1 the study of body function chapter 1 physiology –fundamentally represents the study of how...
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The Study of Body Function CHAPTER 1• Physiology
– fundamentally represents the study of how living organisms work
• Molecules cell tissue organ organ system
• how organisms accomplish tasks essential for life
– function & integration• body parts work together at various
levels of organization (cellular and tissue organization) & whole organism
– mechanisms & their effects• sequence of events
– Parts of larger stories (workings of human organism itself)
– Nothing works in isolation– Integrated entity
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History of Physiology
http://www.awakenyourwarrior.com/pages/philosophercoach.htmlhttp://www.health.gov.mt/impaedcard/issue/issue1/ipc0012206.jpg
http://www.answers.com/topic/william-harvey?cat=health
http://www.nndb.com/people/033/000100730/
AristotleErasistratus
William Harvey Claude Bernard
speculated on fx of human body
good health assoc’d with balance of
humours
Father of Physiology
applied physical laws to study of human body
Studied cardiovascular and nervous systems
1st to study biology
quantitatively
Father of Modern Physiology
observed the milieu interieur remained remarkably constant despite constantly changing
environment
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Father of American Physiology• Early 19th century in US
– physiology treated as an aspect of theory & practice of physics
– 1824, Thomas Jefferson, Univ of VA• Robley Dunglison
– English physician– Professor of Anatomy,
Physiology, Surgery, Materia Medica, Pharmacy & History of Medicine, 1825
– teaching was an explanation of “successive theories”
– published several books & articles
» Human Physiologywww.healthsystem.virginia.edu
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Homeostasis & Feedback Control
• Homeostasis– maintenance of a relatively stable
internal environment• basically represented by the state
of equilibrium of the body’s internal environment by dynamic processes of feedback and regulation
– reason for regulatory mechanisms– not an easy accomplishment
• every organ system is involved with the maintenance and necessitates integrated function
– major foundation for medical diagnostic procedures
http://www.harvardsquarelibrary.org/unitarians/cannon_walter.html
Walter Cannon
1871-1945
coined the term homeostasis in his book, The Wisdom of the Body
How is the maintenance of homeostasis accomplished?
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Feedback mechanism
• Set point– normal range of
measurements & values– factor or event being
regulated is called the variable
• Control systems that promote homeostasis are characterized by 3 interdependent components:– receptor– control or integration center– effector
Why referred to as a “loop”?
“loop” emphasizes feedback mechanism because it is a continuous cycle to maintain homeostasis
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QUESTION
• Is our internal environment absolutely constant?
• Are we always in a state of balance?
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Negative Feedback Mechanism
• Most common homeostatic control mechanism
• Reverse direction control mechanism– works by output of system
causes a decrease or shuts off the original stimulus
– continuous, ongoing processes
• All negative feedback mechanisms have the same goal Preventing sudden severe
changes in the body
ANTAGONISTIC EFFECTORS
effectors have antagonistic (opposite) actions
allows for finer degree of control
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Positive Feedback Mechanism
• Same direction control system– enhance or exaggerate the
response over the original stimulus, thus the output is increased
• Usually control episodic or infrequent events that do not require continuous adjustments– examples?
• Limited – Proceed with very little control– Human body doesn’t use PFM alot
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MRI, T1 weighted
Goiter
Homeostatic Imbalance
Homeostatic imbalance places an individual at higher risk of disease,
which typically are a result of certain pathological conditions & aging
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Homeostatic Regulation
• Regulatory mechanisms for homeostasis– intrinsic
• within organ
– extrinsic• “outside” organ
– nervous & endocrine systems» innervation by nerve fibers» hormones
Advantages/Disadvantages?• Intrinsic mechanisms need to
focus the effect– More specific for organ
Can also be a disadvantage because have mechanisms that automatically turn on
– Bleeding out, but increase heart rate because of decreased heart rate so causes you to bleed out MORE.
