Week 5 Flashcards

Question

What are metabolic pathways

Answer 1

Reactions which self-regulate to respond to changes in the levels of substrate or products

Answer 2

a cell changing its metabolism in response to signals from other cells

Answer 3

Energy comes from breakdown of glucose, fatty acids and amino acids into acetyl CoA Acetyl CoA enters the Krebs cycle to produce energy in 2 ways: - as ATP (substrate-level phosphorylation) - through NADH/FADH2 which is processed through oxidative phosphorylation to produce more ATP

Answer 4

as body functions use up energy, ATP is converted to ADP and an inorganic phosphate ADP and inorganic phosphate are used to create ATP for energy

Answer 5

Acetyl CoA (precursor to cycle) is produced from AAs, fatty acids and glucose Series of reactions that oxidise Acetyl CoA to CO2 Electrons lost from these reactions are used in oxidative phosphorylation to produce ATP Some steps release energy that is directly captured as ATP (substrate level-phosphorylation)

Answer 6

Electrons from the Krebs cycle are transferred into the electron transport chain in mitochondrion via an electron carrier As electrons pass down the electron transport chain it releases energy which is used to pump protons out of the mitochondrion forming an electrochemical gradient when protons flow back down their gradient they pass through ATP synthase (enzyme) => ATP synthesis Electrons eventually join O2 to form water

Answer 7

energy required to maintain life expressed in kcal/day

Answer 8

body size age sex species body temperature hyperthyroidism (increase) hypothyroidism (decrease) pregnancy & lactation growth genetic factors

Answer 9

~2-4 hrs after a meal blood glucose levels return to basal levels and continue to decrease until the next meal Insulin levels decline and glucagon levels rise which triggers release of fuels from the body stored

Answer 10

during fasting liver produces glucose by glycogenolysis (release of glucose from glycogen) and gluconeogenesis (synthesis of glucose from noncarbohydrate compounds (mainly amino acids but also lactate & glycerol))

Answer 11

when an animal has fasted for 3 or more days prolonged period of low glucose cause animal to die due to lack of appropriate energy sources to maintain vital cells

Answer 12

increase in blood glucose (after digestion of carbohydrates) is detected by pancreatic islet cells beta islet cells respond by releasing insulin into bloodstream insulin signals tissues to store glucose as glycogen or fats glucagon does the opposite and mobilises stores of glucose when levels are low

Answer 13

absorbed by hepatocytes or continues through liver & enters general circulation

Answer 14

glucose can have multiple fates in hepatocytes: 1. oxidised & used as energy source for hepatocyte 2. under influence of insulin, it can be converted to glycogen & stored in liver - however liver has limited space to store glycogen 3. can be converted to TAG (triacylglycerol) ready for export out of liver - storage of TAG in liver can lead to accumulation of fat in liver which prevents normal liver function & causes disease

Answer 15

Brain and neural tissues can only use glucose as substrate for energy They oxidise glucose via cellular respiration to generate ATP Glucose is major precursor of neurotransmitters Clinical signs of low blood glucose are usually neurological

Answer 16

Lactate builds up in anaerobic respiration Lactate + NAD+ <=> pyruvate + NADH + H+

Answer 17

cycling of lactate & glucose between peripheral tissues & liver

Answer 18

Lactate released from cells undergoing anaerobic glycolysis (usually muscle cells when O2 conc is low) taken up by liver and oxidised back to pyruvate Pyruvate use to synthesise glucose (gluconeogenesis) which is returned to blood

Answer 19

Glucose is only fuel for RBCs as they lack mitochondria Glucose used to generate ATP in cytosol via anaerobic glycolysis Pyruvate formed is converted to lactate and released into blood

Answer 20

exercising skeletal muscles can use glucose from blood or their own glycogen stores glucose converted to lactate via glycolysis or oxidised completely to CO2 & H2O

Answer 21

Adipocytes oxidise glucose for energy Adipose cells also metabolise glucose to Acetyl CoA which can be turned into fat and stored

