Endocrinology/Metabolism/Nutrition Flashcards
What does insulin do to the rate of facilitated diffusion of glucose and by what mechanism?
It increases it by increasing the activity and amount of hexokinases and glucokinases.
What does hexokinase/glucokinase do?
Phosphorylation of glucose so it can’t leak back out of the cell during glycolysis
What are the effects of the hormones epinephrine and glucagon on glycogen?
Stimulate glycogen breakdown through activation of phosphorylase and prevent glycogen synthesis by increases cytosolic levels of cAMP
Where is glucagon released from?
Pancreatic alpha cells
Each mole of glucose can produce how much ATP?
38 moles
What are the steps of glycolosis and what are the final products?
Glucose –> glucose-6-phosphate –> fructose-6-phosphate –> fructose 1,6 diphosphate –> DHAP/G3P –> 1,3 - DGP –> 3-PG –>2-PG –> PEP –> pyruvate
Final products:
2 pyruvate
2 ATP
4 H
What are the steps to the Kreb’s Cycle and what are the final products
acetyl coA ->
citrate –> isocitrate –> alphaketogluterate –> succinol coA –> succinate –> fumarate –> malate –> oxaloacetate
Final products:
4 CO2
16 H (NADH and FADH2)
2 ATP
What are the products of oxidative phosphorylation?
30 ATP (by chemiosmotic mechanism)
4 ATP (from NADH and FADH2)
How is cellular respiration regulated? What are 3 mechanisms?
By concentrations of ATP and ADP.
1. Imp enzyme in glycolysis is phosphofruktokinase which is inhibited by ATP and promoted by ADP.
2. Citrate inhibits phosphofructokinase allowing kreb’s cycle to catch up to glycolosis
3. Finate amount of ADP so can overproduce ATP
Why is the pentose phosphate pathway important (2 reasons)?
- It can break down glucose and make energy independent of the enzymes of the Kreb’s cycle.
- Means of producing fat from carbs.
What is a lipoprotein and list 4 types and their differences?
A predominent plasma lipid in the fasting state containing various combinations of triglycerides, cholesterol, phospholipids, and protein.
- VLDL - high triglycerides, moderate cholesterol and phospholipid
- IDL - VLDL but some triglycerides are removed and slightly more cholesterol and phospholipid.
- LDL - Almost all triglycerides removed, high cholesterol and phospholipid
- HDL - high concentration of protein, smaller amounts of cholesterol and phospholipids
What is lipoprotein lipase’s function?
It degrades TG (and phospholipids) in the bloodstream being carried by chylomicrons.
What hormones are secreted by adipose tissue?
leptin and adiponectin
What are the 3 functions of the liver in lipid metabolism?
- Degrade fatty acids for energy use
- Synthesize triglycerides (mainly from carbs but also protein)
- Synthesize other lipids from fatty acids ie cholesterol and phospholipids
What are the three steps that the body uses to form ATP from triglycerides?
- Split (Hydrolyze) TG into fatty acids and glycerol. Glycerol enters the cytoplasm and into glycolosis to form pyruvate.
- Carrier mediated transportation - Fatty acids bind with carnitine to enter the mitochondria.
- Beta oxidation - progressive release of acetyl-CoA and hydrogen ions from fatty acids (with acetyl coA entering into Kreb’s cycle).
Name 3 ketone bodies and explain how we can generate ATP from ketones.
Acetoacetic Acid, beta hydroxybutyric acid, and acetone
After fatty acids are split into acetyl CoA, two molecules condense to form acetoacetic acid which is transported to tissues for energy. They diffuse into tissues where reverse reactions occur and acetyl CoA formed which enter the citric acid cycle.
What are the principle intermediates in converting acetyl CoA into fatty acids?
Malonyl-CoA and NADPH
What hormones regulate fat utilization?
Epinephrine
Insulin
Glucocorticoids
Thyroid Hormone
How does the body downregulate triglyceride metabolism in the presence of high carbs?
