Please enable JavaScript.
Coggle requires JavaScript to display documents.
Tissue and Cellular Injury (Reversible Cell Injury (Hydropic Swelling…
Tissue and Cellular Injury
Effects of cellular injury
The effect of cell injury depend on
The type of injured cell
Nature and severity of injurious agents
The order of changes in an injured cell
2) functional
3) morphologic changes ( lesion)
1) biochemical
The first important effect of cell injury
It involves a change in the chemistry of one or more metabolic reactions within the cell
The severity of the injury determined the outcomes
Reversible or sub lethal cell injury
It occurs when cell damage mild and cells survive
cells are injured but not killed
the cells return to the previous state of health if the injurious agents can be removed
Irreversible cell injury --> cell death.
It results in damage of the nucleus
Types
Apoptosis: normal(leaves falling) as in menses, aging
Necrosis: pathological
Caused by severe injury
Agents and Causes of Cell Injury
Physical agent (Trauma)
Types are contusion, abrasion, laceration, incised wound, gunshot wounds
Asphyxial injuries include suffocation, strangulation, chemical poisons (carbon monoxide), drowning
Blunt force injuries include car accidents and falls
Excessive heat or cold
Unintentional and intentional injuries
Radiation .
Chemical agent
Endogenous products
example: Urea
Exogenous agents
Therapeutic drugs
example: hormones
Nontherapeutic agents
example: Lead and alcohol
Highly toxic substances are called poisons
Examples are: Chronic exposure causes damage e.g. air pollinates and insecticides
Heavy metals bind to DNA and proteins
Poisons can kill in very small amounts
Reduced oxygen supply ( hypoxia )
main cause of cell injury and it caused by Ischemia (reduced blood supply to the tissue)
causes of ischemia
Hematologic diseases ( aneamia)
Cardiac diseases (congestive heart failiur)
Vascular diseases (arteriosclerosis, embolism and thrombosis)
Pulmonary diseases ( COPD)
Cellular Events in hypoxia
Cytoplasm develops vacuoles
Loss of calcium homeostasis and increased intracellular calcium.
Defects in membrane permeability
Mitochondria swell because of Ca++ ion accumulation.
ATP depletion because mitochondria are damaged
Anaerobic respiration- lactic acid is produced
Lysosomes- swell and release hydrolytic enzyme
Generation of reactive oxygen free radicals.
Cell death occurs
Dilation of endoplasmic reticulum
Free Radicals
How does it cause injury?
Lipid peroxidation
DNA fragmentation
Cross-linking of proteins
example
Hydroxyl radicals OH
superoxide O2 & CCL3
Pathogens
cause damage when they invade cells
Pathogens produce toxins
Genetic abnormalities ( Down's Syndrome)
Nutritional imbalances
Lipid deficiency
Hyperlipidemia
Glucose deficiency
Vitamin deficiencies
Protein-calorie malnutrition
Malabsorption syndromes
Protein deficiency
Abnormal immunological reaction
autoimmunity
immunodeficiency
Hypersensitivity
Reversible Cell Injury
Cloudy Swelling
Cause
Failure of the Na+ and K+ Pump in the cell membrane
Example
Heart causes dilatation and decrease cardiac efficiency
Definition
Reversible cell injury characterized by excess water accumulation inside the cell . it is the most common form of degeneration which will be change to the more advanced form (hydropic swelling )
Hydropic Swelling (degeneration)
cause
Failure of the Na+ and K+ pump in the cell membrane
Example
Epidermal cells in burns
Beta cells of islets of Langerhans in early diabetes mellitus
Definition
Reversible cell injury characterized by excess water accumulation inside the cell forming vacuoles in the cytoplasm. It is more advanced than cloudy swelling
The damaged organ become swollen and on section have pale and swollen appearance
Process of hydropic degeneration
Na+ and water move into cell
K+ moves out of cells
Hypoxia => ATP decreases
More water moves into cell (excess cell hydration)
Extensive vacuolation occurs
Amyloidosis
Amyloid
waxy glycoprotein substance deposited in the extracellular tissues particularly around the vessels and in basement membranes
Amyloidosis
Definition
abnormal accumulation of amyloid in the tissues in amounts sufficient to impair normal functions of the affected organs
Cause
Abnormal accumulation of amyloid in the tissue
Example
Kidney + heart + GI tract
Mucoid swelling
(mucoid degeneration)
Cause
Excess mucin inside the epithelial cells of the mucous membranes
Example
Catarrhal inflammation
Hyaline changes
(Hyalinosis)
A microscopic glossy appearance
Example
Dense collagen particularly in benign tumors
Pathological Calcification
Dystrophic calcification
Example
Heart valve in elderly individual
more common
Cause
Pathological deposition of Ca+ salt in injured necrotic tissue.
