Carbohydrate & Lipid Metabolism and Urinary System

Flashcards about Carbohydrate Metabolism, Fatty Acid Catabolism, the Urinary System, Glomerular Filtration, Tubular Reabsorption, and Tubular Secretion. .

What is the overall reaction for glucose catabolism and ATP synthesis?

C6H12O6 + 6 O2 --> 6 H2O + 6 CO2 + 36-38 ATP + Heat

Define oxidation in the context of cellular respiration.

Removal of hydrogen atoms from a molecule (e.g., glucose).

Define reduction in the context of cellular respiration.

Addition of hydrogen atoms to a molecule (e.g., oxygen).

What are the three main reaction divisions of glucose catabolism?

1. Glycolysis, 2. Citric acid cycle, 3. Electron transport chain (ETC).

Where does glycolysis take place?

Cytosol

Where does the citric acid cycle take place?

Mitochondrial matrix

Where does the Electron Transport Chain (ETC) take place?

Inner mitochondrial membrane

What are the two divisions of glucose catabolism?

Glycolytic (anaerobic) and Oxidative (aerobic) catabolism

What happens to glucose during glycolysis?

A 6-carbon glucose molecule is split into two 3-carbon pyruvate molecules.

What are the two phases of glycolysis?

1. Energy investment phase, 2. Energy payoff phase

What is the net result of the energy investment phase?

2 molecules of ATP used, 2 three-carbon phosphorylated compounds.

What is the main event of the energy payoff phase?

PO43- transferred to ADP producing ATP and compounds oxidized to produce NADH

What is the overall yield of glycolysis?

Used 2 ATP, Made 4 ATP, Made 2 NADH, Split glucose into two 3 carbon pyruvate molecules

What determines the fate of pyruvate?

Amount of O2

What happens to pyruvate in the absence of oxygen (anaerobic)?

Pyruvate is reduced to lactate, NADH gives electrons back to pyruvate to produce 2 lactate molecules, Pyruvate reduced and NADH oxidized to NAD+ for glycolysis

What happens to pyruvate when oxygen is present (aerobic)?

Pyruvate enters the mitochondria for further oxidation, Pyruvate loses carbon to produce acetate and CO2. CO2 exits cell and enters bloodstream to be expired in lungs, Acetate + CoA + NAD+ --> Acetyl-CoA + NADH, 2 acetyl-CoA molecules enter citric acid cycle.

List the 4 steps of the citric acid cycle.

1. Citrate synthesis, 2. First oxidation, 3. ATP Synthesis, 4. Second oxidation

What is the role of Acetyl CoA in the citric acid cycle?

Acetyl CoA donates 2 carbon acetyl group to 4 carbon oxaloacetate forming 6 carbon citrate and CoA.

What is produced per glucose molecule from start of glucose catabolism?

10 NADH, 2 FADH2, 4 ATP

What occurs during oxidation phosphorylation?

Potential energy from glucose used to make ATP

What 3 processes are involved in oxidative phosphorylation?

1. Transfer of electrons between electron carriers, 2. Generation and maintenance of H+ concentration gradient, 3. Use of gradient to drive release of ATP.

What is the role of the electron transport chain(ETC)?

Releases energy stored in electrons of NADH and FADH2.

What ultimately happens to the electrons in Complex IV of the electron transport chain?

Complex IV transfers the electrons to oxygen-the final electron acceptor- to form H2O.

What is chemiosmosis?

Electrochemical gradient becomes kinetic energy when H+ flow through ion channels across membrane.

What happens to NADH in the electron transport chain?

NADH is oxidized to NAD+ and Electrons passed to first electron carrier in enzyme complex I reducing the complex.

What is the role of Complex I in the electron transport chain?

Complex I uses energy to pump H+ (protons) against concentration gradient from mitochondrial matrix to intermembrane space.

What is the role of Complex IV in the electron transport chain?

Complex IV transfers electrons to final electron acceptor (O2).

What is the big picture of glucose catabolism and ATP synthesis?

C6H12O6 + 6 O2 --> 6 H2O + 6 CO2 + 36-38 ATP + Heat

What are the 2 reasons why the body stores nutrients?

More energy is taken in than we can immediately use and Body needs a supply of nutrients to oxidize between meals.

What are the 2 major storage forms of energy?

Glycogen and Adipose (fat).

What are the 2 major processes of glucose anabolism?

Glycogenesis and Gluconeogenesis

Define glycogenesis.

Enzyme catalyzed reactions add glucose molecules to growing glycogen molecule.

Define glycogenolysis.

Breakdown of glycogen into glucose

Define gluconeogenesis.

Synthesis of new glucose from non-carbohydrate molecules

How is glycerol used in gluconeogenesis?

Glycerol from triglyceride metabolism can be used to make more glucose.

How are pyruvate and lactate used in gluconeogenesis?

Pyruvate and lactate from glycolysis can be used to make more glucose.

How are Intermediates from the citric acid cycle used in gluconeogenesis?

Intermediates from the citric acid cycle can be used to make more glucose.

How are glucogenic amino acids used in gluconeogenesis?

Certain glucogenic amino acids can be used to make more glucose.

What happens during fatty acid catabolism?

Lipolysis breaks up fatty acids and glycerol. Glycerol is converted to glyceraldehyde-3- phosphate and enters glycolysis.

What is the role of β-oxidation in fatty acid catabolism?

Produces acetyl CoA and ketone bodies through ketogenesis.

What is ketogenesis?

Process in liver producing ketone bodies from acetyl CoA

What occurs in ketogenesis?

2 acetyl CoA molecules combine to form a 4 carbon ketone body. Liver cannot metabolize ketone bodies and releases into blood.

