Download CHAPTER 1 The Study of Body Function

The Study of Body Function
• Physiology
CHAPTER 1
– 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
1
History of Physiology
Father of Physiology
speculated on fx of
human body
applied physical laws to
study of human body
good health assoc’d
with balance of
humours
Studied cardiovascular
and nervous systems
Aristotle
http://www.awakenyourwarrior.com/pages/philosophercoach.html
Erasistratus
http://www.health.gov.mt/impaedcard/issue/issue1/ipc0012206.jpg
Father of Modern Physiology
observed the milieu interieur
remained remarkably constant
despite constantly changing
environment
1st to study
biology
quantitatively
William Harvey
http://www.nndb.com/people/033/000100730/
Claude Bernard
2
http://www.answers.com/topic/william-harvey?cat=health
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
www.healthsystem.virginia.edu
– 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 Physiology
3
Homeostasis & Feedback Control
coined the term
homeostasis in his book,
The Wisdom of the Body
• 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
Walter Cannon
1871-1945
http://www.harvardsquarelibrary.org/unitarians/cannon_walter.html
How is the maintenance of homeostasis accomplished?
4
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
5
QUESTION
• Is our internal environment absolutely constant?
• Are we always in a state of balance?
6
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
7
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
8
Homeostatic Imbalance
Goiter
Homeostatic imbalance places an
individual at higher risk of disease,
which typically are a result of certain
pathological conditions & aging
MRI, T1 weighted
9
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.
10
tissues (cells with similar functions )
primary tissue
types
Cells
basic
unit of
structure
&
function
organ
primary tissues grouped into
anatomical & functional units
Activities & interactions of tissues
determine the physiology of organ
http://www.dundee.ac.uk/biocentre/SLSBDIV4ebl.htm
simplest structural unit that complex,
multicellular organism can be
divided into retaining functional
characteristics of life
smallest unit of life
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Muscle Tissue
• Specialized for contraction
• Three types of muscle tissue:
Skeletal
– 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
–
Cardiac
– 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
Smooth
– peristalsis (wave-like contractions; lumen)
Which muscle type is termed voluntary muscle?
involuntary muscle?
12
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
13
Epithelial Tissue
Pseudo-stratified
squamous
epithelium
Simple
squamous
epithelium
cover body surfaces & line body cavities
Simple stratified
transitional
classified according to number
of layers & shape
perform a variety of functions - boundary
14
ET forms
boundaries &
thus serves as
a barrier
to be effective
Site of
regulation for
substances
entering/leaving
the body
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.)
http://www.nature.com/nrm/journal/v2/n4/fig_tab/nrm0401_285a_F1.html
Glands
Exocrine duct
16
Exocrine
Glands
classification
• Components:
– duct
– secretory unit
• acinus
• myoepithelial cells
http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Epithelia/Epithel.htm
17
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
18
Adipose tissue
BONE
BLOOD
Dense irregular CT
19
Organs & Organ Systems
architecture of most organs are similar
organ described as a structure composed
of 2 or more tissue types
20
Stem cells
• tissues of an organ are
comprised of differentiated
cells
produce ALL specialized
cells types of body
– highly specialized
capable of forming
unrelated cell types
• 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
http://www.scq.ubc.ca/stem-cell-bioengineering/
• adult stem cells
– multipotent
• form related cell types
21
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 lifesustaining processes
Cells are the basic units of the
society & almost all exhibit
fundamental activities common
to all forms of life.
22
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
Properties of these barriers
determine what moves between
compartments
– who serves as the “barriers”?
• Plasma membranes of cells and
Epithelial cells and blood vessel 23
walls