Metabolism Exam # 4 Flashcards
(19 cards)
Metabolism -
Use of food absorbed in the GI tract : For energy (ATP) - active transport, DNA replication, Protein synthesis and muscle contraction. For building blocks - amino acids for proteins, hormones, and cellular components. Storage for later energy needs - glycogen and adipose are storage forms.
Metabolic reactions -
Metabolism = the sum of all chemical reactions in the body.
2 branches : Catabolism - breaking down and energy yielding. Anabolism - building up and energy requiring
ATP is energy “currency” supplying the energy for anabolic reactions. Catabolic reaction result in a generation of ATP. ATP has 2 “high energy” bonds (adenosine monophosphate ~P~P) breaking the bond resuls in energy transfer from molecule to molecule.
Energy Transfer - electron shuffling. Oxidation is a loss of electron and Reduction is a gain of an electron. Coenzyems act as carriers of hydrogen ions and electrons. NAD+ , FAD (oxidized form) NADH+ H+, FADH2 (reduced form).
Carbohydrate Metabolism -
Glucose is the prefered energy source for human cells. So carbohydrate metabolism is ultimatley glucose metabolism. Hepatocytes convert glactacose and fructose to glucose. Excess glucose can be converted into amino acids, triglycerides and glycogen. Fates of Glucose: ATP production - Glucose catabolism. Amino acid synthesis - excess glucose can be converted into amino acids. Glycogen synthesis - glycogen is a polymer and storage form of glucose. Triglyceride synthesis - (aka Lipogenesis) - when glycogen storage is maxed out the remaing glucose covers to glycerol and combines with fatty acids to form triglycerides.
Glucose Catabolism - Cellular respiration ,citric acid cycle.
- Glycolysis - in the cytosol breaks down each glucose molecule into 2 molecules of pyruvic acid. No oxygen is required and can be refered to as anaerobic cellular respiration.
- Pyruvic acid enters the mitochondrial matrix, where the citric acid cycle oxidizes it to CO2. During glycolysis and the citric acid cycle Phosphorylation forms small amounts of ATP, and formation of acetyl-CoA.
- Citric acid cycle - oxaloacetic acid (OOA) combines with acetyl - CoA and goes through a series of oxidation and reductions which result in the ETC.
- Electron transport chain (ETC) - reducing power is generated and converted into ATP via electron carriers. During the electrons being transported it forms small amounts of energy that cause hydrogen ions to be pumped inbetwwen the membrane of the mitchochondria and establish a electrochemical gradient.
Chemiosmosis - is the electrochemical gradient that is used to generate ATP. Hydrogen ions create ATP and their flow spins a rotor resulting in inorganic phosphate into ADP.
Oxidation phosphorylation - ATP is formed via chemiosmosis with electro transport proteins playing a key role.
Substrate level phosphorylation - when inorgainc phosphate is added to ADP creating high energy bond by its chemical reaction. Glycolysis and citric acid cycle both use this process.
Summary of energy yield with oxygen as the terminal electron acceptor per molecule of glucose:
Each NADH generates 3 ATP and each FADH2 genertates 2 ATP.
ETC (reducing power is converted to ATP): Total ATP from ETC = 10 NADH (x3) 2 FADH2 (x2) = 34
Blood glucose homeostasis -
Glycogenesis - (anabolic) excess glucose is converted into glycogen. Insulin is a stimulator of glycogenesis.
Glycogenolysis - (catabolic) literally glycogen lysis, is the conversion of glycogen to glucose. This is stimulated by glycogon and epinephrine.
Gluconeogenesis - ( “new glucose”) from proteins and fats. (non - carbohydrate sourse). Is stinulated by cortisol, glucagon,epinephrine and GH.
Transport of lipids by lipoproteins -
Lipoproteins are made up of varying amounts of proteins, triglycerides, phospholipids and cholesterol.
high density - more protein and smaller
low density - more lipid and larger
chylmicrons - very, very low density lipoproteins, Used for transport of lipids in lacteals.
VLDL’s - very, low density lipoproteins, VLDL’s are used for the transport of triglycerides for storage.
LDL’s - low density lipoproteins, “the bad cholesterol” cholesterol forming plaques in arteries.
