Lecture 7 - Carbohydrate, lipid and amino acid metabolism

What is the absorptive state?

ENERGY FROM OXYDIZING NUTRIENTS ENTERING THE BLOODSTREAM FROM GUT → IMMEDIATE USE OR STORAGE

What is the difference in absorptive and post absorptive state between carnivores/omnivores and ruminants?

• Carnivores & Omnivores

Absorption takes approximately 4h and animals eat 3 meals a day

- 12h of absorptive state

- alternate periods of energy storage and utilization

• Ruminants

Digestion is more continuous

What is the postabsorptive state?

NUTRIENTS MOBILIZED FROM BODY’S STORAGE

What is energy stored as? (2)

Energy stored as glycogen (glycogenesis) and fat

Can essential amino acids be synthesized in the body?

No

What is the main regulator of the absorptive phase of glucose?

Insulin (look at page 21)

Look at and explain the figure on page 28

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Where is the syntheses glycogen occur? (2)

Liver and Skeletal muscle

What enzyme coverts glucose-6-phosphate into glycogen?

Glycogen synthase

Where do the triglycerides produced in the liver get transported too?

Adipose tissue (packed in lipoproteins)

What is glycogen storage disease?

A animal does not have glucose-6-phosphates and cannot store (ask later)

What are the two types of Equine polysaccharide storage myopathy?

• Type 1: increase expression of glycogen synthase (GSY1), but not branching enzyme

• Type 2: Abnormal glycogen deposition without GSY1 or GBE1 mutation

What does the VLDL (very-low density lipoproteins) do?

Produced in liver and transport triglycerides to rest of body

Where do the chylomicron remnants go back to?

Liver

Lipids are hydrophobic and cannot travel freely so how are they transported?

• FFA bind to albumin

• All other lipids transported in lipoproteins

Where are lipoproteins synthesized?

In liver

• chylomicrons the exception (synthetized in small intestine)

• VLDL (TG & cholesterol from liver to peripheral tissues)

• LDL (low density lipoprotein): cholesterol to tissues

• HDL (high-density lipoprotein): cholesterol from tissues to liver

What are the bad cholesterol and where are they transported?

VLDL, LDL (bad cholesterol) transports cholesterol to cells

What is the good cholesterol and where is it transported?

HDL (good cholesterol) produced in liver, collects cholesterol

from cells and transports to liver

• Cholesterol excreted as bile

Explain the figure on page 47

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What is TG synthesized from for monogastrics?

TG synthetized from glucose in liver

What is TG synthesized from for ruminants?

TG synthetized from acetate in adipose tissue

If glucose is low what is used as cellular fuel?

Amino acids

What are amino acids composed of and what process septerates them>

Amino group and organic acids (energy source) Separated by deamination

Explain the figure on page 64

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Fill in the blanks

What is the main regulator of post absorptive phase for glucose?

Glucagon

What is Glycogenolysis?

When glucose concentrations fall below a certain level the liver starts to mobilize glycogen reserves

What is gluconeogesis?

Making glucose from non-carbohydrate sources

What is the Cori cycle?

lactate produced in muscle cells converted to glucose in liver and can return to muscle cells

What is glucose sparing?

In postabsorptive state tissues shift to utilizing lipids as main energy source

What are the triglycerides broken down by?

hormone-sensitive lipase

What is insulin secreted by?

Secreted by beta cells in response to high blood glucose

What are 4 things insulin does in the body?

• Increase uptake of glucose in the cells of organs

• Stimulates synthesis of glycogen and inhibits degradation

• Increases consumption of glucose for ATP production

• Inhibits gluconeogenesis

What cell secretes glucagon?

Secreted by alpha cells in response to low blood glucose

What are 3 things glucagon does?

• Stimulates glycogenolysis in the liver

• Stimulates gluconeogenesis in the liver

• Stimulates lipolysis in adipose through activation of hormone-sensitive lipase

Insulin promotes protein ________ and inhibits protein _________

synthesis, degradation

What hormones promoted the uptake of AA

Insulin and glucagon

What causes the mobilization of glucose from glycogen

Epinephrine

How does fatty liver occur

Fatty liver occurs when excessive fatty acid mobilization occurs or impaired ability to export via apolipoproteins