Patho Unit 1
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balanced sets of chromosomes in any number
An abnormal number of chromosomes in a cell
- phenotype – characteristic facial
- features, some degree of mental retardation. Small rather square head, upward slanting
- eyes, small low set and malformed ears, fat pad at the back of the neck, an
- open mouth, large protruding tongue, short and stubby hands with fingers that
- curl inward, only a single palmar crease, Genotype
- – caused by nondisjunction during the first meiotic division resulting in a
- trisomy of chromosome 21 or translocation of part of chromosome 21 breaks off
- and attaches to another chromosome (usually 14).
phenotype – Short in stature, body proportions are normal, There is an absence of ovaries so she doesn’t menstruate and shows no signs of secondary sex characteristics. Variations of the syndrome with abnormalities ranging from essentially none to webbing of the neck with redundant skin folds, nonpitting lymphedma of the hands and feet and congenital heart defects. Abnormalities of kidney development and changes in nail growth, high arched palate, short fourth metacarpal and strabismus, may have trouble with special perception, visual motor coordination, mathematics and other learning abilities. Genotype - absence of all or part of the X chromosome.
genotype – presence of one or more extra X chromosomes in the normal male XY complement. Phenotype – enlarged breasts, sparse facial and body hair, small testes and the inability to produce sperm. Tall stature with abnormal body proportions in which the lower part of the body is longer than the upper part. The body may become heavy in later life, with female distribution of subcutaneous fat and variable degree of breast enlargement. There may be deficient secondary male sex characteristics such as a voice that remains feminine in pitch and sparse beard and pubic hair. There may be sexual dysfunction along with infertility. Some degree of language impairment and learn to talk later and often have difficulty learning to read and write.
cri du chat syndrome
genotype - the consequence of deletion of part of the short arm of chromosome 5. Phenotype - characteristic cry, low birth weight, mental retardation, microcephaly (abnormally small head), and heart defects.
fragile X syndrome
genotype – X-linked disorder associated with a fragile site on the X chromosome. Affects males more than females. Phenotype – long face with large mandible, large everted ears and large testicles, hyperextensible joints and a high arched palate, and mitral valve prolapse
Identify common characteristics associated with Down
Small rather square head, upward slanting eyes, small low set and malformed ears, fat pad at the back of the neck, an open mouth, large protruding tongue, short and stubby hands with fingers that curl inward, only a single palmar crease
Identify common characteristics associated with Turner Syndrome
Short in stature, body proportions are normal, There is an absence of ovaries so she doesn’t menstruate and shows no signs of secondary sex characteristics. Variations of the syndrome with abnormalities ranging from essentially none to webbing of the neck with redundant skin folds, nonpitting lymphedma of the hands and feet and congenital heart defects. Abnormalities of kidney development and changes in nail growth, high arched palate, short fourth metacarpal and strabismus, may have trouble with special perception, visual motor coordination, mathematics and other learning abilities
Autosomal dominant inheritance
- Single mutant allele transmitted by affected parent to offspring regardless of sex
- Affected parent has 50% chance of passing on
- Unaffected relatives/siblings do not pass on
- May also manifest as a new mutation
Autosomal recessive inheritance
- Only manifested when both members of the gene
- pair are affected
- Both parents may be unaffected by are carriers of the defective gene
- Affects both sexes
- One in four for affected child
- Two in four for carrier child
- One in four for normal (non carrier unaffected)
- homozygous child
- Age of onset = early in life
- Symptomatology tends to be more uniform
- Caused by deficiencies in enzymes rather than abnormalities in structural proteins.
- Almost always associate with X (female) chromosome
- Female heterozygotes rarely experience effects of defective gene
- Unaffected mothers carries one normal and one mutant allele on X chromosome
- 50% chance of transmitting to son and 50% of daughters will be carriers the son then passes on to all the daughters but none of their sons.
probability of a particular defect occurring again if the type of mating which produced it is repeated.
The ability of a gene to express its function. 75% penetrance means 75% of persons of a particular genotype present with recognizable phenotype.
the manner in which the gene is expressed in the phenotype which can range from mild to severe. For example, polydactyly may be expressed as extra toes in one generation and extra fingers in another
- Caused by multiple genes and in many cases, environmental factors
- Number of genes not known and do not follow a clear cut pattern of inheritance
- Can occur during fetal life, at birth or later in life
- i.e. cleft lip and palate, club foot, congenital dislocation of the hip, congenital heart disease, pyloric stenosis and urinary tract malformation
- Environmental factors play a role in disorders of multifactoral inheritance that develop in adult life such as coronary artery disease, diabetes mellitus, hypertension, cancer, manic depressive psychosis, schizophrenia.
