- 1. Introduction to Physiology
- Physiology is defined as the study of function of living
organism so human physiology attempts to explainhowandwhyhumans
function.
- Physiology is where we figure out how stuff works.
2. Levels of Structure
- In order to understand how something is built and how something
works, you must look at all of its components and analyze them both
individually and together.
- In doing these collective and separate analyses, you must
examine things at multiple structural levels, i.e., one must break
them down from large to small this is called reductionism
- An organism (such as a human being) may be broken down as
illustrated on the left.
Organelle Cell Tissue Organ Organ System Organism 3. Levels of
Structure
- The basic unit of life is the cell.
- All living organisms are composed of one or more cells.
- The human body contains about 100 trillion cells.
- There are about 200 different types of cells in the human
body.
- The different types of cells have different features but for
the most part, all cells are made up of organelles and various
macromolecules (e.g., proteins, lipids, carbohydrates and nucleic
acids).
- Organelles themselves are made of these macromolecules and
macromolecules are polymers of smaller molecules which consist of
atoms of various chemical elements.
4. A Prototypical Cell 5. Important Organelles
- Plasma Membrane-> Separates the cell exterior from the cell
interior (cytoplasm).
- Nucleus-> Membrane bound structure that contains
deoxyribonucleic acid (DNA) which is the set of instructions for
the synthesis of all the bodys proteins.
- Mitochondria -> Structure bound by a double membrane and the
site at which the energy stored in sugars and other organic
molecules is transferred to ATP, the chemical which acts as the
currency for energy in the cell.
- Ribosomes -> Not bound by a membrane. Sites of protein
synthesis.May be free floating in the cytoplasm or bound to the
endoplasmic reticulum.
6. Important Organelles
- Rough Endoplasmic Reticulum -> Membranous set of tubes with
ribosomes studded along its surface.Site of the synthesis of
proteins that are destined to be exported from the cell.
- Smooth Endoplasmic Reticulum -> ER w/o the attached
ribosomes.Site of cellular lipid synthesis, among other
things.
- Golgi Apparatus -> Membrane bound organelle responsible for
determining the direction of proteins synthesized in the rough
ER.
- Lysosomes -> Membrane bound organelle that houses digestive
enzymes that can be used to break down ingested toxins or worn out
cell parts.
7. More Levels of Structure
- Similar cells and cell products come together to formtissues
.
- A structure made of 2 or more tissue types that perform a
particular function is anorgan .
- A group of organs with a unique collective function is anorgan
system .
8. 9. Integumentary System
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- - Skin, hair, sweat and oil glands
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- Forms the external body covering
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- Protects deeper tissues from injury
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- Involved in vitamin D synthesis
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- Prevents desiccation, heat loss, and pathogen entry
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- Site of pain and pressure receptors
10. Skeletal System
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- The 206 bones of the human body
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- Protects and supports body organs
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- Provides a framework that muscles can use to create
movement
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- Hemopoiesis (synthesis of blood cells)
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- Bone contains 99% of the bodys store of what mineral?
11. Muscular System
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- The 600+ muscles of the body
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- Thermogenesis (generation of heat)
12. Nervous System
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- Brain, spinal cord, and peripheral nerves
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- Fast-acting control system of the body
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- Monitoring of the internal and external environment and
responding (when necessary) by initiating muscular or glandular
activity
13. Endocrine System
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- Pituitary, Thyroid, Thymus, Pineal, Parathyroid, Adrenal,
Pancreas, Small Intestine, Stomach, Testes, Ovaries, Kidneys,
Heart
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- Long-term control system of the body
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- Regulates growth, reproduction, and nutrient use among other
things.
14. Cardiovascular System
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- Heart, Blood vessels (arteries, veins, and capillaries)
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- The heart pumps blood thru the blood vessels.
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- Blood provides the transport medium for nutrients (glucose,
amino acids, lipids), gases (O 2 , CO 2 ), wastes (urea,
creatinine), signaling molecules (hormones), and heat.
15. Lymphatic/ImmuneSystem
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- Lymphatic vessels, Lymph nodes, Spleen, Thymus, Red bone
marrow
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- Attacking and resisting foreign invaders (pathogens i.e.,
disease-causing organisms)
16. Respiratory System
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- Nasal cavity, pharynx, trachea, bronchi, lungs
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- Constantly supply the blood with O 2 , and remove CO 2
17. Digestive System
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- Oral cavity, esophagus, stomach, small intestine, large
intestine, rectum, salivary glands, pancreas, liver,
gallbladder
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- Ingestion and subsequent breakdown of food into absorbable
units that will enter the blood for distribution to the bodys
cells
18. Urinary System
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- Kidneys, ureters, urinary bladder,
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- Removal of nitrogenous wastes
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- Regulation of bodys levels of water, electrolytes, and
acidity
19. Reproductive System
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- Testes, scrotum, epididymis, vas deferens, urethra, prostate
gland, seminal vesicles, penis
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- Ovary, uterine tube, uterus, cervix, vagina, mammary
glands
20. Stayin Alive
- Your body has about 100 trillion cells in it.
