Human Physiology

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Human Physiology
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Human Physiology

• Structure and function of the human body!

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STRUCTURE
HOW IT IS BUILT
FUNCTION
WHAT IT DOES
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• Pathophysiology
• - How physiological processes are altered in
  disease or injury.
• Comparative physiology
• - Other animals.

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• Symbols and such!
• i.e. that is, id est
• e.g. for example, exempli gratia
• . Therefore
• Then, leads to
• -l inhibits

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• Same as
• ? Different from
• ? Something that can flow either way
• ? Increase
• Decrease
• Change
• NB Nota Bene (note well )

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Green titles

• Blue important!
• Pink examples, extra info

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• Lecture map
• Process of science
• Homeostasis, positive and negative
• feedback
• - Tissues

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• How do we know all this?

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The Scientific Method

• Make OBSERVATION- notice the world around us!
• Pose QUESTION
• Propose HYPOTHESIS
• - Potential explanation for observation/answer to
  question
• - Must lead to testable predictions
• Design execute EXPERIMENTS
• - Collect data
• Draw CONCLUSION (yes or no to hypothesis)
• Start over with new questions!!!

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CREATIVITY AND CHANCE

• Alexander Fleming, 1920
• - Culture dish of bacteria became contaminated
  with mold-GOOD/BAD LUCK
• - NOTICED no bacteria grew near the mold.
• - THOUGHT OUTSIDE THE PETRI DISH
• - Hypothesis this mold inhibits bacterial
  growth.
• - Data fluid extracted from mold inhibited
  bacterial growth.
• - Conclusion yes!
• Later, the fluid was isolated as penicillin.
• CHANGED THE WORLD (gave you 30 extra years in
  YOUR life!)

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CAUSE -gt EFFECT
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Science

• Looks for the truth!
• Investigates reality.
• Descriptive
• Cause-gt effect
• Predictive!
• Necessary/sufficient
• Logic and intuition

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• What is enough proof?!

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• Redi and maggots

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PROOF

• Reproducible!!!
• Proper controls!!!

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Rodolfo and the mystery yeast
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Rodolfo and the mystery yeast
a tale of good controls!!!
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Do Expt look for effect (or no effect), caused
(or not) by the variable you are testing. NB
data results facts CONTROLS show that your
result is specific to the cause tested, and is
not due to other variables. C- Negative
control shows that you can get NO effect.
Especially good when experimental variable did
yield an effect. C Positive control
shows that you CAN get an effect. Especially
good when experimental variable did not yield an
effect.
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Theories in BIOLOGY

• Theory the solid truth as best we know it now!
  Something that has been tested and proven (so
  far)!

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Types of data

• Qualitative - observations
• Quantitative - measurements

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Some tools

• Double blind expts.
• Statistics!

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Process

• Labs groups
• Collaboration!
• Literature.
• Oral Presentations (posters, talks).
• Peer reviewed journals.
• Funding National Institutes of Health (NIH).
• Biotech and pharmaceutical companies.

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Types of expts.

• in vivo in organisms
• in vitro in glass

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Development of New Drugs

• First cellular models, i.e. in vitro.
• Then animal models, i.e. in vivo.

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Development of New Drugs

• CLINICAL TRIALS
• Phase I
• Drug tested on healthy human volunteers.
• Determine safety
• Phase II
• Drug tested on target population, for efficacy.
• Phase III
• Large number of participants, both safety and
  efficacy.
• If passes trials, goes to FDA for
  approval!!!
• Phase IV
• Test for other uses of the drug.

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• Clinical trials
• - Very few womyn and ethnic minorities in
  clinical trials until the past few years.
• - Informed consent.
• Tuskegee syphillis study.
• Vioxx companies as clients of FDA

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• HOMEOSTASIS

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Homeostasis

• What?
• Homeostasis maintaining constancy of internal
  environment.
• aka Dynamic constancy!!!
• - Within a certain normal set point/range.
• - See table 1.2!
• A live system lots of constant changes to stay
  the same!

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Homeostasis
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Homeostasis

• Set point desired homeostatic value
• e.g. 37 o C for human body temperature!

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Homeostasis

• Homeostasis means staying the same.
• Organized systems disintegrate.
• Preventing disintegration requires energy (ATP).
• Ex Sweating when hot shivering when cold.

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Homeostasis

• How?
• Homeostasis is maintained mostly by negative
  feedback LOOPS.

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Homeostasis

• Regulatory mechanisms
• - Intrinsic
• Within organ being regulated, through various
  proteins and other molecules.
• - Extrinsic
• Outside of organ, through nervous or hormonal
  systems.

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• Negative Feedback Loops

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Negative Feedback Loops

• Negative Feedback loops defend the set point
• by producing a change in the OPPOSITE direction
  to the change.

