Chamberlain's portion Flashcards by Christine Shiao

What do stomach mucous neck cells produce? Parietal? Enterochromaffin-like, chief, D, G cells?

Mucous
HCl and Intrinsic Factor
Histamine
Pepsin + gastric lipase
Somatostatin
Gastrin

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What do pancreatic proteases secrete?

HCO3-

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What is the purpose of taste receptors in the small intestine?

Sweet (glucose) receptors stimulate paracrine release of glucagon-like peptide (GLP) which upregulates glucose transporters in nearby enterocytes for absorption and stimulate afferent neurons

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What does glucagon do?

During low blood glucose, it is released by alpha cells in the pancreas, liver releases glucose into blood

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What does insulin do?

During high blood glucose, beta cells in pancreas releases insulin, liver inhibition, body’s cells absorb glucose

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How is the equilibrium point for glucose determined?

Intersection of insulin and glucagon curve will change as hormones and autonomic activity changes

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What happens to the equilibrium point for glucose in diabetics?

Increases

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What are the actions of somatostatin on the stomach and pancreas?

D cell (delta cell in pancreas) secretes SST which inhibits G cells, insulin, and glucagon

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How does insulin regulate carb + fat metabolism and storage?

Glucose uptake into cells
Protein, fat, glycogen synthesis
Growth and gene expression
Satiety signal

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What transporter is used for transporting glucose into cells?

GLUT4

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What enzymes are involved in protein, fat, and glycogen synthesis?

Protein - mRNA translation, ribosome synthesis
Fat - FA synthase, lipoprotein lipase to absorb FAs
Glycogen - glycogen synthase (phosphorylase inhibited), activate glycolysis

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What are the channels and receptors involved in the process of insulin release in response to high blood glucose?

Glucose
Glycolysis
Increase in ATP
Closes K+ channel leads to depolarization
Opens Ca2+ channel
Calcium releases insulin from vesicles

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What is the sympathetic NS influence on glucose levels?

Increases blood glucose; E+NE increases release of glucose from the liver and decreases uptake by cells. Can lead to insulin resistance

Stimulates alpha receptors that increases glucagon release

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What is the parasympathetic NS influence on glucose levels?

Decreases blood glucose; Ach stimulates beta cells in cephalic phase to increase insulin release

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What is the normal fasting blood glucose range? How does insulin and glucagon keep this homeostatic range?

70-110 mg/dl
Insulin decreases blood glucose
Glucagon increases blood glucose

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What nutrients are absorbed in the duodenum?

Iron, calcium, magnesium

What nutrients are absorbed in the jejunum?

Vitamin C

What nutrients are absorbed in the ileum?

Vitamin A, D, E, K, B12

What vitamins are transported by the portal system?

Water-soluble vitamins: B1, B2, B3, B6, B7, B12, Vitamin C, Folic acid

What vitamins are transported by the lacteals and thoracic duct to the venous system?

Lipid-soluble vitamins: A, D, E, K

What water-soluble vitamins are absorbed via passive transport?

B1, B6, B7 in jejunum

What water-soluble vitamins are absorbed via active transport?

B2, C, B12 (in ileum) in jejunum

What water-soluble vitamins are absorbed via facilitated transport?

B3, B7, folic acid in jejunum

How are fat-soluble vitamins absorbed?

Solubilized within micelles for transport into enterocytes. Chylomicron containing vitamins will be exocytosed from enterocyte and into lacteals to bypass liver

What does ONLY the small intestine absorb/secrete?

Water and electrolytes Absorption by enterocyte villi Secretion of HCO3- by enterocyte crypts of Lieberkuhn

What does ONLY the large intestine absorb/secrete?

K+, HCO3- Only crypts of Lieberkuhn No villi

What do both the large and small intestine absorb?

Net water, Na+, Cl-, K+

What are the two different types of diarrhea?

Secretory - Cl- secretion from overstimulation of Cl- channel by E. coli or cholera; serotonin released Osmotic - increased solutes in lumen pulls water into lumen

Why is Na+ important in absorbing nutrients?

It's used to cotransport with glucose or Cl- in jejunum | It's exchanged with H+ (buffered by HCO- in lumen)

How much water is secreted and reabsorbed in the GI daily?

9000 ml/day secreted | 8900 ml/day reabsorbed

Where is visceral fat?

Around kidney, heart, GI (between organs and peritoneum)

What are the potential problems with having visceral fat?

Metabolic syndrome=insulin R, dyslipidemia, type 2 DM, hypertension

Why is cortisol elevated with increase in visceral fat?

Visceral fat has more cortisol receptors than subcutaneous fat This enhances FFA uptake and inhibits lipolysis Redistributes fat from peripheral to abdominal area Cortisol in turn increases visceral fat-->vicious cycle!

Why is a decrease in only 2 BMI points so effective in preventing hiatal hernia and adipokine production?

There is a substantial decrease in visceral fat with just 2 BMI points. This decreases metabolic syndrome risk factors

How does cortisol interact with various fats?

Cortisol increases FFA which increases insulin R | Increases inflammation because fat releases TNF

How do adipokines damage IRS receptors?

Adipokines secrete TNFalpha and IL-6 when prompted by macrophages in visceral fat and adipocytes Cytokines causes inflammation and oxidative damage IRS proteins are phosphorylated, and thus inhibits GLUT4 translocation Spatial disruption of IRS

How does visceral fat affect coronary arteries?

The adipokines that are secreted by adipocyte macrophages cause oxidative damage + insulin R ROS + insulin R = Atherosclerosis

Outline what happens in the orexigenic pathway.

Inhibited Leptin leads to activity of NPY-AgRP neurons of arcuate nucleus NPY-AgRP neurons stimulates feeding behavior via stimulating the lateral hypothalamus to vagal PNS, brainstem for simple and cerebral cortex for complex feeding behaviors NPY-AgRP neurons inhibits PVN which normally increases energy use and weight loss

Outline what happens in the anorexigenic pathway.

Activated leptin leads to activity of alpha-MSH/CART neurons of the arcuate nucleus Alpha-MSH/CART neurons inhibit lateral hypothalamus which normally increases appetite Alpha-MSH/CART neurons stimulate PVN which normally increases energy use and weight loss by increasing: cortisol (move glucose), thyroid hormones (increase metabolism and oxygen use), sympathetic activity (increase lipolysis)