Topic 14 Flashcards
1
Q
Digestion involves..
A
- digestive tract
- accessory organs
2
Q
Digestion
A
breakdown of large food pieces into smaller molecules
3
Q
Absorption
A
from human to enterocytes (small intestinal cells) of villi to blood/lymph
4
Q
Motility
A
smooth muscle contractions in tract. mix (segmentation, churning) move (peristalsis)
5
Q
Secretion
A
digestive juice into lumen
6
Q
Mouth contains..
A
salivary glands
7
Q
Salivary glands
A
saliva moistens and prevents cavities (lysozyme and antibodies)
8
Q
PSNS stimulate secretion of what saliva
A
thin, enzyme rick saliva
9
Q
SNS stimulate secretion of what saliva
A
much rich saliva
10
Q
Mouth aids in what processes
A
digestion and absorption
11
Q
Mouth digestion
A
mechanical (chewing) and chemical.
12
Q
Mouth breaks down carbohydrates into..
A
disaccharides and oligosaccharides. (using salivary amylase)
13
Q
Mouth breaks down triglycerides into..
A
fatty acids and monoglycerides (using lingual lipase)
14
Q
Mouth absorption
A
no food just some drugs (ex: nitroglycerine for angina/ vasodilator)
15
Q
Pharynx and esophagus aids in..
A
swallowing
16
Q
Swallowing occurs in 3 phases
A
- buccal phase
- pharyngeal phase
- esophageal phase
17
Q
Buccal phase
A
voluntary. food is compacted by the tongue into a bolus and moves pharynx by tongue pressing on hard palate.
18
Q
Pharyngeal phase
A
involuntary. food in pharynx triggers signals to swallowing centre (medulla) and initiates swallowing reflex
19
Q
Esophageal phase
A
food mols down esophagus (peristalsis). somatic motor neurons to skel. muscle (upper 1/3). middle is mix of PSNS and motor. lower 1/3 is PSNS to smooth muscle.
20
Q
Food can’t enter or re enter..
A
- mouth: tongue on hard palate
- nasopharynx: uvula, soft palate elevated.
- trachea: glottis and epiglottis closed
21
Q
Stomach mechanical digestion
A
churning/motility
22
Q
Stomach chemical digestion consists of..
A
- carbohydrates
- lipids
- proteins
23
Q
Stomach chemical digestion of carbohydrates
A
salivary amylase unti pH <7
24
Q
Stomach chemical digestion of lipids
A
lingual lipase (tongue), gastric lipase (chief cells), until pH <5-6
25
Food in stomach digestion =
buffer: pH doesn't change right away
26
Stomach chemical digestion of proteins
HCl (pariental cells) denatures proteins and acts on pepsinogen (chief cells)
27
Stomach protected from self digestion by..
alkaline mucus (mucus cells) barrier can be penetrated by alcohol, aspirin, vinegar, bile.
28
Stomach absorption
very little absorption of food. some drugs like alcohol and aspirin.
29
Small intestine mechanical digestion
segmentation and peristalsis
30
Small intestine chemical digestion involves..
- pancreas
- gallbladder/liver
- intestinal wall
31
1st step of chemical digestion in the small intestine
neutralize acid so pancreatic enzymes can work. alkaline fluid (HCO3) from duct cells of pancreas and gallbladder.
32
2nd step of chemical digestion in the small intestine
pancreatic enzymes into intestinal lumen from pancreatic acinar cells
33
Regulation of pancreatic enzyme secretion
fatty acids and amino acids in duodenum increase cholecystokinin (CKK = hormone)
34
Effects of CCK
- high pancreatic enzyme secretion
- stimulate gallbladder contractions/release bile.
- low gastric motility (slow emptying) and low gastric secretion
35
In small intestine we have..
- - di- and oligosaccharides – too big to be absorbed
- - amino acids – can be absorbed peptides (most too big to be absorbed)
- -fatty acids and monoglycerides (can be absorbed)
36
3rd step of chemical digestion in the small intestine
intestinal wall enzymes further break down on microvilli of enterocytes
37
Lactase deficiency
lactose intolerance. remains undigested and bacteria in large intestine ferment lactose (gas, diarrhea)
38
Celiac disease
gluten damages villi. low absorptive area for everything so bacterial fermentation in large intestine (gas diarrhea)
39
Lipids/fats in intestinal wall digestion
none! no digestion
40
Absorption of the small intestine is the main site due to..
- large surface area (folds, villi)
| - nutrients = small molecules
41
H2O in the small intestine
approx. 8500 mL/ day absorbed at small intestine, assuming that..
- -H2O ingested in food/ drink = ~2000 mL/day
- -H2O from secretions = ~7000 mL/day
so. . 9000mL/day enters small intestine, ~500 mL/day lost to large intestine
42
Absorbed nutrients from small intestine go to..
