Notes on the Web
Human Body: An Introduction to Anatomy & Physiology

Bruce G. Stewart

General Objectives

Related Textbook Readings

Lecture Outlines, Notes, and Selected Exercises

I. Anatomy, Physiology and Their Subdisciplines

A. Anatomy - the study of structure

1. Gross anatomy - the big picture... large body structures; can be studied from different perspectives depending on the focus

a. regional anatomy (e.g. everything in the head)

b. systemic anatomy (e.g. system by system which is our primary approach in a general anatomy and physiology course)

c. surface anatomy (e.g. for learning where to take the pulse or where to do a hypodermic injection)

2. Microscopic anatomy - the small stuff... beyond human ability to see with the unaided eye

a. cytology - the study of cells which includes the "anatomy" or physical makeup of the parts; this aspect can be thought of as "cell anatomy."

b. histology - the study of tissues which includes the "anatomy" or physical makeup of the type of cells and their organization in to tissue types; this aspect can be thought of as "tissue anatomy."

3. Developmental anatomy and embryology

a. developmental anatomy - a discipline that follows (by the comparative method of science!) the distinctive stages of anatomical development over time spans of the human life; of course, these changes are connected to changes in physiology

b. embryology - the discipline that includes the developmental changes from conception to birth

B. Physiology - the study of function

1. cell physiology - the study of function at the cellular level (e.g. the process of energy extraction and convertion by mitochondia)

2. tissue physiology - the study of function at the histological level (e.g. the processes involved in producing muscle tissue contractions); this requires knowledge and application of principles of cellular physiology

3. organ and system physiology - the study of the function of individual organs or entire body systems (e.g. neurophysiology, cardiovascular physiology, osteophysiology)

C. Structure and Function are Complementary

1. This may seem self-evident, but it is worth mentioning; the anatomy (including cytology, histology and gross) of the a particular structure or system determines its ability to perform particular functions. Physiology also relates to the anatomy of structures, particularly in the area of development and maintenance.

2. This complementarity is good reason to study both anatomy and physiology at the same time!

II. Hierarchical Levels of Organization of Life

A. Text Box and Table on Complexity

Hierarchical complexity refers to the many levels of organization and interaction in living things. Sylvia Mader (2003) notes that each level has properties that are more than a simple sum of its parts. Because living systems are so much more highly organized and complex than non-living systems, English biologist and author, Richard Dawkins, has even termed chemistry and physics as the "simple sciences!" He does not mean "easy" sciences, but rather that biology has so many more levels with unique properties and interactions. As one moves up the hierarchy from chemical to ecosystem, there are emergent properties (Johnson and Losos 2008) that are unique to that level and which cannot be understood by simply knowing the lower level components and their functions.

The next table lists these levels along with a brief description of each. Read over the whole table, but for our human anatomy and physiology class, you need know only the information for the levels up to the multicellular, complex organism. 
TABLE.   Hierarchical Levels of Organization of Life: Subatomic Through Ecosystems
Level Examples Fields of Study (there are many others) Definition or Properties
subatomic particles protons, neutrons, elections atomic and nuclear physics fundamental particles of matter; affected by nuclear and electromagnetic forces
atoms atoms of oxygen, carbon, nitrogen, hydrogen, etc. chemistry, physics smallest unit of an element; affected by electromagnetic forces, and possesses unique chemical and physical properties
molecules a molecule of insulin biochemistry, molecular biology smallest unit of a compound; affected by electromagnetic forces, and has unique chemical and physical properties
organelles nucleus, cell membrane, ribosomes, etc. cytology, molecular biology, physiology organized part of a cell with unique chemical functions
cells an amoeba, a muscle cell, a bone cell cytology, physiology smallest unit of life that can perform all life processes
tissues muscle tissue, nervous tissue, vascular tissue, reproductive tissue, connective tissue, epithelial tissue histology, physiology groups of cells that perform the same function
organs a heart, a bone, a lung, a pituitary gland, etc. anatomy, physiology groups of tissues that help perform a certain function
organ systems skeletal system, nervous system, respiratory system, cardiovascular system, reproductive system, endocrine system, muscular system, excretory system, integumentary system anatomy, physiology groups of organs that help perform a certain function
complex multicellular organisms a fox squirrel, a robin, a roundworm, etc. human anatomy and physiology, natural history, behavior, morphology, physiology, systematics, mammalogy, herpetology, ornithology, ichthyology, entomology, etc. (these "ologies" apply to populations and communities as well. an organized and coordinated group of organ systems that existed independently as a unit that can perform all of life’s processes
populations all fox squirrels in a given bottomland forest, all post oak trees in a given forest natural history, population ecology a group of organisms of the same species living within a defined area
communities a bottomland hardwood forest, a pond, a freshwater stream, etc. natural history, community ecology a group of populations of different species that live in a defined area
ecosystems similar to the communities above but including all living and non-living components landscape ecology, ecosystem ecology a group of interacting communities that occur in a defined area; includes living and non-living components