Plasma calcium and metabolism : normal
Metastatic Calcifications
other causes
Vitamin D disorders
Renal failure
Increased parathyroid hormone
Destruction of bone tissue
Cause
Pathological deposition of Ca+ salt in injured living tissue.
Plasma calcium level and metabolism: abnormal (hypercalcaemia)
less normal
Fatty changes
Example
Liver
Fatty change in the liver
Accumulation of fats in the liver
Increased movement of free fatty acids to the liver
Failure of conversion of fatty acids to phospholipids, or triglycerides
Failure of transport (exit mechanisms) system
Cause
Excess accumulation of fat in non – fatty tissues
Pigmentation
Endogenous
Bilirubin
Iron free yellowish pigments formed from red blood cells (hemoglobin) breakdown
Haemosiderin
Iron containing brown granules formed from red blood cells or hemoglobin breakdown
Melanin
colours skin, hair iris and choroids
. It form in the skin by the melanocytes from the amino acid tyrosine which converts to melanin by enzyme tyrosinase .
Lipochrome
Yellowish brown pigments of lipid origin
Example
Brown atrophy of the Heart
Exogenous
Ingestion
Cause
chronic ingestion of metals such as silver and lead or food like carrots
Example
Lead- cause blue pigmentation of oral mucous and gum.
Carrots – cause yellowish red skin pigmentation caused by carotene
Injection
Cause
Tattooing
Inhalation
Cause
Coal dust (Carbon)
Example
Coal dust causes black pigmentation in the lung (Anthracosis)
Pathological conditions caused by disturbed pigment metabolism
Brown atrophy of the heart
Cardiac disorders characterized by the presence of excess lipochrome pigments inside the myocardial cells
Decreases melanin pigments cases
Albinism: Hereditary disease characterized by absence of melanin pigment due to deficiency of tyrosinase enzyme . The hair is white , while the skin , iris and choroids are pink .
Leucoderma : Acquired disease characterized by deficiency of melanin and manifested by white skin patches .It may be idiopathic or secondary to syphilis
Haemosidrosis
Accumulation of excess haemosidrin deposits in the tissues giving a brown colour
Types
Localized
Occur around areas of bleeding
Example
varicose veins
Generalized
Causes
Prolonged iron therapy
Repeated blood transfusion
Excessive destruction of RBCs as in haemolytic anaemia
Increased melanin pigments occurs as a result of
Melanomas : pigmented tumors of melanocytes
Addison's disease : brown pigmentation of the skin and mucous membranes caused by adrenocortical insufficiency
Prolonged exposure of the skin to the sun
Jaundice
accumulation of bile pigments ( bilirubin) causing yellow colour of the tissues
Causes
Excess production of unconjugated bilirubin due to increase rate of RBCs destruction
Decreased binding of unconjgated bilirubin due to deficiency of binding enzymes or presence of some drugs
Decreased excretion of conjugated bilirubin into bile due to billiary obstruction . Because bilirubin is water soluble , it is excreted in the urine and give rise to bilirubinuria and dark urine
Types
Heamolytic jaundice
Results from excess RBCs haemolysis
Physiologic jaundice newborn
It results from immaturity of the enzyme glucurnyle transferase .It occurs between second and fifth days of life and disappear in two weeks
Hepatocellular ( toxic ) jaundice
Results from severe liver diseases such as cirrhosis or malignancy which fail to excrete bilirubin into bile.
Obstructive Jaundice
Results from obstruction of the biliary passage by stenosis , stones or cancer