1. Embryology & Human Biology

2. REPRODUCTION & EMBRYONIC
DEVELOPMENT OF AN ORGANISM
Organisms have
the ability to
reproduce by
sexual or asexual
means

3. I. Embryonic Development:
The basic body plan is established early in
development
• Process of DEVELOPING a multicellular
EMBRYO is quite complex and takes many
steps

4. A. _FERTILIZATION : fusion of egg and sperm
during sexual reproduction to produce a diploid
zygote cell

5. B. _CLEAVAGE: repeated mitotic divisions of a
zygote that makes a mass of cells
• Takes several days
• Cells have no function yet

7. C. _GASTRULATION: development of a
multilayered embryo

8. • Cell Differentiation: embryo forms DIFFERENT
tissue layers and cells SPECIALIZE to carry out a
particular FUNCTION

9. • Cause:
a. Different GENES are ACTIVATED and
signal cells to have different functions
(example: liver, heart, blood cells, muscle
cells)
b. The ENVIRONMENT can also influence
differentiation
Ex: Metamorphosis
Ex: Nutrition and Lifestyle

10. Metamorphosis
• _CHANGE in an animal’s APPEARANCE or
structure from one stage to another through cell
growth and differentiation
• May be influenced by change in HABITAT or
behavior

11. Nutrition/Lifestyle:
• Diabetes (type2): poor diet high in sugar leads to
insulin insensitivity
**body’s insulin tries to
push the “gas pedal”
but cells can’t react

12. II. THE HUMAN BODY
• Later in embryonic development,
organs, made up of various tissue
types, and organ systems work
together to support the needs of
the entire organism

13. • The body has been organized into 11 body systems
that work together to maintain homeostasis and
supports the major PROCESSES required for LIFE

14. _HOMEOSTASIS : steady internal state or
condition

15. The body has FEEDBACK mechanisms that
respond to changes in the organism's environment
and will REVERSE the direction of the
UNWANTED change

16. The body’s NERVOUS and ENDOCRINE
systems along with other systems monitor body
conditions inside and out

17. Changes in an organism’s homeostasis could be due
to:
a. _DISEASE AGENTS such as bacteria 0r
viruses
b. Changing PHYSICAL, CHEMICAL, or
ENVIRONMENTAL conditions such as
temperature, atmosphere, light exposure

18. III. EXAMPLES OF HOMEOSTASIS
• Cells function in a NARROW range of
physical conditions
a. Temperature: body sweats to maintain normal
level
b. Blood pH: breathing controls CO2 levels in blood
c. Blood Sugar: insulin secreted from pancreas
removes glucose from the blood

19. How is your homeostasis How does your body react to
disrupted on a daily basis? correct the situation?