III. Humans Share Critical Properties and Process of Life in General

A. Text Box on Properties and Processes of Life (Including Homeostasis)

Humans are made of Cells - Cellular Organization

The cell theory includes an expression of consistent observations made for over 300 years since the invention of the microscope. These observations have shown that all living things have a fundamental unit of structure called the cell. Cells are small structures surrounded by a complex membrane that encloses an even more complex array of cell organelles that perform the various critical processes of life. The entire body of some organisms is composed of only a single cell, whereas some others have trillions! The human brain alone has billions of cells. All living things are made of cells.

Humans Obtain and Manage Energy and Nutrients - Metabolism and Nutrient Management

A rock can passively have its energy increased!  When sunlight strikes a rock, the temperature of the rock and the total amount of thermal energy it possesses increases. However, a rock cannot control this process, nor can it use the energy to do work or to obtain nutrients.

Living things by contrast can obtain and control energy through processes like photosynthesis and metabolism. Photosynthesis is the conversion of visible sunlight energy into other stored or usable forms of energy. Metabolism is the process of converting energy from a stored form (e.g. energy in a sugar molecule) to other forms. All living things perform metabolism, but for those that cannot photosynthesize it is the only way to get usable energy. One type of energy releasing metabolism is called aerobic respiration. It is basically the opposite of photosynthesis and therefore requires energy rich molecules like simple sugars and oxygen to work. The energy from photosynthesis and metabolism can be used to do work such as building molecules of the body structure and creating movement.

Nutrients are substances that an organism takes in and uses for growth and maintenance. Some nutrient molecules, like glucose, provide two needs for living things. One is that chemical energy is stored in these molecules and that energy can be extracted by metabolic processes by organisms. The other provision is the chemical elements found in nutrient molecules. These molecules contain atoms and and molecular arrangements that serve as raw materials for building their own molecules that make up their bodies.

To summarize, all forms of life show metabolic activity; they extract & transform energy from their environment and use it for manipulating materials in ways that assure their own maintenance, growth, development & reproduction. All living things obtain and manage nutrients for the purpose of extracting energy and obtaining raw materials needed for the structure and function of their bodies.

Humans Maintain Their External and Internal Conditions in Balance - Homeostasis

Living things must keep levels of internal conditions at levels appropriate for other life processes to occur. These include things like temperature, pH (acid levels), nutrients, hormones, water, waste concentrations, and many others. Similarly, external conditions must be appropriate for life. For example, lizards thermoregulate (adjust their body temperature) by such behaviors as orienting in certain ways to the sun and moving to rocks that have appropriate temperatures. In this way, their can keep their muscle tissues at temperatures for optimum performance. This helps them capture prey and escape from predators. The term that refers to all ways that an organism regulates its internal and external environment is homeostasis. The ability to respond to stimuli in the environment is often called irritability. This ability allows all forms of life to use homeostatic controls that maintain the living state even when internal and external conditions change. These controls may be behavioral or physiological.

Feedback mechanisms are used to adjust conditions so as to maintain a livable balance for many physiological and physical conditions of the human body. These fall into two main categories: positive feedback mechanisms and negative feed back conditions. Negative feedback loops are very common in living things. For example, when your blood sugar rises, special cells in your pancreas release insulin which promotes cellular uptake of glucose. Lowered glucoses shuts down insulin release. (Another hormone, glucagon, is important in blood sugar levels and it has its own negative feedback loop). Negative feedback is illustrated frequently with a familiar example: the thermostat's control of room temperature. See your text for this example.

