chapter 19 - homeostasis (part 1)
TRANSCRIPT
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HOMEOSTASIS
Powerpoint@lecture Slides Are Prepared By Biology Lecturer, KMPk
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.1 Concept of homeostasis
.2 Negative feedback mechanism
.3 Human Homeostatic organs:
9.3.1 Structure and functions of liver
9.3.2 Structure and functions of kidney
TOPICS
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PREVIOUS LESSON
Water movement through xylem Pressure flow hypothesis
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OBJECTIVES
t the end of this lesson, students should be able to:
xplain the concept of homeostasis and describe the
homeostatic control system.
xplain the negative feedback in controlling blood
glucose
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19.1 CONCEPT OF
HOMEOSTASIS
HOMEOSTASIS(homois same
stasis - standing)
Maintenance of aconstant internal
environment withina living organism
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19.1 CONCEPT OF
HOMEOSTASIS
A feedback system A cycle of events in which the status of body
condition is continually monitored, evaluated,
changed, re monitory, re-evaluated and so on
Variables involved
Body temperature
Blood pressure
Blood glucose level
Blood pH
Controlled conditions
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19.1 CONCEPT OF
HOMEOSTASIS
Stimulus
Any disruption that changes a controlled
condition
Feedback Systems
3 Basic Components
Receptor
Effector
Control Center
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19.1 CONCEPT OF
HOMEOSTASIS
Receptor:
A body structure that
monitors changes in a
controlled condition
Sends INPUT in the form
of nerve impulses or
chemical signals to acontrol center
Eg: hypothalamus
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Control center
Receives and controls
information (INPUT)
from the receptor
Triggers the action
(OUTPUT) that will
correct the change
19.1 CONCEPT OF
HOMEOSTASIS
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19.1 CONCEPT OF
HOMEOSTASIS
Output from the
control center can
occur in several forms:
nerve impulses,hormones , or
other chemical signals
Eg: pituitary gland,
adrenal gland
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Effector
A body structure
that receives output
from the controlcentre
Produces a response
or effect thatchanges the
controlled condition
Eg: thyroid gland,
liver, muscle
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19.1 CONCEPT OF
HOMEOSTASIS
H OM EOSTATI C
CONTR OL
SYSTEM
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19.1 CONCEPT OF
HOMEOSTASIS
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19.1 CONCEPT OF
HOMEOSTASIS
FEEDBACK SYSTEMS
NEGATIVE POSITIVE
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19.2 NEGATIVE
FEEDBACK MECHANISM
Used by most of the
body's systems
Information caused
by the feedbackcauses a reverse of
the response
Output turns
down or shuts
off the original
stimulus
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19.2 NEGATIVE
FEEDBACK MECHANISM
Example: Regulation of blood glucose levels
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19.2 NEGATIVE FEEDBACK
MECHANISM
Regulation of blood
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19.2 NEGATIVE
FEEDBACK MECHANISM
Insulin
Causes the body cells to take up glucose from
the blood
Stimulates the liver, muscle cells and other
tissues to store glucose as glycogen
Blood glucose level return to normal
Set point : desired level
Glucose GlycogenInsulin
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19.2 NEGATIVE
FEEDBACK MECHANISM
When blood glucose level decrease,
- cells of islets of Langerhans in the pancreas
Release glucagon
Glucagon
Stimulates the liver cells to convert glycogen to glucose
Blood glucose level return to normal (set point)
GlucoseGlycogenGlucagon
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19.2 NEGATIVE
FEEDBACK MECHANISM
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CONCLUSION
H OM EOSTATI C
CONTR OL
SYSTEM
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Concept of
homeostasis in
regulating blood
pressure
CONCLUSION
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CONCLUSION
Liver converts
glycogen to
glucose
normal blood
glucose level
Blood glucose
level fallsSoon
after ameal
Long
after a
meal
Blood glucose
level rises
normal blood
glucose level
Too
High
Too
Low
Pancreassecretes
insulin
Pancreas
secretes
glucagon
Liver, musclecells coverts
glucose to
glycogen
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Concept of homeostasis
CONCLUSION
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NEXT LECTURE
19.3 Human Homeostatic Organs: liver and
kidney
19.3.1 Structure and functions of liver