- liver via hepatic portal vein (blood
| - into lacteals (lymph) from thoracic duct from left subclavian vein
43
Fat digestion/absorption in small intestine requires bile from..
- liver (synthesizes)
| - gallbladder (stores)
44
Bile consists of..
- H2O
- bile salts (from cholesterol)
- cholesterol (only excretory route)
- bile pigments (bilirubin from rbc breakdown)
- ions
- detoxified/ inactivated drugs, toxins, hormones
45
Function of bile salts: emulsification
breaks up larger globules of fat into many small droplets
46
Function of bile salts: micelle formation
keeps fat digestion products in solution
47
Micelle
bile salts and phospholipids. interior is hydrophobic. exterior is hydrophilic.
48
3 regulatory phases of gastric motility/secretion
- cephalic phase
- gastric phase
- intestinal phase
49
Cephalic phase
prepares stomach for food. triggers are thought site, smell, taste of food. if no food enters stomach there is low pH inhibits secretion
50
Gastric phase
food in stomach distension, activates starch receptors. food buffer pH slowly, reaches 3 when stomach nearly empty when pH < 3. shuts down NS (enteric) and low gastrin so low acid and enzymes.
51
Intestinal phase
controls rate of chyme (=food and gastric juice) entry into duodenum.
52
Gastric emptying is regulated so that..
- acid can be neutralized in small intestine (or enzymes won't work)
- tonicity doesn't overwhelm small intestine
- there is time for dig/abs in small intestine
53
During intestinal phase initially for a short time..
get high gastric secretion. duodenal gastrin release (due to duodenal stretch)
54
During intestinal phase inhibitory signals cause low gastric motility/slow emptying due to:
- CCK released due to presence of fa, aa
- enterogastric reflex (enteric NS). triggered by aa/peptides, acid, duodenal stretch, hypertonicity decrease motility directly and signals CNS to SNS
55
During intestinal phase inhibitory signals cause low gastric secretion (acid, enzymes) due to..
- secretin: release due to acid
| - CCK: released due to aa and fa
56
Digestion from stomach and duodenum hormone
gastrin: high acid, gastric enzyme secretion (lipase and pepsinogen)
57
Digestion from duodenum only hormones
- secretin causes HIGH alk. flood secretion from ducts of pancreas and gallbladder and LOW gastric secretion
- CCK causes HIGH pancreatic enzyme secretion and contraction of gallbladder and LOW gastric motility, secretion
58
Large intestine haustral contractions
slow, weak. allow mixing, absorption of salts and H2O
59
Large intestine mass movements
due to food in stomach via gastrocolic reflex (powerful waves of contractions from transverse colon to rectum). move fecal mass into rectum
60
Rectal (defecation) reflex stimulation
feces in rectum (stretch receptors in rectal wall)
61
Rectal (defecation) reflex CNS
sacral segment of spinal cord (PSNS)
62
Rectal (defecation) reflex effectors
- smooth muscle of rectum (contract) and internal anal sphincter (relaxes)
- external anal sphincter (skel. muscle) under voluntary control
63
Digestion of large intestine
none but get bacterial fermentation of undigested nutrients. bacterial synthesize some vitamins (B6 B5, K, folate, biotin)
64
Absorption of the large intestine
- H2O: 400 mL/day via osmosis
- Na active transport
- fermentation products (vitamins)
- drugs (anaesthetics)
65
Secretion of the large intestine
K, HCO3
66
Glucose absorbed
from blood into body cells to insulin increase uptake into skel. muscle and fat.
67
Glucose in cell is used for..
- catabolism by cells (ATP)
| - anabolism: glycogen (75% in skel. muscle, 25% in liver) and 1% of body’s energy stores
68
Lipids absorbed: Cholesterol
used to make steroid hormones, bile salts, cell membranes
69
Lipid absorbed: triglyceride in blood then to tissue cells than fa..
- oxidized produces ATP
- stores as TG in adipose tissue (99% body energy store)
- used to synthesize
70
Amino acids absorbed
enter cells by 2 AT or facilitated transport. GH high entry into most cells. insulin high entry into skel. muscle. in cells AA used mainly for protein synthesis (not store) used for energy when glucose low
71
Metabolic rate
bodys rate of energy use: sum of all chemical reactions and mechanical work
72
Factors effecting MR
1) SNS ⇑ MR
2) hormones e.g. epi, TH ⇑ MR
3) body temp - 1⁰C rise ⇒ 10% ⇑ in MR
4) exercise ⇑ MR
5) food ingestion ⇑ MR
6) sleep ⇓ MR
73
Basal metabolic rate (BMR)
energy body needs for essential activities e.g. HR, kidney function, breathing.
