PHYSIOLOGY

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PHYSIOLOGY

• Ch. 1

THE STUDY OF BODY FUNCTION
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Human Physiology

• Study of how the human body functions.
• How organisms accomplish tasks essential for
  life.
• Pathophysiology
• How physiological processes are altered in
  disease or injury.

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History of PhysiologyAncient Greeks

• Aristotle (384 - 322 BC)
• Blood flows between arteries and veins
• The heart is the seat of intellect and a furnace
  that heats the blood
• The lungs ventilate the furnace and air acts as a
  cooling agent

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History of PhysiologyAncient Greeks

• Herophilus (335 - 280 BC)
• Identified pulse as a function of heartbeat, and
  showed that it varied when disease was present
• Arteries are thicker walled than veins
• The brain is the seat of intellect

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History of PhysiologyAncient Greeks

• Erasistratus (310 - 240 BC)
• Postulated the existence of capillaries
• The brain is the origin of all nerves
• Blood is made in the liver from food, and air
  (pneuma) is a living force that is transformed
  into a vital spirit.

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History of Physiology

• Galen (130 - 201 AD)
• Dissection of Barbary apes was basis for his book
  of human anatomy - stood as the authority for
  1400 years
• Known for his voluminous writings about
  philosophy, medicine, and physiology.

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Galen's physiological teaching (after C.Singer
Greek Biology and Greek Medicine)
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• "In the universe there are four elements - fire,
  air, water and earth and in the living body
  there are four humours, black bile, yellow bile,
  sanguine and phlegm. Out of the excess or
  deficiency or misproportion of these four humours
  there arise disease by restoring the correct
  proportion diseases are cured"

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History of PhysiologyRenaissance Physiologists

• Andreas Vesalius (1514 - 1564)
• Dissected human cadavers while he lectured.
  Introduced anatomical drawings.
• De Humanis Corporis Fabrica (The Structure of the
  Human Body) was the first anatomy text based on
  human dissection.

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History of PhysiologyRenaissance Physiologists

• William Harvey (1578 - 1657)
• Proposed that the heart is a pump (not a furnace)
  and that blood circulates (does not return along
  the same pathways.
• The blood flows from the right ventricle of the
  heart to the lungs

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Robert Hooke (1635 - 1703)
British physicist who first observed and
described cells
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Schleiden Schwann
Cell Theory 1839

• All living things are
• comprised of cells.

Matthais Schleiden
Theodor Schwann
(1818-1882) German physiologist
(1804-1881) German microscopist
2. All cells come from pre-existing cells.
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History of PhysiologyModern Physiologists

• Claude Bernard (1813 - 1878)
• The advent of the thermometer allowed
  physiologists to determine that the internal
  temperature of all healthy human beings fell
  withina narrow range
• Bernard developed the concept of the milieu
  interieur - a constant internal state

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History of PhysiologyModern Physiologists

• Walter Cannon (1871 - 1945)
• In his book The Wisdom of the Human Body, Cannon
  coined the term homeostasis to describe this
  internal constancy.

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Homeostasis

• Maintaining constancy of internal environment.
• Dynamic constancy.
• Within a certain normal range.
• Maintained by negative feedback loops.
• Regulatory mechanisms
• Intrinsic
• Within organ being regulated.
• Extrinsic
• Outside of organ, such as nervous or hormonal
  systems.
• Negative feedback inhibition.

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Feedback Loops

• Sensor
• Detects deviation from set point.
• Integrating center
• Determines the response.
• Effector
• Produces the response.

Fig 1.1 P. 7
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Negative Feedback

• Defends the set point.
• Reverses the initial deviation.
• Produces change in opposite direction.
• Examples
• Insulin decreases plasma glucose.
• Body temperature.

Fig 1.3 P. 8
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Negative Feedback
Fig 1.4 P. 8
Fig 1.6 P. 10
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Positive Feedback

• Action of effectors amplifies the changes.
• Is in same direction as change.
• Examples
• Oxytocin (parturition).
• Voltage gated Na channels (depolarization).

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Hierarchy of Life
Atom
Molecule
Cell
Tissue
Organ
Organ System
Organism
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Muscle

• Elongated cells are highly specialized to
  contract and produce most types of body movement
• Three types of muscle tissue
• Skeletal Muscle
• Cardiac Muscle
• Smooth Muscle

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Nervous Tissue

• Found in the central nervous system (brain and
  spinal cord) or peripheral nervous system
  (nerves, sensory receptors, ganglia)
• Two major cell populations
• Neurons specialized for the generation and
  conduction of electrical impulses
• Neuroglia supporting cells serve to protect,
  support, and insulate neurons

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Epithelial Tissues

• Cells fit closely together to form membranes or
  sheets
• Covers surfaces the tissue has one free surface
• Avascular
• Functions include protection, absorption,
  filtration and secretion

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Epithelial Tissues

• Classified by two criteria
• Cell shape
• Squamous - scale-like
• Cuboidal - cube-like
• Columnar - column-shaped

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Epithelial Tissues

• Number of layers
• Simple one cell layer
• Stratified two or more layers

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Fig 1.14 P. 15
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Connective Tissue

• The most abundant and widely distributed of the
  tissue types
• Large amount of noncellular material (matrix)
  between the cells
• With few exceptions (cartilages, tendons and
  ligaments), connective tissues have a rich supply
  of blood vessels
• Functions include protection, support, and
  binding together other tissues of the body

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Fig 1.21 P. 18
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