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biology 2a03 > week 11 (digestive) > Flashcards

week 11 (digestive) Flashcards

(43 cards)

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1
Q

define: energy, potential E, kinetic E

A
  • E = ability to do work measured by joules and calories
  • kinetic = E of mvt.
  • potential = E to be used up
    ⤷ in storage
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2
Q

question: anabolic vs catabolic?

A
  • anabolic = req. E
    ⤷ small molecules built into large ones
  • catabolic = req. no E
    ⤷ E released
    ⤷ large molecules built into smaller ones
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3
Q

name: major general processes in assimilation (4)

A
  1. digestion
    - chemical breakdown of larger nutrients into smaller mol.
  2. absorption
    - transport of small mol. from GI to blood
  3. secretion
    - transport of substances to lumen of GI tract to aid digestion and absorption
  4. motility
    - mvt. of GI content along length of GI tract (peristalsis)
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4
Q

explain: digestive sys. of sponges

A
  • phagocytosis
  • water brought in through choanocytes
  • digestion happens intracellularly
    ⤷ choanocytes have endocytic vacuoles
  • flagellum beat to make currents and move nutrients
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5
Q

explain: digestive sys. of cnidarians

A
  • bring food into a gastrovascular cavity
  • digestion occurs extracellularly and intracellularly
  • vacuoles lining cav. have enz. to break down nutrients
  • diffuses out to epidermis to be passed around org.
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6
Q

explain: path of one-way gut system (GI tract)

A
  • mouth, pharynx, esophagus
    ⤷ mech. breakdown of food
  • stomach
    ⤷ acidic compartment for digestion
  • upper and smaller intestines
    ⤷ digestion and absorption
  • lower and larger intestines (colon + rectum + cecum)
    ⤷ absorp. of water
  • anus
    ⤷ release of indigestible mat.
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7
Q

explain: differences in avian digestive sys.

A
  • has crop for food storage
  • stomach has 2 parts
    ⤷ proventriculus = chemical digestion
    ⤷ gizzard = mechanical digestion (pebbles grind food here)
  • has cloaca (ceaca)
    ⤷ no specific tract for urine
    ⤷ everything waste leaves here
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8
Q

explain: differences in pseudo ruminants digestive sys.

A
  • has cecum
    ⤷ has gut bac.
    ⤷ allows digestion of weeds and grass
  • eat their poop
    ⤷ digesting again allows second change to extract more nutrients
    ⤷ first poops = cecotropes
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9
Q

explain: differences in ruminants digestive sys.

A
  • 4 chambered stomach
    ⤷ rumen, reticulum, omasum, abomasum
  • has cecum

PATH:
- passes esophagus into rumen and reticulum
⤷ have bac. to digest cellulose and prod. CO2 and methane
- regurgitate food (cud) from rumen to mouth
- food enters again -> into omasum and abomasum
⤷ abomasum secretes digestive enz.
- into small intestine
- into cecum + large intestine

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10
Q

question: why don’t humans eat grass?

A
  • can’t digest cellulose like cows
  • can easily extract from other veggies
    ⤷ bc we have access
  • cows only eat grass
    ⤷ so can extract all the nutrients they need from it
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11
Q

explain: structure of GI tract tissue

A
  • layers:
    ⤷ mucosa
    ⤷ submucosa
    ⤷ musc. layer
    ⤷ serosa
  • submucosa and muscularis externa have enteric NS
    ⤷ controls GI function
    ⤷ part of ANS
    ⤷ contract/relax naturally
  • smooth musc. allows GI motility
  • peristalsis = smooth musc. propelling contents through
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12
Q

name: layers of GI tract tissue from innermost to outermost

A

MUCOSA (inner to outer)
- mucous mem.
⤷ has enterocytes
- lamina propria
- muscularis mucosae

SUBMUCOSA

MUSCULARIS EXTERNAL (inner to outer)
- circular musc.
- longitudinal musc.

SEROSA

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13
Q

name + explain: digestive enzymes (4)

A
  • amylase
    ⤷ splits carbs into simple sugars
  • proteases and peptidases
    ⤷ splits prot. into peptides and AA
  • lipases
    ⤷ splits fats into free fatty A and glycerol
  • nucleases
    ⤷ splits nucleic A into nucleotides
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14
Q

explain: carb breakdown and absorption process

A

MOUTH (salivary amylase)
- glycogen -> glycogen and oligosaccharides
- starch -> starch and oligosaccharides
- nothing happens to disaccharides and cellulose

NOTHING HAPPENS IN STOMACH

SMALL INTESTINE (pancreatic amylase, disaccharidases)
- glycogen, oligosaccharides, starch -> disaccharides -> monosaccharides
- cellulose stays cellulose the whole time

  • monosaccharides get absorbed by epithelial cells in intestine
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15
Q

question: how does breakdown of processed foods differ? why might it cause weight gain and insulin spikes?

