1. 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
How you work is all directed by the molecules in the organism
Everything is all related to each other
Function and Integration
Cellular level and tissue organization too
MISCONCEPTION that all is known (we know some, but there is A LOT still left to learn)

2. History of Physiology Father of Physiology
applied physical laws to study of human body
Studied cardiovascular and nervous systems
speculated on fx of human body
good health assoc’d with balance of humours
Aristotle
Erasistratus
Father of Modern Physiology
observed the milieu interieur remained remarkably constant despite constantly changing environment
Aristotle
Claim to fame: he stated that an individual who is in good health (function properly) is associated with balances of humours (which are blood (spring), phlegm, yellow bile (summer) and black bile)
Erasistratus
Greek anatomist and royal physician
He applied the physical laws of that time to study of human body, so made it more scientific rather than just an observation
Found info on 2 organ systems and found:
Nervous: Was able to distinguish between motor and sensory for the nervous system, and knew they were linked to the brain
Cardio: looked at heart rhythms (arthymologist) and able to distinguish arteries and veins
William Harvey
English Physician
Collected data and numbers
Looked at not just that we have vessels that carry blood away from heart, but that we have arteries, capillaries and veins that have specific functions.
Claude Bernard
Homeostasis
1st to study biology quantitatively
William Harvey
Claude Bernard

3. 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 Physiology
Actually a British man
26 year old practicing physician
Was made an offer of 1500 year salary, room and board and supplies for his students.
Took the job because of the paycheck which allowed him to marry the young lady he was interested in.
Great talker, made stories of everything that was there so you could follow one event to the next

4. 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
Human body in a state of EQUILIBRIUM
Actually a dynamic process that requires us to have information of what is going on
Feedback mechanisms along with regulation
Walter Cannon
How is the maintenance of homeostasis accomplished?

5. 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
HOW is the maintenance of homeostasis accomplished?
By control mechanisms such as FEEDBACK
Variable: event/factor that is being regulated
Has a set point, which is the normal range of values, that it should fall within
Receptor: senses the variable that we are looking at
If it senses an increase it sends info to a CONTROL/INTEGRATION CENTER (flows alongs afferent pathways, so TOWARDS the central nervous system)
Control or Integration Center: decides what to do and sends info through a efferent pathway
Effector: element that brings the variable back to homeostatic range, so back to it’s set point.
Why referred to as a “loop”?
Why referred to as a “loop”?
“loop” emphasizes feedback mechanism because it is a continuous cycle to maintain homeostasis

6. QUESTION Is our internal environment absolutely constant?
Are we always in a state of balance?
Absolutely constant? NO
We have a dynamic balance or consistency
Not just one value but conditioned around a set point
Always in a state of balance?
Not true yes or no 6

7. 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
Reverse control: if we increase it we are going to decrease it, and vice versa
Output of the system causes it to go into the opposite direction
Continuous because sometimes we overshoot and have to go into another direction
EX: glucose levels
Have an event that causes a rise in blood/glucose level
Respond by stimulate cells to release insulin to get blood-glucose level back to set point
ANTAGONISTIC EFFECTORS
effectors have antagonistic (opposite) actions
allows for finer degree of control

8. 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
Output is ALWAYS increased
Example?
Blood clotting, want to stop leakage of blood by initiating a sequence of events that forms a blood clot to stop the leakage
Are parameters that help limit blood clotting
Childbirth, can’t stop it.
Lactation, release of milk from breast.

9. Homeostatic Imbalance
Goiter
 Breakdown of some element of homeostasis
Goiter – enlarged thyroid gland
Homeostatic imbalance places an individual at higher risk of disease, which typically are a result of certain pathological conditions & aging
MRI, T1 weighted

10. 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.
By standing up, causes blood pressure to fall which causes the heart rate to increase.
Have receptors in vascular system that picks up on changes of the system which causes a response to get you back to homeostasis.

11. tissues (cells with similar functions )
organ
primary tissues grouped into anatomical & functional units
tissues (cells with similar functions )
primary tissue types
Activities & interactions of tissues determine the physiology of organ
Cells
basic unit of structure & function
4 Primary Tissue Types
Epithelial
Connective
Muscle
Nervous
The activities and actions of the tissues determine the physiology of tissues d
simplest structural unit that complex, multicellular organism can be divided into retaining functional characteristics of life
smallest unit of life

12. Which muscle type is termed voluntary muscle? involuntary muscle?
Muscle Tissue
Skeletal
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)
Cardiac
Involved with MOVEMENT
Skeletal – cells are controlled individually or as groups. So if you activate a muscle like your bicep, you don’t necessarily activate all of the fibers there.
Voluntary? – skeletal: because you have control
Involuntary? – cardiac and smooth; don’t have to tell your heart to beat.
Smooth
Which muscle type is termed voluntary muscle? involuntary muscle?

