Digestive System Flashcards

(28 cards)

1
Q

4 basic processes

A
  1. digestion: mechanical and chemical breakdown of food into smaller pieces
  2. motility: SMOOTH MUSCLE movement of food down the digestive tract. Peristalsis. Mixing. Churning and segmentation.
  3. secretion: digestive juice to the lumen
  4. absorption: enterocytes of the intestinal wall absorb materials then into blood or lymph.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

mouth

A

salivary glands

  • moisten food to shape the food into a bolus.
  • prevents cavities (lysozyme and antibodies)
  • PSNS thin saliva with amylase rich
  • SNS thick mucus rich saliva
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Mouth DIGESTION

A

mechanical: chewing into smaller pieces

chemical:

  1. carbs: polysach–> salivary amylase –> oligo and disach
  2. fats: triglycerides –> lingual lipase –> monoglyc and FA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Mouth ABSORPTION

A

none

some drugs such as nitroglycerine (angina) –> vasodilator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pharynx/Esophagus

A

3 phases
1. Buccal phase: voluntary, where we swallow the bolus
2. pharyngeal phase: involuntary, food triggers signals to the swallowing centre (medulla) and stimulates the swallowing reflex
3. esophageal phase: food goes down via peristalsis 1/3 somatic NS skel muscle
2/3 mix of both
3/3 PSNS smooth muscle

food cant enter…

  1. mouth: because tongue on hard palette.
  2. nasopharynx: because soft palette and uvula is raised
  3. trachea: because epiglottis and glottis is down. respiration stops
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Stomach DIGESTION

A

mechanical: churning

chemical
1. carbs –> salivary amylase until ph is below 7
2. fats –> lingual lipase and gastric lipase (chief cells) until ph <5-6
3. proteins –> HCL (parietal cells) denatures it and activates pepsinogen (chief cells)
pepsinogen –> HCL –> pepsin + FB
proteins –> pepsin –> aa and peptides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Stomach ABSORPTION

A

little if any, vinegar, bile, aspirin, alcohol (penetrates mucus –> alkaline and from mucus cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Small Intestine DIGESTION

A

mechanical: segmentation

chemical 3 steps

  1. neutralize alkaline fluid
    - presence of acid in the duodenum leads to the secretion of secretin (hormone) which causes the pancreatic and gallbladder ducts to secrete HCO3- and causes a decrease in gastric acid secretion (parietal cells)
  2. pancreatic enzyme release (pancreatic acinar cells)
    1. carbs polysac –> pancreatic amylase –> oligo and disach
    2. lipids triglycerides –> pancreatic lipase w/ bile salts –> monoglic and FA
    3. proteins
      trypsinogen –> enterpeptidase –> trypsin
      trypsinogen –> trypsin –> trypsin + FB
      chymotrypsinogen –> trypsin –> chymotryp
      procarboxypeptidase –> trypsin –> carboxpeptidase
      proteins –> proteases –> aa and peptides
  3. intestinal wall (enterocytes using microvilli)
    1. carbs: oligosach and disach –> oligosaccdases disachdases –> monosach.
      sucrose –> sucrase –> gluc + fruct
      lactose —> lactase –> gluc + galact
      maltose –> maltase –> gluc + gluc
    2. proteins: peptides –> aminopeptidases + dipeptidases –> smaller peptides and aa
    3. lipids –> none, no lipase on intestinal wall
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

REGULATION of Pancreatic Enzyme Secretion

A

presence of aa and fatty acids in the duodenum

  • release of CCK
    1. increases gallbladder rel. of bile.
    2. decreases gastric secretion and motility.
    3. increases pancreatic enzyme rel.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

@ SI, WHAT CAN BE ABSORBED?

A
  1. carbs: none olgosach and disach too big
  2. lipids: yes FA and Monoglycerides
  3. proteins: yes to aa no to peptides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Lactase Deficiency

A

lactose intolerance, bacteria fermentation, gas and diarrhea, no lactose digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

celiac disease

A

gluten damages villi and decrease SA, bacteria fermentation, gas and diarrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Small Intestine ABSORPTION

A

where most absorption occurs
to enterocyte and out of enterocyte to blood or lymph.

