Chapter 1
An Introduction to studying the human body
Outline:
1. Definition of Anatomy and Physiology. Anatomy—deals with structural
characteristics. Physiology-deals with functional characteristics.
Anatomy and physiology are closely related. Anatomical information provides
clues about functions, and physiological mechanisms can be explained only in
terms of the underlying anatomy.
All specific functions are performed by specific structures.
2. Anatomy branches--- Gross anatomy, microscopic, development
Gross anatomy or macroscopic anatomy involves the examination of large
structures usually visible with unaided eye. There are many forms of gross
anatomy e.g., surface anatomy-general form and superficial markings; regional
anatomy-focuses on specific areas of body such as head, neck, trunk; system
anatomy-study of the structure of organ systems; developmental anatomy-study
of changes in form between conception and physical maturity; microscopic
anatomy-includes two main divisions-cytology – study of the internal structure of
individual cells and histology is examination of tissues-groups of specialized cells
and cell products working together to perform specific function.
3. Physiology is the study of the function of anatomical structures.
Physiology branches--- Neurophysiology, Cardiovascular, Immunology etc.
4. Levels of organization: Chemical (atoms and molecules, cellular-cell, tissue,
organs, organ system, organism).
5. Noninvasive diagnostic techniques (inspection, palpation-to examine by
touching, auscultation-listening to internal sound, percussion-by tapping or to
determine by resonance the condition of internal organ).
http://www.youtube.com/watch?v=ux607iZi8-k
6. Basic life processes (metabolism, responsiveness, movement, growth,
differentiation and reproduction)
7. Structural and functional organization: chemical-cell-tissue-organ-organ systemorganism
8. Homeostasis: homeo-unchanging+stasis-standing refer to stable internal
environment This term was coined by Walter Canon and refer to tendency to
maintain internal stability. Homeostasis is absolutely vital to an organism’s
survival. Homeostatic regulation is the adjustment of physiological system to
preserve homeostasis.
Two general mechanisms are involved in homeostatic regulation, a)
autoregulation or intrinsic regulation-when cell, a tissue, organ or organ system
adjusts its activity automatically e.g. response to hypoxia-when oxygen levels
decline in a tissue, the cells release chemicals to widen or dilate local blood
vessels-this increase rate of blood flow providing more oxygen to the region.
b) extrinsic regulation-by the activity of nervous and endocrine system e.g.,
exercise-nervous system issues commands that increase heart rate and respiration
to increase blood circulation bringing more oxygen to active muscles.
Homeostatic regulation is always to keep the characteristics of the internal
environment within certain limits
9. Homeostatic control mechanisms---consists of a) a receptor-sensor that is
sensitive to a particular stimulus , b) control center or center integration center,
which receives and processes the information supplied by the receptor, and c) an
effector, a cell or organ that responds to the commands of the control center
either to oppose or enhance the stimulus. Homeostatic regulation is maintained by
negative and positive feedback mechanisms.
Human body can effectively maintain homeostasis but infection, an injury or a
genetic abnormality is so severe that homeostatic mechanisms cannot fully
compensate for them. When this happens, organ systems begin to malfunction,
producing state of illness called disease.
Homeostasis and state of equilibrium: Homeostatic regulation controls aspects
of the internal environment that affects every cell in the body. A state of
equilibrium exists when opposing processes or forces are in balance.
10. Anatomical terms: Superficial anatomy—locating structures on or near the body
surface.
Anatomical Landmarks help to remember both the location of a particular
structure and its name e.g., brachium refers to the arm.
Anatomical position: when the body is in this position, the hands are at the sides
with the palms facing forward and the feet are together---see figure A.1( page 28)
person lying down in the anatomical position is said to be supine –when face up,
and prone when face down.
11. Anatomical regions: Two methods are used to map the surface of the abdomen
and pelvis.
http://www.youtube.com/watch?v=oeFoxTi02yg
Clinicians refer to four abdominopelvic quadrants formed by imaginary
perpendicular lines that intersect at the umbilicus. This method provides useful
references for the description of aches, pains, and injuries. The location can help a
physician determine the possible cause—tenderness in right lower quadrant
(RLQ) is a symptom of appendicitis.
