Chapter 19 - Homeostasis (Part 1)

7/30/2019 Chapter 19 - Homeostasis (Part 1)

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HOMEOSTASIS

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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
http://c/Documents%20and%20Settings/kmpk/Desktop/homeostasis/Example%20of%20Negative%20Feedback.WMVhttp://c/Documents%20and%20Settings/kmpk/Desktop/homeostasis/Example%20of%20Negative%20Feedback.WMV


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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