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http://www.dundee.ac.uk/biocentre/SLSBDIV4ebl.htm
Cells basic unit of
structure &
function
simplest structural unit that complex, multicellular organism can be
divided into retaining functional characteristics of life
smallest unit of life
tissues (cells with similar functions )
primary tissue types
organ primary tissues grouped into anatomical & functional units
Activities & interactions of tissues determine the physiology of organ
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Muscle Tissue• Specialized for contraction• Three types of muscle tissue:
– skeletal - SkM• generally attached to bone via tendon;
exceptions (tongue & diaphragm)– myofibers
• 4th wk of development, myoblasts• arranged in bundles (variation in strength)• graded contractions
– controlled individually– cardiac - CM
• wall of heart, myocardial cells• form continuous sheet• intercalated discs
– couple cells mechanically & electrically– smooth - SmM
• nonstriated, fusiform (spindled) shape• forms sheet, circularly &/or longitudinally
arranged– peristalsis (wave-like contractions; lumen)
Which muscle type is termed voluntary muscle? involuntary muscle?
Skeletal
Cardiac
Smooth
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Nervous Tissue
• Consists of:– neurons
• highly specialized to generate & conduct nerve impulses
– an electrical event• constructed of cell body
(soma), dendrites & axon– each has structural
attributes & function– supporting cells
• also known as neuroglial, or glial cells
• nonconducting cells that support, insulate & protect neuron
• more abundant• limited ability to divide
http://www.mhhe.com/biosci/ap/histology_mh/neurons.jpg
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Epithelial Tissue
cover body surfaces & line body cavities
classified according to number of layers & shape
perform a variety of functions - boundary
Simple squamous epithelium
Simple stratified
transitional
Pseudo-stratified squamous epithelium
http://www.nature.com/nrm/journal/v2/n4/fig_tab/nrm0401_285a_F1.html
a | Schematic drawing of intestinal epithelial cells. The junctional complex, which is located at the most apical region of lateral membranes, is circled. b | Electron micrograph of the junctional complex in mouse intestinal epithelial cells. The tight junction is circled.
(Mv, microvilli; TJ, tight junction; AJ, adherens junction; DS, desmosome.)
ET forms boundaries &
thus serves as a barrier
to be effective
Site of regulation for substances
entering/leaving the body
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Glands
Exocrine duct
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• Components:– duct– secretory unit
• acinus• myoepithelial cells
Exocrine Glands
http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Epithelia/Epithel.htm
classification
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Connective Tissue
• Characterized by:– large amt of extracellular
material in the spaces between connective tissue cells
• extracellular matrix, or ECM
– fibers & ground substance
– vary in composition & arrangement between tissue types
– comprised of varied cell types
• Categorized into– CT proper– supportive CT– liquid CT
areolar CT
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Adipose tissue
BLOOD
BONE
Dense irregular CT
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Organs & Organ Systems
architecture of most organs are similar
organ described as a structure composed of 2 or more tissue types
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Stem cells• tissues of an organ are
comprised of differentiated cells– highly specialized
• differentiation begins during embryonic development– zygote/embryo
• totipotent stem cells– blastocyst
• pluripotent stem cells– trilaminar embryo
• ectoderm, mesoderm & endoderm
– give rise to 4 primary tissue types
• adult stem cells– multipotent
• form related cell types
http://www.scq.ubc.ca/stem-cell-bioengineering/
produce ALL specialized cells types
of body
capable of forming unrelated cell types
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Hierarchical system to structural organization
levels of cellular organization
human body is a complex society of differentiated cells, which combine structurally & functionally to carry out life-
sustaining processes
Cells are the basic units of the society & almost all exhibit
fundamental activities common to all forms of life.
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Body Fluid Compartments
• Extracellular fluid - ECF– fluid in blood & spaces that
surround cells• Plasma – found in blood• interstitial, or tissue fluid –
found between cells• Intracellular fluid – ICF
– fluid within cells• Mainly comprised of water
– aqueous compartments• Composition varies between
compartments– ECF considered more
“homogenous” than ICF• What organ plays impt role
in ECF composition/volume?– KIDNEYS
• Compartmentalization– who serves as the “barriers”?
• Plasma membranes of cells and Epithelial cells and blood vessel walls
Properties of these barriers determine what moves between
compartments