History of Anatomy and Physiology, Terminology & Homeostasis

 

 

Until the modern era, Anatomy & Physiology did not exist as "sciences" --

the history of medicine reflects the history of anatomy & physiology.

 

Early (prerecorded history): "Shamans" were the persons with knowledge of body functions, the use of herbs, etc..

 

"Healers" traditionally have three necessary qualities:

 

   1.Knowledge

   2.Authority

   3.Connection with the supernatural

 

 

Babylon

 

First recorded evidence of medicine as a profession.

 

Code of Hammurabi contained rules related to medicine and malpractice.

 

     "If a physician make a large incision with an operating knife and

     cure it, or if he open a tumor (over the eye) with an operating

     knife, and saves the eye, he shall receive ten shekels in money.

     If the patient be a freed man, he receives five shekels.

     If he be the slave of some one, his owner shall give the

     physician two shekels.

 

     If a physician make a large incision with the operating knife,

     and kill him,

     or open a tumor with the operating knife, and cut out the eye,

     his hands shall be cut off.

 

     If a physician make a large incision in the slave of a freed man,

     and kill him, he shall replace the slave with another slave.

     If he had opened a tumor with the operating knife, and put out

     his eye, he shall pay half his value.

 

     If a physician heal the broken bone or diseased soft part of a

     man, the patient shall pay the physician five shekels in money.

     If he were a freed man he shall pay three shekels. If he were a

     slave his owner shall pay the physician two shekels. "

 

Wide use of herbs/drugs, e.g., opium.

Beer was believed to be good for the heart and liver.

 

Ancient Egypt: High degree of medical knowledge as evidenced by numerous medical papyri.

 

Circumcision: Earliest record of circumcision: rite of passage for boys.

 

 

Ancient Greeks

 

Balance of 4 body fluids or "humors." Blood (from heart, sanguine), bile (from liver; choler), black bile (from spleen; melancholic), and phlegm (from

brain; phlegmatic). Correlation to four seasons and the four elements.

 

 

Hippocrates --"Father of Medicine." Born 460 BC.

He stressed natural causes of disease rather than displeasure of the gods. Observational medicine that was focused on patient and patient's

environment, i.e., "holistic."

Hippocratic physicians stressed detailed observation of patient's body and

body products (sweat, urine, ear wax, feces, etc.). "Hippocratic Oath" & idealized doctors.

 

Cult of Ascelpius, Origin of cadeceus

 

Aristotle -- data collection, embryological observations. "The History of

Animals", "On Sense and the Sensible," and "Parts of Animals" are some of the earliest writings dedicated to anatomy, physiology and general biology.

Aristotle believed heart was the seat of intelligence. (Herophilus and Plato

thought that brain was).

 

Ptolemy established a museum in Alexandria, Egypt. Dissections allowed for a short time.

 

 

Chinese Medicine

 

Chinese medicine, like Greek-Hippocratic tradition, stressed balance (Taoist philosophy) and was primarily noninvasive (pulse reading, observational, questioning of patient).

 

Health is maintained when there is a balance between "yin" (female or the shaded aspect, the earth, darkness, the moon, and passivity) and "yang" (male, light, sun, heaven, the active principle in nature). There are five "Elements" in traditional Chinese medicine: wood, fire, earth, metal, and water -- water and metal are associated with yin, wood and fire are associated with yang, while earth belongs to both yin and yang because it assists both.

 

 

 

Roman Era

 

Galen -- Second century AD. "Father of Anatomy." Observational & experimental. Surgeon to gladiators in Pergamon (Turkey). Moved to Rome and eventually became physician to Emperor Marcus Aurelius. Performed pioneering experiments on circulation, respiration, urine formation, and

nervous system. Stressed anatomical accuracy, but often came to the wrong conclusions based on accurate observations.

 Galen's Works: On the Natural Faculties. Many of Galen's writings have been lost.

 Galen was considered dogma by the Church for about 1500 years.

 

The "Hospital" -- from hospices formed by early Christians for service to poor. (Similar hospices were established by Buddhists in India and Sri Lanka).

 

 

Middle Ages

 

"Folk medicine" was dominant. Greek and Roman teachings were lost.

Some women figures of note: Metradora, Trotula, and Hildegard of Bingen.

Metrodora and Hildegard both compiled catalogs of diseases and treatments.

Hildegard's medical and mystical writings often overlapped.

 

 

Little European progress in anatomy and physiology. Church forbade human dissection until 1235. Galen was considered dogma and people who challenged Galen's writings were frowned upon, occasionally burned at the stake.

