MODULE 4 | Physiologic Mechanisms Flashcards
is the existence and maintenance of a relatively
constant environment within the body despite
fluctuations in either the external environment or the
internal environment.
Homeostasis
What are the 3 Cells’ fluid environment variables?
✓ temperature
✓ volume
✓ chemical content
Most homeostatic mechanisms are governed by these two system
Nervous System and Endocrine System
Not precise at set point
Fluctuations
Maintenance of homeostasis:
➢Negative Feedback Mechanism
➢Positive Feedback Mechanism
Most systems of the body are regulated by this mechanism
Negative feedback mechanism
It means that any deviation from the set point is
made smaller or is resisted
Negative
3 components of negative feedback mechanism
- Receptor
- Control Center
- Effector
A component of NFM where it monitors value of variable
Receptor
A component of NFM where establishes the set point
Control Center
A component of NFM where it changes the value of the variable
Effector
Example of Negative feedback mechanism
Thermoregulation
➢ is the control of body temperature
THERMOREGULATION
➢The core of the human body includes the organs of
the:
thorax, abdomen and the head
Normal value of core temperature
37°C
Less heat is carried from the
core to the surface of the body,
maintaining core temperature.
Vasoconstriction
More heat is carried from the
core to the surface
Vasodilation
Effector of Vasoconstriction and Vasodilation
Smooth muscles
in arterioles in
the skin
raising
skin hairs and trapping an
insulating layer of still, warm
air next to the skin.
Muscles contract
lowering the
skin hairs and allowing air to
circulate over the skin,
encouraging convection and
evaporation.
Muscles relax
Effector of muscle contract and muscle relax
Erector Pili Muscles
Produces own body heat
Endotherm
Does not produces its own heat
Ectotherm
Can regulate body temperature
Homeotherm