Study guide exam 1 Flashcards
what is meiosis
results in 4 non-identical haploid daughter gametes after two divisions.
what is nondisjunction?
nondisjunction where there is failed separation of chromosomes during anaphase, so either whole chromosomes (error occurring in meiosis I) or chromatids (error occurring in meiosis II) move to the same pole of the cell. This leaves one gamete short of some genetic information, and the other with additional genetic information.
sister chromatids fail to separate normally during meiosis or mitosis.
what is chromosomal mosaic
usually occurs if trisomy 21 is de novo (mutation occurs after fertilization in 1 cell but not the rest), causes some cells to have trisomy 21 and some to be regular.
cri du chat
rare genetic condition that is caused by the deletion (a missing piece) of genetic material on the small arm (the p arm) of chromosome 5. Not hereditary.
The symptoms of cri du chat syndrome vary among individuals. The variability of the clinical symptoms and developmental delays may be related to the size of the deletion of the 5p arm.
The clinical symptoms of cri du chat syndrome usually include a high-pitched cat-like cry, mental retardation, delayed development, distinctive facial features, small head size (microcephaly), widely-spaced eyes (hypertelorism), low birth weight and weak muscle tone (hypotonia) in infancy. The cat-like cry typically becomes less apparent with time.
Most individuals who have cri du chat syndrome have difficulty with language. Half of children learn sufficient verbal skills to communicate. Some individuals learn to use short sentences, while others express themselves with a few basic words, gestures, or sign language.
Other characteristics may include feeding difficulties, delays in walking, hyperactivity, scoliosis, and significant retardation. A small number of children are born with serious organ defects and other life-threatening medical conditions, although most individuals with cri du chat syndrome have a normal life expectancy.
example of a chromosomal deletion condition
gamete with lost DNA+normal DNA=some normal genes and some missing (cri du chat)
sex chromosome aneuploidy
1/500 males and 1/900 females. Less severe than autosomal. All forms except absence of ANY X allows for survival.
Trisomy X, turner and klinefelter
turner syndrome
sex chromosome aneuploidy
(not hereditary, random and due to nondisjunction)
1 X chromosome, no X or Y (45 chromosomes)aka 45,X
(a) Only in females, not intellectually disabled, but dumb. Short stature, thick neck, wide nipples, coarctation of aorta, sterile. Usually d/t meiotic error in the father
extra skin on the neck (webbed neck), puffiness or swelling (lymphedema) of the hands and feet, skeletal abnormalities, heart defects and kidney problems.
do not start their periods or develop breasts without hormone treatment at the age of puberty
Klinefelter syndrome
Klinefelter syndrome–sex chromosome aneuploidy—2X1Y, 47,XXY (not hereditary, random and due to nondisjunction)
(a) STERILE. Male appearance, female like breasts. Mod. Mental impairment high pitched voice, small testes. Mosaicism common
cystic fibrosis
autosomal recessive
gene responsible encodes a chloride ion channel in some epithelial cells. Dec. chloride transport NaCL imbalance very thick mucous, dehydrated, clogging of dig. Organs and pancrease. Death from lung disease or HF before age 40 in 50% of those affected.
(1) Males=females. Common in consanguinity. Common in siblings but not parents. ¼ of offspring of carrier parents will be affected, ½ will be carriers.
explain x link recessive
males hemizygous, females homozygous. Males will be more affected since they only have 1 X chromosome.
i) X inactivation happens after fertilization. ½ x chromosomes inactivated, not the same in each cell.
fragile X
x linked dominant
intellectual disability, second most common genetic cause of intellectual disability. Males always exhibit symptoms, females not always
Caused by duplication in CGG multiple times (200), number of repeats increases from generation to generation. Huntington and myotonic dystrophy are also caused by this mechanism
A boy who has the full FMR1 mutation has fragile X syndrome and will have moderate intellectual disability. They have a particular facial appearance, characterized by a large head size, a long face, prominent forehead and chin and protruding ears. In addition males who have fragile X syndrome have loose joints (joint laxity), and large testes (after puberty).
Affected boys may have behavioral problems such as hyperactivity, hand flapping, hand biting, temper tantrums and autism. Other behaviors in boys after they have reached puberty include poor eye contact, perseverative speech, problems in impulse control and distractibility. Physical problems that have been seen include eye, orthopedic, heart and skin problems.
