Biology 322 Human Anatomy I Basic Cytology

Recall: SYSTEMS are composed of one or more organs, all serving a common function ORGANS are composed of one or more types of tissues, all serving a common function TISSUES are composed of one or more types of cells and their products, all serving a common function CELLS are composed of different types of organelles, all serving a common function ORGANELLES are composed of different types of molecules, all serving a common function

- Produce complex molecules from simpler precursers, All cells in the human body share some important characteristics: - Obtain nutrients from surrounding extracellular matrix and secrete waste products into it. - Use oxygen to metabolize fuel molecules - Produce complex molecules from simpler precursers, either for their own use or for export AND break complex molecules back down into smaller ones - Interact with other cells - Reproduce themselves (this characteristic is lost in some cells and retained in others)

Cells: - Highly organized; composed of organelles and cytoplasm - Arise from prexisting cells Some exist as stem cells to replace more specialized ones - In human, all eukaryotic: nuclei and other organelles surrounded by membranes, with an extensive system of membranes to manufacture cellular products and distribute them within the cell. However: cells of each tissue and organ are specialized to carry out its specific physiologic functions. Some cells are highly specialized & can perform only one function, while others are relatively unspecialized with many functions.

Cells: Size is highly variable Average = 10 micrometers diameter Range = 4 micrometers (sperm) 100 micrometers (oocyte) Skeletal muscle cells may be 300 millimeters long Nerve cells may be more than a meter long

Cells: Shape is highly variable:

As we discuss the different tissues and organs of the human body in this course, we will discuss the specific structures and functions of their cells. To do that, you will need to understand the structures and functions of different cellular organelles…

Independent Study: Your textbook discusses the organelles of most cells, which were also discussed in Basics of Life (BIOL 241). You should understand the basic structure and function of each of the following: Nucleus Ribosomes Endoplasmic reticulum Golgi complex Mitochondria Lysosomes Peroxisomes Vesicles Cytoskeleton You should also understand the basic structure and function of cilia and flagella You will be responsible for these on exams

Plasma Membrane: Also called "plasmalemma" May have special names in specific types of cells e.g. "sarcolemma" in muscle cells, "neurolemma" in nerve cells Keeps inside in and outside out while - Controlling movement of ions/ molecules into and out of cell - Interacting with other cells and with extracellular materials around the cell - Allowing cell to recognize and respond to chemical signals such as hormones, growth factors, and neurotransmitters

Plasma Membrane: Basic structure = double layer of phospholipids with proteins and cholesterol embedded within it This is the “fluid mosaic” model you learned about in Basics of Life (BIOL 241) and other courses.

Plasma Membrane: Has specialized junctions for cell-to-cell attachment and/or communication

Plasma Membrane: Tight junctions: Protein molecules in plasma membranes of two adjacent cells form bonds; hold cells strongly together and prevent materials from passing between them

Plasma Membrane: Desmosomes: Protein molecules in plasma membranes of two adjacent cells form bonds in isolated spots; hold cells strongly together

Plasma Membrane: Gap Junctions: Protein molecules in plasma membranes of two adjacent cells form channels between them; allow molecules to flow from cell to cell

Let’s put those cells (and the things they produce) together to form tissues