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Physiology > Unit 6 Feeding and DIgestion > Flashcards

Unit 6 Feeding and DIgestion Flashcards

1
Q

What are the Major Nutrient Molecules

A

water, proteins/amino acids, lipids, carbohydrates

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2
Q

Vitamins

A
  • participate in catalysis
  • solubility affect mode of uptake and potential toxicit
  • some obtained from symbiotic bacteria (vitamin C, K, B12)
  • Coprophagy - improves vitamin uptake
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3
Q

Essential Amino Acids

A
  • eight of them
  • must come from diet
  • during starvation, protien comes from muscles
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4
Q

Lipids

A
  • essential for membrane production
  • animals cant produce omega-3 or omega 6
  • must come from diet
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5
Q

steps of eating and digestion

A
  • nutrient sensing
  • mechanical digestion
  • chemical processing
  • egestion
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6
Q

The breakdown of energy

A

gross energy —-> indigestible energy (feces)

  • digestible energy —–> unetabolizable energy (urine)
  • -Metabolizable energy—> heat
  • —net energy
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7
Q

Acquiring food

A

sensing- prey with Gustatory receptors, energy emitted as heat or light

  • lateral line
  • electromagnetic receptors

small partibles- filter feeding
large particles - chewing, capture and swallow
fluids and soft tissues- nectal, blood, milk and milk like secretions

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8
Q

Filter feeding

A
  • Planktivorous fishes - filter water over fills and sieve out the flanction
  • some frogs use mucous covered fileter plates on gills to entrap particles
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9
Q

Fluid feeding

A
  • sucking (baby)

- cutting and licking (lamprey + vampire bat)

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10
Q

Solid feeding

A
  • teeth, beaks, great variety

- carnivores, herbivores, omnivores

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11
Q

Solid feeding- teeth types

A
  • usually undifferentiated in non-mammalian vertebrates (homodonts) - sharks, fish, amphibians, reptiles
  • venemous snakes have specialized fangs to inject venom and elastic ligaments which allow their jaws to stretch
  • mammalian teeth are very specialized (incisors, canines, and molars) (heterodonts)
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12
Q

3 basic types of Alimentary sytems

A 
Batch reactors (hydra) 
Continuous-flow, stirred tank reactors (ruminants forestomach) 
Plug-flow reactors (human small instestine)- composition varies along the tube
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13
Q

Essential parts of the Alimentary system

A
  1. Headgut- mouth, buccal cavity, pharynx
    - –receiving food
  2. Foregut - esophagus, stomach
    - —food conduction, storage and digestion
  3. Midgut - small intestine
    - ——chemical digestion, absorption
  4. Hindgut - colon, rectum
    - —water/ion absorption, defecation
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14
Q

Headgut

A
  • salivary glands (mucins-lubrication, digestive enzymes)
  • mastication: teeth, beak etc.
  • tongue (unique to vertebrates)
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15
Q

taste buds

A

figure 7-16

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16
Q

Foregut

A

Esophagus - gizzard (some birds, some fish), crop (some birds)

  • stomach - cellular level view
  • –monogastric (carnivores, omnivores)
  • –digastric (ruminants)
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17
Q

Gastric Pit

A 
mucous neck cells ----mucus
cheif cells --------Pepsin
parietal cells -----HCl
G-cell-------Gastrin 
-low pH is optimal for gastric enzymes

Men can pass gass, men pass Hot gas

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18
Q

Platypus and gastric brooding frog

A

-do not have low pH

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19
Q

Monogastric stomach

A
  • pylorospasm and pyloric stenosis -infants
  • gastroesophageal Reflux - Hcl irritates wall
  • —avoid foods that stimulate stomach acid or relax sphincter
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20
Q

Ruminant Stomachs

A

esophagus—rumen—reticulum—–omasum—Abomasum—small intestine

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21
Q

Other examples of Foregut Fermenters

A

Kangaroo, sloth, colombus monkey

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22
Q

MIdgut

A
  • most nutrient absorption occurs here

- duodenum (secretions), jejunum (secretions and absorption, ileum (absorption)

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23
Q

Anatomy of intestinal epithelium

A
  • longitudinal smooth muscle
  • circular smooth muscle
  • epithelial layer: submucosa, mucosa
  • villi
  • microvilli
  • tight junctions and desmosomes
  • hormones and antimicrobial stem cells
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24
Q

HIndgut

A
  • storage of undigested food, absorption of water, ions

- major site for bacterial digestion in herbivorous reptiles, birds, most herbivorous mammals

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25
Q

two types of hindgut fermenters

A
  • colon fermenters: horses, zebras, tapirs, sirenians, elephants, rhinos, marsupial wombats
  • cecal fermenters: rabbits, many rodents, hydraxes, howler monkeys, koalas, opossums
  • terminates in rectum or cloaca
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26
Q

