Download Organ system

Lauralee Sherwood
Hillar Klandorf
Paul Yancey
Chapter 1
Homeostasis and Integration:
The Foundations of Physiology
Kip McGilliard • Eastern Illinois University
1.1 Introduction
 Characteristics of living things
• Organize themselves using energy and
raw materials from their surroundings
(metabolism)
• Maintain integrity in the face of disturbances
(homeostasis)
• Reproduce
1.1 Introduction
 Explanation of biological adaptations
• Mechanistic (proximate) explanation
• Emphasizes mechanisms
• Cause-and-effect sequences
• Evolutionary (ultimate) explanation
• Variation and natural selection
• Species must cope with selective pressures
• Adaptations -- beneficial features that
enhance overall survival of the species
1.1 Introduction
 Adaptations reflect evolutionary history including
cost-benefit trade-offs
• Example: Shivering in mammals
• Cost -- requires energy
• Benefit -- maintains body temperature in the cold
1.1 Introduction
 Physiology is an integrative discipline
• Closely interrelated with anatomy, physics,
chemistry, biochemistry, molecular biology, and
genetics
 Physiology is a comparative discipline
• Comparing physiological features in different
types of organisms
• Krogh principle -- for every adaptation, there
will be a particular species in which it is most
conveniently studied
1.2 Methods in Physiology
 Scientific method
1. Ask a question about nature
2. Propose alternative hypotheses to explain
the phenomenon
•
•
•
Hypothesis = Tentative explanation about some
aspect of nature
Induction = Taking specific information and
creating a general explanation
Hypotheses must be testable and falsifiable
1.2 Methods in Physiology
 Scientific method
3. Design experiments that test the
hypothesis by making testable predictions
•
Deduction = Making specific predictions based
on a hypothesis and testing those predictions
4. Conduct experiments
5.
Refine earlier questions and hypotheses,
and design new tests
1.2 Methods in Physiology
 Scientific method
• When a hypothesis has been consistently
supported and all alternative hypotheses
have been falsified, a hypothesis may be
elevated to a scientific theory.
1.3 Levels of Organization in Organisms
 Basic functions essential for survival of the cell
• Self-organization
• Self-regulation
• Self-support and movement
• Self-replication
1.3 Levels of Organization in Organisms
 Examples of specialized functions of some
cells
• Gland cells secrete digestive enzymes.
• Neurons generate and transmit electrical
impulses.
• Kidney cells selectively retain needed
substances while eliminating unwanted
substances in the urine.
• Muscle cells produce movement.
1.3 Levels of Organization in Organisms
(a) Chemical level: a molecule in the
membrane that encloses a cell
(b) Cellular level: a cell in the
stomach lining
(c) Tissue level: layers of
tissue in the stomach wall
(d) Organ level: the
stomach
(e) Body system level:
the digestive system
(f) Organism level: the whole body
Figure 1-2 p8
1.3 Levels of Organization in Organisms
 Levels of organization
• Cell = Smallest unit capable of carrying out
the processes associated with life
• Tissue = Group of cells with similar structures
and functions
1.3 Levels of Organization in Organisms
 Four primary tissue types
• Epithelial tissue
• Exchange of materials
• Connective tissue
• Connects, supports, and anchors various body
parts
• Muscular tissue
• Contraction and force generation
• Nervous tissue
• Initiation and transmission of electrical impulses
1.3 Levels of Organization in Organisms
Organ: Body structure that integrates
different tissues and carries out a
specific function
Stomach
Epithelial tissue:
Protection,
secretion, and
absorption
Connective
tissue:
Structural
support
Muscle tissue:
Movement
Nervous tissue:
Communication,
coordination, and
control
Figure 1-3a p9
Figure 1-3b p9
INTERACTION: Differences between cell
and tissue types
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1.3 Levels of Organization in Organisms
 Levels of organization
• Cell = Smallest unit capable of carrying out
the processes associated with life
• Tissue = Group of cells with similar structures
and functions
• Organ = Two or more tissues organized to
perform a particular function
• Organ system = Collection of organs that
interact to accomplish a common activity
1.4 Size and Scale among Organisms
 Organisms range in size from unicellular
prokaryotes to large multicellular eukaryotes
over a scale of 1020
 Scaling = Study of the effects of size on
anatomy and physiology
1.4 Size and Scale among Organisms
Volume
grows
along three
dimensions
Surface area
grows along
two dimensions
Bandicoot
Elephant
Figure 1-4 p11
1.4 Size and Scale among Organisms
 Larger organisms have smaller surfacearea-to-volume ratios
• Surface area is related to the square of the
radius
• Volume is related to the cube of the radius
• Advantage of smaller surface-area-to-volume
ratio (larger animals) -- better retention of heat
• Disadvantage -- reduced ability to obtain enough
nutrients to meet the needs of the larger volume
1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Claude Bernard documented the ability of
mammals to maintain a relatively constant state
of the internal environment (milieu interieur).