Trisomy 21 (from book)
trisomy 21 (3 copies of 1 chromosome). small, low set ears, broad short ears, short eyelashes, protruding tongue. 20-25% survive until birth. increased risk of heart disease d/t high cholesterol levels.
having heart defects, digestive problems such as gastroesophageal reflux or celiac disease, and hearing loss. Some people who have Down syndrome have low activity of the thyroid gland (hypothyroidism) -
trisomy vs quadrosomy
(1) Triploidy—3 copies of each chromosome—most are spontaneously aborted or are stillborn
(2) Tetraploidy—92 chromosomes—mostly in aborted fetuses.
aneuploidy
cell doesn’t contain multiple of 23 chromosomes
trisomy or monosomy (1+ chromosome lost or gained, polyploidys are aneuploidys, but not all aneuploidys are polyploidys)
trisomy vs monosomy
ypes of aneuploidy
trisomy: 3 copies of 1 chromosome (trisomic)—trisome 13, 18, 21 or X can survive
ii) Monosomy—presence of only 1 copy of chromosome in a diploid cell—lethal
iii) Loss of chromosome material has more serious consequences than duplication of chromosome material***
partial trisomy
extra portion of chromosome in each cell. NOT as severe as complete trisomies.
Duchenne muscular dystrophy
DMD is a rapidly progressive form of muscular dystrophy that occurs primarily in boys. It is caused by an alteration (mutation) in a gene, called the DMD gene that can be inherited in families in an X-linked recessive fashion, but it often occurs in people from families without a known family history of the condition. Individuals who have DMD have progressive loss of muscle function and weakness, which begins in the lower limbs. The DMD gene is the second largest gene to date, which encodes the muscle protein, dystrophin. Boys with Duchenne muscular dystrophy do not make the dystrophin protein in their muscles.
Duchenne muscular dystrophy affects approximately 1 in 3500 male births worldwide. Because this is an inherited disorder, risks include a family history of Duchenne muscular dystrophy.
The symptoms usually appear before age 6 and may appear as early as infancy. Typically, the first noticeable symptom is delay of motor milestones, including sitting and standing independently. The mean age for walking in boys with Duchenne muscular dystrophy is 18 months. There is progressive muscle weakness of the legs and pelvic muscles, which is associated with a loss of muscle mass (wasting). This muscle weakness causes a waddling gait and difficulty climbing stairs. Muscle weakness also occurs in the arms, neck, and other areas, but not as severely or as early as in the lower half of the body.
breathing complications and cardiomyopathy are most common causes of death
epigenetics
chemical changes that cause dramatically different phenotypes. Methylation on DNA can cause certain pieces not to be able to be transcribed by mRNA. This affects the expression of genes
explain hypertrophy
compensatory increase in SIZE of cells d/t mechanical load/stress. Increases the size of the affected organ
a. Stretching, pressure, volume overload. Kidneys and heart are prone to this
i. Adaptive—changes to adapt (i.e. increase muscle size)
ii. Compensatory—changes to compensate—i.e lose a kidney the other enlarges
iii. Physiologic—increased demand in absence of pathology
iv. Pathologic—from pathologic cause—enlarged heart d/t HTN
explain atrophy
a. Two categories:
i. Physiologic—normal event (age related gonad atrophy d/t dec. hormone stimulation, dec. in size of thamus in early childhood, aging causes atrophy in brain cells)
ii. Pathologic—occurs d/t decreases in workload, pressure, use, blood supply, nutrition, hormone stim or neural stim (for example disuse atrophy from bed rest or immobilization)
b. What’s different in atrophic muscle cells?
i. Less ER, fewer mitochondria, fewer myofilaments in muscle cells
describe hyperplasia
increase in NUMBER of Cells—d/t inc rate of cellular division
a. Requires that cells undergo mitosis—usually d/t production of growth factors stimulating cells after injury or can be from stem cells (liver cells injured new cells can regenerate from intrahepatic stem cells).
b. Can be compensatory hyperplasia or hormonal hyperplasia
i. Compensatory hyperplasia: adaptive that enables organs to regenerate
1. Remove a piece of the liver, rapid hyperplasia ensues.
2. Callus—resp to injury from mechanical stimulus
3. Wound healing d/t inflammatory process
ii. Pathologic hormonal hyperplasia—abnormal proliferation of normal cells d/t excessive hormonal stimulation or GF on target cells
1. Ex. Endometrial hyperplasia d/t imbalance of estrogen and progesterone. If continues over time the regular growth inhibiting control mechanism can fail and lead to malignancy
2. Ex. BPH or thyroid enlargement d/t excessive levels of TSH
describe dysplasia
—NOT A TRUE ADAPTIVE CHANGE—abnormal changes in size, shape and organization of mature cells. Is related to hyperplasia and referred to as atypical hyperplasia
a. DISORDERLY, but not referring to cancer
b. Common in epithelial tissue of cervix, endometrium, GI and respiratory tract mucosa. Can be reversible if don’t involve the entire thickness of epithelium
i. When dysplastic changes penetrate the basement membrane it’s considered an invasive neoplasm.
describe metaplasia
REVERSIBLE replacement of one mature cell type by another cell type.
a. Associated with tissue damage, repair and regeneration.
b. Adaptive response==new cell type may be better suited to withstand an adverse environment.
i. Example: long term cig. Smoker with chronic irritation from smoke causes normal ciliated columner epithelial cells to be replaced by stratified squamous epithelial cells (don’t secrete mucous or have cilia)
c. Results from reprogramming of stem cells
describe anaplasia
lost the unique characteristics that define them as a certain tissue type.