- Involves multiple genes at different loci with each gene exerting a small additive effect in determining a trait
- Predictable but with less reliability than single gene traits.
- NO ENVIRONMENTAL EFFECTS
Describe the cellular changes and conditions in which the cellular changes of atrophy occur:
- Decrease in the size of a tissue/organ resulting from a decrease in cell size of the individual cells or in the number of cells.
- Occurs in normally formed Organs
- Cell atrophy is caused by disuse and reduced function or demand, a loss of trophic stimuli, insufficient nutrients, decreased blood from persistant cell injury, aging
- Atrophy is adaptive and reversible
- i.e. menopause, casted arm, paralyzed limbs.
Describe the cellular changes and conditions in which the cellular changes of hypertrophy occur:
- Increase in cell size as well as an increase in the amount of functioning tissue mass
- results from an increased workload imposed on an organ/body part
- commin in cardiact and skelatal muscle tissue, which can not adapt to an increase in workload through miotic division and formation of more cells
- May be from normal physiologic or abnormal pathologic conditions
- EX - increase in muscle mass from working out - normal.
- Pathologic hypertrophy may be adaptive or compensative.
- Adaptive: thickening of urinary bladder from long continued obstruction of urinary outflow
- Compensatory: enlargement of remaining organ or tissue after a part is surgically removed or rendered inactive.
Describe the cellular changes and conditions in which the cellular changes of hyperplasia occur:
- Increase in number of cells in an organ or tissue
- It occurs in tissues with cells that are capable of miotic division (i.e. epidermis, intestinal epitheliam and gladular tissue NOT Nerve cells/skelatle and cardiact muscle).
- Controlled process that occurs in response to an appropriate stimulus and ceases after the stimulus has been removed.
- Stimuli might be physiologic or nonphysiologic.
- Physiologic Hyperplasia: occur as the result of hormal stimulation or increased functional demands as a compensatory mechanism (breast and uterine enlargemtn during pregnancy are examples)
- **Hypertrophy and hyperplasia are two distinct processes, they may occur together and are often triggered by the same mechanism**
- Nonphysiologic hyperplasia: excessive hormonal stimulation or the effects of growth factors on target tissues. Excessive estrogen production can cause endometrial hyperplasia and abnormal menstral bleeding.
Describe the cellular changes and conditions in which the cellular changes of metaplasia occur:
- Reversible change in which one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type.
- Involves the reprogramming of undifferentiated stem cells that are present in the tissue undergoing the metaplastic changes.
- Occurs in response to the crhonic irritation and inflammation and allows for substitution of cells that are better able to survive under circumstances in which a more fragile cell type might succumb.
Describe the cellular changes and conditions in which the cellular changes of dysplasia occur:
- Characterized by deranged cell growth of a specific tissue that results in cells that vary in size, shape and appearance.
- Chronic irritation or inflammation.
- pattern is most frequently encountered in metaplastic squamous epithelium of the respiratory tract and unterine cervix.
- Strongly implicated as a precursor of cancer
- sequential mutations in proliferating cell populations
- Deprives the cell of oxygen and interrupts oxidative metabolism and the generation of ATP.
- Can result from an inadequate amount of oxygen in the air, respiratory disease, ischemia (decreased blood flow caused by circulatory disorders), anemia, edema, or inability of the cells to use oxygen.
- Hypoxia literally causes a power failure in the cell with widespread effects on the cell's functional and structural components.
- As oxygen falls, oxidative metabolism ceases, cell reverts to anerobic metabolism, uses limited glycogen stores and cellular pH falls, reduction in pH can have profound effect on the intracellular structures.
- Electrically uncharged atom or group of atoms that has an unpaired electron.
- Free radicals may be intiated within cells by (1) absorption of extreme energy sources (e.g. ultraviolet light radiation), (2) endogenous reactions when oxygen is reduced to water created by systems involved in electron and oxygen transportand (3) enzymatic metabolism of exogenous chemicals or drugs.
- Cause several damaging effects (1) lipid peroxidation which is the destruction of polyunsaturated lipids leading to membrane damage and increased permeability (2) attacking critical proteins that affect ion pumps and transport mechanisms (3) fragmenting DNA causing decreased protien sythensis and (4) damaging mitochondria causing the liberation of calcium into the cytosol.
