GI Structure Blatter

Question 1

What is the ultimate input of all energy

Answer 1

Food intake is all energy input

Question 2

What requires energy output

Answer 2

Internal work- heat pdtion, temp reguluation

External work- skeletal muscles

Question 3

Explain
Neutral Balance
Positive Energy Balance
Negative Energy Blanace

Answer 3

1. Neutral- homeostasis where energy input= output
2. Positive- Energy input> output so storage as adipose and weight gain
3. Negative- Energy output> input so we use storage. 1st carbs, then fat, then proteins

Question 4

How does GI contribute to homeostasis and why (2)?

Answer 4

Transfer water, electrolytes and nutrients (carbs, lipids, proteins, vitamins, cofactors) from external to internal to maintain constant internal environment and distribute energy to organism

Question 5

Overall Function of the GI system

Answer 5

1. Digestion and absorption
2. Excretion of waste
3. Fluid electrolyte balance
4. Immune function
5. None immune defense- epithelial cell permeability, secretions, peristalsis

Question 6

What is the immune system in the gut? Functions?

Answer 6

GALT- gut-associate lymphoid tissue- important for protection against microbial pathogens and permits immunologic tolerance to potentially immunologic dietary substances

Question 7

4 basic digestive processes

Answer 7

1. Motility- myscular contractions that move food
2. Secretion- exocrine secrete digestive juices and endocrine- hormones that regulations GI tract
3. Digestion- degrade to carbs, fat and proteins
4. Absorption- Absorable units plus water, electrolytes, vitamins go from lumen to circulatory tract

Question 8

Difference in endocrine and exocrine in GI

Answer 8

Exocrine- secrete digestive juices

Endocrine- secretes enzymes that regulate GI

Question 9

Accessory digestive organs (4)

Answer 9

1. Salivary glands
2. Exocrine pancreas
3. Biliary system- gallbladder and liver
4. Endocrine gland and cells

Question 10

4 common features throughout the GI tract

Answer 10

1. Mucosa
2. Submucosa
3. Muscularis externa
4. Serosa or adventitia

Question 11

What are the parts of the the mucosa?

Answer 11

1. Epithelial- protection, secretion and absorption
2. Lamina propria- CT, lymphoid tissue and glands
3. Muscularis mucosae- smooth muscle that increases SA
4. Exocrine cells
5. Endorcine/pacrine cells

Question 12

Parts of the submucosa

Answer 12

CT, large blood vessels, submucosal glands, and lymphoid tissue

Submucosal nerve plexus (Meissners plexus)

Question 13

Parts of the mescularis externa

Answer 13

contractions that move mix aboral

two layers- inner circular and outer longitudinal and between the layers is the Myenteric (auerbachs plexus)

Question 14

Function of the serosa

Answer 14

CT that covers the GI tract with squamous moesthelial cells. Secretion of serous liquid is lubrification and prevents friction

Question 15

Name the sphincter between each part of GI tract

Answer 15

Mouth/pharynx–> pharyngoesophageal sphincter– esophagus– gastroesophageal sphincter— stomach– pyloric– small intestine- ileocecal sphincter- large intestine- internal/external anal sphincter

Question 16

Origination of GI oscillations

Answer 16

The slow waves originate at the intestinal pacemakers (Cajal) and control the timing and force of contractions… activity is autonmous but can be modulated by neural and hormonal

Question 17

Explain the break down of neural regulation in the GI

Answer 17

Somactic- oral phase of swallowing and tonus of external anal spinchter

ANS-

Question 18

Function of intestinal smooth muscle cells

Answer 18

1. Effector organ of GI motility

2. Intestinal pacemaker- responsible for contractile activity

Question 19

Explain function, location of synthezise and transport of hormones in the GI tract

Answer 19

Function- regulate contractility and secretions

Synthesized and released by endocrine glands

transport via blood stream to target sites

Question 20

Gastrin
Source
Primary Stimulation
Function

Answer 20

1. G-cells of the stomach
2. stimulated by protein in the stomach, stretch, and nerves

3. Stimulates HCL and cheif cells
Trophic to stomach and SI
Enhances gastric motility
Constricts the pyloric sphincter 
causes gallbladder contractions
Induces colonic mass movements
Enhances pancreatic secretion