- For your life toNOTend abruptly, these cells need to have the
correct amount of:
-
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- Ions (sodium, calcium, etc.)
21. The Cells Environment
- In order to keep the right amount of stuff in the cell, weve
got to make sure that all the fluid surrounding our cells (i.e.,
theextracellular fluid ) has the right assortment of nutrients,
ions, etc.
- We keep both our cells and the fluid surrounding our cells in a
dynamically stable environment via a process
calledHOMEOSTASIS.
22. Homeostasis
- Defined as the bodys ability to maintain stable internal
conditions in spite of the changing external conditions.
- Our body needs to have the right amount of stuff (i.e.,
temperature, blood glucose, pH etc.)at all times in order to
function properly.
- First, lets refer to all this stuff as different variables
23. Lets use a thermostat as an example
- In order to keep the temperature in my house at the right
level, the thermostat must first measure the current temperature in
the house.
- After the thermostat measures the temperature, it compares the
current value to a preset standard value.
-
- If there is no difference then theres nothing to do.
-
- However, if its too hot or too cold, the thermostat has to send
a signal to the furnace or air conditioner to change the
temperature of the house so that it equals the standard value.
24. Lets clarify some stuff.
- In the previous example we had a:
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- Measuring implementthermostat
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- Control centeralso the thermostat
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- A preset or standard value for the variable
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- Effectorsthe air conditioner and furnace
- Similar situations arise in the human body where there are lots
of variables that we want to maintain at certain precise
levels
25. Blood Pressure
- BP is avariablethat weve got to maintain at a certain
level
- We havesensory receptorsthat measure the BP in the body.Theyre
located in the aorta (the big blood vessel coming out of the heart)
and in the carotid arteries (the large vessels that bring blood to
the brain).
- These pressure receptors measure BP and then send the info (we
can call thisinput ) to acontrol centerin the brain the particular
BP control center is in themedulla oblongataof the brain
26. Blood Pressure
- We call the connection btwn the receptor and the control center
theafferent pathway .
- In the control center, the input BP is compared with a set
value.
- If there is a difference between the current BP value and the
reference BP value then weve got an error.
- And weve got to fix that error!
27. Blood Pressure
- The control center will signaleffector organs such as the heart
in this case to alter their activity.This process is calledoutput
.
- The connection between the control center and the effector
organ is called theefferent pathway.
28. Blood Pressure
- Suppose the current BP is too high.
- The effector must act in a way to decrease it so the medulla
oblongata (the control center) would signal the heart to decrease
the force and rate of its contractions;this would decrease BP.
- Notice that the original stimulus was anIncreasein BP and the
bodys response was to act so as toDecreaseBP.
- The stimulus is opposite the response!
29. Negative Feedback
- The movement of a variable in one direction causes the body to
enact processes that cause the variable to move in the opposite
direction (so as to return the value to the correct level) we call
itnegative feedback
30. Increased BP Sensed by pressure receptors in aortic arch and
carotid sinus Input sent via afferent pathwayto medulla
oblongataCurrent BP compared with set point and error signal
generated Output sent along efferent pathway to heart and blood
vessels Heart rate & force of contractiondecrease Blood vessel
diameter increases BP DECREASES 31. Why isNegative Feedbackso
common in the body?
- Every time a variable starts changing too much, weve got to
bring it back to normal.Weve got to counteract its change.
- Other examples you will encounter:
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- Maintenance of blood [Ca 2+ ], blood [Glucose], blood pH, and
many others
32. When does a negative feedback process end?
- A negative feedback process begins when a particular variable
leaves its homeostatic range.
- The process ends when that variable is back within its normal
range.
- Negative feedback processes (or loops) are
self-terminating.
33. Homeostasis is Important!
- Most of the physiological processes that occur in your body are
designed to maintain homeostasis.
34. 35. 36. What this means is that the homeostatic variables
are NOT kept rigidly fixed upon a single value.They are kept within
a certain range, and when they exit that range thats when negative
feedback loops turn on to bring them back. 37. What about Positive
Feedback?
- Positive feedback occurs when the responsemagnifiesthe stimulus
that produced it.
- In other words, a variable is altered and then the bodys
response alters that variable even moreinthe same direction .
38. PositiveFeedback in Blood Clotting 39. Dangerous Positive
Feedback Rise in body temperature Increase in body metabolism
Increase in bodyheat production 40. What stops a positive feedback
loop? 41. Water, water everywhere!
- About 60% of the human body is water
- 2/3 of this water is found within your cells so we refer to it
asintracellular fluid (ICF)
- The other 1/3 is outside your cells so we call itextracellular
fluid (ECF)
- The 2 main types of ECF are:
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- The fluid that surrounds the cells thetissue
fluidorinterstitial fluid
- Minor types of ECF include cerebrospinal fluid and intraocular
fluid