Lipid metabolism — Flashcards

Flashcard 251: Anorexia = _____cholesterolemia

Answer: Hyper

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Flashcard 252: _____ Cholesterol or _____ bile salts = ↑ risk of gallstones

Answer: ↑

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Flashcard 253: Characteristics of _____: Hepatosplenomegaly Pancytopenia Bone pain/fractures Failure to thrive and delayed puberty

Answer: Gaucher disease

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Flashcard 254: What is the normal range of Triglycerides, serum?

Answer: From 35 to 160 mg/dL

Flashcard 255: What is the normal range of Cholesterol, serum (Recommendation)?

Answer: From 0 to 200 mg/dL

Flashcard 256: What is the status of the following in **Carnitine deficiency**? - Acetoacetate - Arachidonic acid - Glutathione - Homocysteine - Lactate - Palmitate (oxidation)

Answer: - **Acetoacetate:** Decreased (impaired ketogenesis) - **Arachidonic acid:** Unaffected - **Glutathione:** Unaffected - **Homocysteine:** Unaffected - **Lactate:** Unaffected - **Palmitate (oxidation):** Decreased (long-chain fatty acids require the carnitine shuttle)

Extra: In **carnitine deficiency**, the transport of long-chain fatty acids (LCFAs) like **palmitate** (C16) into the mitochondria is impaired. **Consequences:** 1. **Impaired β-oxidation**: LCFAs cannot enter the mitochondrial matrix. 2. **Hypoketotic hypoglycemia**: Since β-oxidation is the primary source of acetyl-CoA for ketogenesis and ATP for gluconeogenesis during fasting, levels of ketone bodies (like **acetoacetate**) and glucose fall. 3. **Other metabolites**: Arachidonic acid (membrane phospholipid component), glutathione (antioxidant), homocysteine (methionine cycle), and lactate (glycolysis) are not directly involved in the carnitine shuttle pathway and remain largely unaffected.

Flashcard 257: An 18-month-old boy presents with neurologic regression. - He developed a gradual regression of developmental milestones such as inability to sit with support. - Poor head control, loss of social smile. - Physical exam: enlarged liver and spleen, hypotonia, lack of deep tendon reflexes in all limbs. - Cherry-red spot on fundoscopic exam. The patient most likely has an accumulation of which substrate?

Answer: Sphingomyelin (Due to Niemann-Pick disease, caused by deficiency of sphingomyelinase) Note: Hepatosplenomegaly is present in Niemann-Pick disease but absent in Tay-Sachs disease (which involves GM2 ganglioside accumulation).

Flashcard 258: A 12 y/o girl is involved in a motor vehicle accident. - Abdominal CT is negative for traumatic injury. - She is incidentally found to have an abnormal intra-abdominal mass. - Biopsy of mass reveals ectopic tissue. - On microscopy, these cells have a highly developed smooth endoplasmic reticulum. - These cells most likely receive stimulation from which of the following agents? a. Parathyroid hormone b. Progesterone c. ACTH d. Aldosterone e. Dopamine

Answer: c. ACTH Cells with highly developed smooth endoplasmic reticulum (SER) are characteristic of tissues that synthesize steroids, cholesterol, and lipids (e.g., adrenal cortex, gonads, liver). Ectopic adrenal tissue (adrenal rests) is a common incidental finding in the abdomen and is stimulated by ACTH. - PTH: Regulates calcium; protein-secreting cells (parathyroid) use Rough ER. - Progesterone/Aldosterone: These are steroid hormones themselves, not trophic stimulators. - Dopamine: Inhibits prolactin release.

Flashcard 259: Accumulation of the following presents with what disease? - Cerebroside sulfate - Galactocerebroside - Globotriaosylceramide - Glucocerebroside - GM2 ganglioside - Sphingomyelin

Answer: - Cerebroside sulfate: Metachromatic leukodystrophy (peripheral neuropathy and ataxia) - Galactocerebroside: Krabbe disease - Globotriaosylceramide: Fabry disease - Glucocerebroside: Gaucher disease - GM2 ganglioside: Tay-Sachs disease - Sphingomyelin: Niemann-Pick disease

Flashcard 260: 3 y/o patient presents with cherry-red spots and loss of motor skills. - Physical exam: No splenomegaly - What is the most likely enzyme deficiency that causes this disease?

Answer: Hexosaminidase A deficiency due to Tay-Sachs disease.