What is the name of the study of body structures people can see with the unaided eyes?

Anatomy is the identification and description of the structures of living things. It is a branch of biology and medicine.

The study of anatomy dates back more than 2,000 years, to the Ancient Greeks. There are three broad areas:

• human anatomy
• animal anatomy — zootomy
• plant anatomy — phytotomy

Human anatomy is the study of the structures of the human body. An understanding of anatomy is key to the practice of medicine and other areas of health.

The word “anatomy” comes from the Greek words “ana,” meaning “up,” and “tome,” meaning “a cutting.” Traditionally, studies of anatomy have involved cutting up, or dissecting, organisms.

Now, however, imaging technology can show us much about how the inside of a body works, reducing the need for dissection.

Below, learn about the two main approaches: microscopic anatomy and gross, or macroscopic, anatomy.

In medicine, gross, macro, or topographical anatomy refers to the study of the biological structures that the eye can see. In other words, a person does not need a microscope to see these features.

The study of gross anatomy may involve dissection or noninvasive methods. The aim is to collect data about the larger structures of organs and organ systems.

In dissection, a scientist cuts open an organism — a plant or the body of a human or another animal — and examines what they discover inside.

Endoscopy is a tool for diagnosing illness, but it can also play a role in research. It involves a scientist or doctor inserting a long, thin tube with a camera at the end into different parts of the body. By passing it through the mouth or rectum, for example, they can examine the inside of the gastrointestinal tract.

There are also less invasive methods of investigation. For example, to study the blood vessels of living animals or humans, a scientist or doctor may inject an opaque dye, then use imaging technology, such as angiography, to see the vessels that contain the dye. This reveals how the circulatory system is working and whether there are any blockages.

MRI scans, CT scans, PET scans, X-rays, ultrasounds, and other types of imaging can also show what is happening inside a living body.

Medical and dental students also perform dissection as part of their practical work during their studies. They may dissect human corpses.

Human body systems

Students of gross anatomy learn about the major systems of the body.

There are 11 organ systems in the human body:

• the skeletal system
• the muscular system
• the lymphatic system
• the respiratory system
• the digestive system
• the nervous system, including the central and autonomic systems
• the endocrine system, which regulates hormone production
• the cardiovascular system, including the heart
• the urinary system
• the reproductive system
• the integumentary system, which includes the skin, hair, and nails, among other areas

These systems all work together and depend on each other to function.

Microscopic anatomy, also known as histology, is the study of cells and tissues of animals, humans, and plants. These subjects are too small to see without a microscope.

Through microscopic anatomy, people can learn about the structure of cells and how they relate to each other.

For example, if a person has cancer, examining the tissue under the microscope will reveal how the cancerous cells are acting and how they affect healthy tissue.

A researcher may apply histological techniques such as sectioning and staining to tissues and cells. They may then examine them under an electron or light microscope.

Sectioning involves cutting tissue into very thin slices for close examination.

The aim of staining tissues and cells is to add or enhance color. This makes it easier to identify the specific tissues under investigation.

Histology is vital for the understanding and advancement of medicine, veterinary medicine, biology, and other aspects of life science.

Scientists use histology for:

Teaching

In teaching labs, histology slides can help students learn about the microstructures of biological tissues.

Diagnosis

Doctors take tissue samples, or biopsies, from people who may have cancer or other illnesses and send the samples to a lab, where a histologist can analyze them.

Forensic investigations

If a person dies unexpectedly, the microscopic study of specific biological tissues can help experts discover the cause.

Autopsies

As in forensic investigations, experts study tissues from deceased people and animals to understand the causes of death.

Archeology

Biological samples from archeological sites can provide useful data about what was happening thousands of years ago.

People who work in histology laboratories are called histotechnicans, histotechnologists, or histology technicians. These people prepare the samples for analysis. Histopathologists, also known as pathologists, study and analyze the samples.

The technician will use special skills to process samples of biological tissues. The tissues may come from:

• patients seeking a diagnosis
• suspects in a crime, if it is a forensic lab
• the body of a person who has died

The process involves:

1. trimming samples and applying solutions to preserve them
2. removing any water, replacing it with paraffin wax, and putting the sample in a wax block to make it easier to slice
3. slicing the tissue thinly and mounting the slices on slides
4. applying stains to make specific parts visible

Next, a histopathologist examines the cells and tissues and interprets what they see. Others can use the histopathologist’s findings to decide on the best course of treatment or help determine how a death, illness, or crime occurred.

To become a histotechnologist in the United States, a person needs certification from the American Society for Clinical Pathology. They can start by taking a degree that includes math, biology, and chemistry, then getting onsite experience. Or, a person can attend an accredited histology program. Higher qualifications are also available.

To become a pathologist, a person usually needs a degree from a medical school, which takes 4 years to complete, plus 3–7 years of internship and residency programs.

Most people working in healthcare have had training in gross anatomy and histology.

Paramedics, nurses, physical therapists, occupational therapists, medical doctors, prosthetists, and biological scientists all need a knowledge of anatomy.