Reactive Oxygen Species
- ROS - Oxidative stress - occurs when excess ROS overwhelms endogenous antioxident systems.
- Generated either (1) directly during autoxidation in mitochondria or (2) enzymatically by enzyms in the cytoplasm, such as xanthine oxidase or cytochrome. Once produced it can be inactivated spondaneously or more rapidly by the enzyme superoxide dismutase.
- Begins with a biochemical interaction between a toxic substance and the cell's plasma membraine which is ultimately damaged, leading to increased permeablility.
- The two general mechanisms include (1) direct toxicity caused by combination of chemical wi th a molecular component of the cell membrane or organelles and (2) formation of reactive free radicals and lipid peroxidation.
Tearing, shearing or crushing of tissue
bleeding into the skin or underlying tissues as a consequence of a blow that squeezes or crushes the soft tissues and ruptures blood vessels without breaking the skin
Results from removal of the superficial layers of the skin that was caused by friction between the skin and the unjuring object.
- Tear or rip resulting when the tensile strength of the skin or tissue is exceeded. Jagged and irregular and the edges are abratted.
- Often tissue "bridges" of small vessels or nerves that have been stretched but not broken, crossing from one side of the wound to the other.
- Lacerations to internal organs may occur from blows but cannot be seen externally.
Blunt force blows/impacts can cause a bone to break or shatter.
- Penetrating (bullet remains in the body)
- Perforating (bullet exits)
- Gunshot victims can be alert and acting normal even though their wounds may be fatal.
- Caused by a failure to received or utilize oxygen. Deprivation of oxygen may be partial (hypoxia) or total (anoxia).
- Suffocation - oxygen failing to reach the blood - lack of oxygen in the environment or blockage to external airway.
- Strangulation - Compression and closure of blood vessels and air passages.
- Chemical asphyxiants - either prevent the delivery of oxygen to the tissues or block utilization.
- Drowning - an alteration of oxygen delivery to tissues resulting from the breating in of fluid.
Disease producing potential of a microorganism depends on its ability to (1) invade and destroy cells, (2) produce toxins, and (3) produce damaging hypersensitivity reactions.
Immunologic and inflammatory injury
- Cellular membranes are injured by direct contact with cellular and chemical components of the immune and inflammatory responses such as phagocytic cells and substances such as histamine, antibodies, lymphokines, complement and proteases.
- Complement is responsible for many of the membrane alterations that occur during immunologic injury
- Membrane alterations are associated with a rapid leakage of potassium.
- Cellular swelling, the most common degenerative change is caused by the shift of extracellular water into the cells.
- Injury - Hypoxia -> ATP Production decreases -> Sodium and water move into cell; Potasium move out of cell -> Osmotic pressure increases -> More water moves into cell -> cisternae of endoplasmic reticulum distend, rpture and form vacuoles -> Extensive vacuolation - Hydropic Degeneration
- Oncosis (means swelling) is a form of cell death where the mechanism is failure of the Na+/K+ pumps of the plasma membrane. Caused by ischemia and possibly by toxic agents that interfere with ATP generation.
- Cellular swelling is reversible and is considered sublethal.
Lipids and Carbohydrates
- Lipids and Carbohydrates can accumulate throughout the body but are usually in the spleen liver and CNS.
- Accumulations of cells in the CNS can cause neurologic dysfunction and severe mental retardation.
- Lipids accumulate in Tay Sachs disease, Niemann-Pick disease, and Gaucher disease.
- The mucopolysaccharidoses (carbohydrates are in excess) are progressive disorders that usually involve multiple organs, including the liver, spleen, heart and blood vessels.
- They are found in reticuloendothelial cells, endothelial cells, intimal smooth muscle cells, and fibroblasts throughout the body. These carbohydrate accumulations can cause clouding of the cornea, joint stiffness, and mental retardation.
- Lipds accumulate in heart and kidneys but most comonly are in the liver. (fatty change)
- Hepatic metabolism and secreation of lipids is crutial to proper body function, imbalances and deficiencies in these processes lead to major pathologic changes.
- Protein accumulation probably damges cells in two ways:
- 1. Metabolites produced when the cell attempts to digest some protiens are enzymes that when released from lysosomes can damage cellular organelles
- 2. excessive amounts of protein in the cytoplasm push against cellular organelles, disrupting organelle function and intracellular communication.
