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125 Lecture 11
nutrients and the initial part of the GI tract
43
Anatomy
Undergraduate 1
05/15/2013

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Term
why do essential physiological processes of life require energy and raw materials?
Definition

for homeostasis, movement, growth, repair, reproduction, electrochemical activity, etc

 

 

Autotrophs can live on inorganic nutrients alone whereas heterotrophs require complex organic compounds from other organisms in their diet.

Term

carbohydrates provide 17kj/g of energy.

 

how much do proteins and lipids provide?

Definition

lipids 22kj/g for membranes, energy storage, heat insulation

 

proteins 39kj/g for structural components, enzymes

Term
whta do vitamins mainly needed for?
Definition

they are mainly co-factors for enzymes

 

inorganic salts are required for bones, respiratory pigments etc

 

water is required to act as a solvent, a transport medium and lubricant etc

Term
list some fucntions of water (5)
Definition

solvent

 

transportation

 

hydrostatic support (eg eyeball)

 

evaporative cooling

 

cleaning agent (eg for eyes)

Term

out of the 20 amino acids, 8 are essential amino acids. this means they must be obtained from food in a pre fabricated form. name these 8 essential amino acids

 

neumonic Tymothy Took Mega PILL Viagra

Definition

Trytophan

Methionine

Valine

Threonine

Phenylalanine

Leucine

Isoleucine

Lysine

Term
how many calories is 1 joule?
Definition

0.239 calories

 

woman who does light work requires 8.8 x 106 J/day

man light work = 10.5

man moderate work = 14.3

man heavy work = 18.9

Term

the average water intake is 2500mls

 

how is this intake accounted for (3)

Definition

Drinks 1,400ml

 

Food 800ml

 

cellular respiration 300ml

 

 

a little water is produced as a by product of cellular respiration

Term
the average total water loss is also 2,500 ml. how is this accounted for? (3)
Definition

Urine 1500ml

faeces 350 ml

Sweat 550ml

Term
name the 4 basic digestive processes
Definition
  • Digestion
  • Absorbtion
  • Motility
  • Secretion

Digestion, absorbtion and motility done by GI Tract

 

Secretion done by Accessory glands

Term

what am i? i am a tube essentially 4.5 metres in length and my job invoves the physical and chemical breakdown of food.

Definition
GI Tract
Term
the accessory glands secrete digestive fluids into the GI Tact. what makes up the accessory glands?
Definition

salivary glands

 

 pancreas

liver

 

 gall bladder

Term
between the pharynx and the esophagus which sphincter would you find?
Definition
the upper esophageal sphincter
Term
which sphincter would you find between the esophagus and the stomach?
Definition
the lower esophageal sphuncter
Term
which sphincter would you find between the small intestine and the colon?
Definition
the ileocceal sphincter
Term

match the function with the organ:

 

im involved in mechanical breakdown of food with saliva, initiation of chemical digestion of carbs by salivary amylase

Definition
Mouth
Term
which part of the body is involved in conduction of food to the esophagus?
Definition

the pharynx

 

the esophagus is involved in food conduction to the stomach

Term
the stomach is involved in mechanical breakdown of food, secretion of acid, pepsinogen and intrinsic factor. What does intrinsic factor do?
Definition

Intrinsic factor helps with the absorbtion of Vitamin B12 across the wall of the stomach

 

the stomach initiates the chemical digestion of proteins by pepsin, secretion of gastrin into bloodstream and the transformation of food into chyme.

Term
what is gastrin?
Definition

gastrin is a peptide hormone that stimulates secretion of HCL (gastric acid) by the parietal cells of the stomach. it aids in gastric motility

 

 

 

 

Term
what is chyme?
Definition
Chyme is the semifluid mass of partly digested food expelled by the stomach into the duodenum
Term
where does absorbtion of digestion end-products, water, ions and vitamins occur?
Definition

the small intestine

 

 

also the secretion of enterogastrones into blood stream and secretion of bicarbonate rich fluid.

Term
what are enterogastrones - give some examples of enterogastrones
Definition

an enterogastrone is any hormone secreted by the mucosa of the duodenum in the lower GI tract in response to dietary lipids that inhibits the forward motion of contents of chyme.