Positive feedback can be described as a cascade of events that stop only when they hit a "wall." That is, they stop when a job is completed. An example of this is the beautiful cascade of events that occur when you injury yourself and have a loss of blood. The blood clotting process covered in detail in a chapter later in your textbook is an intricate set of chemical steps that proceeds full force until the bleeding is stopped.

Internet Learning Activity - Ben's Bad Day. Visit this link and follow the instructions to observe how Ben's body responds to various challenges to maintain homeostasis.Note how Ben's body can detect stimuli (both internal and external) and then respond appropriately to keep his internal conditions. All living things must be able to accomplish similar feats.

Human Beings Reproduce and Pass Genetic Codes to Future Generations - Reproduction and Heredity

Life is unique in its possession of a chemical coding mechanism that allows organisms to produce offspring of their own kind. One special type of nucleic acid, DNA, is the code-carrying molecule. All living things possess their own copies of the genetic instructions to operate their bodies. These instructions are contained in subsets of DNA codes called genes. Furthermore, these instructions can be duplicated and passed on to reproductive cells that develop into offspring directly or through combinations in sexual reproduction. Aspects of an organism that are due to this genetic code are referred to as genetically inherited characteristics. All living things exhibit distinctive patterns of heredity. This is not to say that the phenotype (form) of an organism is not influenced by environmental factors. Maybe you remember the long running "nature versus nuture" debate in psychology. The genetic code dictates the "nature" component of living organisms, and all organisms share this property.

DNA is the storehouse of genetic information for all organisms. Mutations, however, introduce variations in the patterns, and this allows survival in changing environments. Nature is the testing ground for the combination of patterns that come to be expressed in each individual. This is concept of mutation is especially important in human disease where we are have to be constantly working to develop vaccines for the lastest flu mutant. Also, much human suffering is caused by mutations that create homeostatic and physiological breakdowns of many sorts.

Humans Exhibit Growth and Development

From the beginning of the life of each organism, its body undergoes an amazing series of changes. Cells are replicated, materials are constructed, body size increases, and body form develops. The master plan for these processes is found in the coded instructions (genes) of DNA. Growth and development follow this genetic program faithfully. (Although do not forget that the genetic program received may be different in detail to that of the parents, and that environment plays an important role.)

Think of the process of metamorphosis in butterflies. This has intrigued humans throughout history. Sexual reproduction between a male and female of the same species produces a fertilized egg (zygote). This zygote divides and produces immense numbers of descendant cells that differentiate into the various tissues, organs and organ systems of the caterpillar (the larval stage). This herbivorous (plant eating) larva enters the pupa stage in which the entire body is overhauled and transformed. Finally, the adult butterfly emerges in all its glorious beauty!

From the moment of its emergence, each living thing goes through a series of developmental stages, a continuum of changes in form and behavior. These developmental stages unfold at about the same rate and in the same way for all organisms of a given species. You yourself went through distinctive stages (e.g. the "terrible twos")

B. Aspects of Human Life Functions as Listed in Marieb -

1. Boundaries, Movement, Responsiveness, Digestion, Excretion, Metabolism, Reproduction, Growth

a. Read these in your textbook, and note how they fit in with the previous material in these Notes on the Web.

b. Example: boundaries are required to maintain safe internal conditions for homeostasis. This would fall under the general property of homeostasis.

c. Example: responsiveness (=irritability) is the ability to respond to external and internal stimuli. This is also required to maintain homeostasis.

d. Example: excretion is required to keep from... well... filling up with nasty waste! This is also required to maintain homeostasis.

e. Examples: other "life functions" listed by Marieb are directly described previously (e.g. metabolism). Read and learn the materials in the Notes on the Web and the brief materials in your text on all of these.

C. Survival Needs as Listed in Marieb - Nutrients, Oxygen, Water, Normal Body Temperature, Atmospheric Pressure

1. As with the "life processess" mentioned in "B" above, the survival needs described in your text fall under previously discussed categories, particularly homeostasis. Nonetheless, learn the brief materials in your text on these to add to our Notes on the Web.