A
  • breaks down into glucose + gets into blood faster
  • increases blood sugar -> pumps more insulin -> spike
  • fat storage and E usage impacted by the amount of time the glucose spends in blood + time it takes to remove it
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16
Q

explain: swallowing

A
  • initiated voluntarily but proceeds automatically
  • 3 phases
  1. buccal
    - conscious
    - manipulating + mech. breakdown of food into bolus
    - involves teeth + hard palate
  2. pharyngeal
    - becomes involuntary
    - pushing bolus down
    - pushes down on epiglottis to prevent from choking
  3. esophageal
    - peristalsis down esophagus
  4. bolus passes cardiac sphincter and enters stomach
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17
Q

name: main functions of stomach (4)

A
  • storage of ingested food
  • mechanical breakdown
  • disruption of chemical bonds
  • production of intrinsic factor (IF)
    ⤷ helps w/ vitamin B12 absorp.
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18
Q

explain: structure of stomach

Study These Flashcards
A
  • still has the 4 layers like GI tract
    ⤷ mucosa, submucosa, musc. layer, serosa
  • musc. contracts to break food
  • surface = columnar epithelial cells w/ tight junctions to prevent leakage of stomach fluid
  • gastric pits protect cells from acidity by secreting juice into lumen
    ⤷ keeps cells away from lumen
19
Q

explain: what happens w/ gastric juices in stomach + cells of mucosa layer of stomach

Study These Flashcards
A
  • gastric juice secreted into lumen by gastric pits
    ⤷ mixes w/ food to make chyme

CELLS
- chief cells
⤷ secretes precursor for pepsin
- parietal cells
⤷ secrete H+
⤷ creates acidic envrt. (pH = 2)
- enteroendocrine cells (G cells)
⤷ secretes gastrin int blood
- mucous neck cells
⤷ secretes mucous
⤷ protect cells from acid damage

20
Q

explain: cephalic phase of gastric activity

Study These Flashcards
A
  • only a few minutes
  • prod. of acid and enz. by gastric mucosa controlled by CNA
  • CNS prepares stomach to receive food
    ⤷ starts when you start thinking of food
  • increases production of gastric juices
  • directed by vagus nerve that innervates submucosa plexus of stomach
21
Q

explain: gastric phase of gastric activity (local, neural, hormonal resp.)

Study These Flashcards
A
  • food arrives in stomach
  • stim. by = distention of stomach + increase pH + undigested material in stomach
  • 3 - 4 hours
  • bolus -> chyme

LOCAL
- gastric walls stretching -> stim. parietal cells to secrete H+

NEURAL
- stim. of stretching triggers short reflex to activate stomach secretory cells
⤷ causes mixing waves
- spreads food out and mechanical mixing

HORMONAL
- neural stim. + presence of peptide and AA in chyme -> stim. secretion of gastrin from G cells -> stim. chief and parietal cells
⤷ releases more pepsinogen, HCl, mucous
⤷ stim. mixing

22
Q

explain: intestinal phase of gastric activity (hormonal and neural resp.)

Study These Flashcards
A
  • chyme enters small intestine
    ⤷ pyloric sphincter opens up
  • goal is to control rate of gastric emptying to ensure absorption proceeds well

HORMONAL
- triggered by chyme reaching duodenum
- lipids and carbs stim GIP and CCK
⤷ GIP stops contractions and production from chief and parietal cells
- low pH stim. secretin
- partially digested prot. stim G cells to secrete gastrin

NEURAL
- chyme leaving stomach decreases stretch
- stretch in duodenum -> enterogastric reflex
⤷ inhibits gastrin production + gastric contraction
- stim. pyloric sphincter to slow chyme
^stops stomach contractions

23
Q

name + explain: parts of small intestine

Study These Flashcards
A
  • duodenum
    ⤷ site of pancreatic juice secretion
    ⤷ site of bile secretion
  • jejunum
    ⤷ most absorption happens here
  • ileum
24
Q

question: how is SA increased in GI tract?

