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PATHOLOGY & PATHOPHYSIOLOGY

CHAPTER 2: CELLULAR PATHOLOGY

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OBJECTIVES

Discuss the factors that can cause injury to cells

Differentiate between the various ways that cells adapt to

stressors

Look at the two ways that cell death can occur

Classify body cells into three categories according to their

ability to undergo regeneration


CELL STRESSORS

Physical agents, e.g. trauma, electric shock, extreme cold/heat

Chemical agents, e.g. insecticides, alcohol and heavy metals

Biological agents, e.g. viruses, bacteria and worms

Nutritional agents (deficiency, obesity and starvation)

Free radicals

Lack of oxygen


CELL STRESSORS

NUTRITIONAL AGENTS:

Malnutrition:

Person does not ingest adequate amounts of nutrients for

normal body function

Protein-energy malnutrition: When you break down lean

tissue (fat-free tissue: skeletal muscles, viscera and cells of

the immune system or blood) in order to supply your body

with energy. It occurs in cases of starvation or serious

illnesses, e.g. cancer


CELL STRESSORS

NUTRITIONAL AGENTS:

Malabsorption:

Inability of the small intestine to absorb

one/more necessary nutrients, e.g.

gastro-intestinal infections, pernicious

anaemia and coeliac disease


CELL STRESSORS

NUTRITIONAL AGENTS:

Obesity:

Obesity is defined as a condition characterised by excess body fat

Clinically, obesity and overweight have been defined in terms of the BMI

(body mass index)

Overweight is a BMI of ≥ 25 and obesity is BMI of ≥ 30

It is the 2nd leading cause of preventable death in the US

Research suggests that fat distribution may be a more important factor

for morbidity and mortality than overweight or obesity

Two types: central and peripheral obesity

Central obesity is more of a health risk than peripheral obesity


OBESITY

Obesity increases risk for:

Hypertension

Type 2 diabetes

Coronary heart disease

Gallstones

Hernias

Varicose veins

Osteo-arthritis

Post-operative complications

Infertility

Carpal tunnel syndrome

Sleep apnea

Cancer of endometrium, prostate, colon, uterus, ovaries, kidneys,

gallbladder and breast (in post-menopausal women)


Weight loss is important as it improves metabolic or

hormonal abnormalities

Prevention:

OBESITY

Regular good quality meals

Increased activity

Education! (parents, children,

teenagers and adults)


OBESITY

Treatment of Obesity:

Healthy diet:

Must be individualised

500 to 1000 kcal/day less than current dietary intake

A reduction of dietary fat without a calorie deficit will not result in

weight loss

Frequent contact with a dietician/nutritionist

Increased physical therapy:

Reduces body fat

Prevents the loss of muscle mass that often occurs with weight loss

Exercise should be started slowly

Aim for 30 minutes of moderate activity for most days of the week


OBESITY

Treatment of Obesity:

Behaviour therapy:

Self-monitoring of eating habits

Stress management

Stimulus control

Problem solving

Social support

Relapse control

Pharmacotherapy

Surgery


CELL STRESSORS

What does a cell do when it is under “stress”?

The cell tries to adapt in order to secure its survival by

undergoing changes in their size, number and type

When a cell experiences prolonged or overwhelming stress it

will become injured or die


CELLULAR ADAPTION

ATROPHY:

Cells become smaller in size

Why does atrophy occur?

The cell is not getting what it needs OR the cell is not as necessary for the

body anymore

Atrophy of a cell decreases its energy requirements

Occurs when there is:

disuse

denervation

loss of endocrine stimulation

inadequate nutrition

decreased blood flow to a cell


CELLULAR ADAPTION

HYPERTROPHY:

Increase in cell size

Why does hypertrophy occur?

Occurs when there is an increase in workload on cells that cannot divide

(skeletal muscle, cardiac muscle)

The cell requires more nutrients and oxygen

Examples:

Skeletal muscles that become bigger due to exercise

Increase in the size of cardiac muscle cells if a person has high blood

pressure

One kidney becomes bigger if the other one is removed


CELLULAR ADAPTION

HYPERTROPHY:


CELLULAR ADAPTION

METAPLASIA:

Reversible change in which one cell type is replaced by another cell type

Why does metaplasia occur?

Usually occurs in response to chronic irritation and inflammation

Aim is to protect

Examples:

Trachea of smokers

Intestinal

Cervical http://ocw.tufts.edu/Content/51/lecturenotes/551831/552054


CELLULAR ADAPTION

DYSPLASIA:

Deranged cell growth in a tissue that results in cells that vary in size,

shape and organisation

Why does dysplasia occur?

Examples:

Respiratory tract

Uterine cervix

Associated with chronic irritation

and inflammation

Warning sign of impending cancer


CELL INJURY

When cell adaptation is not enough to protect the cell…

Mild injury

Repair

Healing

Severe injury

Apoptosis

Necrosis

Cell death


CELL INJURY

APOPTOSIS:

“Programmed cell death”

Examples:

After 100–120 days red blood cells are destroyed in the spleen by means of

apoptosis

Occurs in the uterus during the menstrual cycle

Occurs in breast tissue once the baby is weaned

A normal process that occurs at the

end of the lifespan of a cell

http://www.systembio.com/rnai-libraries/pathway-focused/apoptosis/overview


CELL INJURY

NECROSIS:

Abnormal cell death, e.g. during a heart attack, a part of the heart muscle

dies

Differs from apoptosis in that it provokes inflammation around the dead

cells

Examples:

Abscess

Infarction

In the centre of TB granulomas Necrotic leg wound caused by a brown

recluse spider bite http://en.wikipedia.org/wiki/Necrosis


CELL INJURY

GANGRENE:

This term is used when a considerable

mass of tissue undergoes necrosis

The dead tissue becomes invaded by

anaerobic bacteria

The affected area is brown or black

and smells foul


TISSUE REPAIR AND HEALING

REGENERATION:

Injured cells are replaced with new cells of same

type or with scar tissue

Depends on the type of cell and amount of

damage

There are 3 types of cells (depending on how they

regenerate):

Labile

Stable

Permanent


QUESTIONS

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PATHOLOGY & PATHOPHYSIOLOGYforum.dougans-international.com/files/files... · CELL INJURY NECROSIS: Abnormal cell death, e.g. during a heart attack, a part of the heart muscle dies