REPRODUCTION & EMBRYONICDEVELOPMENT OF AN ORGANISM Organisms have the ability to reproduce by sexual or asexual means
I. Embryonic Development:The basic body plan is established early indevelopment• Process of DEVELOPING a multicellular EMBRYO is quite complex and takes many steps
A. _FERTILIZATION : fusion of egg and spermduring sexual reproduction to produce a diploidzygote cell
B. _CLEAVAGE: repeated mitotic divisions of azygote that makes a mass of cells• Takes several days• Cells have no function yet
C. _GASTRULATION: development of amultilayered embryo
• Cell Differentiation: embryo forms DIFFERENT tissue layers and cells SPECIALIZE to carry out a particular FUNCTION
• 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
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
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
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
• The body has been organized into 11 body systems that work together to maintain homeostasis and supports the major PROCESSES required for LIFE
_HOMEOSTASIS : steady internal state or condition
The body has FEEDBACK mechanisms that respond to changes in the organisms environment and will REVERSE the direction of the UNWANTED change
The body’s NERVOUS and ENDOCRINE systems along with other systems monitor body conditions inside and out
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
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
How is your homeostasis How does your body react todisrupted on a daily basis? correct the situation?
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