DLA 1+2+3+4 and Lecture 1+2

Question 1

what are the two regulated steps of glycolysis?
what do those enzymes do?
ATP used?

Answer 1

1. glucokinase / hexokinase
   convert glucose to glucose 6-phosphate
2. PFK-1
   irreversible reaction of fructose 6-phosphate to fructose 1,6- bisphosphate

2 ATP are used

Question 2

Aldolase A and B

location? function?

Answer 2

aldolase A is in muscle; aldolase B is found in the liver

aldolase B is needed for fructose metabolism

these two enzymes convert fructose 1,6-biphosphate to either G3P or Dihydroxyacetone phosphate

Question 3

what enzyme in glycolysis results in NADH

Answer 3

Glyceraldehyde 3-phosphate dehydrogenase

Question 4

what enzymes in glycolysis results in ATP formation?

Answer 4

Phosphoglycerate kinase 
pyruvate kinase (irreversible reaction)

Question 5

function of LDH?

Answer 5

convert between pyruvate and lactate

can go either way

Question 6

the higher the NADH levels the more (blank) produced?

Answer 6

lactate

Question 7

what is a reducing sugar?

Answer 7

sugar that has a free aldehyde or keto group

Question 8

Review of GLUT 1, 2, 3, and 4?

Answer 8

GLUT 1 = neurons and RBC

GLUT 2 = liver

GLUT 3 = neurons

GLUT 4 = adipose tissue and muscle (insulin-responsive)

Question 9

glucokinase vs hexokinase?

Answer 9

glucokinase:
In the liver and pancreatic B cells
have a high Km and high Vmax
more active when blood sugar is high

hexokinase:
most other tissues
low Km

Question 10

The key enzyme in the PPP and main products?

Answer 10

enzyme: G6PD

forms NADPH

forms ribose phosphate
requires vitamin B1 or TPP for the enzyme transketolase

Question 11

The fates of pyruvate

Answer 11

either the TCA cycle if oxygen is present

cori cycle if no oxygen is present

Question 12

Fate of the cori cycle?

Answer 12

converts lactate from the skeletal muscles and RBC’s to glucose (in the liver)

Question 13

The actions of arsenic?

Answer 13

inhibits the enzyme glyceraldehyde 3-phosphate dehydrogenase

inhibits mitochondrial enzymes, as well

Question 14

presentation of lactic acidosis?

Answer 14

high anion gap metabolic acidosis

low pH
decreased HCO3
decreased CO2

elevated lactate levels

Question 15

the 3 irreversible reactions in glycolysis?

Answer 15

glucokinase

PFK-1

pyruvate kinase

Question 16

Role of Fructose 2,6 biphosphate

Answer 16

high blood levels: insulin active 
dephosphorylated 
active PFK-2 
increases fructose 2,6 biphosphate 
allosterically activates PFK-1 for glycolysis 

low blood levels: glucagon active 
phosphorylated 
FBP-2 active 
decreases fructose 2,6 biphosphate 
activates fructose 1,6 biphosphatase for gluconeogenesis

Question 17

blood supply of the foregut?
blood supply of midgut?
also hindgut?

Answer 17

foregut: celiac
midgut: superior mesenteric
hindgut: inferior mesenteric

Question 18

The development of the stomach?

Answer 18

distal part of the foregut shows a fusiform dilation which has right and left surfaces and anterior and posterior borders

as the size of the stomach grows the posterior border or greater curvature grows faster than the anterior border or lesser curvature

the stomach does rotate 90 degrees

Question 19

dorsal and ventral mesogastrium?

Answer 19

dorsal: greater omentum, gastrosplenic ligament, and splenorenal ligament
ventral: falciform ligament and lesser omentum

Question 20

congenital hypertrophic pyloric stenosis

Answer 20

narrowing of the lumen of the pyloric canal due to hypertrophy of the muscles

stomach of baby will be distended and will lead to projectile vomiting

vomitus is not bile stained

will be seen between 3 weeks to 5 months after birth

can be seen by barium swallow or ultrasound

Question 21

development of the duodenum

Answer 21

develops from the caudal part of the foregut and the cranial part of the midgut

as the stomach rotates the duodenum takes on a C-shape and rotates to the right.

Question 22

Duodenal stenosis

Answer 22

partial occlusion of the lumen due to incomplete recanalization

leads to vomiting which is bile stained

Question 23

duodenal atresia

Answer 23

complete occlusion of the lumen due to failure to recanalize

will see polyhydramnios
vomiting will begin right after birth

will see double bubble sign!

Question 24

development of the liver and biliary apparatus

Answer 24

The hepatic diverticulum arises during the 4th week of development from the caudal part of the foregut

this will extend into the septum transversum

hepatic diverticulum has cranial and caudal parts

cranial part forms the liver
caudal part forms the gallbladder and cystic duct

Question 25

major papilla

Answer 25

dividing point between the foregut and midgut

hepatopancreatic ampulla - common opening for bile duct and pancreatic duct

Question 26

development of the pancreas?

Answer 26

the pancreas develops from two endodermal buds from the distal end of the foregut

the ventral and dorsal buds fuse by the 7th week

Question 27

annular pancreas

Answer 27

due to bifid ventral pancreatic bud

can wrap around the duodenum and cause an obstruction

Question 28

development of the spleen

Answer 28

the spleen is derived from mesenchymal cells between the layers of dorsal mesogastrium