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Tissues   

This is a great outline and you may download and print these two pages to study from

 

 

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             Astrocytes

 TISSUE RESPONSE TO INJURY

             Inflammatory and repair processes

  1. Inflammation most injuries promote an inflammatory response.  A cut produces four symptoms: heat, redness, swelling and pain.
    1. The injury will tear cells, releasing their contents.  This signals an inflammatory response.  Injured cellssignal nearby blood vessels to dilate, increasing blood flow to site.  The remainder of the process will be covered in physiology
  2. Repair 2 ways
    1. Regeneration replacement of destroyed tissue by new tissue
    2. Fibrosis proliferation of a fibrous connective tissue called scar tissue

TISSUES THROUGHOUT LIFE 

  1. EPITHELIAL TISSUE THINS
  2. AMOUNT OF COLLAGEN DECLINES
  3. TISSUE REPAIR LESS EFFICIENT
  4. WOUNDS HEAL SLOWLY
  5. BONE, MUSCLE AND NERVOUS TISSUES ATROPHY
  6. THESE ISSUES MAY BE DUE TO POOR DIGESTION OR POOR CIRCULATION IN ADDITION TO THE NATURAL AGING PROCESS

 

What you need to know:

Here's a video that I made for you with many of the slides that I'll use on the exam

43:00

This is an excellent video covering the 4 tissue types as well as membranes.  His objectives are the same as yours.

Cell to Cell Junctions  You need to know these

2:51

This chart has links to each tissue type.  When you look at a tissue, ask yourself the following questions: which of the 4 tissue types am I looking at?  Then:

  1. What is the cellularity?  (how many cells are there)
  2. How much matrix is there?
  3. What does the matrix look like?
  4. Are there fibers?
  5. Where are the nuclei?

Click on any of the links below to find out more and to see slides

Introduction Epithelial Tissues

 

Linings and Coverings Simple

Epithelia

Squamous
Cuboidal
Columnar
Pseudostratified
Classifying or Naming Epithelia Stratified

Epithelia

Squamous
Transitional
Cuboidal and Columnar
Glands Exocrine Glands Ducts and Tubules
Endocrine Glands
Connective Tissues Fluid Connective Tissues Lymph
Blood
Connective Tissues Proper Loose Connective Tissues Areolar
Loose Connective Tissues and Inflammation Adipose
Reticular
Dense Connective Tissues Regular(collagen)
Irregular(collagen)
Regular(elastic)
Supportive Connective Tissues Osseous Tissue Compact
Cancellous
Cartilage Hyaline
Elastic
Fibrocartilage
Muscle  Tissues Non-striated Smooth Muscle
Striated Skeletal Muscle
Cardiac Muscle
Nervous Tissues Neurons Multipolar Neurons in CNS
Nerves Nerves of the PNS
Receptors Miessner's and Pacinian Corpuscles

Detailed explanation of cellular junctions:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/J/Junctions.html

Adherens Junctions

Adherens junctions provide strong mechanical attachments between adjacent cells.

  • They hold cardiac muscle cells tightly together as the heart expands and contracts.
  • They hold epithelial cells together.
  • They seem to be responsible for contact inhibition.
  • Some adherens junctions are present in narrow bands connecting adjacent cells.
  • Others are present in discrete patches holding the cells together.

Adherens junctions are built from:

  • cadherins  transmembrane proteins (shown in red) whose
    • extracellular segments bind to each other and
    • whose intracellular segments bind to
  • catenins (yellow). Catenins are connected to actin filaments

Inherited mutations in a gene encoding a cadherin can cause stomach cancer. Mutations in a gene (APC), whose protein normally interacts with catenins, are a common cause of colon cancer.

Loss of functioning adherens junctions may accelerate

Gap Junctions

Gap junctions are intercellular channels some 1.52 nm in diameter. These permit the free passage between the cells of ions and small molecules (up to a molecular weight of about 1000 daltons).

They are cylinders constructed from 6 copies of transmembrane proteins called connexins.

Because ions can flow through them, gap junctions permit changes in membrane potential to pass from cell to cell.

Examples:

  • The action potential in heart (cardiac) muscle flows from cell to cell through the heart providing the rhythmic contraction of the heartbeat.
  • At some so-called electrical synapses in the brain, gap junctions permit the arrival of an action potential at the synaptic terminals to be transmitted across to the postsynaptic cell without the delay needed for release of a neurotransmitter.
  • As the time of birth approaches, gap junctions between the smooth muscle cells of the uterus enable coordinated, powerful contractions to begin.

Several inherited disorders of humans such as

  • certain congenital heart defects and
  • certain cases of congenital deafness

have been found to be caused by mutant genes encoding connexins.

Desmosomes

Desmosomes are localized patches that hold two cells tightly together. They are common in epithelia (e.g., the skin). Desmosomes are attached to intermediate filaments of keratin in the cytoplasm.

Pemphigus is an autoimmune disease in which the patient has developed antibodies against proteins (cadherins) in desmosomes. The loosening of the adhesion between adjacent epithelial cells causes blistering.

Carcinomas are cancers of epithelia. However, the cells of carcinomas no longer have desmosomes. This may partially account for their ability to metastasize.