Metabolism Flashcards
Stage I to III of metabolic pathway of carbohydrates
Carbohydrates –> monosaccharides –> acetyl CoA –> TCA cycle
catabolic pathway
break down molecules
anabolic pathway
build up molcules
energy yield of carbs, proteins, and lipids
carbs –> glucose –> 4 calories
protein –> amino acids –> 4 calories
lipids fats –> 9 calories
carbohydrate break down: simple vs complex
maltose, lactose, and sucrose monosaccarides
maltose - glucose + glucose
lactose - glucose + galactose
sucrose - glucose + fructose
high fructose syrup vs sucrose
sucrose = “real sugar” – 50% glucose and 50% fructose
high fructose syrup = “corn syrup” –mix of ratios of monosaccharides
→ ex: 40% glucose to 55% fructose
absorption of carbohydrates?
______________monosaccharides (glucose, galactose, fructose) is what is eventually absorbed in the end
absorption vs digestion
absorption = monosaccharides
digestion = break down of disaccharides
lactose intolerance
- what is the enzyme deficiency
- symptoms?
lactase = breaks down lactose into glucose + galactose
- if lactase deficiency than lactose enters large intestine/ colon and is broken down by bacteria that releases carbon dioxide, hydrogen gas, etc.
symptoms:
- this leads to bloating, diarrhea, and dehydration
monosaccharide absorption into intestinal mucosal cells
name the 2 transporters and if they require energy/ cofactors?
- if so what?
GLUT-5 transports fructose –> energy and sodium (Na+) independent transport
SGLT-1 (sodium-glucose cotransporter-1): transports glucose and galactose.
- it is energy and Na+ dependent
monosaccharide absorption at basal membrane
- which transporter
after monosaccharides are in the mucosal cell they are transported across the basal membrane to circulation/ portal vein via GLUT-2
circulation order of carbohydrates/ glucose
small intestine –> portal vein –> liver –> circulation as blood glucose in muscle, fat, RBC, and CNS
Location/ Description of the 5 GLUT Transporters
GLUT1
RBC, blood brain barrier, retinal barrier, placental barrier, testis barrier
–> all through blood circulation
–> high-affinity glucose transport system
Location/ Description of the 5 GLUT Transporters
GLUT2
GLUT2 - liver, kidney, pancreatic B-cells, Serosal surface of intestinal mucosa
- high capacity, low affinity transporter
- helps monsaccharides through the basal membrane
GLUT transporters summary
diabetes, normal, and prediabetes
normal - less than 100 mg/dl
prediabetes - 100 to 125
diabetes - 126 or higher
how can Hb1AC be used to diagnose diabetes?
HbA1C count is expressed as a percentage of hemoglobin
normal - less than 5.7%
prediabetes - 5.7 to 6.4%
diabetes - 6.5% or higher
Oral Glucose Tolerance Test
subject fasts for 10-12 hours (blood drawn)
given flavored drink with 75g glucose
2 hours after glucose load = additional samples drawn
normal, prediabetes, and diabetes OGTT result
OGTT chart
Subject #1: Normal response, blood glucose rises and then falls, within 90 minutes
Subject #2: A normal fasting plasma glucose, has impaired glucose tolerance, a 2-
hour reading >140 mg/dL and pre-diabetic
Subject #3: Diabetic
