physiology 3 dr. anne valle office: sci-265 email: [email protected]

Physiology 3

Dr. Anne ValleOffice: SCI-265

Email: [email protected]

Chapter 1 ObjectivesIntroduction to basic concepts of physiology

• Scientific Method

• Levels of Organization

• Homeostasis

- Feedback loops

Homework: Read Fox Chapter 1

Human Physiology

• Physiology (physo = nature; logos = study): study of how the body works to maintain life- cell tissue organ organ system organism

• Pathophysiology: how physiological processes are altered in disease or injury

• Arist (384 – 322 BCE) – speculated on body function

• Erasistratus (304 -~250 BCE) considered the father of physiology - applied physical laws to the study of human function

• Galen (130 -201 A.D.) - believed the working body was not understandable without knowledge of its structure

• William Harvey (1578–1657)-blood pumped in a closed system of vessels

• Claude Bernard (1813 – 1878) – internal environment remains constant despite everchanging external environment

• Walter Cannon (1871 – 1945) – coined the term ‘homeostasis’

History of Physiology

Scientific Method

• Discovery-based science - making observations and measurements regarding the natural world

• Hypothesis-based science (aka the scientific method) -conduct and analyze experiments to test a hypothesis1. develop a testable hypothesis to answer a scientific question based on natural observations 2. design and conduct experiments in an objective, unbiased, repeatable manner3. analyze data and form conclusions that either support or deny the hypothesis

Discovery-based Science

• Is there a difference in resting heart rate between people who exercise and those who don’t?- Measure heart rate in people who exercise- Measure heart rate in people who don’t exercise- Analyze data and from conclusions

• Study establishes a correlation (relationship) between exercise and heart rate but not causation

Hypothesis-based Science

• Hypothesis - a tentative answer to a question- an explanation on trial

Scientific MethodHypothesis-based science:

• Form hypothesis: question to be answeredPeople who exercise regularly have lower resting heart rate

• Treatment group: individuals subject to the test condition Randomly choose a group who must exercise (experimental group)

• Control group: similar individuals not subjected to treatmentRandomly choose a group that is not allowed to exercise (control)

• Dependent variable: outcome you are measuringHeart rate

• Unbiased: double-blind (placebo) study Random groups

• Analyze data and form conclusions

“Controlled experiment” establishes causation

Scientific Method

• Introduce yourself to your neighbor

• With your neighbor design a controlled experiment for the hypothesis that using echinacea speeds recovery from a cold

• Treatment?

• Control?

• Dependent variable?

• How would you avoid bias?

Scientific Method to Develop New Drugs

• Biomedical research - test effectiveness & toxicity of a new drug - first in vitro (tissue culture) then in vivo (animal models)

• Clinical trials performed:– Phase I Trials: Toxicity and metabolism tested in healthy human

volunteers (no toxic effects observed)– Phase II Trials: Effectiveness and toxicity tested in target population

(effective with minimal toxicity)– Phase III Trials: Widespread test of drug in diverse population (gender,

ethnicity, other health problems)– Phase IV Trials: Drug is tested for other potential uses (sent to FDA for

approval)

Levels of Organization: Chemical and Molecular

Chemical orMolecular Levels

Atoms incombination

Complex proteinmolecules

Protein filaments

Organ System Level

The heart

Cellular Level

Heart muscle cell

Tissue Level

Cardiacmuscletissue

OrganLevel

Cardiovascular

Reproductive Urinary

Digestive Respiratory

Lymphoid Endocrine Nervous

Muscular Skeletal

Integumentary

OrganismLevel

Molecular compositionof the human body

Water67%

Proteins20%

Carbohydrates 3%

Lipids10%

Elemental compositionof the human body

Hydrogen62%

Oxygen26%

Carbon10%

Nitrogen1.5%

Other Elements:

CalciumPhosphorusPotassiumSodiumSulfurChlorineMagnesiumIronIodineTrace elements

0.2%0.2%0.06%0.06%0.05%0.04%0.03%0.0005%0.0000003%(see caption)

