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: 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 257: Cultured fibroblast taken from an infant suffering from hypotonia & seizures. -It shows an impaired ability to oxidize very long chain fatty acids (VLCFA) & Phytanic acid. -The defect most likely localized to:

Answer: Peroxisomes due to oxidizing very long chain fatty acids & phytanic acid. They usually metabolize in the peroxisomes. Symptoms: neurological symptoms (seizures & hypotonia)

Flashcard 258: A 3 y/o girl comes with several months of fatigue and difficulty walking. -Physical examination: Decreased power in all extremities but no ataxia. -Cardiac auscultation: 1/6 systolic murmur & an S3 gallop. -Labs: Glucose 37 mg/dL Creatine kinase 304 U/L (normal XX: 10 - 70) Urinalysis: Protein, glucose, ketones, Leukocyte esterase, nitrites: all Negative -Muscle biopsy: Very low carnitine content. -Which substance has deficient synthesis in this patient's disease?

Answer: Acetoacetate (Ketone bodies) Due to Primary carnitine deficiency (impairs fatty acid transport into mitochondria) Symptoms: Cardiac & skeletal muscle cells injury, and impaired ketone body production by the liver during fasting periods.

Flashcard 259: 72 y/o woman found lying on the floor in her home for the past 2 days. - She fell and injured her right hip, was unable to get up and call for help. - She did not drink anything during that time. - Physical exam: dehydration, right hip tenderness. - Labs: serum glucose 72 mg/dL & positive urine ketones. - Radiographs: right femoral neck fracture. - Increased activity of what enzyme is most likely contributing to both the serum & urine lab findings?

Answer: Hormone-sensitive lipase In starvation, HSL breaks down adipose triglycerides into glycerol and fatty acids. - Glycerol: Substrate for gluconeogenesis (maintaining serum glucose). - Fatty acids: Substrate for ketogenesis (producing urine ketones).

Flashcard 260: Which organelle is the primary site for the initial $\beta$-oxidation of **Very Long Chain Fatty Acids (VLCFAs)**?

Answer: Peroxisomes

Extra: Very Long Chain Fatty Acids (VLCFAs, >22 carbons) cannot enter the mitochondria directly. They undergo initial $\beta$-oxidation in **peroxisomes** until they are shortened to medium or long-chain fatty acids, which are then transported to the **mitochondria** for complete oxidation. Defects in peroxisomal VLCFA oxidation lead to conditions like **Zellweger syndrome** and **X-linked adrenoleukodystrophy**.