Playlist: Cells, Tissues, and Skin
After an introductory segment on cell characteristics, this program discusses the way human body cells function and combine into the structures that sustain life. Topics include membrane permeability and the processes of passive and active transport; cytoplasm, with its cytosol, organelles, and inclusions; the constituent parts of the nucleus and the stages and processes of the cell cycle; the four basic tissue types; and the skin, the body’s largest organ. A viewable/printable instructor’s guide is available online. A Films for the Humanities & Sciences Production. A part of the series The Human Body: How It Works. (22 minutes)
The human body consists of many types of cells. Common characteristics include the plasma membrane, nucleus, organelles, and cytoplasm.
Cell membranes are semipermeable barriers that surround cells, controlling which particles enter and leave the cells.
Diffusion is essential to all living things. It is the process by which particles spread from regions of higher concentrations to regions of lower concentrations. Diffusion distributes molecules rapidly over short distances.
Simple and facilitated diffusion allow particles to enter and exit cells without the use of energy. The concentration gradient determines the net direction of flow.
Osmosis is the diffusion of water through a semipermeable membrane, from a low concentrate solution to a highly concentrated solution. Vocabulary: hypertonic, hypotonic, and isotonic.
Active transport processes use energy to allow particles to enter and leave cells against concentration gradients. Types of active transport include solute pumping and vesicular transport.
Cytoplasm is a clear, colorless substance that fills the area inside the cell membrane and outside the nucleus. It consists of cytosol, inclusions, and organelles, which include endoplasmic reticulum, Golgi apparatus, mitochondria, and more.
The nucleus contains the genetic code to produce nearly every cell in the body. Nuclear pores regulate the entry and exit of large particles. Vocabulary: histone proteins, DNA, and RNA.
Cells go through a sequence of changes called the cell cycle that leads to cell division. Vocabulary: interphase, mitosis, cytokinesis, and differentiation.
Groups of cells that work together for a common goal are called tissues. The human body has four basic types: epithelial, connective, muscle, and nerve.
The skin is the largest organ. It is composed of three layers: the epidermis, dermis and subcutaneous. Vocabulary: keratinocytes, melanocytes, homeostasis, and integumentary system.