13. Nervous Tissue Consists of: neurons supporting cells
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
Highly modified cells for communication. Conduct a nerve impulse (action potential: an electrical event)
Support cells (non conducting cells): cannot generate nerve impulse may be able to communicate in other ways
More neuroglial than neurons
Neurons cannot divide (as of now) referred to amiotic

14. Epithelial Tissue cover body surfaces & line body cavities
Pseudo-stratified squamous epithelium
Simple squamous epithelium
cover body surfaces & line body cavities
Ex: skin, respiratory tract, urinary..
Serves as a boundary. Police of what can enter and exit tissues and organs
Classified according to the number of layers
One (simple) more than one (stratified)
Flat (squamous), cube (cuboidal) and rectangular (columnar)
Always classify TOP layer
Simple stratified
classified according to number of layers & shape
transitional
perform a variety of functions - boundary

15. ET forms boundaries & thus serves as a barrier to be effective
Site of regulation for substances entering/leaving the body
Boundaries are not exclusive to epithelial tissues
Find junctional complexes: usually found on apical (top) surface and has a tight junction, adherens junction, and desmosome.
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.)

16. Glands Exocrine duct Predominantly an epithelial tissue type
Retain port of cells that forms a duct
Exocrine gland: gland that makes a product that secretes it to lumen, has a duct that goes to surface
Epithelial cord degenerates and you end up with clusters of epithelial cells forming an endocrine gland: secretion does not go into duct (DUCTLESS glands = Endocrine gland)
Exocrine duct

17. Exocrine Glands Components: duct secretory unit acinus
classification
Components:
duct
secretory unit
acinus
myoepithelial cells
Duct: helps move the product to be expressed on the surface – ALWAYS simple cuboidal epithelial
Secretory unit:
Acinus: actually make and secrete a product
Myoepithelial cells: lie around the outside of the secretory portion, epithelial cells that have contractile proteins that squeeze secretory portion to help move it to be expressed on the surface of the duct.
Simple tubular: one duct and tubular secretory portion
Simple acinar: one duct and circle secretory portion
Compound: more than one duct

18. Connective Tissue Characterized by: Categorized into
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
PANTYHOSE: binds and supports
Wide diversity of tissues that fall underneath the category
Fiber types: collagen, reticular and elastic
Bone compared to areolar CT: both have ground substances, fibers and cell types. But how it all comes together is different
Liquid CT: BLOOD
areolar CT

19. Adipose tissue BONE Dense irregular CT BLOOD
Bone and Cartilage = Supportive Connective Tissue
Liquid: Blood
CT Proper: (two categories: loose and dense)
Dense irregular CT
BLOOD

20. Organs & Organ Systems architecture of most organs are similar
Most organs have all four tissue types.
Integument organ: Epithelial on top, CT, nerve tissue (innervated), muscle tissue (arrector pili muscle)
11 Organ systems in human body.
Not circulatory: USE CARDIOVASCULAR, lymphatic vessels are not part of cardiovascular system
Not Immune: USE LYMPHATIC SYSTEM, add lymphatic vessels to here.
architecture of most organs are similar
organ described as a structure composed of 2 or more tissue types

21. 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
produce ALL specialized cells types of body
capable of forming unrelated cell types
Stem cells allow for possibilities to treat diseases and aging
Now can be specialized for certain functions.
Can give diabetic pancreatic islets instead of insulin injections
Stem cells come from two different sources (adult and embryonic)
Sperm and egg fuse together become diploid and divides to form cleavage stage embryos (called totipotent stem cells)
Totipotent – can produce all types of stem cells in the body. EVERYTHING, can make four identical individuals
As you go through cleavage stage development, see embryo start to take the form of a blastocyst (starting to differentiate)
Pluripotent – capable of forming UNRELATED cell types, limited, can’t make anything we want
Then form trilaminar embryo with three germ layers that gives rise to 4 primary tissue types
Multipotent stem cells- forms related cell types, further restricted. There are instances that you can take neuroglial cells and can make them into a neuron.

22. 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
Hiccups in the system are seen in TISSUES
Everything that is dysfunctional ^^
Cells are the basic units of the society & almost all exhibit fundamental activities common to all forms of life.

23. 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
We are aqueous critters, so mainly composed of water. **
Primary solvent is WATER
Why is ECF considered more homogenous than ICF fluid? ** ASKED/SITUATION ON TEST.
Have a wide variety of different cell types that are gonna be much more individualistic than the ECF fluid compartment.
Interstitial fluid and plasma can exchange with each other so they tend to be more similar to each other in their composition
Properties of these barriers determine what moves between compartments