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Roles in a negative feedback loop

• Sensor or sensors
• Detects deviation from set point.
• e.g. thermoreceptor cells in skin
• Integrating center or centers
• Decides the response.
• e.g. neural circuits
• Effector or effectors
• Produces the response.
• e.g. sweat glands

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Negative Feedback Loops
effector

• effector

effector
Sensors are triggered
temp.
set point
time
Sensors are triggered
effector
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Negative feedback

• Sensitivity the point at which a deviation from
  the set point is detected by the sensor as a
  change!
• e.g.
• Set point 72o F
• Sensitivity .5o F
• Normal range 72o /- .5o F

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Negative Feedback Loops
effector

• effector

effector
temp.
sensitivity
range
sensitivity
set point
time
effector
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Homeostasis

• Note in a real system, rather than seeing a set
  point, we actually see more of a homeostatic
  range (due to sensitivity of the sensors, the
  effectiveness of the effectors, and other factors
  in the system).

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Negative Feedback
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Antagonistic effectors

• Antagonistic effectors
• Effectors which operate on the same system, but
  have antagonistic (i.e. opposite) effects.
• a system with antagonistic effectors usually
  maintains homeostasis more consistently than one
  without them. Why? See lab!
• Push-pull
• - Ex. shower temperature room temp. with a
  heater and AC unit hot plate in lab.

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Negative feedback

• Inhibition of negative feedback
• effector shuts off when set point is
  re-achieved (so as not to overshoot the set
  point!).
• e.g. endocrine system working to maintain
  homeostatic hormone levels biochemical pathways
  working to maintain homeostatic levels of the end
  product

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• Positive feedback cascades

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Positive Feedback

• - Action of effectors amplifies the changes.
• - Is in same direction as change.
• - Positive feedback cascades (not loops!).
• - Can be part of overall negative feedback!
• Ex. blood clotting, induction of labor.

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Structure of our body

• What types of tissues constitute our bodies?

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Primary Tissues

• The body composed of 4 different primary tissues
• - Nervous, epithelial, muscle, connective.
• Organs
• - Composed of at least two primary tissues.
• Systems
• - Organs that are located in different regions of
  the body and perform related functions.

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Nervous Tissue

• Neurons (nerve cells)
• Specialized for action potential conduction.
• Dendrites
• - Receive input.
• Cell body
• - Nucleus.
• - Metabolic center.
• - Integrate inputs.
• Axon
• - Conducts nerve impulses output.

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Nervous Tissue

• Glial cells
• - Provide support andare stem cells?!

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Epithelial Tissue

• Provides barrier and regulates transport between
  external and internal environments.
• Types Simple
• - One cell layer thick.
• - Transport.
• Stratified
• - Many layers of cells.
• - Protection.

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Epithelial Tissue

• Stratified can be
• keratinized, e.g. epidermis (tougher!).
• nonkeratized

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Epithelial Tissue

• Shapes squamous, columnar, cuboidal.

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Epithelial Tissue
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Epithelial Tissue

• - Many junctions between cells
• - Apical/basolateral specialization of pm.
• - Basement mb.
• - High rate of turnover.
• - Form glands.

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Exocrine Glands

• Epithelial cells.
• - Secretions are released through ducts.
• - Simple tubes or acini.
• E.g.
• - Tear glands.
• - Sweat glands.

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Endocrine Glands

• Epithelial cells.
• - Lack ducts.
• - Secrete hormones into capillaries/lymphatic
  system.
• - May be discrete organs.

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Muscle Tissues

• Specialized for contraction.
• 3 types of muscle tissue
• - Skeletal.
• - Cardiac.
• Smooth.
• Skeletal and cardiac muscle have similar
  mechanisms of contraction.

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Striated muscle (skeletal)
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Skeletal Muscles

• Striated.
• Voluntary.
• Attached to bones by tendons.
• Fibers arranged in parallel.
• Produce graded contractions.

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Cardiac Muscles

• Striated.
• Found only in the heart.
• Co-ordinated contractions.
• Intercalated discs couple cells together.

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Smooth Muscles

• Not striated.
• Automatic.
• Internal organs.

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Connective Tissue

• Large amounts of extracellular material in the
  spaces between connective tissue cells.
• 4 types of connective tissue
• - Connective tissue proper.
• - Cartilage.
• - Bone.
• - Blood.

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Connective Tissue Proper

• Loose connective tissue
• Scattered collagen and tissue fluid.
• - Dermis of skin.
• - Adipose tissue
• Dense fibrous connective tissue
• - Regularly arranged.
• - Collagen oriented in same direction.
• E.g. tendons.
• - Irregularly arranged.
• - Resists forces applied in many directions.
• E.g. sheaths.

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Connective Tissue
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Connective Tissue
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Connective Tissue

• Cartilage
• Chondrocytes.
• - Elastic, supportive, protective.
• - Joints.

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Connective Tissue

• Bone
• - Osteoblasts form bone
• - Osteocytes are trapped (maintenance)
• - Osteoclasts resorb bone
• Blood
• - WBC, RBC, plasma.

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Connective Tissue
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Connective Tissue
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Body-Fluid Compartments

• Intracellular compartment
• Fluid inside cells. (2/3 of body H20!)
• Extracellular compartment
• - Blood plasma.
• - Interstitial fluid.
• Note 65-75 of total body weight is H20!

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Organ systems
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Organ skin!
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Organ skin!
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Organ skin!