Chapter 7.4 Homeostasis and Cells

Daily Objectives Compare and contrast how unicellular and multicellular organisms maintain homeostasis. Explain why cell specialization is important for multicellular organisms.

Homeostasis Homeostasis is relatively constant internal physical and chemical conditions. Both unicellular and multicellular organisms must maintain homeostasis. In the box on your notes draw a diagram that will help you remember homeostasis.

Homeostasis Homeostasis is relatively constant internal physical and chemical conditions. Both unicellular and multicellular organisms must maintain homeostasis. In the box on your notes draw a diagram that will help you remember homeostasis.

Homeostasis

Unicellular Organisms Cells are the basic living units of all organisms, but sometimes one cell is the entire organism In order to maintain homeostasis unicellular organisms must: Grow Respond to the environment Transform energy Reproduce

Unicellular Organisms include: Prokaryotes (Bacteria) Remarkably adaptable Live almost everywhere (including inside of us) Eukaryotes (Protists , algae, and yeast) Have a nucleus Contain membrane bound organelles Live in a variety of places Able to do everything necessary to live independently

Examples of Unicellular Organisms

Multicellular Organisms Always Eukaryotes Like unicellular organisms, multicellular organisms show all the characteristics of life However, multicellular organisms depend on communication and cooperation among specialized cells Cell specialization - Cells throughout an organism develop in different ways to perform different tasks

Analogy for Cell Specialization _______________________________________________

Examples of Specialized Animal Cells Red Blood Cells – Specialized to transport oxygen Contain a protein (hemoglobin) that binds to oxygen Pancreatic Cells – Specialized to produce enzymes (proteins) that make it possible to digest food What organelles would pancreatic cells have a lot of? Skeletal Muscle Cells – Specialized to produce a force using a dramatically overdeveloped cytoskeleton → so organisms can move

Examples of Specialized Animal Cells

Levels of Organization Used to make it easier to describe multicellular organisms Cells → Tissues → Organs → Organ Systems → Organism

Tissues A group of similar cells that perform a particular function Example: skin tissue, muscle tissue, or nerve tissue

Organs Many tasks within the body are too complicated to be carried out by just one type of tissue Many groups of tissues work together as an organ → each tissue performs an essential task to help the organ function In most cases, organs complete a series of specialized tasks Example: lung, heart, and brain

Organ Systems A group of organs that work together to perform a specific function is called an organ system Example: Cardiovascular System Respiratory System Digestive System

Importance of Cell Specialization Organization of the body’s cells into tissues, organs, and organ systems creates a division of labor among those cells that makes multicellular life possible

Cellular Communication Cells in a large organism communicate by chemical signals that are passed from one cell to another These signals can speed up or slow down activities in the cell, or completely change what the cell is doing Ex. Hormones in the body

Review of Daily Objectives Compare and contrast how unicellular and multicellular organisms maintain homeostasis. Explain why cell specialization is important for multicellular organisms.