 

Islam

Arab Moslems and Arabian Jews (e.g., Treatise on Hygiene by Rabbi Moses Maimonides or Moshe ben Maimon), however, had well developed medical practices, many adapted from Greek and Roman teachings. First "medical school" in Europe in 9th Century was staffed by many Moslem and Jewish physicians. Arabia preserved many Greek and Roman texts and reintroduced these texts to Europe. Rhazes (Al-Razi) and Avicenna (lbn-Sina) were key figures in Islamic medicine.

 

 

Many Asian and New World Indian cultures had a more advanced knowledge of medicine than Europeans at this time. Asian Indians recognized diabetes and knew that diet could affect it; early accounts of "vaccination" (variolation, actually).

 

 

New World Medicine before Columbus

 

New World Indians indirectly introduced curare, quinine, ipecac, and scurvy

treatment to Europeans.

Aztecs had detailed knowledge of anatomy, especially the heart, from human sacrifices.

 

Renaissance:

Greater frequency of dissections as Church's hold on science weakened.

DaVinci: "Science comes by observation, not by authority." Merged art and anatomy.

 

Andreas Vesalius: Published "De Humani Corporis Fabrica" in 1543 when he was 28.

He is called "Father of Modern Anatomy" because of his precise anatomical observations. Challenged Galenic teachings.

 

17th and 18th Century:

William Harvey described the circulation of blood (challenge to Galen account of circulation) in his "On The Movement of the Heart and Blood in Animals" in 1628. Described flow of blood in a circuit.

Anton van Leeuwenhoek -- used microscope, observed "cells" and "animalcules." First report of spermatozoa, blood cells, and striations in muscle.

Descartes -- philosopher/scientist. Split mind and body. Attributed bodily functions to mechanistic analysis. Early model of involuntary reflex.

Thought pineal gland was the site of the soul, or anatomical interface between "spirits" within body. Basically he had a hydraulic view of the body

-- nerves were hollow tubes that conducted spirits -- spirits inflated muscles.

Jenner -- small pox vaccination developed from cowpox. Eventually vaccination supplanted "variolation" (using extracts from small pox sores for inoculation) which had been used in Europe and Asia for centuries. Lady Montagu reported on use of variolation (often incorrectly reported as vaccination) in Turkey, but the practice never caught on with the upper classes in England.

 

Influenced by the Greek Humoral theory, blood-letting was widely practiced in Europe and American from the middle ages until well into the 19th century.

 

19th Century:

Growth of scientific method in anatomy, physiology, and medicine.

Formulation of Cell Theory --- Cells as the basic unit of life (structural and functional uints) and "all cells come from preexisting cells." (except first cell). Spontaneous generation

disproven

Germ theory of disease. Advances in microscopy, staining techniques.

Pasteur: contributed to "germ theory of disease."

Galvani and Volta -- electrical nature of muscle and nerve function.

Darwin -- Comparative anatomy is a reflection of evolutionary processes

rather than separate creations of God.

Surgical advances; rise of aseptic surgery and anesthesia.

 

20th Century

Rediscovery of Mendelian Genetics.

Role of chromosomes in inheritance.

Discovery of Insulin

Electron Microscope allowed fine definition of anatomical structures, e.g.,

muscle fibers, synapses.

Elucidation of protein and DNA structures.

Growth of biochemical and molecular techniques.

Cell biology, molecular biology, developmental biology (embryology), etc. all add to the study of modern anatomy and physiology.

Imaging Technology -- X-rays, CT scans, MRIs, etc.

 

 

 

Life

 

What is Life Anyhow?

Physiological Definition -- A Cell or Organism has:

1) Responsiveness or irritability: ability to respond to environmental change.

 

2) Movement or contractility

3) Metabolism--incorporates respiration, digestion, absorption, circulation,

synthesis, secretion, and excretion.

4) Growth

5) Reproduction

 

Viruses are often considered "non-living" since their reproduction can only occur with cells, but they are made of protein and have DNA or RNA.

 

 

Body Organization & Terminology

 

Chemical: Atoms or elements: basic units of all matter (nucleus, electrons);

2 or more atoms form a molecule. Molecule with 2 or more elements is a

compound.

 

Cell: Basic structural and functional component of life. Heterogeneous in structure and function.

 

Tissue: collection of cells that perform specific function

 

Organ: collection of 2 or more tissues, integrated to perform a particular

function.E.g., stomach, heart, skin, bone.

 

System: collection of organs which serve a general function; digestive,

nervous, circulatory, integument, etc.

 

Organism: An integrated collection of systems.

 

Superorganism: "Integrated collection of organisms." For example, coloniesof bees, ants and termites. Individuals have specialized functions (workers, soldiers, queen, drone). The Borg on Star Trek.

 

 

Anatomical Position

 

   1.Body standing erect.

   2.Head facing forward.

   3.Legs together and feet pointed forward

   4.Palms turned forward

 

Why is having a standard anatomical position important?

