Contributed by:
Definition and mechanism of Homeostasis will be discussed in the presentation. In biology, homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits.
1.
Section 28-2
“Homeostasis”
Write everything that is
underlined
2.
28.2 Mechanisms of Homeostasis
KEY CONCEPT
Homeostasis is the regulation and
maintenance of the internal
environment of the body
3.
28.2 Mechanisms of Homeostasis
I. Homeostasis
Conditions within the body must remain within
a narrow range – like your body temperature
a. Homeostasis involves keeping the
internal environment within set ranges
4.
28.2 Mechanisms of Homeostasis
b. Control systems help maintain
homeostasis.
pore
– sensors gather data sweat
– control center receives
glands
data, sends messages hair
follicle
– communication system muscle
delivers messages to
target organs, tissues
– targets respond to
goose
bump
change
5.
28.2 Mechanisms of Homeostasis
II. Feedback Loops
a. Negative feedback loops are
necessary for homeostasis
• Feedback compares current
conditions to set ranges.
• Negative feedback stops the
change
6.
28.2 Mechanisms of Homeostasis
b. Negative Feedback Loop Example:
Holding
breath,
CO2 levels
rise
O2 / CO2 level
returns to normal
Control system
forces exhale,
inhale
7.
28.2 Mechanisms of Homeostasis
c. Positive feedback increases change
– Example: Torn blood vessel
stimulates release of clotting factors
platelets blood vessel
fibrin
clot
white blood cell
red blood cell
–growth hormones stimulate cell
division
+1-315-636-4485
+91 98151-74050 