 Walter B. Cannon coined the term
“homeostasis”
 Homeostasis = Maintenance of a consistent
internal state
 Homeostasis is not a fixed state, but a dynamic
steady state.
1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Majority of cells in a multicellular organism are
not in direct contact with the external
environment.
 The internal environment consists of the
extracellular fluid.
• Plasma
• Interstitial fluid
Extracellular fluid
Cell
Interstitial fluid
Plasma
Blood
vessel
Intracellular fluid
Figure 1-5 p12
1.5 Homeostasis: Basic Mechanisms and
Enhancements
Homeostasis is essential for proper cell function, and most cells,
as a part of an organized system, contribute to homeostasis
Maintain
Body systems
Homeostasis
Is essential
For
survival
of
Make up
Cells
Stepped Art
Fig. 1-6, p.12
1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Homeostatically regulated factors of the internal
environment
•
•
•
•
•
Concentration of energy-rich molecules
Concentration of O2 and CO2
Concentration of waste products
pH
Concentration of water, salt, and other
electrolytes
• Volume and pressure
• Temperature
• Social parameters
1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Animals vary in their homeostatic abilities
(e.g. thermoregulation)
• Regulators
• Use internal mechanisms to defend a relatively
constant state
• Conformers
• Internal state varies with that of the environment
• Avoiders
• Minimize internal variations by avoiding
environmental disturbances
1.5 Homeostasis: Basic Mechanisms and
Enhancements
Figure 1-7a p14
Figure 1-7b p14
Figure 1-7c p14
1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Negative feedback is the main regulatory
mechanism for homeostasis
• Negative feedback occurs when a change in
a controlled variable triggers a response that
opposes the change.
1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Components of a negative feedback system
• Sensor -- Measures the variable being regulated
• Integrator -- Compares the sensed information
with a set point
• Effector -- Makes the corrective response
 Examples
• Control of room temperature
• Mammalian thermoregulation
1.5 Homeostasis: Basic Mechanisms and
Enhancements
Deviation in
controlled variable
(detected by)
* relieves
-
Sensor
(informs)
Set
Point
Integrator
(sends instructions to)
Effector(s)
(brings about)
Compensatory response
*
(results in)
Controlled variable
restored to normal
(leads to)
Negative feedback to shut off the
system responsible for the response
Fig. 1-8a, p.13
Fall in room temperature
below set point
* Relieves
Thermometer
+
Set
Point
Thermostat
+
Furnace
Heat output
Fall in room temperature
below set point
*
(negative feedback)
Fig. 1-8b, p.13
Fall in body temperature
below set point
* Relieves
Temperature-monitoring
nerve cells
+
Temperature
control center
Set
Point
+
Skeletal muscles
(and other effectors)
Heat production through
shivering and other means
Fall in body temperature
below set point
(negative feedback)
Fig. 1-8c, p.13
ANIMATION: Negative feedback system
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1.5 Homeostasis: Basic Mechanisms and
Enhancements
 Additional design features of negative
feedback systems
• Antagonistic control
• Two effectors with opposite effects
• Behaviors as effectors (e.g. avoiders)
• Anticipation or feed forward system
• Predicts an oncoming disturbance before a
regulated state is changed
• Acclimatization systems
• Alter existing feedback and other components
over time to work better in a new situation
1.5 Homeostasis: Basic Mechanisms and
Enhancements
Controlled variable
Sensor
Integrator
Set point
Effector to
decrease variable
Effector to
increase variable
e.g., furnace
e.g., air conditioner
(a) Antagonistic effectors
Stepped Art
Fig. 1-9a, p.16
Controlled variable
Oncoming disturbance
Sensor
Sensor
Integrator
Anticipator
Effector
Activates corrective
response before the
variable is disturbed
(b) Anticipation or feedforward control
Stepped Art
Fig. 1-9b, p.16
ANIMATION: Feedback control of
temperature
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1.6 Regulated Change
 Some internal processes are not always
homeostatic
•
•
•
•
•
•
•
Dormancy
Locomotion
Growth and development
Neural signaling
On-demand regulation (e.g. digestion of food)
Reset systems -- change set point
Positive feedback systems
1.6 Regulated Change
 Positive feedback systems
• Output is continually enhanced so that the
controlled variable continues to move in the
direction of the initial change.
