7.4$homeostasis$and$cells$ - north medford high school...
TRANSCRIPT
7.4 Homeostasis and Cells
Cells have the same basic composi6on, and the same kinds of organelles, but not all living
things are the same
Unicellular Organisms ! Homeostasis – rela6vely constant internal physical
and chemical condi6ons
! Single-‐celled organisms (protozoans, yeast, algae, bacteria) are living too
! Maintain homeostasis
! Grow
! Respond to the environment
! Transform energy
! Reproduce
Mul6-‐cellular Organisms ! Cells have a certain job in the body and
are specialized for their task
Human trachea epithelial cells -‐ have cilia to catch debris when you breathe in air !
Pollen grains from pine tree -‐ Tiny, lightweight, protec6ve covering . Float in the wind un6l they land on seed cone
Levels of Organiza6on ! Cells make…
! Tissues, which make…
! Organs, which make…
! Organ systems, which makes…
! Organisms
Cellular Communica6on ! Cells are specialized, but
interdependent
! Cells MUST communicate effec6vely and this is done by means of “chemical signals”.
! Some cells form a connec6on to another cell, called cellular junc.ons
! Signals pass through junc6ons, but only if they have the right receptor – specific protein that has specific shape that molds to a specific molecular messenger
Ex: juncAons in the heart – electrical signals pass through junc6ons to make heart contract and pump blood