Anatomists prefer more precise terms to describe the location and orientation of
internal organs. They recognize nine abdominopelvic regions (fig 1-6b, page
17). Figure 1-6c page 17 shows the relationships among quadrants, regions and
internal organs.
12. Anatomical Directions—Table A1, page 29.
13. Sectional Anatomy: one of the ways to understand the relationships among the
parts of a three-dimensional object is to slice through it and look at the internal
organization. It is important now that imaging techniques enable us to see inside
the living body.
14. Body planes and sections—Figure A.1 page 28. Any slice through a threedimensional object can be described in reference to three sectional planes. A
plane is an axis. Transverse or horizontal plane lies at right angles to the long
axis of the body. Frontal plane and the sagittal plane are parallel to the long
axis of the body. It divides the body into anterior and posterior portions. Sagittal
plane extends vertically, dividing the body into right and left halves. A cut that
passes along the midline and divide body into equal left and right halves is a
midsagittal plane, a cut dividing body into two unequal halves is parasagittal
plane.
15. Body Cavities – Body cavities are dorsal and ventral body cavities (Fig A.5,
page 32-33).
Dorsal body cavity is located in the dorsal side of the body and has brain and
spinal cord.
Ventral body cavity is on the ventral side of the body and divided into thoracic
and abdominopelvic cavities. Internally two are separated by the diaphragm, a
flat muscular sheet.
Thoracic cavity contains the lungs and heart: associated organs of the respiratory,
cardiovascular and lymphatic systems.
The thoracic cavity is subdivided into the left and right pleural cavities,
separated by a mass of tissue called the mediastinum. Each pleural cavity,
surrounds a lung, is lined by a shiny, slippery serous membrane called pleura that
reduces friction as lung expands. The visceral pleura cover the outer surfaces of
a lung, whereas the parietal pleura cover the mediastinal surface and the inner
body wall.
Mediastinum consists of a mass of connective tissue that surrounds, stabilizes,
and supports the esophagus, trachea and thymus. It also contains the pericardial
cavity that surrounds the heart. The serous membrane associated with the heart is
called the pericardium (parietal and visceral).
The abdominopelvic cavity extends from the diaphragm to the pelvis. It is
subdivided into a superior abdominal cavity and an inferior pelvic cavity.
Abdominal cavity extends from the inferior surface of the diaphragm to the level
of the superior margins of the pelvis and contains the liver, stomach, spleen, small
intestines and most of the large intestines.
The pelvic cavity is the portion of the ventral body cavity inferior to the
abdominal cavity. It contains ovaries, uterine tubes, and uterus in females and
prostate seminal glands in males. Peritoneum covers ovaries and uterus in female
and superior portion of urinary bladder in both sexes.
Origin of biomedical sciences:
Hippocrates
Greek physician; “Father of medicine”
Established a code of ethics (Hippocratic Oath)
Urged physicians to seek natural causes of disease rather than attributing them to acts of
the gods and demons
Birth of modern medicine:
Maimonides (Moses ben Maimon)
Jewish physician who wrote 10 influential medical texts
Was physician to Egyptian sultan, Saladin
Avicenna (Ibn Sina) from Muslim world
“The Galen of Islam”
Combined both Galen and Aristotle’s findings with original discoveries
Wrote The Canon of Medicine, used in medical schools for 500 years
Robert Hooke
Made many improvements to compound microscope—two lenses: ocular lens (eyepiece)
and objective lens (near specimen)
Invented specimen stage, illuminator, coarse and fine focus controls
His microscopes magnified only 30X
First to see and name “cells”
Published first comprehensive book of microscopy (Micrographia) in 1665
Antony van Leeuwenhoek
Invented a simple (single-lens) microscope with great magnification to look at fabrics
(200X)
Published his observations of blood, lake water, sperm, bacteria from tooth scrapings, and
many other things
Matthias Schleiden and Theodor Schwann
Examined wide variety of specimens
Concluded that “all organisms were composed of cells”
First tenet of cell theory
Considered to be perhaps the most important breakthrough in biomedical history
All functions of the body are interpreted as effects of cellular activity