4.5 Extracellular Junctions, Glands, and Membranes

Objectives: Describe the structure and function of three types of

extracellular junctions. Describe the difference between an exocrine and an

endocrine gland with examples. Describe the way the body’s membranes are organized. Name and describe the major types of membranes in

the body.

Extracellular Junctions Tight Junction: Impermeable barrier forms because

adjacent plasma membrane proteins join together. Keeps things from leaking (stomach or kidney tubules).

Gap Junction: Two adjacent plasma membrane channels joins. Allows ions, sugars, and small molecules to pass between the two cells. Strengthens the cells but also allows them to share

resources. Adhesion Junction: Adjacent plasma membranes do

not touch but are joined by extracellular filaments. Allows the tissues to stretch.

Glands Consists of one or more cells that produce

and secret a product. Exocrine: secrete their product onto the outer

surface or into a cavity. Sweat glands, mammary glands

Endocrine: secrete their products internally and are transported by the bloodstream. Pituitary gland or thyroid

Composed of epithelial tissue, but supported by connective.

Membranes

Line the internal spaces of organs and tubes that open to the outside.

Mucous Membranes: line the interior walls of the organs and tubes that open to the outside of the body

Serous Membranes: line cavities Synovial Membranes: line freely movable

joint cavities and are composed of connective tissues.

Membranes Continued Meninges: membranes found within the posterior

cavity. Composed of connective tissue and serve as a protective covering for the brain and spinal cord.

Cutaneous membrane: skin. Forms the outer covering of the body. Next chapter!

In Class Work

The next two slides are your work for today before you are allowed to work on your Tissue Competency.

Please complete the questions on a sheet of paper and turn them in before the end of class.

Medical Focus. P 74-75

Name the four major types of cancer and state the type of tissue they are found in.

Differentiate between a malignant and benign tumor.

What is metastasis and why is it important to catch cancer before it occurs?

Why are chemo and radiation double-edged swords?

Content Check-ups

Page 65 Page 73

Now you can work on your sketches. The slides are also posted online, as are the

rubrics for the past two competencies. Last day for grading/fixing before conferences:

Wednesday.