HDL’s - High density lipoproteins, “good cholesterol” because they transport lipids for excreation by becoming a part of the bile in the liver.
Good cholesterol - under 200 mg/dl triglycerides 10 - 190 mg/dl. LDL’s under 130 mg/dl and HDL’s over 40mg/dL.
Metabolism of Lipids -
Can be oxidized to produce ATP (fat burn) via beta- oxidation and citric acid cycle. Extra lipid (fat) adipose is stored, mostly subcutaneously. Structural uses for lipids are: phospholipids, cholesterol in plasma membranes, steroid hormone, and myelin sheath.
Lipid Catabolism: Lipolysis
98% of energy storage in the body is in the form of triglycerides.
Lipolysis - the process in which triglycerides are converted to glycerol and fatty acids.
4 lipase that are secrested for digestion. Lingual, gastric, pancreatic and lipoprotein.
Calorie -
calorie = heat required to raise 1 gram of water from 14C to 15C.
Ketogenesis -
the formation of ketone bodies. Ketosis - ketone bodies in the blood from ingesting alot of fatty foods, fasting, a low carbohydrate diet or uncontrolled diabetes.
Liver plays arole by condensing acetyl-CoA from beta oxidation to form ketone bodies.
Lipid Anabolism : Lipogenesis
Extra carbohydrates and proteins ingested are converted into lipids via lipogenesis. Insulin stimulates this process.
Protein Catabolism -
Amino acids in the body are recycled by breaking down worn out cells and hemoglobin. The ammonia that forms is toxic to the body and converted into urea and excreted in our urine. Deaminated amino acids can become glucose, fatty acids, ketone bodies or Kerbs cycle intermediates. Deamination - the removal of amine group from an amino acid resulting in molecules that can be converted into pyruvic acid.
Protein Anabolism- aka protein synthesis
8/20 amino acids are essential. Essential must be provided in the food we eat! Nonessential amino acids can be made by the body. PKU - phenylketonuria, the metabolism of phenylalanine is impaired so it bulds in blood. If left untreated mental retardation.
Metabolic crossroads -
Molecules play a key role in metabolism because of various pathways they can enter. Glucose-6-phosphate (G-6-P) Fates: Synthesis of glycogen - if glucose is abundant in the blood. (G-6-P) is present in blood between meals. Synthesis of nucleic acids - converted into ribose- 5 -phosphate first. Glycolysis - enters pathway at 2nd step.
Pyruvic acid Fates: depends on oxygen and ATP availability. Lactic acid in anerobic conditions. Production of alkaline. Gluconeogenesis - pyruvic acid to OAA to G-6-P
Conversion to acetyl-CoA for enterance to Krebs cycle when ATP is low and oxygen is abundant.
Acetyl-CoA fates - enters krebs cycle and combines withOOA or used for synthesis of ketone bodies, fatty acids and cholesterol.
Metabolic Adaptions, Absorptive “fed” state-
Nutrients are entering the blood stream and ready for conversion into proteins, triglycerides and glycogen. Anabolism and energy stored) insulin is predominate in the fed state.
In All Tissue –
Glucose is readily avaliable for ATP. In the muscle, glucose is being converted into glycogen and amino acids are being converted into protein. In the liver, glucos is being converted into glycogen and glycerol for triglyceride. Keto acids form amino acids are also used for ATP and amino acids are converted into protein. In adipose, glucose is converted into fatty acids. Fatty acids and glycerol combine to form fats.
Postabsorptive state - Fasting
Absorption of nutrients from the alimentary canal is complete. Body needs for glucose are met without food ingestion. Glucagon ids the predominate hormone.
Body temperature homeostasis -
Core Temperature - Vital organ and deep structures are kept at 98.6 F (37C)
Shell temperature - skin subcutaneous layer, large fluctuations 4 - 6 degree C cooler but can also be higher!
Heat is generated by metabolism and so much of temperature regulation is dependent upon heat transfer.
Mechanisms of heat transfer: Conduction - heat exchange by direct contact with clothes, water on air (surroundings in general)
Convection - heat transferd via the movement of air.
Radiation - heat transfer due to radiating heat, no contact required (body heat furnace)
Evaporation - “Evaporative cooling”conversion of a liquid into a vapor. Includes insensible water loss and swearing.
