Digestion 2- Pancreas and beyond

Question 1

How many islets of lagerhans are there and what organ are they located in?

Answer 1

1-2 million cells dispersed in the exocrine pancreas.

Question 2

3 types of cells that make up the islets of langerhans

Answer 2

1. Alpha cells secrete glucagon
2. Beta cells secrete insulin
3. Delta cells secrete somatostatin (fewest, inhibitory, located between alpha and beta cells)

Question 3

What type of junctions do the islets of langerhans have?

Answer 3

Gap junctions activated by calcium transfer.

Tight junctions and desmosomes (cell to cell contact)

Question 4

Glucagon is derived from

Answer 4

Preprohormone

Question 5

Glucagon stimulates the release of

Answer 5

Stimulates hepatic (liver) release of glucose by glycogenolutic or gluconeogenic actions during fasting, exercise, or neonatal.

Question 6

Glucagon targets what?

Answer 6

Targets the liver and adipose cells to release glucose. Glucagon interacts with liver and adipose cells through a G protein coupled receptor. The secondary messenger is PKA.

Question 7

What stimulates glucagon to be released from alpha cells?

Answer 7

Amino acids, acetyl choline, epi, NE, VIP from the gut and CCK from the gut.

Question 8

What inhibits glucagon to be released from the alpha cells?

Answer 8

Glucose, insulin, somatostatin (inhibitory), ketones, Free fatty acids, glucose lipid 1 and glucose inhibition protein.

Question 9

Insulin peptide looks like what

Answer 9

A chain with 21 amino acids linked to B chain with 30 amino acids. Linked by disulfide bond.

Question 10

How is insulin synthesized?

Answer 10

As pro-insulin

Question 11

Insulin receptor has how many domains?

Answer 11

2 alpha domains that bind to insulin and 2 beta domains that has tyrosine kinase domains. Once bound, phosphorylation occurs and it can internalize the insulin that is bound.

Question 12

What activates insulin release from beta cells?

Answer 12

Glucose, amino acids, ketones, Free fatty acids, glucagon, acetylcholine.

Growth hormone and cortisol.

Question 13

What activates insulin release from beta cells?

Answer 13

Somatostatin, epinephrine, and NE.

Question 14

How are insulin and glucagon release related?

Answer 14

They are oppositely related. What activates glucagon release, inhibits insulin release.

Question 15

Normal blood glucose levels

Answer 15

80-100 mg/DL

Question 16

How does glucose, glucagon, and insulin levels change throughout the day?

Answer 16

Glucose- Increases when you eat, then returns to normal. Fluctuates throughout the day.

Glucagon- Pretty stable throughout the day. Not much change.

Insulin- Bounces around WRT glucose levels. As glucose levels increase, so do insulin levels.

Question 17

What are insulin levels like at night?

Answer 17

Stable. Low. Same with glucose levels.

Question 18

What does the A1C measure? What is a normal level?

Answer 18

How good the patient is at stabilizing their blood glucose levels.

Normal level is 7.

Question 19

Somatostatin is increased by __ and decreased by ___

Answer 19

increased by NE and decreased with Ach

Question 20

What is the function of somatostatin?

Answer 20

Regulates growth hormone, increases in the blood after a fat or protein rich meal. Allows for what is currently in the intestine to be reabsorbed.

Decreases acid secretion in the stomach.
Decreases intestinal motility.
Slows rate of absorption.

Question 21

Why is pancreatic cancer so hard to diagnose?

Answer 21

Variety of symptoms since it plays so many roles in the body.

Question 22

Once nutrients are absorbed in the small intestine, where do they go?

Answer 22

In the small intestine, they are absorbed into the villus, and eventually the central lacteal within the villus. The lymphatic vessel meets the thoracic duct, which dumps into the left subclavian vein.

Question 23

What is a villus? What does it contain and where is it located?

Answer 23

Absorb nutrients in the small intestine. Contains a vein, artery, capillary, and central lacteal (lymphatics, fat transfer)

Question 24

If there are a lot of fatty acids in the small intestine, CCK is secreted. What does it do?

Answer 24

If CCK is secreted by the small intestine, then it will increase in the plasma as well.

This causes the gall bladder to contract to release bile into the common bile duct.

Also relaxes the sphincter of oddi, which allows bile to flow into the duodenum

Question 25

hemoglobin is broken down into

Answer 25

Bilirubin

Question 26

What helps break down bilirubin?

Answer 26

Bacteria

Question 27

Before bilirubin can be released from the body as feces or urine, it most be converted into?

Answer 27

Urobilinogen.

Question 28

Pancreatic lipase converts triglyceride into

Answer 28

2 Monoglyceride and a free fatty acid.

Question 29

What do you need in order to break down primary bile salts into secondary bile salts? (need secondary in order to properly break down fats)

Answer 29

Bacteria!

Question 30

4 cells of the intestinal glands from superficial to deep

Answer 30

Superficial
1. Absorptive cell- Digests and absorbs nutrients.
2. Goblet cell- Secretes mucous
3. Enteroendocrine cell- Secretes secretin and CCk. They are concentrated at the sphincter of oddi.
4. Paneth cell. Secretes lysozyme and is capable of phagocytosis. Deep in crypts.
Deep
** Also have stem cells.

Newer cells are deep, they mature and die as they move superficially.

Question 31

Glycocalyx of the intestine contains

Answer 31

Mucin, enzymes, and transport carriers.

Question 32

How do amino acids travel from lumen to inside intestinal cell and then to interstitial fluid(blood)?

Answer 32

Lumen–> Cell by syntransport with Na+. (a form of secondary active transport)
Cell –> intestinal fluid by amino acid transporters.

Question 33

Glucose polymers such as __ and __ are broken down by ___ into which 3 disaccharides?

Answer 33

Glucose polymers such as starch and glycogen are broken down by amylase into:
maltose (glucose + glucose)
sucrose (glucose + fructose)
lactose (glucose + galactose)

Question 34

How do carbohydrates travel from lumen to inside intestinal cell and then to interstitial fluid(blood)?

Answer 34

Lumen –> cell
Fructose travels by a glucose transporter. Glucose and galactose use symport (a form of secondary active transport) with Na+

Cell –> Intestinal fluid (blood) by GLUT. Glucose transporter by facilitated diffusion.

Question 35

Ileum is in what quadrant of the abdomen?

Answer 35

The lower right quadrant. It is the terminal part of the small intestine. Attaches to the cecum of the large intestine.

Question 36

The appendix. What is it attached to?

Answer 36

Located in the lower right quadrant, attached to the cecum.

Vestigeal organ.

If ruptures, will release harmful bacteria into abdominal cavity.

Question 37

Histology of large intestine

Answer 37

Do not see villus (micivili on cells) because only SOME water absorption occurs here. Not nearly as much absorption as the small intestine.

Instead, it has many pores in the mucosa made of simple columnar epithelium that absorb water/goblet cells that secret mucus. Lots of lymphatic nodules.

Question 38

9 liters of fluid dumped into the GI tract each day. How does it get reabsorbed/released?

Answer 38

Small intestine reabsorbs 8 liters.

Large intestine absorbs 90% of the 1 remaining liter.

Question 39

What reflex moves feces into the rectum?

Answer 39

Gastrocolic reflex. Neuronal reflex. Stretch receptors signal sacral spinal cord

Question 40

Control of the internal and external anal sphincter?

Answer 40

Internal- parasympathetic nerves control. Smooth muscle.

External- Sympathetic. Skeletal muscle control. Voluntary.