PATHOLOGY & PATHOPHYSIOLOGY

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1 PATHOLOGY & PATHOPHYSIOLOGY CHAPTER 2: CELLULAR PATHOLOGY

2 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

3 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

4 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

5 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

6 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 2 nd 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

7 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)

8 OBESITY Weight loss is important as it improves metabolic or hormonal abnormalities Prevention: Regular good quality meals Increased activity Education! (parents, children, teenagers and adults)

9 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

10 OBESITY Treatment of Obesity: Behaviour therapy: Self-monitoring of eating habits Stress management Stimulus control Problem solving Social support Relapse control Pharmacotherapy Surgery

11 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

12 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

13 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

14 CELLULAR ADAPTION HYPERTROPHY:

15 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

16 CELLULAR ADAPTION DYSPLASIA: Deranged cell growth in a tissue that results in cells that vary in size, shape and organisation Why does dysplasia occur? Associated with chronic irritation and inflammation Warning sign of impending cancer Examples: Respiratory tract Uterine cervix

17 CELL INJURY When cell adaptation is not enough to protect the cell Mild injury Severe injury Repair Apoptosis Cell death Healing Necrosis

CELL INJURY APOPTOSIS: Programmed cell death A normal process that occurs at the end of the lifespan of a cell Examples: http://www.systembio.

18 CELL INJURY APOPTOSIS: Programmed cell death A normal process that occurs at the end of the lifespan of a cell Examples: After 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

19 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

20 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

21 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

22 QUESTIONS

Biochemistry of Nutrition. Prof K Syed Department of Biochemistry & Microbiology University of Zululand Room no. 247

Biochemistry of Nutrition. Prof K Syed Department of Biochemistry & Microbiology University of Zululand Room no. 247 Biochemistry of Nutrition Prof K Syed Department of Biochemistry & Microbiology University of Zululand Room no. 247 SyedK@unizulu.ac.za Unit 5 Malnutrition (dietary excesses & deficiencies) Obesity Kwashiorkor