Chemical and Molecular Level


Atoms incombination


Protein filaments

Organ System Level

The heart

Cellular Level

Heart muscle cell

Tissue Level

Cardiacmuscletissue

OrganLevel

Cardiovascular




Muscular Skeletal

Integumentary

OrganismLevel

Levels of Organization: Cellular

Levels of Organization: Cellular

• Basic units of structure and function

Levels of Organization: Tissue


Atoms incombination


Protein filaments

Organ System Level

The heart

Cellular Level

Heart muscle cell

Tissue Level

Cardiacmuscletissue

OrganLevel

Cardiovascular




Muscular Skeletal

Integumentary

OrganismLevel

Levels of Organization: Tissue _____tissue _____tissue _____tissue _____tissue

• Cells with similar functions grouped into the 4 primary tissues

Levels of Organization: Organ


Atoms incombination


Protein filaments

Organ System Level

The heart

Cellular Level

Heart muscle cell

Tissue Level

Cardiacmuscletissue

OrganLevel

Cardiovascular




Muscular Skeletal

Integumentary

OrganismLevel

Levels of Organization: Organ

• Anatomical and functional units made of two or more primary tissues

Skin—The Largest Organ• Outer layer of protective cornified epidermis • Next layer the dermis contains connective tissue, glands, blood

vessels (BVs), nerves• Inner layer the hypodermis contains adipose tissue, BVs, nerves

Stem Cells

• Most cells in organs are highly specialized or differentiated

• Many organs retain small populations of adult stem cells– less differentiated so can become many cell typesExample: bone marrow stem cells can give rise to all of the different

blood cell types

Body-Fluid Compartments

• Our body has both intracellular and extracellular compartments:Intracellular - inside cells (cytoplasm)Extracellular - outside cells (blood plasma, interstitial fluid)

• Compartments separated by the cell’s plasma membrane

Levels of Organization: Organ System


Atoms incombination


Protein filaments

Organ System Level

The heart

Cellular Level

Heart muscle cell

Tissue Level

Cardiacmuscletissue

OrganLevel

Cardiovascular




Muscular Skeletal

Integumentary

OrganismLevel

Levels of Organization: Organ System

• Organs located in different regions of the body that perform related functions are grouped into systems

Organ System Level

Cardiovascular

Reproductive

Urinary



Muscular Skeletal

Integumentary

OrganismLevel

Organismal Level

Chemical levelAtoms combine to form molecules.

Cellular level Cells are made up of molecules.

Tissue levelTissues consist of similar types of cells

Organ levelOrgans are made up of different types of tissues.

Organ system level Organ systems consist of different organs that work together closely.

Organismal levelThe human organism is made up of many organ systems.

Cardiovascular system

OrganelleMoleculeAtomsSmooth muscle cell

Smooth muscle tissue

Connective tissue

Blood vessel(organ)

HeartBloodvessels

Epithelialtissue

Smooth muscle tissue

1 2

3

4

56

Homeostasis

• Our organ systems work together to maintain homeostasis despite constant challenges

Homeostasis

• Maintenance of a state of dynamic constancy– internal conditions are stabilized above and below a physiological set

point by negative feedback loops

Homeostasis and Negative Feedback Loops

All physiological parameters have a set point ‘X’• Sensor: Detects deviation from set point

• Integrating center: Determines response

• Effector: Produces response to re-establish X

Homeostasis• Negative feedback loops – body temperature, blood sugar,

blood pressureExample: control of body temperature Set point: 37 °C

Sensor: Temperature receptorsIntegrating center: BrainEffector: sweat glands/muscles

Homeostasis: Negative FeedbackExample: control of blood sugarSet point: 5 mmol/LSensor: pancreatic cellsIntegration: Endocrine systemEffector: insulin and glucagon

Homeostasis: Negative FeedbackExample: control of blood pressureSet point: normal blood pressure Sensor: barorecptorsIntegration Center: brainEffector: heart / arteries

Homeostasis and Positive Feedback

• Does not maintain homeostasis and is rare

• Occurs when the body needs to amplify a process– Producing blood clots– Creates the LH surge that causes

ovulation– Between the uterus and oxytocin

secretion during childbirth

Homework

• Read Fox Chapter 2• Read the Skills Lab

Note: • Come prepared to each lab session by reading the

assigned lab• Always bring in your lab manual• 1st day of lab bring in the required lab notebook• Lab notebooks will be kept in the lab

physiology 3 dr. anne valle office: sci-265 email: [email protected]

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