What is the largest exocrine and endocrine gland in the body

A

the gut

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27
Q

Two important layers in the gut secretion

A

-myenteric plexus, submucous plexus

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28
Q

Endocrine and Exocrine glands

A
  • exocrine glands- secretes fluids through a duct onto an epithelial surface
  • endocrine glands secrete substances (hormones) direction into the blood
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29
Q

What are three exocrine secretions

A
  1. Water and electrolytes
  2. Bile and Bile salts
  3. Digestive Enzymes
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30
Q

Overview of Exocrine secretions

A
  • review slide on powerpoint
31
Q

Water and Electrolyte secretions

A
  • ~95% of GI secretions are water and mucus
  • thin slippery mucus- lubricates, protects the lining of the gut
  • primary secretions enter in the acinar lumen (end of an exocrine gland)
  • –modifications in the duct produce the final secretory juice composed of water, ions mucus and enzymes
32
Q

Acinar cells

A
  • primary secretions from capaillaries around acinar cells

- secondary modification in ducts

33
Q

The liver produces

A
  • bile (water, cholesterol, lecithin, inorganic salts)
  • bile salts (organic salts derived from Cholesterol)
  • bile pigments (from hemoglobin breakdown)
34
Q

Bile travel pathway

A

-through the hepatic duct to the gallbladder where it is stored

35
Q

Function of Bile

A
  • neutralization of acidic gastric juices
  • facilitation of digestion of fats by breaking them down into small droplets (emulsification)
  • dispersion of lipid-soluble vitamins for transport int he blood
  • removal of waste substances from the liver, (hemoglobin pigments, cholesterol, steroids, hydrophobic drugs.
36
Q

Hyperbilirubinemia

A
  • increased bilirubin in blood (frome heme catabolism)
  • Jaundice
  • normaly excreted in urine (yellow) and feces (brown)
  • causes yellow color of bruises
  • Treatment? broken down by blue light
37
Q

Digestive enzymes

A
  • hydrolysis of polymeric food molecules

- proenzymes (zymogens): inactive form of enzymes which are cleaved to produce active forms

38
Q

Proteases

A
  • endopeptidases, exopeptidases (highly specific enzymes)
  • pepsin (stomach))
  • tripsin and chymotrypsin (released from pancrease to SI
39
Q

Carbohydrases

A
  • amylases- salivary glands, duodenum
  • polysaccharidases
  • glycosidases
  • cellulase- duodum
40
Q

Lipases

A
  • degrade lipids into fatty acids plus mono and di-glycerides
  • fat digesion: 3 steps
  • -emulsification
  • -formation of micelles
  • -digestion by lipases
41
Q

other types of digestive enzymes

A

-nucleases, nucleotidases, nucleosidases, esterases

42
Q

what is the primary stimulus for secretion of digestive enzymes

A
  • presence of food molecules
  • triggers chemoreceptors along the GI tract
  • cephalic influences also stimulate sectretions
43
Q

Secretion differences in the mouth, stomach and intestines (control and speed)

A
  • mouth = neuronal = fast
  • stomach = neuronal and hormonal = medium
  • Intestine = hormonal = slow
44
Q

What are the salivary secretions?

A

-water, electrolytes, mucin, amylase, anitmicrobial agents (lysozyme, thiocyanate)

45
Q

what controls salivary secretions

A
  • cholinergic parasympathetic control

- suppression of secretion cause by sympathetic innervation

46
Q

what are the three gastric secretions

A
  1. HCL
  2. Pepsin
  3. Gastric Mucus
47
Q

Hcl secretion in the gastic intestinal tract

A
  • produced by teh parietal cells of the gastric pits
  • stimulated by parasympatheitc activity in the vagus nerve, gastrin, secretagogues in food
  • alkaline tide may occur in blood pH after a large meal due to loss of H+ to gastric secretions
48
Q

Pepsin secretion in the gastric intestinal tract

A
  • endopeptidase with several gastric variants
  • produces as pepsinogen by chief (zygomatic) cells
  • under parasympathetic control of gastric branch of vafus nerve and hormone gastrin
49
Q

Gastric mucus secretion

A
  • protects gastric epithelium from digestion and from high acidity
  • trapped electrolytes help to neutralize gastric acid
  • from the goblet cells (mucous neck cells)
50
Q

What are the three gastric secretion phases

A
  1. Cephalic Phase
  2. Gastric phase
  3. Intestinal phase
51
Q
  1. Cephalic phase of gastric secretion
A

-secretion in response to sight, smell or taste of food or to conditioned reflex

52
Q
  1. Gastric phase of gastric secrtion
A
  • secretion of Hcl and pepsin in response to food in the stomach
  • mediated by gastrine (endocrine) and histamine (paracine) which bind receptors on parietal cells
  • gastrin is secreted by pyloric mucosa in response to protein-contaning chyme and stomach distention; it also stimulates stomach motility
53
Q
  1. Intestinal phase of gastric secretions
A
  • controled by enteric gastrin (inresponse to partially digested proteins in duodunum), vasoactive intestinal protien (VIP) and gastric inhibitory peptide (GIP) in response to fats, sugars in duodenum
54
Q