Question 21

Secretin

1. Source
2. Primary stimulus
3. Functions

Answer 21

1. S Cells in the Duodenum and jejunum
2. Stimulus is acid in the duodenum
3. Function- stimulates aqueous NaHCO secretion by pancreatic ducts
   Stimulates NaHCO3 rich bile from the liver
   INhbits gastric acid secretion
   Trophic to exocrine pancreas

Question 22

CCK

1. Source
2. Stimulus
3. Function

Answer 22

1. I cells in the duodenum or jejunum
2. Fat, proteins in the doudenum or nerves
3. Function- Stimulates digestive enzymes secretion by pancreatic ancinar cells
   Stimulates pancreatic NaHCO3 secretion
   causes gall bladder secretions

Question 23

Gastric Inhibitory Peptide

Answer 23

1. Source K cells in duodenum and jejunuum
2. Fat, glucose, acid, hypertonicity and distension
3. Function- inhibit gastric acid secretion
   Stimulates insulin secretion by endocrine pancreas
   Inhbitits gastric emptying

Question 24

About of immune cells in GI tract

Answer 24

About 1/2 of the body’s total mass of immune cells

Question 25

Which and from where are pancreatic hormones released

Answer 25

Insulin, glucagon, and somatostatin from the islets of langerhans in the pancreas

Question 26

What happens in catobolism?

Answer 26

Oxidative degradation of complex nutrient molecules (Carb,lipids, and proteins) into simple molecules like lactic acid, CO2, ammonia, and urea Usually exergonic and releases energy in the form of NADH/FADH

Question 27

What happens in anabolic metabolism

Answer 27

Synthetic process where a complex biomolecule is made from simple precursors (sugar, nitrogenous bases, AA, Fatty acids). Usually endergonic and new covalent bonds are formed

Question 28

Explain the basic steps of catobolism in the GI tract

Answer 28

1. GI takes up and degrades macromolecules and absorbs building blocks (hydrolysis of complex molecules) 2. Within the cells- the absorbed building blocks are further degraded (conversion of building block like AA, monosacc, glyercol to acetyl CoA) 3. AcCOa processed in TCA + oxidative phosphorylation make CO2+H20 and ENERGY (oxidation of acetyl CoA)

Question 29

Where is a bulk of digestion and what absorbs it?

Answer 29

In the SI- food is degraded by digestive enzymes and absorbed by epithelial cells When digested nutrients enter the hepatic portal vein and travel to the liver and then through the blood

Question 30

Overall efficiency and enzymes for degradation of protein

Answer 30

Over only 5% of enzymes lost in feces Proteins are degraded by endopeptidases (internal large cleavage) or by exopeptidases- 1 AA at a time of the end-- exopeptidases can be carboxypeptidases or aminopeptidases

Question 31

3 phases of protein digestion

Answer 31

Gastric, pancreatic, and intestinal

Question 32

Discuss gastric phase of protein digstion

Answer 32

Stomach has gastric juices that HCl and members of the pepsin protease family. Pepsin releases large peptide products and some AA which stimulates the release of CCK and initiates pancreatic phase of digestion

Question 33

Discuss pancreas phase of protein digestion

Answer 33

Pancreas has two histologically different areas 1. Islet of langerhan the releases insulin and glucogon 2. Exocrine pancreas is important for DIGESTION and it secretes 1.5L at pH 8 of pancreatic juices with hydolytic enzymes into the duodenum everyday

Question 34

Discuss the intestinal phase of protein degradation

Answer 34

Lining of the intestinal lumen have endo and aminopeptidases activities that further degrade peptides to AA which are absorbed

Question 35

How are monosacc, disaccs, and polysaccs absorbed

Answer 35

Monosacc- directly by the intestinal cells diacc- digested into monosacc by the intestinal cells Polysaccs (starch and glycogen) need to be reduced to smaller building blocks

Question 36

All parts involved in carb digestion

Answer 36

Mouth-starch and glycogen degraded by alpha-amaylase in salive makes glucose, disacc, and trisaccs SI- alpha-amlyase makes glucose, disaccs, and trisaccs. They are further degraded at the intestinal cells by alpha glucosidase; some disaccs have specific enzymes for degradation (lactase and sucrose) Oligosacc. not yet degraded by amylse or intestinal cells reach the ileum where they are degraded by bacteria and produce fatty acids, lactate, H2 and methane and CO2