Answer 22

Body limits amount of AAs used for gluconeogenesis in order to preserve muscle mass Relies on ketones as source of energy As there is limited glucose, the brain must rely on using intermediate energy source ketone bodies => elevated levels of ketone body in blood = ketosis

Answer 23

during starvation the brain uses ketone bodies as energy, therefore it needs less glucose Glucose is still required for use by RBCs Less glucose is used by the body to keep some ‘spare’ Liver needs to produce less glucose per hour during prolonged fasting than short periods

Answer 24

decreased rate of gluconeogenesis Reserves proteins for essential functions such as biosynthetic function and new protein synthesis

Answer 25

adipose tissue continues to break down its triacylglycerol stores providing fatty acids & glycerol to blood for energy in liver fatty acids are converted to ketone bodies which are oxidised for energy

Answer 26

The rate of ketone body production exceeds rate at which they can be used

Answer 27

peak lactation has a high energy demand and cow is incapable of eating enough to support this Body starts mobilising fats to provides energy => ketone production Mobilisation of fats results in weight loss

Answer 28

The breakdown of protein (for AA for gluconeogenesis) becomes tissue or protein specific to guard against vital proteins/cells becoming depleted This occurs due to elevated levels of cortisol resulting in body adapting to state of starvation

Answer 29

Proteins become so depleted that heart, kidney etc stop functioning Animal can develop infection and not have adequate reserves to mount immune response Deprived of vitamin and mineral precursors of coenzymes and other compounds necessary for tissue function Lack of ATP and decreased electrolyte intake, electrolyte composition of cells or blood becomes incompatible with life

Answer 30

transporters for hydrophobic compounds in blood cell adhesion molecules hormones ion channels enzymes

Answer 31

Ingested proteins digested to amino acids in stomach and SI AAs transported to liver via hepatic portal vein AAs used to synthesise new proteins (biosynthesis) or converted to energy sources (gluconeogenesis) AAs also enter general circulation and go into tissues to be synthesised into new proteins

Answer 32

Synthesis of serum proteins & biosynthesis of nitrogen-containing compounds that need AA precursors e.g., non-essential AAs, haeme, hormones, neurotransmitters, DNA Oxidizes AAs to produce energy via Krebs cycle in the fed state

Answer 33

Proteins undergo turnover, constantly being synthesised and degraded, especially in muscle tissue AAs released by protein breakdown enter the same pool of free AAs in the blood from the diet

Answer 34

AAs released from digestion of dietary proteins travel to liver for synthesis of proteins Excess AAs converted to glucose or triacylglycerols Triacylglycerols packaged and secreted in VLDL Glucose stored as glycogen or released into blood if blood glucose levels are low AAs that pass through the liver are converted to proteins in the cells of other tissues

Answer 35

AAs released from muscle protein Some enter blood Some are partially oxidised and the nitrogen is stored as alanine and glutamine which enter the blood (gluconeogenic AAs) AAs enter the liver, nitrogen is converted to urea (excreted in urine) and carbons converted to glucose and ketone bodies which are oxidised for energy

Answer 36

catabolic process in which fatty acids are broken down to generate acetyl CoA which can enter the krebs cycle

Answer 37

Chylomicrons are synthesised in epithelial cells, secreted into lymph, pass into blood & become mature chylomicrons then taken to adipose cells lipoprotein lipase (LP) digests triacylglycerols (TG) of fatty chylomicrons to fatty acids & glycerol FA oxidised in muscle or stored in adipose cells remnants of chylomicrons are taken up by liver and digested

Answer 38

metabolic formation of fatty acids from excess dietary carbs (glucose converted to Acetyl CoA => fat synthesis) or protein in the liver Fatty acids combined with a glycerol molecule => TAGs

Answer 39

packaged with cholesterol, phospholipids and proteins => VLDL VLDLs secreted into blood