 

 

Terms of Location and Position

 

Superior -- Above, toward the head

Inferior -- Below, toward the lower part of the body (Cranial and Caudal are

used for 4 legged animals)

Examples:

1) head is superior to the chest, chest in inferior to the neck

2) the knee is superior to the ankle and inferior to the hip.

 

Anterior -- structures or areas on or near the front surface

Posterior -- structures or regions on or near the back side of body

Examples:

1) nose is on anterior surface

2) gluteal region is on posterior surface (Dorsal and Ventral are used for 4

legged animals, but sometimes used in human anatomy -- e.g., dorsal and

ventral body cavities; dorsal root ganglion)

 

Medial--nearer the midline of the body

Lateral--away from the midline

Examples:

1) Nose is medial to the eyes, the eyes are lateral to the nose.

2) Medial and lateral incisors

 

Internal -- deeper in the body (deep)

External -- toward the outer surface (superficial)

Examples:

1) Ribs are external to the heart and lungs

2) Internal and external iliacs and jugular vessels

3) Hair is superficial.

 

Proximal -- portion of structure (generally an arm or leg) that is closer to

the body

Distal --portion of structure that is farther from the body (Proximal and

Distal relate to a structure's position relative to reference point --proximal

and distal convoluted tubules in nephron of kidney).

Examples:

1) the forearm is proximal to the hand

2) the hand is distal to the elbow

 

Parietal -- refers to the walls of a cavity

Visceral -- refers to the organs contained in a cavity

Examples:

1) parietal peritoneum lines the walls of the abdominal cavity

2 ) abdominal organs are innervated by visceral nerves

 

Ipsilateral -- on the same side of the body

Contralateral -- on the opposite side of the body

Examples:

1) Damage to the motor cortex results in loss of motor ability of contralateral limbs, whereas the ipsilateral side of the body is not affected.

 

PLANES AND SECTIONS

Sagittal Plane -- divides bilateral organism into right and left sides.

Midsagittal (or Median) plane divides the body into right and left halves

that are equal in size and mirror images.

Parasagittal plane divides the body into unequal left and right sides.

Transverse or Horizontal Plane -- divides the body into superior and

inferior portions.

Frontal or Coronal Plane -- divides the body into anterior and posterior

portions (or dorsal/ventral).

 

CAVITIES

 

Dorsal Cavity = Cranial cavity + Vertebral cavity

 

Ventral Cavity

 

     Consists of the:

          Thoracic Cavity--(heart + lungs)

          Abdominopelvic Cavity (Abdominal cavity, Pelvic cavity)

 

Abdominopelvic cavity is divided into 9 regions or 4 quadrants

E.g., intense pain in lower right quadrant can indicate an appendicitis.

 

BODY REGIONS

Axial -- head, neck, thorax, abdomen, and pelvis

Appendicular -- upper and lower extremities (arms and legs)

 

Example: Axial and Appendicular Skeleton

 

 

 

HOMEOSTASIS & FEEDBACK

 

 

Homeostasis is the stability of the internal environment even though the

external environment changes.

Concepts were developed by Claude Bernard and Walter Cannon.

 

Homeostatic Regulation

Autoregulation: local

Extrinsic Regulation: involves integration of nervous and/or endocrine system.

Key things needed in a homeostatic system: receptor, control or integration center, and effector.

Set point is the optimal level for the controlled condition. Set points can be changed.

 

Feedback:

Feedback represents an organism's reception and response to some change in the internal environment.

 

Negative feedback: output of system counteracts the change in the environment. Common.

Negative feedback systems are similar to household heater-thermostat systems.

Negative feedback systems help maintain homeostasis. "Stress" can upset homeostasis.

 

Positive feedback: output of system is in the same direction as the change in the environment.

System goes away from normal set point.

Positive feedback systems exist, but are rare.

Example: Labor. Uterus contracts in response to hormone oxytocin, contraction causes more release of oxytocin, more contraction generated, more oxytocin released, etc, etc. Self-limiting -- once child is born, uterus is no longer stretched.

 

Other negative feedback systems: action potential of neurons and platelet clotting.

 

Homeostasis and Diabetes:

Blood glucose levels must be kept relatively constant. When glucose levels are elevated, the beta cells within the pancreatic islets of Langerhans release insulin. Insulin circulates in the blood and will bind to receptors on the cell membrane of different tissue (muscle, liver, adipose). The receptive tissues are stimulated to take up glucose from the blood, thus blood glucose levels will drop. This is a classic negative feedback system. What if a person can't produce enough insulin? What if a person produces insulin, but the tissues are less sensitive than normal? Both conditions will result in high levels of blood glucose. The above conditions are the two types of diabetes mellitus.

 

Homeostasis and Body Weight Control

Is there a set point for body weight?