- usually excess accumulates primarily in the epithelial cells of the renal confoluted tubule and in the antibody forming plasma cells of the immune system. Several types of renal disorders cause excessive excretion of protien molecules in the urine.
- Accumulations of protein in B lymphocytes can occur during active synthesis of antibodies during the immune response. The excess aggregates of protein are called Russell Bodies, which have been identified in multiple myeloma (plasma cell tumor).
- Pigment accumulations may be normal or abnormal, endogenous (produced within the body) or exogenous (produced outside the body).
- Endogenous pigments are derived, for example, from amino accids - they include melanin and the blood protein. Lipid rich pigments such as lipofuscin give a yellow brown color to cells undergoing slow regressive and often atrophic changes.
- Exogenous pigments include mineral dusts containing silica and iron particles, lead, silver salts, and dyes for tattoos.
- They accumulate in both injured and dead tissue.
- Important mechanism of cellular calcification is the influx of extracellular calcium in injured mitochondria
- Another mechanism that causes calcium accumulation in alveoli, gastric epithelim, and renal tubules is the extretion of acid at these sites, leading to the local production of hydroxyl ions.
- Damage occurs when calcium salts clump and harden, interfering with normal cellular structure and function.
- Dystrophic calcification - occurs in dying and dead tissue; chronic tuberculousis of the lungs and lymph nodes, advanced atherosclerosis, and heart valve injury.
- Metastatic calcification - consists of mineral deposits that occur in undamaged normal tissues as the result of hypercalcemia.
- Uric Acid is the major end product of purine catabolism in the absence of urate oxidase.
- Disturbances in maintaining serum urate levels result in hyperuricemia and the deposition of sodium urate crystals in the tissues leading to painful disorders collectively called gout.
- CELLULAR DEATH eventually leads to cellular dissolution or necrosis.
- Necrosis is the sum of cellular change after local and cell death and the process of cellular self-digestion known as autodigestion or autolysis.
Occurs primarily in the kidneys, heart, and adrenal glands; commonly results from hypoxia caused by severe ischemia or hypoxia caused by chemical injury, especially ingestion of mercuric chloride. Coagulation is caused by protein denaturation, which causes the protein albumin to change from a gelatinous, transparant state to a firm, opaque state.
- Commonly resutls from ischemic injury to neurons and glial cells in the brain.
- Dead brain tissue is readily affected by liquefactive necrosis because brain cells are rich in the digestive hydrolytic enzymes and lipids and the brain contains little connective tissue.
- Cells are digested by their own hydrolases so the tissue becomes soft, liquefies, and is walled off from healthy tissue, forming cysts. This can be caused by bacterial infection especially staphylococci, streptococci and escheria coli.
- Usually results from tuberculous pulmonary infection, especially by mycobacterium tuberculosis.
- Combination of coagulative and liquefactive necrosis.
- Dead cells disintergrate but the debris is not completely digested by the hydrolases.
- Tissues resemble clumped cheese in that they are soft and granular.
- Granulomatous inflammatory wall encloses areas of caseous necrosis.
- Cellular dissolution caused by powerful enzymes, called lipases, that occur in the breast, pancreas and other abdominal structures.
- Lipases break down triglycerides, releasing free fatty acids, which then combine with calcium, magnesium and sodium ions, creating soaps (saponification)
- Necrotic tissue appears opaque and chalk-white.
- Death of tissue and results from severe hypoxic injury, commonly occuring because of arteriosclerosis, or blockage, of major arteries, particularly those in the lower leg.
- Hypoxia and subsequent bacterial invasion, the tissues can undergo necrosis.
- DRY GANGRENE is usually the result of coagulative necrosis. The skin becomes very dry and shrinks, resulting in wrinkles, and its color changes to dark brown or black.
- WET GANGRENE develops when nuetrophils invade the site, causing liquefactive necrosis. This usually occurs in internal organs, causing the site to become cold, swollen and black. A foul order is present and if systemic symptoms become severe, death can ensue.
- A special tiype of gangrene caused by infection of injured tissue by one of many species of clostridium.
- These anaerobic bacteria produce hydrolytic enzymes and toxins that destroy connective tissue and cellular membranes and cause bubbles of gas to form in muscle cells.
- This can be fatal if enzymes lyse the membranes of red blood cells, destroying their oxygen-carrying capacity. Death is caused by shock.
Apoptosis (dropping off) VS Necrosis
Apoptosis is an active process of cellular destruction called programmed cell death - cells need to die otherwise endless proliferation would lead to gigantic bodies.
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