Answer 40

1. Lipoprotein lipase cleaves TAGs in both VLDL and chylomicrons 2. forms fatty acids and glycerol 3. Fatty acids enter adipose cells and are activated forming fatty acetyl CoA 4. This reacts with glycerol-3-phosphate (formed from glucose) to form TAGs 5. stored as large fat droplets in adipose tissue

Answer 41

1. During fasting - adipose TAGs are mobilised (lipolysis) 2. This releases fatty acids and glycerol into blood 3. Fatty acids transported in blood with albumin are oxidised for energy in cells 4. Glycerol used to produce energy via gluconeogenesis in liver Increased amount of fat mobilised during starvation as decreased AAs used

Answer 42

beta-oxidation of fatty acids produces Acetyl CoA during prolonged fasting Acetyl CoA converted to ketone bodies in liver ketone bodies oxidised to produce energy

Answer 43

Beta-oxidation: - fatty acid => acetyl CoA + NADH + FADH Oxidation of acetyl CoA: - into Co2 in Krebs cycle - produces NADH+ & FADH2 through oxidative phosphorylation ATP generation: - ATP generated from NADH and FADH via respiratory electron chain

Answer 44

brain RBCs lens of eye kidney medulla exercising skeletal muscle

Answer 45

hormones that appose actions of insulin by mobilising fuels e.g. cortisol, epinephrine & glucagon

Answer 46

hypoglycaemia is one of the stress signals that stimulates release of cortisol, epinephrine and norepinephrine ACTH is released from pituitary => release of cortisol from adrenal cortex when hypothalamic regulatory centre detects low blood glucose When hypothalamic regulatory centre detects low blood glucose => release of epinephrine from adrenal medulla and norepinephrine from nerve endings

Answer 47

SNS => epinephrine and norepinephrine release: - promotes release of glucagon from pancreas - promotes glycolysis and gluconeogenesis in hepatocytes - binds to muscle cell receptors => glycolysis - activates hormone sensitive lipase => mobilises fatty acids for use as fuel

Answer 48

analysis of different body fluids for purpose of diagnosis or monitoring can asses: - substrates/products - enzymes - hormones

Answer 49

glucose and ketone bodies

Answer 50

triglycerides and cholesterol

Answer 51

hepatocellular - contained in hepatocyte - leak out if there is liver damage - e.g. AST & ALT cholestatic - found on membrane of cells that line bile ducts - increased conc. in blood if there is issue with flow of bile through liver - e.g. ALKP & GGT

Answer 52

high glucose high liver enzymes high cholesterol high urea high insulin high triglycerides

Answer 53

ketosis dehydration body mobilises fat stores => increased fatty acids Less WBCs due to lack of proteins Increase liver enzymes

Answer 54

fat accumulates in hepatocytes due to hypoglycaemia as fat is mobilised from adipose tissue and builds up in liver

Answer 55

Ketosis is caused by excessive mobilisation of fats for energy The liver can become overwhelmed with large amounts of lipids leading to accumulation in hepatocytes

Answer 56

Gas builds up in abomasum due to abnormal contraction => floats in abdomen to LHS Ketosis => inappetence => decreased rumen size => more room for abomasum to move

Answer 57

Amount of energy in feed Not the same as the energy they get out of it

Answer 58

Faecal energy Urine and gas energy Heat Maintenance

Answer 59

measure of how much energy can be used by the animal from a feed

Answer 60

presence of elevated lipid conc in the blood

Answer 61

metabolic disease of ponies, miniature horses and donkeys Fatty infiltration of organs leading to subsequent organ failure

Answer 62

negative energy balance Decreased feed/energy intake Insulin resistance e.g., starvation, lactation, pregnancy, stress, obesity

Answer 63

Low blood glucose => glucagon => lipases convert triglycerides into glycerol and fatty acids in adipose tissue => FAs and glycerol enter blood Excess dietary CHO => converted to glucose => converted to fatty acetyl CoA => converted to triglycerides => packaged as VLDLs => into blood

Week 5 Flashcards

(100 cards)