• Create rapid change
• Example: Oxytocin release and uterine
contractions during mammalian birth
1.6 Regulated Change
Controlled variable
Higher regulator
Sensor
Integrator
Set point
Effector
(a) Reset control of negative feedback by a higher
system or clock
Stepped Art
Fig. 1-10a, p.18
Deviation in
controlled variable
(May use a Sensor)
Integrator or
regulatory
process
Accentuates
the change
Output
(may use an effector)
Stepped Art
(b) Positive feedback
Fig. 1-10b, p.18
Signal from mature fetus
Uterus begins contractions
Stretch
sensors
Contractions
enhanced
Mother’s hypothalamus
Pituitary gland
Oxytocin secreted
(c) Example of positive feedback: birth of a mammal
Stepped Art
Fig. 1-10c, p.18
1.6 Regulated Change
 Disruptions in regulation can lead to illness
and death.
• Pathophysiology -- altered physiology of
organisms associated with disease
• Example: Congestive heart failure is a
positive feedback cycle leading to death
1.7 Organization of Regulatory and Organ Systems
 Homeostasis and other regulation is
hierarchically distributed.
• Regulation at the cellular level
• Intrinsic controls
• Regulation by a tissue or organ for its own benefit
• Extrinsic controls
• Regulatory mechanisms initiated outside an organ to
alter its activity
• Coordinated regulation of several organs toward a
common goal
1.7 Organization of Regulatory and Organ Systems
 Organ systems can be grouped according to
their contributions to the organism.
• Whole-body control systems
• Nervous system
• Endocrine system
• Support and movement systems
• Skeletal system
• Muscular system
1.7 Organization of Regulatory and Organ Systems
 Organ systems can be grouped according to
their contributions to the organism.
• Maintenance systems
•
•
•
•
•
•
Circulatory system
Immune system
Respiratory system
Excretory system
Digestive system
Integumentary system
• Reproductive system
1.7 Organization of Regulatory and Organ Systems
BODY
SYSTEMS
Information from
the external
environment
relayed through
the nervous
system
NERVOUS
SYSTEM
Regulates
ENDOCRINE
SYSTEM
INTEGUMENTARY
RESPIRATORY
SYSTEM
SYSTEM
Urine containing
wastes and
excess water and
electrolytes
Nutrients, water,
electrolytes
Feces containing
undigested food
residue
EXCRETORY
SYSTEM
IMMUNE
SYSTEM
DIGESTIVE
SYSTEM
Sperm leave male
REPRODUCTIVE
Sperm enter
SYSTEM
female
Exchanges with
all other systems.
EXTERNAL
ENVIRONMENT
MUSCULAR
AND SKELETAL
SYSTEMS
Exchanges with
all other systems.
Keeps
internal
fluids in
Keeps
foreign
material out
Protects
against
foreign
invaders
Enables the
body to
interact with
the external
environment
CIRCULATORY SYSTEM
Figure 1-11 p20