Biochem & physio Flashcards
VLDL Metabolism
VLDL is synthesized in the liver from triglycerides, cholesterol, and apolipoproteins.
2. Lipolysis:
VLDL travels in the bloodstream and encounters lipoprotein lipase (LPL) in muscle and adipose tissue. LPL hydrolyzes triglycerides from VLDL, releasing fatty acids for energy and converting VLDL into smaller IDL particles.
3. IDL Fate:
IDL can be taken up by the liver, particularly through the LDL receptor, or further metabolized by hepatic lipase into LDL.
4. IDL Remnants:
VLDL remnants are cholesterol-rich and triglyceride-poor particles that can be further catabolized to LDL under the action of hepatic lipase and LPL.
LDL Metabolism
Formation: LDL is formed from VLDL remnants via the action of hepatic lipase.
Receptor-Mediated Uptake: LDL is taken up by various tissues, including the liver, through the LDL receptor.
Intracellular Metabolism: In peripheral tissues, LDL is used for various functions, including hormone production, cell membrane synthesis, and storage.
Liver Clearance: Excess LDL is also absorbed by the liver via the LDL receptor.
Scavenger Pathway: Damaged LDL can be recognized by scavenger receptors on macrophages, leading to their uptake and potential accumulation as foam cells, contributing to plaque formation.
One Brain, Two Kidneys, Liver, and Pancreas (B-cells), Three Brain and Placenta, Four Muscle and Adipose.” This relates each GLUT transporter to its primary locations in the body: GLUT1 (brain, erythrocytes, placenta), GLUT2 (liver, kidneys, pancreas), GLUT3 (brain, placenta), and GLUT4 (muscle, adipose tissue).
P53 action
p53 acts as a “guardian of the genome,” ensuring that cells with damaged DNA do not progress into S phase for replication. In the G1/S checkpoint, p53 triggers cell cycle arrest, allowing time for DNA repair, or if damage is too severe, apoptosis
Porphyria cutanea tarda (PCT)
a common, manageable porphyria characterized by skin fragility, blistering, and photosensitivity, primarily on sun-exposed areas like the hands. It’s caused by a deficiency of the enzyme uroporphyrinogen decarboxylase (UROD), leading to a buildup of porphyrins in the body.
Dark Urine, Hyperpigmentation, Hypertrichosis
Acute intermittent porphyria (AIP)
rare, inherited metabolic disorder characterized by a partial deficiency of the enzyme porphobilinogen deaminase (PBGD). This deficiency leads to a buildup of porphyrin precursors in the liver, which can trigger symptoms like severe abdominal pain, neurological issues, and psychiatric disturbances.
Lead poisoning
an mimic some symptoms of porphyria, a group of disorders related to heme production, due to its interference with heme synthesis. However, lead poisoning primarily affects a specific enzyme in heme synthesis, ALA dehydratase, leading to an increase in ALA levels without a corresponding increase in porphobilinogen (PBG), unlike acute porphyria.
Achalasia
presents with difficulty swallowing (dysphagia) for both solids and liquids, regurgitation, chest pain, and weight loss. Symptoms often progress gradually over months or years, with some individuals experiencing mild, manageable symptoms initially.
The insulin receptor
transmembrane protein primarily located on the surface of cells, specifically in the plasma membrane. It’s found in tissues like the liver, skeletal muscle, and fat. The receptor’s structure is a dimer, made up of two subunits: the α-subunit, which binds to insulin, and the β-subunit, which contains the tyrosine kinase domain.
Types of Hernias
Inguinal Hernia: The most common type, found in the groin area. It can be indirect (enters the inguinal canal) or direct (pushes through a weakened spot in the abdominal wall).
Femoral Hernia: Occurs in the groin, but below and lateral to the pubic tubercle, as opposed to inguinal hernias which are located above and medial to the pubic tubercle.
Umbilical Hernia: A bulge at the belly button, often seen in infants and can also occur in adults.
Incisional Hernia: A bulge at the site of a previous surgical incision.
Epigastric Hernia: A bulge above the belly button and below the breastbone
Ghrelin’s Role
Ghrelin is a peptide hormone that acts as a signal to the brain, telling it that the body needs food. It increases appetite, promotes fat storage, and can also influence other functions like sleep-wake cycles and glucose metabolism
hunger hormone
