Download B 11.A

B 11.A
Describe the role of
internal feedback
mechanisms in the
maintenance of
homeostasis.
Vocabulary
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Central Nervous System
Peripheral Nervous System
Reflex Arch
Negative Feedback
Positive Feedback
Central Nervous System
The central nervous
system consists of
the brain and spinal
cord and relays
messages,
processes
information, and
analyzes
information.
Peripheral Nervous System
Consists of all the nerves
and associated cells not
part of the brain or
spinal cord:
Sensory Division – from
sense organs to CNS.
Motor Division – from
CNS to muscles and
glands
Reflex Arch
Sensory receptor,
sensory neuron,
motor neuron,
and effector that
are involved in a
quick response
to a stimuli.
Negative Feedback
When the body
senses an
internal change
and activates
mechanisms that
reverse, or
negate, that
change.
Example: When
blood temperature
becomes too high, the
body responds by
cooling itself down.
Positive Feedback
A process in which
the body senses a
change and
activates
mechanisms that
accelerate or
increase that
change.
Example: The
presence of partially
digested protein in the
stomach triggers the
secretion of
hydrochloric acid and
pepsin, the enzyme
that digests protein.
Internal Feedback Mechanisms
Many body functions help maintain homeostasis:
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Feeding
Respiration
Circulation
Excretion
Movement
Body Temperature Control
Homeostasis and Digestive System:
Stomach empty
for several
hours
The individual eats
something and
contractions stop
Stomach muscles begin to
contract causing an
unpleasant sensation
Glucose levels
begin to drop
Homeostasis and
Respiration/Breathing
Exercise causes a
build up of Carbon
Dioxide in the blood.
Oxygen from the air is
brought into the lungs and
the CO2 buildup is sent out
of the lungs by exhaling.
This signals the nerve
impulses in the breathing
center of the brain telling the
diaphragm to contract.
The higher the level of CO2 the
stronger the impulses.
Homeostasis and Circulation
Other hormones are
released into the
bloodstream to help in
the calming process.
When the attack is over hormones
are released to help the kidneys
filter adrenaline from the
bloodstream.
The hypothalamus
detects stress such
as being attacked.
The nervous system releases
adrenaline into the
bloodstream.
Blood is directed toward
muscles and limbs where more
energy is required for running
or fighting.
Homeostasis and Excretion
Excessive salt ingested
causing high salt
concentration in blood.
Filtered blood leaves the
kidneys with a normal salt
concentration.
Blood enters the kidneys where
regulatory hormones control
the filtration of excess salt from
the bloodstream.
Salt and wastes are collected
and carried to the urinary
bladder
Homeostasis and Body Temperature
Muscle fibers connected to
hair follicles tighten to form
warm air pockets
(goose bumps).
Muscles become active
involuntarily causing shivering
(can increase heat production x 5).
Body is exposed to
extremely cold
temperatures.
Hypothalamus activates to
control heat loss.
Blood flow is restricted to all
non essential areas (fingers and
toes) in order to maintain
temperature of vital organs.
Blood Flow and Thermoregulation
Use the link below to view a model of
thermoregulation.
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http://www.teachersdomain.org/asset/lsps07_i
nt_heatexchange/
Thermoregulation
Why do you get a fever when you are sick?
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http://www.teachersdomain.org/asset/tdc02_v
id_fevervid/
Interdependent Body Systems
See if you can maintain a young girl’s
homeostasis in this interactive activity.
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http://www.teachersdomain.org/asset/tdc02_i
nt_bodycontrol/