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Chapter 1 – Introduction!
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Chapter 1An Introduction to !Anatomy and Physiology!
MAPRAUSCH48347!
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SECTION 1-3, 1-4 Introduction
• Anatomy = “to cut”!i.e. the study of structure!
• Physiology = “nature”!i.e. the study of function!
!A&P = the study of structure and function!
Anatomy and Physiology
Chapter 1 – Introduction!
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• Organization !• Responsiveness/irritability!• Growth!• Differentiation !• Reproduction!• Inheritance (DNA) !• Movement!
Characteristics of Living Organisms (1 of 2)!
“Differentiation”
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Characteristics of Living Organisms (2 of 2)!
• Excretion !• Metabolism = the sum of all chemical reactions
occurring within the organism!a. Catabolism• Breaks down complex molecules into
simpler ones!• Releases energy!
b. Anabolism• Builds up complex molecules from
simpler ones!• Requires input of energy!
Chapter 1 – Introduction!
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SECTION 1-5 !Levels of organization progress from molecules to a complete organism!
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Levels of Organization/Organ Systems!
(Figure 1-1)!
Chapter 1 – Introduction!
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Levels of Organization Figure 1-1 !
Cells !contain!
organelles
Organ System! Organism!
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Introduction to the Organ Systems!
Know the major functions and components of each organ system as presented in Spotlight Figure 1-1.!!Note: Blood is not an organ.!
Chapter 1 – Introduction!
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Definition: Homeostasis is the maintenance of relatively constant conditions in the internal environment in the face of environmental change
SECTION 1-6 !Homeostasis is the tendency toward internal balance (see definition below)!
Controlled variable: body temperature, blood pH, blood O2, body fluid [salt], etc., etc.
Why know this? How organisms maintain homeostasis is what physiology is all about.!
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Key Parts of This Definition!
• Relatively constant (e.g. slide 12)!Just what it says - not “absolutely” constant!
• “Internal environment” is the fluid outside of cells:!
Synonyms:!• Extracellular fluid!• Intercellular fluid!• Interstitial fluid!
• Environmental change!e.g. environmental (ambient) temperature!
Chapter 1 – Introduction!
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General Mechanisms of Homeostasis !
• Autoregulation (a.k.a. intrinsic regulation)!E.g. local vasodilation or vasoconstriction!
• Extrinsic regulation!Regulation involving nervous and/or endocrine systems!E.g. exercise (or thinking of it) → ↑ HR, !↑ BP!
!• Homeostasis requires control systems and
control mechanisms!
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Control systems require:!• Receptor!• Control center (integrator)!• Effector!
Control System Elements!
Chapter 1 – Introduction!
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Controller (or Integrator)!
Controller!• Determines the set point!
Set point = desired value of a controlled variable!
• Computes an error signal!Error signal = actual value - desired value!
• Receives information from Receptor!• Sends appropriate instructions to Effector!
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Receptor and Effector!
Receptor!• Monitors the actual value of a controlled
variable!• Constantly sends information to Controller!• E.g. thermoreceptor, baroreceptor!• Does not “know” what the value should be!Effector!• Receives instructions from Controller!• Effects a change in the controlled variable!• E.g. sweat gland, skeletal muscle, smooth
muscle!
Chapter 1 – Introduction!
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Negative feedback control• Stimulus and response are in opposite
directions!Positive feedback control• Stimulus and response are in the same
direction!Feedforward control• Changes the set point; controller makes a
prediction about the future value of the controlled variable!
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Specific Types of Control Mechanisms!
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Negative Feedback Control Figure 1-2!
Chapter 1 – Introduction!
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Negative Feedback - Body Temp. Figure 1-3!
Note: a change in body temperature is
NOT required!
Controller = Hypothalamus!
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Positive Feedback Figure 1-4 !
1. Blood Clotting!
2. Parturition (birth)!• Uterine contraction causes…!• Cervical stretch causes…!• OT release causes…!• Uterine contraction, etc., etc.!
Chapter 1 – Introduction!
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Feedforward Mechanisms Change the Set Point!
Life - The Science of Biology, Purves et al. 2001
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