- High amounts of glycerol 3-phosphate (substrate of glycolysis) – binds triglycerides
- Faster fatty acid synthesis than fatty acid degradation
- Acetyl CoA carboxylase (enzyme in lipogenesis) upregulation – upregulation due to high levels intermediates of the citric acid cycle
What are 5 functions of phospholipids?
o Component of blood lipoproteins
o Component of thromboplastin (cephalins)
o Component of nerve sheath (sphingomyelin)
o Donors of phosphate radicals during different chemical processes
o Component of structural elements of cells (mainly membranes)
How is the concentration of cholesterol regulated?
o Daily cholesterol ingestion
o High dietary saturated fat content (especially when combined with obesity) (increases)
o Low dietary unsaturated fat content (decreases)
o Hypoinsulinaemia or hypothyroidism (increases)
o Genetic disorders (increases)
What are the 10 essential amino acids?
Bonus: what is the 11th for cats only?
Argue on a HILL, Met 3, tripped on a Valise of phennel
Arginine
Histadine
Isoleucine
Leucine
Lysine
Methionine
Threonine
Tryptophan
Valine
Phenylalanine
Bonus: Taurine
What are the functional roles of the major types of plasma proteins and where are they made?
Albumin - provides colloid oncotic pressure, made in liver
Globulin - Enzymatic functions and natural/acquired immunity (50-80% made in liver, rest by lymphoid tissue)
Fibrinogen - forms blood clots, made in liver
What are the two steps the body uses to form energy from protein?
- Deamination - the removal of amino groups from amino acids by transamination (transfer of amino group to some acceptor substance)
(ammonia released by deamination) - Oxidation of deaminated amino acids – Conversion of alpha-keto acid to substance that can enter the citric acid cycle, participate in carbohydrate-lipid metabolism (eg. acetyl CoA) or serve as an alternative energy source (eg. ketone bodies)
Where is urea synthesized?
The liver
What is obligatory protein loss?
25-30g/day of protein are degraded and oxidized each day (with the body preferentially using carbohydrates and fat sources as energy substrates unless multiple week starvation occurs)
Which hormones regulate protein metabolism and how?
- Growth hormone – Increases the synthesis of cellular proteins
- Insulin – Necessary for protein synthesis
- Glucocorticoids – Increases breakdown of most tissue proteins
- Testosterone and estrogen – Increases protein deposition in tissues (estrogen lesser extent)
- Thyroxine – Increases metabolism of cells & thus protein metabolism (if inadequate fat-carbohydrate available)
What is the functional unit of the liver and what are its components?
Liver lobule
Central vein
Cellular Plates
Bile Canaliculi
Portal venules
Sinusoids
Hepatic arterioles
Endothelial cells
Kupffer cells
Spaces of Disse
- Portal blood drains through central vein into hepatic veins and vena cava.
- Cellular plates radiate from central vein with bile canaliculi at center which line plates and transport bile to bile ducts.
- Portal venules provide blood from portal vein to sinusoids which transport blood from portal venules to central vein.
- Hepatic arterioles carry blood from systemic circulation to sinusoids
- S of D: Space b/w endothelium and hepatic cells that connect with lymphatic vessels to remove fluid
The liver has (high/low) blood flow and (high/low) vascular resistance.
High
Low
How does cirrhosis cause portal hypertension and what does that result in?
Cirrhosis increases resistance to blood flow and results in excessive fluid loss and increased capillary blood pressure causing ascites.
What cells release what factor to stimulate and terminate liver regeneration?
Stimulate - Hepatocyte growth factor by mesenchymal cells
Terminate - Transforming growth factor (TGF - B) by hepatocytes
What 3 major vitamins have large stores in the liver
Vitamin A
Vitamin D
Vitamin B12
List 3 substances formed in the liver that are used in the coagulation process.
Fibrinogen
Prothrombin
Factor VII (7)
What are the synonyms for Factor I, II, III, and IV? Which of the coagulation factors are vitamin K dependent?
Vitamin K dependent –> 2, 7, 9, 10