this presentation gives in depth information of phenomenon that is associated with our body and organ systems. the content has been explained conceptually and practically so we can relate with our practical life.

1. SCIENCE WEEK POWERPOINT PRESENTATION
BODY CLOCK

2. WHAT IS BODY CLOCK?
An internal mechanism in organisms that
controls the periodicity of various
functions or activities, such as metabolic
changes, sleep cycles, or photosynthesis.
Biological clock is also known as body
clock.

3. A master clock in the brain
coordinates all the biological
clocks in a living thing, keeping
the clocks in sync. The master
clock is a group of about 20,000
nerve cells (neurons) that form a
structure called the
suprachiasmatic nucleus. The SCN
is located in a part of the brain
called the hypothalamus and
receives direct input from the
eyes
WHAT IS A MASTER CLOCK?

4. A circadian rhythm is any
biological process that
display
san endogenous, untrainable
oscillation of about 24
hours. These 24-hour
rhythms are driven by
a circadian clock, and they
have been widely observed
in plants, animals, fungi,
and cyanobacteria.
CIRCADIAN RHYTHM

5. Ninety minutes before dawn in the eastern United States,
the Nobel committee announced that it was awarding this
year’s Nobel Prize in Physiology or Medicine to three American
biologists for their research on the control of circadian
rhythms.
Jeffrey C. Hall at the University of Maine, Michael
Rosebush at Brandeis University and Michael W. Young at the
Rockefeller University share the prize for their discoveries of
the genetic and biomolecular mechanisms that help the cells of
plants and animals (including humans) mark the 24-hour cycle
of day and night.
DISCOVERY OF BODY CLOCK

6. 1. Sleep and Waking
2. Body Temperature
3. The balance of body fluids
4. Other body functions such as
when you feel hungry
24 hour body clock is responsible for
following controls in body

7. SLEEP AND WAKING

8. Body clock sleep problems have been linked to
a hormone called melatonin, which helps your
body fall and stay asleep.
Light and dark affect how the body makes
melatonin. Most melatonin is made at night.
During the day, light tells your body to make
less melatonin. If you work at night in
artificial light, your body may be making less
melatonin than it needs.

9. BODY TEMPERATURE

10. An overactive thyroid (hyperthyroidism) can
cause a person to feel too hot, while an
underactive thyroid (hypothyroidism) can
cause a person to feel too cold.
The thyroid produces hormones that are
able to influence how much the blood vessels
dilate. In turn, this affects how much heat
can escape the body.

11. THE BALANCE OF BODY FLUIDS

12. Aldosterone is a key steroid hormone critical for
maintaining salt and water balance.
It regulates the concentration of minerals, like
sodium and potassium, in the fluid outside your cells.
When your sodium levels drop, or potassium levels
rise, your body signals your adrenal glands to release
aldosterone into your blood.
Aldosterone signals your kidneys to reabsorb sodium
into the blood, and acts on your sweat glands to
reduce sodium loss through sweat.
Aldosterone

13. The hormones that regulate fluid balance are
tightly controlled through a region of your brain
called the hypothalamus.
It's situated at the base of the brain and acts as
the control center for various hormones that
regulate a wide variety of physiological processes,
including salt and water balance.
A tumor or problem in this area of the brain can
cause inadequate secretion of hormones, which
disrupts fluid balance and other critical processes.
Hypothalamus Involvement

14. OTHER BODY FUNCTIONS SUCH AS WHEN
YOU FEEL HUNGRY

15. Leptin is a hormone, made by fat cells, that
decreases your appetite. Ghrelin is a hormone
that increases appetite, and also plays a role in
body weight.
Levels of leptin -- the appetite suppressor -- are
lower when you're thin and higher when you're
fat.
But many obese people have built up a
resistance to the appetite-suppressing effects
of leptin, says obesity expert Mary Dallman,
PhD, from University of California at San
Francisco.

16. THERE ARE 3 MORE TYPES OF
CLOCKS IN OUR BODY
1. EPIGENTIC CLOCK
3. CIRCADIAN CLOCK
2. MOLECULAR CLOCK

17. An epigenetic clock is a type of a
molecular age estimation method
based on DNA methylation levels.
Pre-eminent examples for
epigenetic clocks are Horvath's
clock, which applies to all human
tissues/cells, and Hannum's clock,
which applies to blood.
1. EPIGENTIC CLOCK

19. The molecular clock is a technique that uses
the mutation rate of biomolecules to deduce the
time in prehistory when two or more life forms
diverged. The bimolecular data used for such
calculations are
usually nucleotide sequences for DNA or amino
acid sequences for proteins. The benchmarks for
determining the mutation rate are often fossil or
archaeological dates. The molecular clock was first
tested in 1962 on the haemoglobin protein variants of
various animals, and is commonly used in molecular
evolution to estimate times of speciation or radiation.
It is sometimes called a gene clock or an evolutionary
clock.
2. MOLECULAR CLOCK

21. A circadian clock,
or circadian oscillator, is
a biochemical oscillator
that cycles with a
stable phase and is
synchronized with solar
time.
3. CIRCADIAN CLOCK

23. SOME REAL LIFE EXAMPLES WHERE
WORKING OF HORMONES TAKES PLACE

24. At least one example of human experience involving
interference with the body clock relates to conditions
completely outside people's control. This is the
situation of the "white nights" or "midnight sun,"
whereby regions in the extreme north—Russia, Alaska,
and Scandinavia—undergo periods of almost constant
daylight from mid-May to late July.
During those times people often line their windows with
dark material to make it easier to go to sleep in a world
where the Sun is nearly as bright at 3:00 A.M. as it is
at 3:00 P.M. The situation is even more pronounced in
Antarctica
WHITE LIGHT

25. Jet lag is a physiological condition which results from
alterations to the body's circadian rhythms
North–south flights that do not cross time zones do not
cause jet lag. However, crossing of the Arctic Ocean or
even the North Pole (often the shortest route between
northeast Europe and Alaska or the Canadian West
Coast and East Asia) does cause a significant time
change.
In general, adjustment to the new time zone is faster
for east–west travel than for west–east. A westward
adjustment takes, in days, approximately half the
number of time zones crossed; for eastward travel,
adjusting to the new time zone takes, in days,
approximately two-thirds the number of time zones
crossed.

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