Welcome to BIO 201

Human Anatomy and Physiology I

with Dr. Fernandez

http://www.gc.maricopa.edu/biology/

• GCC Biology Department Website

• Fernandez web page

• Plastinate web page

• All college announcements and financial

information are sent to your Maricopa

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instructions on the bottom of the Biology

Department Website on how to forward

these messages to an email account that

you check regularly.

Introduction to Anatomy & Physiology

Chapter 1

• “Form ever Follows Function”

– quote by Louis Henry Sullivan

• Levels of organization

• Homeostasis

• Modern Medical Imaging

Anatomy - The Study of Form • Anatomy is the observation and description of biological

structures.

• Gross Anatomy is the study of structures that are visible with naked eye (without magnification). http://www.gc.maricopa.edu/biology/plastinates/Plastination%20PPT%20JJY.htm

• Gross Dissection is the cutting and separation of organs to study their structure and relationships.

• Histology (Microscopic Anatomy) is the study of tissues and cells using magnification (microscopes).

• Pathology is the microscopic anatomy of diseased tissues.

• Comparative Anatomy is the study of more than one species to analyze evolutionary trends and to make predictions.

• Physical Examination techniques of palpation (squeeze), auscultation (listen), and percussion (tap) depend upon a clear understanding of anatomy.

Anatomical Variation

• No 2 humans are exactly alike, and there is significant internal anatomical variation.

• Missing organs:

– e.g. palmaris longus muscle.

• More or less organs than normal:

– e.g. 2 spleens, single kidney, 6 or 4 lumbar vertebrae instead of the typical 5.

• Variation in organ locations: situs perversus (organ in an atypical location – appendix in center or on left)

Physiology - The Study of Function

• Physiology is the study of biological functions.

• Comparative Physiology involves the study of

different species to analyze evolutionary trends

and to make predictions.

• Applied Physiology provides the basis for the

development of drugs and medical procedures.

The Biological Hierarchy of Complexity

• an organism is composed of organ systems

• organ systems are composed of organs

• organs are composed of tissues

• tissues are composed of specialized types of cells

• cells are the basic units of life and are composed of a membrane and organelles

• organelles are functional units of complex macromolecules within cells

• macromolecules are composed of simpler molecules

• molecules are composed of atoms

Human Organ Systems

• Integument

• Skeletal

• Muscular

• Nervous

• Endocrine

• Cardiovascular

• Digestive

• Respiratory

• Urinary

• Reproductive

Homeostasis • The Harvard physiologist and

physician Dr. Walter Cannon (1871-1945) coined the term homeostasis to describe the stable internal environment.

• The internal environment of organisms is actually in a state of dynamic equilibrium, because conditions fluctuate within a range around a certain set point.

• Fluctuations are normally within a small range.

• Loss of homeostatic control causes illness or death.

Example of Homeostatic Control and

fluctuation within a range around a set point

• Room temperature controlled by a thermostat does

not stay exactly at the set point of 68 degrees. It

averages 68 degrees over time as temperature rises

and falls within a narrow range of temperatures.

Negative Feedback • Negative feedback is a mechanism used to maintain homeostasis of

mechanical and physiological systems.

• A thermostat senses a change in temperature and then activates mechanisms to reverse the trend back into the normal range.

Negative Feedback

• The brain can sense a change in temperature and it can activate mechanisms to reverse the trend back into the normal range.

Brain activates shivering

in skeletal muscles

Body temperature

drops below 37 °C

Body temperature

rises above 37 °C

Brain stops shivering in skeletal muscles

Body cools down

Negative Feedback Control of Human

Thermoregulation

• Temperature sensing nerve cells in the brain trigger

vasodilation and sweating above the set point when

hot. The system triggers shivering and

vasoconstriction below the set point when cold.

Structures Needed for a Negative

Feedback Loop

• Receptor = structure that senses change – Example: temperature sensing nerve cells in skin

• Integrator = control center – Example: nerve cells in brain that receive information

from skin and send signals to muscles and glands to control shivering, blood vessel dilation or constriction, and sweating

• Effector = structures that carry out commands of the control center – skeletal muscles that can shiver to generate heat

– sweat glands that release sweat that can evaporate and cool the body

– smooth muscle around blood vessels that regulate blood flow

Positive Feedback Loops • Positive feedback induces a physiological change that leads

to an even greater change in the same direction (self-amplifying).

• Positive feedback is less common than negative feedback.

• Positive feedback produces rapid changes until the cycle is broken, for example as in childbirth.

High Fever- a potentially harmful positive feedback

• If temperature rises above 108 degrees F

due to bacterial infection, metabolic rate

increases resulting in production of even

more heat.

• Can be fatal at

113 degrees.

Major Unifying Principles

in

Anatomy and Physiology

• cell theory: (originally proposed in 1838) – All life forms are made from one or more cells.

– Cells only arise from pre-existing cells.

– The cell is the smallest form of life.

• homeostasis: maintains stable conditions within the body

• evolution: the diversity of cells and organisms are a result of evolution by means of natural selection

• levels of complexity: a hierarchy of structures from molecules to cells to tissues to organs to organ systems to organisms

• unity of form and function: the concepts of physiology and anatomy can not be separated

Early Anatomical Drawings

Radiography

• X-rays, discovered by William Roentgen in 1885, penetrate soft tissues and darken photographic film.

• Photographic film remains white where it is blocked by dense tissues like bone, teeth, and tumors.

• Radiopaque substances can be injected (angiography) or swallowed (upper GI series) for examination of the internal anatomy of vessels or body cavities.

Sonography

• High-frequency ultrasound waves are focused into the body and the waves that echo back are interpreted as images of internal structures.

• Used to assess soft structures like the gall bladder or as in obstetrics to evaluate fetal age, gender, position and development.

Modern Medical Imaging

Modern Medical Imaging Computed Axial Tomography (CAT

or CT scan)

• Low-intensity X-rays applied to the body are analyzed by a computer to produce an image of a slice of the body about as thin as a coin.

• Used to identify tumors, aneurysms, hemorrhages, kidney stones and much more.

Magnetic Resonance Imaging (MRI)

• Magnetic field aligns hydrogen atoms; radio waves realign the atoms; when radio waves are turned off, the hydrogen atoms give off energy depending on tissue type.

• Computer analysis produces a “slice” type image with even better soft tissue resolution than a CT scan.

Positron Emission Tomography (PET scan)

• Assesses the metabolic state of a tissue by monitoring uptake of an injection of radioactively labeled glucose.

• Labeled glucose emits positrons.

• Colliding positrons and electrons give off gamma rays that are analyzed by computer.

• Image of glucose use at

that moment indicates tissue

metabolism that can be used to

diagnose:

– tissue damage

– activity of brain neurons

– presence and growth rate of tumors

Modern Medical Imaging

These scans show where cocaine interferes with the brain's use of glucose

and the metabolic activity of the brain. The left scan is taken from a normal,

awake person. The red color shows the highest level of glucose use (yellow

represents less use and blue shows the least). The right scan is taken from a

cocaine abuser on cocaine. Note the loss of red compared to the left scan

indicating that the brain on cocaine is not using as much glucose and there

are many areas of the brain that have reduced metabolic activity. The

continued reduction in the neurons' ability to use glucose results in disruption

of many brain functions.

END