Transamination does what?

Amino acids enter hepatocytes and amino group is removed

What does the Urinary System consist of?

Composed of paired kidneys and urinary tract

What are the functions of the kidneys?

Removal of metabolic wastes, Fluid and electrolyte balance, Acid-base balance, Detoxification, Maintenance of blood pressure, Regulation of erythropoiesis, Activate vitamin D, Gluconeogenesis.

What structures carry urine from the kidney?

Paired ureters

What structure stores urine?

Urinary bladder

What structure expels urine from the body?

Urethra

What does the hilum provide an opening for?

Entrance and exit of renal artery, vein, nerves and ureter.

How much of cardiac output comes from renal arteries?

25% (1200 ml/min)

What is the function of nephrons?

Filter blood and modifies fluid that passes through renal tubules.

What does a renal corpuscle consist of?

Glomerulus and glomerular (Bowman’s) capsule.

What is the glomerulus?

a group of fenestrated capillaries

What does the glomerulus filter?

Blood

What are the components of the glomerular capsule?

outer parietal layer and an inner visceral layer

What describes the Parietal layer of the Glomerular Capsule?

Simple squamous epithelium

What describes the Visceral layer of the Glomerular Capsule?

Modified epithelial cells (podocytes) wrap around glomerular capillaries

What 3 regions make up the renal tubule?

1. Proximal tubule, 2. Nephron loop or Loop of Henle, 3. Distal tubule.

What type of epithelium is the proximal tubule?

Simple cuboidal epithelium

Which limb of the nephron loop has simple squamous epithelium?

Descending limb (thin descending limb)

Which limb of the nephron loop has simple cuboidal epithelium?

Ascending limb (thick ascending limb)

What are the components of the Juxtaglomerular Apparatus (JGA)?

Composed of macula densa and juxtaglomerular cells (JC).

What does the juxtaglomerular apparatus regulate?

1. Blood pressure, 2. Glomerular filtration rate.

What 2 components make up the collecting system?

1. Cortical collecting duct, 2. Medullary collecting system.

Which type of nephron is more numerous?

Cortical nephrons (80%)

What surrounds the nephrons loops of juxtamedullary nephrons?

Vasa recta capillaries from efferent arteriole

What are the Three Functions of Nephrons?

Filtration, Reabsorption, and Secretion

What is glomerular filtration?

Blood filtered as it passes through glomerular capillaries.

What substances are reclaimed during tubular reabsorption?

Filtrate --> Peritubular capillaries

What substances move during tubular secretion?

Peritubular capillaries --> into filtrate

What substances are retained during glomerular filtration?

Large Substances in the blood

What 3 layers make up the filtration membrane?

1. Capillary endothelial cells, 2. Basal lamina, 3. Podocytes.

What is prevented by the Capillary endothelial cells?

Prevents formed elements from leaving capillaries.

What is prevented by the Basal lamina?

Prevents most proteins from entering capsular space. Negative charges repels smaller proteins.

What types of substances pass through during glomerular filtration?

H2O, Small dissolved solutes, Electrolytes, Very small proteins, Amino acids, Nitrogenous wastes (Urea, NH4 +, uric acid and creatinine).

What does GFR stand for?

Glomerular Filtration Rate

What two main pressures determine how much filtration occurs?

Hydrostatic and colloid osmotic pressures

What is Glomerular Hydrostatic Pressure (GHP)?

Force of fluid on wall of a container. Equal to blood pressure (50 mm Hg). Force pushes H2O out of capillary into interstitial space.

What is Glomerular Colloid Osmotic Pressure (GCOP)?

Pressure created by proteins in plasma. About 30 mm Hg. Osmotic gradient pulls H2O into capillaries by osmosis and opposes filtration.

What is Capsular Hydrostatic Pressure (CHP)?

Pressure of filtrate inside capsular space. About 10 mm Hg and opposes filtration.

How is Net Filtration Pressure (NFP) calculated?

NFP = GHP - (GCOP + CHP)

How does constriction or dilation of afferent and efferent arterioles affect GFR?

changes GFR

What is the effect of Afferent Arteriole Constriction on GHP and GFR?

Decreases GHP and GFR

What is the effect of Efferent Arteriole Constriction on GHP and GFR?

Increases GHP and GFR

What is the effect of Vasodilation of Afferent Arteriole on GHP and GFR?

Increases GHP and GFR

What is the effect of Vasodilation of Efferent Arteriole on GHP and GFR?

Decreases GHP and GFR

What are the two types of GFR Regulation?

Autoregulation (within) and Neural or hormonal factors (external).

What two processes are involved with Autoregulation of GFR?

Myogenic mechanism and Tubuloglomerular feedback.

What type of transport has a substance pass between adjacent tubule cells?

Paracellular Route

What type of transport has a substance move through tubule cells?

Transcellular Route

How is HCO3- reabsorbed?

Blood CO2 reacts with H2O to produce H2CO3 catalyzed by carbonic anhydrase (CA). H2CO3 dissociates into HCO3- and H+.

How is reabsorption promoted in the proximal tubule?

Aquaporin channels promotes reabsorption

Where are H+ secreted?

proximal tubules

What substances are secreted in proximal tubules?

NH4 +, creatine and small amount of urea are secreted. Penicillin and morphine are secreted

Describe the role of the Thin Descending Limb of the Nephron Loops.

Freely permeable to H2O and Less permeable to Na+ and Cl-. H2O moves out by osmosis but few solutes follow.

Describe the role of the Thick Ascending Limb of the Nephron Loops.

Impermeable to H2O. Transports NaCl into tubule cells with Na+/K+/2 Cl- symporters. Filtrate less concentrated as ions are pumped into interstitial fluid.