D. Aspects of Homeostatis Discussed in Marieb - Mechanisms, Negative Feedback, Positive Feedback, Imbalances.

1. As with the previous sections, these topics have been discussed in your Notes on the Web, however, read and learn the material from your textbook to supplement our Notes on the Web.

E. Eleven body systems - integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic/immune, respiratory, digestive, urinary, reproductive. A major part of API and APII involve learning how these various body systems contribute to the critical processes of life, including homeostatis, of the normally functioning human body.

IV. Language of Anatomy

A. Anatomical Position - see textbook for images. Standup! Place yourself in the standard anatomical position: face forward with your legs more or less parallel (feet slightly apart), your arms downward but held slightly away from your hips, and your thumbs on the outside.

1. Note that descriptions of anatomy throughout our book and in our labwork, etc. use directional terms as if the body was in the anatomical position.

2. Know all of the directional terms found in your text plus one additional one defined in the list below:

Note that all of these directional terms are relative and may be used to describe relationships that are far from the extreme ends of the body. For example, the knee is superior to the foot even though both are inferior to the hip joint.

B. Regional Terms Used to Describe the Human Body

1. Major Divisions (two)

a. Axial (head, neck and trunk)

b. Appendicular (appendages and their connections to the trunk)

2. Regional Terms - Specific Area Terminology

a. Examine and learn those labeled on the diagram in your book. You should learn the technical term and may define it by the short common description found in parentheses after it

b. For the record, the following text box shows most of these terms. The terms required for you to commit to memory at this time are shown in bold. The detailed subdivision terms you can learn as you go through the body systems later. Some of these regions can be seen from the anterior view, some from the posterior view, and some from both views.

  • Cephalic
  • nasal
  • oral (=buccal)
  • frontal
  • orbital
  • mental
  • otic
  • occipital
  • Cervical
  • Thoracic
  • axillary
  • sternal
  • mammary
  • Abdominal
  • brachial
  • antecubital
  • Pelvic
  • inquinal
  • Pubic
  • Upper Limb (= Upper Extremity)
  • acromial
  • brachial (arm)
  • antecubital
  • olecranal
  • antebrachial (forearm)
  • Manus
  • digital (fingers)
  • carpal
  • metacarpal
  • palmar
  • Lower Limb (=Lower Extremity)
  • coxal (hip)
  • femoral (thigh)
  • patellar
  • politeal
  • crural (leg)
  • sural (calf)
  • fibular or peroneal
  • hallux
  • umbilical
  • Pedal
  • tarsal (ankle)
  • calcaneal
  • metatarsal
  • digital
  • plantar
  • hallux (big toe)
  • Back (dorsum/dorsa)l
  • vertebral
  • scapular
  • lumbar
  • sacral
  • gluteal
  • perineal

C. Study of Non-human Mammals in Human Anatomy: An Explanation and Historical Note

A large proportion of human anatomy courses across the nation (and in Oklahoma) use non-human mammalian dissection materials to help teach students understand human anatomy. You may wonder why this is of educational value. Mammalian anatomy, particularly between certain mammal groups, is amazingly similar... so similar that you would be challenged at first to distinguish between some organs (e.g. kidneys, hearts, etc.) from a human and another mammal! In fact, the similarities can be so striking that the famous Greek anatomist, Galen of the 2nd century AD, actually based much of his human anatomy descriptions on non-human primates (e.g. apes). Galen could not always research internal human anatomy by using cadavers so he used other closely-related species that were so similiar that no one successfully challenged his accuracy for some fourteen centuries!