Intenstinal and pancreatic Secretion

A
  • small intestin: succus entericu
  • -bunner’s glands- secrete alkaline mucus
  • -crypts of lieberkuhn- secrete enzyme-rich alkaloid fluid
55
Q

What controls the pancrease and its secretion

A

-peptide hormones from the upper intestine
-endocrine secriton: insulen
exocrine secretions: many numerous secrtion

56
Q

What enzymes does the large intestine secrete

A

-none

57
Q

Absorption pathway

A

-gut lumen–epithelial cell: apical surface -cytosol –basal surface– blood or lymphde

58
Q

5 types of nutrient uptakes in the intestine

A
  • simple diffusion
  • facilitated diffusion
  • active transport
  • chylomicrons into central lacteal
  • endocytosis
59
Q

feeding enzymes (review slides_

A
  • GLUT 2, SCLT ect
60
Q

lipid transport in the body

A

-di/triglyceride surrondd by lipase –> micelle
micelle migrate to brush border and release their contents— triglycerides reassemble in smooth endoplasmic reticulum - exocytosis or chlomicron into the central lacteal

61
Q

Nutrient Transport in the Blood

A
  • through central lacteal (80% of chylomicrons)
  • into capillaries which then drain to hepatic portal vein and travel to liver where glucose is converted to glycogen for storage
62
Q

What occurs during fasting

A
  1. use up glycogen storage (hours)
  2. Catabolism of triglycerides and structural proteins (weeks)
  3. Gluconeogenesis, ketogenesis (weeks)

Day 2- blood-glucose stabilized, fatty acids 4X, ketones 100-300X

day 40 - ketones supply 2/3 of brain’s energy needs

63
Q

Hibernation

A
  • metabolic rates lowered (only replace protein structures)

- bears recycle urea nitrogen back into animo acids

64
Q

Aerophagia

A

(burping)
Caused by excess air in the stomach or gases created by digestion
-relazation of the lower esophageal sphincter
—vents gastric air

65
Q

Colon Canger

A
  • develos in the cells lining the colon and/or rectum
  • people who have a diet righ in fat and read meat are at a greater risk
  • easy to treat but symptoms don’t manifest until later
66
Q

Crohn’s Disease

A
  • inflammatory bowel disease, characterized by abdominal pain, diarrhea and weight loss
  • immune related disease in which the body’s immune system attacks the GI tract, possibly directed as microbial antigens
  • large part of the risk is genetics as well as smoking an stress
67
Q

Diarrhea

A
  • osmotic diarrhea = excessive solutes in the lumen of the intestine prevents absorption of water
  • secretory diarrhea - water secreted in the small intestine is not reabsorbed
  • inflammatory and infectious = micobial or viral pathogens destroy intestine epithelial cells
  • results do include bloody diarrhea and lower water reabsorption
68
Q

Diverticulitis

A
  • outpockets along the wall of the colon
  • they become inflamed due to infection from waste blockage and bacteria build up
  • symptoms= cramps and abdominal pain, chills or fever and alternating diarrhea and constipation
69
Q

Gallstones

A
  • hard crystalline masses that form int he gall bladder or bile ducts
  • form when there is an imbalance in the substances that make bile
  • symptoms= pain in upper abdomen and back, nauseau, vomiting bloating and indigestion
70
Q

Gas

A

-bloating (small bowel bacteria overgrowth)

by large amount of bacterial growth within the small intestine which use up nutrients that would otherwise be absorbed causing malnourishment.

conditions causing this= crohns disease
diabetes and scleroderma

treatment = antibiotics, drugs that speed intestinal movement

71
Q

Heart burn (acid indigestion)

A

-the burning senstion (irritation) of teh esophagus caused by stomach acid

caused by = the lower esophageal sphinctor does not tight as it shood from:

  • —too much food in the stomach
  • —too much pressure on the stomach (obesity, pregnancy, constipation)

as a result, food and digestive juices from the stomach flow backward up into the esophagus

72
Q

Jaundice

A

-bilirubin–> bile pigment in fat layer under the skin
-normally involved in the breakdown of red blood cells
abnormal= disruption of the meabolism in livier or excretion–> bilirubin build-up
from:
1. liver damage
2. gallbladder blockage
3. Rapid destruction of RBC’s

73
Q

Pyloral Spasms

A
  • pyloric stenosis is a narrowing of the opening in the stomach leading to the small intestine - the muscle surronding the opening is enlarged
  • when the stomach empties into the small intestine the muscle spasm, causing projectile vomitting
74
Q

Vomiting

A
  • controled by the bilateral vomitting centers with are located in the medulla
  • recives signals from 4 major sources
    1. CTZ
    2. visceral afferents from the GI tract
    3. Visceral afferents from outside the GI tract
    4. Afferents from extramedullary centers in the brain

Physiology (9 decks)

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