MECHANISMS OF CELL INJURY
This program will discuss MECHANISMS of Cell Injury.
HYPOXIA

Hypoxia is caused by inadequate oxygenation. This can come about in several ways. Perhaps the most common cause of hypoxia in animals is the lack of blood to a tissue. Can you think of any ways in which the blood supply to a tissue could be reduced or cut off?

Even with a normal blood supply, an animal can become hypoxic. How?

HYPOXIA MECHANISMS

Why is it important that cells get oxygen?

What is the mechanism of hypoxia-induced cell death?

A. IT PRODUCES FREE HIGH ENERGY OXYGEN RADICALS WHICH DAMAGES CELL MEMBRANES

or

B. IT STOPS OXIDATIVE PHOSPHORYLATION

Now, let's move on to other causes of cell injury..

PHYSICAL AGENTS
Can you think of any physical agents that might induce a cell to die?
RADIATION

Question - What are the two theories as to the mechanism of radiation induced cell injury?

But hey, you don't have to live near Chernobyl to experience effects of radiation, right!!!. The most common source of radiant energy induced damage to animals and humans is? Answer »

Chemical agents and drugs can be cause of cell death... Just one example of a chemical agent inducing cell death is that of cyanide. Do you remember the mechanism of poisoning by cyanide?

Can you think of a realistic way in which an animal might become poisoned with cyanide. Answer »

Infectious agents are another adverse influence that can cause cell injury and death. Every species has its own herpes virus, and herpes viruses are responsible for many different diseases. Do you know some diseases that are caused by herpes viruses?

HERPES INCLUSION BODY

Herpesviruses replicate initially in the nucleus, where non-enveloped viral particles accumulate leading to rapid and severe nuclear changes.

Nucleoli shrink, and chromatin is dissolved or peripheralized at the nuclear membrane. Interference with the host cells genetic material leads to cell death.

The lesions associated with herpes virus infections often include necrosis, as shown in this trachea, from a cow with infectious bovine rhinotracheitis.
The pathogenesis of this form of cell death is
VIRUS IN CELL ->CELL NECROSIS ->MUCOSAL ULCERATION ->HEMORRHAGE & INFLAMMATION
That's enough about herpes viruses - let's move on to something new.
IMMUNOLOGICAL REACTIONS
Immunological reactions as a cause of cell death...

This dog doesn't have autoimmune hemolytic anemia, but he could have. If he did, would you be able to explain to the owners why he didn't have enough red blood cells? Answer »

Genetic derangements can also be responsible for the death of cells. Name one example of a genetic disease.

NUTRITIONAL IMBALANCES

My favorite nutritional imbalance, and hence the one we're going to go over, is that of selenium and/or vitamin E deficiency.

The most common syndrome seen in association with selenium or vitamin E deficiency is White Muscle Disease.

Grossly, white muscle disease produces pale patches or streaks in the muscle, and can involve skeletal muscles such as those of the thigh, shoulder (even the tongue) as well as the heart

Just how does a deficiency of Selenium or vitamin E cause cell injury and death???
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