Human and ape anatomy are so similar that the Church did not realize the basis for Galen's excellent research. The Church therefore adopted Galen's human anatomy writings as the final word (revealed from God) without knowing that much of his work was actually based on the anatomy of apes! It wasn't until 1543 AD that Andreas Vesalius published his great human anatomy treatise, "De Humani Corporis Fabrica," which finally cracked the dogmatic position of the Church and others on the details of Galen's work. It was not a peaceful transition, and some were put to death for questioning Galen! Consider the following quote from Moore (1993):

Initially Vesalius had much opposition, since even suggesting that such an ancient and respected authority as Galen might have erred was not in the best of taste. One brave, free spirit who suffered because he thought otherwise was Michael Servetus (1511-1553), a scholar of broad interests, mainly theological, but also a serious student of Galen. In the course of his studies, he came to the conclusion that Galen was not correct in all matters. Servetus hypothesized, for example, that blood does not pass directly through those Galenic pores from right ventricle to the left but instead goes from the right ventricle to the lungs, where it picks up air, and then back to the left ventricle. Mainly because he questioned Galen, whom the Church had named as the authority on anatomy and physiology, Servetus was captured while at prayer and, after a brief trial, was sent up in flames on October 27, 1553. Lest the reason be in doubt, one of his offending books was hung from his neck so it too was consumed on the pyre.

Now you can realize that honorable people have actually sacrificed their lives in order to find the scientific truth of human anatomy! You should also now realize the great educational value that you can gain by conscientiously studying the non-human, mammalian specimens we will explore in some of our lab sessions. Specifically, we will dissect minks for muscles and sheep brains for the nervous system. Also, some histological slides used to study microscopic anatomy will be from non-human mammals.

D. Anatomical Variability

It is important to understand that each individual varies in many details of anatomy and physiology. This fact often passes by the beginning student of human anatomy. They examine the drawings and figures in their textbooks and wonder, "Why can't we just learn this on the diagrams?" "Why do we have to identify these structures on the a specimen?" The answer, in part, is that the diagrams do not look exactly like the real thing! Your textbook authors, Marieb and Hoehn (2007), state that about 90% of structures will fit a "textbook description." This means that 10% do not! Study of actually specimens and the ability to identify structures on multiple specimens of the same organ (for example) are required for the student to understand anatomy at a deeper level.

E. Body Cavities and Membranes

1. Dorsal Body Cavity - central nervous system cavities both of which are continuous with one another

a. cranial cavity - brain

b. vertebral (=spinal) cavity - spinal cord

2. Ventral Body Cavity - houses visceral organs

a. thoracic cavity - portion above the diaphram and within the ribs and muscles of the chest

  • pleural cavities - lungs
  • mediastinum - esophagus, trachea, and others along with the pericardial cavity housing the heart

b. abdominopelvic cavity - below the diaphram

  • abdominal cavity - stomach, intestines, spleen, etc.
  • pelvic cavity - protected by bony pelvis and containing the urinary bladder, some reproductive organs, and the rectum

3. Membranes of the Ventral Body Cavity - thin double-layered tissue linings called the serosa or serous membrane

a. parietal serosa - lines walls

  • parietal pericardium - heart
  • parietal pleura - lungs
  • parietal peritoneum - abdominopelvic

b. visceral serosa - surrounds (adheres to surface of) organs

  • visceral pericardium - heart
  • visceral pleura - lungs
  • visceral peritoneum - abdominopelvic

c. serous fluid - reduces friction and contains white blood cells that help remove abrasive materials to keep the fluid clean.

F. Abdominopelvic Quadrants - note superficial organs found in each as shown in your text. You do not have to memorize these at this time.

a. right upper quadrant

b. left upper quadrant

c. right lower quadrant

d. left lower quadrant

G. Other Body Cavities - know the oral and digestive, nasal, orbital, middle ear, and synovial cavities as described in your text. (You do not have to memorize these at this time.)

V. Medical Imaging - Review these various incredible tools. Only three will included as testing material, but you will benefit from having a bit of knowledge about all of them. The three to learn now are: Postitron Emission Tomography (PET), Sonography (ultrasound imaging), and Magnetic Resonance Imaging (MRI).

Reminder about Textbook Study

As with other topics, your textbook has excellent presentations of the materials on the introduction to anatomy and physiology. While you should focus on the specific material in the Notes on the Web, you should always use your textbook as a resource for illustrations and for understanding content that your notes cover. Check the general objectives above to make sure that you have covered all of the topics in the textbook readings.

As with all materials throughout the semester, you will have opportunities to ask questions or ask that any relevant material from your assignments be discussed in class.

Related Internet Resources

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