gluctose and galactose –> 2 AT –> fac. trans
fructose –> fac trans –> fac trans
aa –> 2 AT –> fac trans
di + tri peptides –> endocytosis –> aa –> 2 AT –> fac trans
Monoglyc, FA >12C, fat sol vita, cholesterol –> simp diff –> exocytosis and diff into lymph lacteal
FA <12C –> simp diff –> diff blood
H20 –> osmosis –> osmosis(blood and lymph)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

water Abs in SI

A

9000 ml/day enters the SI. 7000 ml from secretions and 2000 from diet. 500 goes to the LI. where 100 lost in the feces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

where do the nutrients go from the SI

A

hepatic portal vein in the liver

lacteal –> thoracic ducts –> left subclavian vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Bile is made of…

A

water
bile salts
bile pigments from bilirubin (RBC breakdown)
cholesterol
ions (HCO3)
detoxified inactivated drugs, toxins, hormones

17
Q

function of bile salts

A

emulsify fats into smaller droplets
create a micelle keeps fats in the solution (bile salts and phospholipids)
- hydrophobic inner
- hydrophillic outer

micelle diffuses to enterocyte –> FA and MGS diffuse into the enterocyte

18
Q

@ the enterocyte

A

FAs and MG –> FA DIGLYC (in SER) -TRIGLYC –> proteins, cholesterol, and phospholipids added in Golgi –> cholymicron (watersol) –> exocytosis –> lymph

19
Q

Gastric motility/secretion

A

3 regulatory phases
1. cephalic phase: preparing stomach for food
- smell, thought, sight, taste.
PSNS + enteric (mostly PSNS)
- increase in gastric acid, gastric enzymes, motility, and gastrin secretion

  1. gastric phase
    food in stomach, activates stretch receptors
    same thing as before except mostly enteric
    - aa and FA trigger presence of food
    - Ca, alcohol, caffeine, aa, peptides may increase digestion too

stops when pH is below 3

  1. Intestinal Phase
    - controls rate of which chyme (bolus + gastric juice) enters the SI.
    1. stop ovewhelming the SI with tonicity
    2. proper reabs.
    3. acid can be neutralized
  • intially, duodenal stretch causes an increase in gastric acid for a short time.
  • inhibitory signals cause
    1. decrease in gastric motil by…
      CCK rel
      enterogastric reflex (enteric NS): triggered by aa/peptides, acid, duodenal stretch, hypertonicity
      –> done directly or via CNS to SNS.
    2. decrease in gastric secretion
      Secretin and CCK
20
Q

Hormones

A

Gastrin (stomach and duodenum): increase gastric acid and enzyme secretion

secretin: (duodenum) decrease gastrin secretion and increase HCO3 secretion

CCK: (duodenum) due to aa and fa. increase gallbladder contraction, pancreatic enzyme secretion, decrease gastric motil and secretion.

21
Q

Large intestine MOTILITY

A

haustral contractions: weak and slow allow reabs of salts and water and mixing,

mass movements: due to food in stomach, power waves from the gastrocolic reflex pushing food from the tranverse colon to the rectum.

fecal mass in rectum cause the urge to poop.

22
Q

Rectal defecation reflex

A

stim: feces in rectum
CNS: sacral segment of spinal cord PSNS
effector: smooth muscle of the rectal walls,
internal sphincter relaxes
external sphincter contracts (skel m. voluntary) not part of reflex

23
Q

Large Intestine DIGESTION

A

none, fermentation or creation of vitamins (b5,b6,k,folate,biotin)

24
Q

Large Intestine ABSORPTION

A

400, 100 lost in feces.
Na via active transport
some fermentation products (gases, vitamins)
drugs, rectally (anaesthetics)

25
Large Intestine SECRETION
HCO3 and K
26
Fate of absorbed nutrients
1. Glucose: blood to body cells via insulin. glycogen in skel m. 75% and liver 25% (1% of entire energy stores) 2. Lipids cholesterol --> cell membrane, bile salts, steroids triglycerides --> 3 FA and Glycerol by lipase on endothelial cells ---> oxidized for ATP ---> storage as TG in adipose tissue 99% storage ---> membranes and myelin 3. Amino Acids - enter cell via 2 ATP or Fac trans - GH increases entry of this into cells - insulin increases this to skel muscle - for protein synthesis - not stored, excess converted to fat - can be used as energy when glucose is low.
27
Metabolic rate
body's rate of energy use. sum of all mechanical and chemical reactions. factors affects MR 1. SNS increases MR 2. hormones (TH, EPI) increase 3. body temp (1 degree increase MR 10%) 4. exercise increase 5. food ingestion increases 6. sleep decreases
28
Basal metabolic rate
energy body needs for essential activities