Anaplasia can be explained as when a cell ‘reverts’ to a more stem-cell like state, one that is often distorted. Often seen in cancer cells, the cell no longer functions as part of the tissue that surrounds it. As the cell undergoes mitosis, it produces cells that also display anaplasia. In this way, a malignant tumor is born.
asphyxiation vs strangulation
lack of oxygen from environment OR from blockage of respiratory airway.
vs
hypoxia from impaired blood flow to brain.
Injury/death results from impaired CEREBRAL blood flow
axphyxiation
- Suffocations—lack of oxygen from environment OR from blockage of respiratory airway. Methane or co2 common.
- Choking—obstruction of airway (by object or compressional if chest trappedpetichiae)
chemical asphyxiation
prevent delivery of oxygen to tissues or block o2 use
- CO!!—odorless, colorless, nonirritating, undetectable. Caused by incomplete combustion of fuels like gas.
i. Causes death by indusing CNS depression
ii. CO binds with Hgb instead of o2 because affinity 300x more. carboxyhemaglobin
iii. Widespread ischemia, but pt only feels sleepy, may appear cherry red (skin and mucous membranes) - Symptoms: ha, giddiness, tinnitus, c/p, confusion, nausea, weakness and vomiting
- Population most affected: fetuses, infants, HF patients, pulmonary patients, anemia
iv. Dx by carboxyhemaglobin levels
how does dehydration occur when edema is present?
Dehydration can develop d/t fluid sequestering
hypertonic vs hypotonic fluid imbalances
hyper–>pulls fluid out of cells and causes dehydration
hypo–>pushes fluid in and can cause cell to burst
acid base determination
pH low=acitic, pH high alkalotic
HCO3 low acidotic, HCO3 high alkalotic
CO2 low acidotic, CO2 high alkalotic
can compensate partially or fully.
explain respiratory compensation
a) respiratory system compensates for changes in pH by altering rate/depth of ventilation to inc or dec retained CO2
i) shallow breathing retains co2 (increases acidity potential)
ii) rapid breathing blows of co2 (decreases acidity potential)
iii) renal compensation
(1) if respiratory acidosis the kidneys attempt to compensate by resorbing bicarb and excreting H+
(a) occurs more slowly but very effective
(2) respiratory aclokalosis—kidneys decrease rate of H+ in urine and reduce rate of resorption of bicarb
iv) respiratory compensation
(1) if metabolic acidosis the lungs attempt to compensate by rapid/deep breathing to blow of co2 (potential acid)
(a) occurs within minutes
(2) if metabolic alkalosis lungs compensate with slow shallow breathing to preserve CO2
what would an ABG look like with compensated alkalosis/acidosis
pH is WNL but HCO3 and CO2 both high or both low
what would an ABG look like with partially compensated alkalosis/acidosis
pH near normal, CO2 and HCO3 both high or low
describe metabolic acidosis
a) Lactic acidosis d/t poor perfusion or hypoxema (rapid)
b) Renal failure, dka or starvation (slow)
c) When severe buffers become depleted and can no longer compensate to keep bicarb/carbonic acid 20:1
symptoms: e) Symptoms: HA, lethargy, confusion, coma. Kussmaul respirations (deep and rapid hyperventilation)
describe anion gap
used in determining cause of metabolic acidosis
i) Elevated anion cap
(1) DKA, lactic acidosis, injestion, renal failure
ii) Normal anion gap
(1) Diarrhea, ureterosigmoidoscopy, early renal failure
describe metabolic alkalosis causes and symptoms
a) Hypochloremic metabolic acidosis–if d/t vomiting/diarrhea renal comp not effective d/t loss of HCl and Cl which stim bicarb retention (tX NaCl to replenish chloride so kidneys can excrete bicarb)
b) Hyperaldosteronism—sodium bicarb retention and loss of H and K
c) Diuretics can cause mild alkalosis d/t excretion of NA, K, Cl more than bicarb
d) Symptoms: weakness, muscle cramps, hyperactive reflexes, tetany, confusion, convulsions, a-tach, shallow slow ventilation, s/s low calcium
describe respiratory acidosis causes and symptoms
a) d/t: head injury/drugs, paralysis of resp. muscles, d/o of chest wall, COPD, pna.
b) Renal compensation takes 3-4 days to kick in with inc retention of bicarb. Hgb/phosphate system first
c) s/s: HA, blurred vision, breathlessness, restless, lethargy, disorientation,muscle twitching, tremors, convusions, coma. Respi rate rapid the depressed and resp center adapts to inc co2
d) treatment: restore alveolar ventilation