 

 

 

 

Term
where does absorption of ions and water, transformation of chyme into poop and storage of poop occur?
Definition

in the colon.

 

the poop is stored in the rectum prior to elimination

 

the anus controld defacation

 

 

Term
what does saliva contain? (4)
Definition

amylase

lysozyme

mucus

bicarbonate

Term
which nervous system helps regulate perostalsis in the GI tract?
Definition
Nervus plexus - enteric nervous sytem
Term

name the 4 layers of the GI tract starting from the middle outwards

 

 

Definition

1. Mucosa - made from 3 layers of epithelium

 

2. Submucosa - made from connective tissue, blood and lymphatic vessels. This part has a very rich blood supply

 

3. Muscalaris is made from a circular and a longitudinal layer

 

4. Serosa - outermost layer made from connective tissue that supports the intestines

Term
Name the 3 layers of the mucosa?
Definition

Mucous membrane

lamina propria

muscalaris mucosae

 

 

the lamina propria is made from connective tissue, capillaries, nerves and lymphoid tissue

 

the mucous membrane is composed of epithelial cells known as enterocytes which include absorptive cells, exocrine cells, goblet cells & endocrine cells

Term
which layer of the mucosa is made from epithelial enterocytes including absorptive, exocrine, goblet and endocrine cells?
Definition
The mucous membrane
Term
name the 3 main mouth and salivary glands?
Definition

Sublingual gland

 

Submandibular gland

 

Parotid gland

Term

saliva is secreted at 0.5ml/min. it contains salivary amylase that digests glycogen and start and lingual lipase

 

 

Definition

Lubrication (mucus)

Buffering and diluting noxiou substances

Antibiotic action through lysozyme & lactoferrin

 

 

 

Term
which muuscular tube ~25cm long connect the pharynx to the stomach?
Definition

the esophagus

 

its upper and lower esophageal sphincters are usually closed but backflow can occur leading to heartburn

Term
which type of muscle would you find in the upper 1/3 of the esophagus?
Definition

in the upper 1/3 you would find skeletal muscle

 

 

 

in the lower 2/3 you would find smooth muscle

Term
which organ can expand from 50ml to 1-2 litres?
Definition
the stomach
Term
where are parietal cells contained? what do they secrete?
Definition

they are contained in the mucosa of the gastric glands.

 

 

upto 2 litres of HCL can be secreted per day!

 

Term
which cells secrete pepsinogen?
Definition

cheif cells

 

pepsinogen is the inactive zymogen to pepsin

pepsinogen is activated when it encounters the acidic environment of the stomach

Term

true or false?

mucus (neck cells), gastric lipases, intrinsic factor and rennin are also secreted into the stomach?

Definition

this is true

 

Intrinsic factor is required for the absorbtion of vitamin B12

 

and rennin coagulates milk.

Term
describe the mechanism of gastric acid secretion
Definition

H+ ions made from CO2 and H20 by carbonic anhydrase (CA) are actively transported into the lumen in exchange for K+

 

Bicarbonate ions are exchanged for chloride ions, which diffuse into  the lumen.

 

The nett result is accumulation of HCL in the lumen

Term
what is a zymogen?
Definition

it is an inactive enzyme precursor

 

 

Term
name the zymogen synthesised in the stomach which gives rise to pepsin
Definition
pepsinogen
Term
what is the zymogen to the active enzyme Chymotrypsin produced in the pancreas?
Definition
Chymotrypsinogen
Term

name the zymogens for Trypsin, Carboxypeptidase and Elastase, all of which are synthesised in the pancreas

Definition

Trypsinogen - Trypsin

Procarboxypeptidase - Carboxypeptidase

Proelastase - Elastase

Term
in the first stage of the activation of Chymotrypsinogen, Trypsin cuts between which amino acid numbers?
Definition

between 15 and 16

 

the final Chymotrypsin has 3 subunits: A, B and C linked by interchain disulphide bonds

Term
pepsinogen is not activated until it encounters what?
Definition

HCL in the stomach.

 

Once activated, it becomes pepsin. Pepsin can activate more pepsinogen.

 

Pepsin then starts to degrade proteins into smaller polypeptides

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