hospital.

Root Word• Hist

• (From a Greek word histos, meaning web. It is used to mean the tissues of the body.)

• Combining forms Hist/i/o

5

•Find the meaning of:• histo/chemistry ………………………..• histo/patho/logy ……………………….• histo/logist ……………………………• histo/lysis ……………………………

• Cells and tissues are very small and need to be examined using an instrument known as a microscope.

• Find the meaning of:• micro- …………………..• micro/scope ………………….• micro /scopy …………………..• micro/scop/ist …………………….

CASE HISTORY 1

• The object of this exercise is to understand words associated with a patient's medical history.

Diagnosis of an AIDs related infection• Mr A, a 34-year-old HIV positive patient with symptoms of AIDs,

was admitted to the unit following a chest X-ray that revealed a left upper lobe mass.

• A CT scan confirmed the presence of a mass within the peripheral aspect of the left upper lobe, and a small left pleural effusion.

• CT guided fine needle aspiration of the left upper lobe mass was performed and the biopsy material sent to the histology laboratory for analysis by the duty pathologist.

• Cytological examination of direct smears using optical microscopy revealed a mucoid background, moderate cellularity, polymorphonuclear leucocytes , and lymphocytes .

• A significant number of oval yeast-like cells • No malignant cells were observed.

• A sample of the biopsy material was sent for culture and sensitivity testing to the microbiology laboratory.

• The report was positive for encapsulated fungal yeast forms morphologically compatible with pathogenic cryptococcus species (Cryptococcus neoformans).

• Mr A's diagnosis was cryptococcosis, a condition seen mainly in AIDs patients and others with compromised immune systems.

Word Help• AIDs acquired immune deficiency syndrome• aspect part of a surface facing a designated

direction• aspiration withdrawal by suction of a fluid• biopsy removal and examination of living tissue• budding performing asexual reproduction by

producing buds that grow into new cells• cellularity state/condition of being made up of

cells• compromised lacking the ability to mount an

adequate immune response• cryptococcus a yeast-like fungus that causes

disease in humans• cryptococcosis abnormal condition of infection

with cryptococcus• CT computed tomography, a technique of using

X-rays to image a slice or section through the body• culture & sensitivity testing growing

microorganisms in the laboratory and testing them for sensitivity to antibiotics

• effusion a fluid discharge into a part/escape of fluid into an enclosed space

• encapsulated enclosed on a capsule or sheath

• histiocytes the word means a tissue cell (actually a large cell found in connective tissue that helps defend against infection)

• HIV-positive presence of antibodies to the human immunodeficiency virus in the blood, it indicates the virus has infected the body

• lobe a division of an organ into smaller sections, here a lobe of the lung

• malignant dangerous, life threatening• mass lump/collection of cohering cells• morphologically referring to the form and

structure of an organism• mucoid resembling mucus• peripheral pertaining to the periphery i.e. the

surface of an organ• pleural pertaining to the pleura/pleural

membranes that surround the lungs• polymorphonuclear pertaining to or having

nuclei of many shapes