Lecture 31: Nutrition Flashcards Preview

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Flashcards in Lecture 31: Nutrition Deck (27):
1

Macronutrients

Carbohydrates
Protein
Lipids

2

Micronutrients

Minerals
Vitamins

3

Basal metabolic rate

Energy expenditure at rest, warm, awake, several hours after a mean
High in males tan in females
Decreases with age after reaching adulthood
Different in between organs and tissues
Brain is 25% of BMR

4

Total energy expenditure

Basal metabolic rate + thermic effect of food + physical activity

5

Protein digestion

1. Dietary protein broken down by pepsin into polypeptides and amino acids
2. Broken down into oligopeptides and amino acids by pancreatic proteases and peptidases
3. Broken down completely to amino acids by intestinal peptidases to be absorbed by small intestine and taken to liver

6

Carbohydrate digestion

1. Starch, lactose, sucrose, cellulose taken in by both and broken into disaccharides by alpha-amylase
2. Broken down by pancreatic amylase
3. Broken down by sucrase, lactase, maltase and isomaltase
4. Absorbed by small intestine and sent to liver (cellulose secreted as feces)

7

Lipid digestion

1. Emulsification by bile salts and digestion by pancreatic lipase (triacylglycerols cannot cross membrane by simple diffusion, not soluble in water, present in big droplets)
2. Free fatty acids, glycerols and cholesterol taken up by enterocyte and reesterified into chylomicrons in lymph to be send to blood

8

Emulsification

Big fat globules are broken into small droplets
Bile acids act as detergents
Increased surface area
More exposure to lipase

9

Lipolysis

Breakdown of triacylglycerols
Resulting monoacylglycerols are taken up into intestinal cells

10

Monoacylglycerols

Taken up into intestinal cells
Synthesized into triacylglycerols and secreted in form of chylomicrons

11

Pancreatic lipase

Digests triacylglycerols into 2-monoacylglycerols releasing 2 fatty acids

12

Chylomicron metabolism

1. Intestinal mucosal cells secrete TG rich chylomicrons
2. Enters capillaries
3. Degraded by lipoprotein lipase into glycerol (to liver) and fatty acids (to adipose)
4. Chylomicron remnants bind to specific receptors on the liver and are endocytosed

13

VLDL metabolism

1. Secreted by liver
2. Enters capillaries
3. Lipoprotein lipase digests into fatty acid (to adipose) and glycerol (to liver)
4. Left is LDL which is sent to extra hepatic tissues and on liver and are endocytosed

14

Muscle metabolic profile

Takes up fatty acids form adipose, and VLDL/fatty acids/ketone bodies from liver
Sends alanine and lactate to liver

15

Brain metabolic profile

Takes glucose and ketone bodies from liver

16

RBC metabolic profile

Take glucose from liver
Send lactate to liver

17

Heart metabolic profile

Takes glucose/VLDL/fatty acids/ketone bodies from liver
Takes fatty acids from adipose

18

Adipose tissue metabolic profile

Sends fatty acids to muscle and heart, fatty acids and glycerol to liver
Takes VLDL/fatty acids/glucose from liver

19

Diabetes mellitus

Chronic disorder of carbohydrate, fat and protein metabolism
Elevation of plasma glucose levels (hyperglycaemia) because of defect or deficiency of insulin secretion from pancreas
Increased thirst, unexplained weight loss, increased urination
Metabolism resembles the post-absorptive or fasting state with low insulin

20

DM Type 1

Destruction of pancreatic beta cells (often autoimmune response)
Complete absence of insulin, increased levels of glucagon even when dietary glucose is present

21

DM Type 2

Insulin resistance
Insulin is secreted but the cellular response is impaired
Later impaired glucose-stimulated insulin secretion develops as well

22

Insulin resistance

Signalling interrupted
Fatty acids, inflammatory cytokines and other molecules trigger other signalling cascades that interfere with intracellular insulin cascade from receptor binding

23

Hyperglycaemia effect of diabetes

Decreased glucose uptake into muscle and adipocytes
Ongoing gluconeogenesis
Glycogen breakdown in liver

24

Amino acid uptake with diabetes

No insulin so amino acid uptake and protein synthesis are not stimulates: gluconeogenesis precursors

25

Fatty acid uptake with diabetes

No insulin, high glucagon
Increase hormone sensitive lipase activity
Fatty acids taken in as gluconeogenesis intermediates

26

Lipoprotein uptake with diabetes

Insulin inhibits VLDL secretion and activated lipoprotein lipase
No insulin causes decrease in clearance of TG-righ lipoprotein, increased VLDL secretion

27

Characteristics of cancer cells

1. Uncontrolled growth
2. Growth without attachment
3. Growth without external growth factors
4. Dedifferentiation