The document discusses homeostasis, which is the maintenance of a constant internal environment in the body. It provides examples of how homeostasis works in humans to regulate body temperature, blood glucose concentration, and blood water potential. The skin plays a role in regulating body temperature through sweating and vasodilation. Blood glucose is regulated by insulin and glucagon in response to food intake and exercise. Osmoreceptors detect changes in blood water potential and signal the pituitary gland to release antidiuretic hormone to restore normal water levels. Homeostasis works through a negative feedback loop involving stimuli, receptors, and corrective mechanisms.

1. HOMEOSTASIS
Teacher Angel

2. What is Homeostasis?

4. HOMEOSTASIS
is the maintenance of a constant
internal environment.
The internal environment refers to
conditions within the body of an organism.
By ensuring a relatively stable internal
environment, homeostasis allows an
organism to be independent from changes
in the external environment.

5. One of the reasons is because the
enzymes in your body can oly work
within a certain range of
temperatures. Changes in body
temperature may result in enzyme
inactivation or even danaturation. This
explains why people suffering from
high fever must consult a doctor, as
high fevers can be fatal.
Why does body temperature
have to be kept constant?

6. EXAMPLE OF
HOMEOSTASIS IN HUMANS

7. STRUCTURE OF HUMAN SKIN
Your Skin forms a protective covering over your body surface. It also plays a role
in the regulation of your body temperature and excretion. How does your skin
perform these functions?

8. REGULATING BODY
TEMPERATURE
1.
In humans, normal body
temperature fluctuates around
the value of 37 °C (98.6 °F), but
various factors can affect this
value, including exposure,
hormones, metabolic rate, and
disease, leading to excessively
high or low temperatures.

9. 2. REGULATING BLOOD
GLUCOSE CONCENTRATION
Blood normally contains
about 70-90 mg of glucose
per 100 cm^3 of blood.
Glucose levels in your blood
rise after a sugary meal and
fall after during vigorous
physical exercise or
starvation.

10. DIFFERENCE BETWEEN
INSULIN & GLUCAGON
INSULIN is a hormone
produced in the
pancreas, it lowers
glucose levels;
GLUCAGON
stimulates the
breakdown of glycogen
to produce more
glucose in the liver.

11. 3. REGULATING BLOOD WATER
POTENTIAL
The thirst centre of the brain is stimulated by the
osmoreceptors so the individual is alerted to
change their behaviour (ie. to drink more water).
This whole system works via negative feedback, as
when osmoreceptors detect a rise in water
potential, they send fewer impulses to the pituitary
gland, so less ADH is released and the normal
water potential of the blood can be restored. ADH
also affects urea concentrations in the body, as it
can stimulate more urea channels to be inserted
onto the membranes of the collecting ducts, also
contributing to the homeostasis of blood water
potential.

12. HOMEOSTASIS
STIMULI RECEPTORS CORRECTIVE
MECHANISM
detectable
changes in
internal
environment
detect changes
and send nerve
impulses to trigger
self-corrective
mechanism
reverse the
effects of
changes
detected

13. Learning Activity # 1
(Individual Performance)
For 1 hour activity, choose a
partner and follow the
instructions provided in the
worksheet: "Negative Feedback
to Regulate Homeostasis"
Then, Answer all the questions
given and submit your paper to
your teacher once your done.

14. QUIZ #1: HOMEOSTASIS
REVIEW PAGE 246 & 249
(BIOLOGY MATTERS BOOK)

15. Learning
Activity #2
(Group Performance)
Bring the following Materials:
1/2 ILLUSTRATION BOARD
WATER COLOR
MARKET
PRINTED LABELS OF THE
STRUCTURE OF THE SKIN
GLUE
"THE STRUCTURE OF HUMAN SKIN"

16. THANK YOU
FOR ATTENDING!