Study These Flashcards
A
  • increasing gut length
  • increasing surface undulations
    ⤷ circular folds
    ⤷ villi
    ⤷ microvilli
25
question: how does peristalsis work?
- contraction cycles between smooth visceral musc. ⤷ between longitudinal and circular msuc.
26
explain: bile
- solution of digestive chem. and liver waste prod. - prod. in liver - stored in gall bladder - phospholipids ⤷ helps uptake lipids - bile salts ⤷ helps emulsify fats - bile duct ⤷ opens into duodenum when food enters
27
name: exocrine secretions into the intestine
- bile - pancreatic enz. **exocrine = don't get into blood endocrine = insulin and glucagon
28
name: examples of pancreatic enz.
- amylase ⤷ for starches and glycogen - proteases ⤷ for protein ⤷ secreted as inactive and get activated in intestine - lipases ⤷ for triglycerides (fats) - nucleases ⤷ for nuc. A
29
name + explain: hormones in the stomach
- gastrin ⤷ stim. prod. and secretion of gastric A
30
name + explain: hormones in duodenum
- **gastric inhibitory peptide (GIP)** ⤷ inhibits gastric secretions from G cells (stops stomach) - **secretin** ⤷ increases chyme pH and bile release - **cholecystokinin (CCK)** ⤷ stim. expulsion of bile from gallbladder ⤷ stim. secretion of pancreatic enz. ⤷ reduces appetite - **vasoactive intestinal peptide (VIP)** ⤷ stim. intestinal blood flow (vasodilation) ⤷ inhibits acid prod. by stomach
31
explain: purpose of large intestine (colon)
- absorption of water and inorganic ions - stores remaining indigestable materials ⤷ until feces are eliminated - starts from ileum until anus
32
explain: role of leptin, PYY, ghrelin, and insulin on appetite
LEPTIN - LONG TERM - prod. by fat/adipose tissue - suppresses appetite - body fat decreases -> leptin decreases -> appetite increases PYY - SHORT TERM - secreted by small intestine after meals - appetite suppressor - recep. on hypothalamus GHRELIN - SHORT TERM - secreted by stomach walls - triggers feelings of hunger - recep. on hypothalamus INSULIN - LONG TERM - secreted by pancreas - lowers blood sugar - works both ways ⤷ pulling sugar out -> glucose crash -> increase app. ⤷ increase sugar -> feeling of satiety - after meals = increase insulin -> suppresses appetite
33
question: what is ozempic?
- semaglutide ⤷ a glucagon-like-prot-1 (GLP-1) agonist ⤷ mimics GLP-1 - for type II diabetes patients to manage blood sugar lvls - used in US for weight loss ⤷ not the intended purpose
34
explain: mechanism of ozempic
- GLP-1 = hormonal peptide released in small intestine - mediates glucose dependent insulin secretion ⤷ stim. insulin secretion to lower blood glucose ⤷ reduces glucagon release to lower blood glucose - synthetic GLP-1 = long lasting and more resistant to degradation **increases insulin -> suppresses appetite **also acts on hypothalamus to decrease appetite and increase feelings of satiety
35
name + explain: cells of mucosa layers in intestine
- **enterocytes** ⤷absorptive cells w/ the microvilli - **goblet cells** ⤷ release mucous - **enteroendocrine cells** ⤷ secrete hormones - **paneth cells** ⤷ secrete antimicrobial mol.
36
explain: relationship between glucose and insulin
- glucose lvls rise from meals or sympathetic resp. ⤷ causes insulin release - insulin pulls sugar out of blood and into cells ⤷ goes to musc., liver, and fat cells for storage
37
explain: insulin resistance
- continuous insulin spikes -> resistance ⤷ recep. to resp ⤷ insufficient insulinprod. - cells no longer resp. to insulin -> glucose stays in blood -> blood sugar stays high -> cells don't get their ATP -> cells die - can also change blood viscosity -> changes bp ⤷ causes strain to heart
38
question: how to reduce glucose spikes (+ why is excess glucose in cells bad?)
- excess glucose -> mitochondrial overload ⤷ too much ATP - lower spikes by adding protein to meals ⤷ longer break down time = less sharp spike ⤷ more time for insulin to release and work
39
explain: protein breakdown and absorption process
NOTHING HAPPENS IN MOUTH STOMACH (pepsin) - proteins -> large polypeptides SMALL INTESTINE (trypsin, chymotrypsin, carboxypeptidases) - large polypep. -> dipeptides -> amino AA - AA get absorbed by epithelial cells through AA-Na cotransporters ⤷ enters blood directly **protein breakdown takes longer -> longer time for glucose to enter blood -> increases satiation hormones
40
question: how are lipids digested and transported?
- digestion based on hydrophobicity ⤷ bile emulsifies lipids into micelles ⤷ dietary fats break into fatty A and monoglycerides - transport based on physical properties ⤷ short fatty A chains and glycerol diffuse into blood ⤷ triglycerides move into lymphatic vessels as chylomicrons (packaged) -> taken into lacteals to get into blood
41
question: how do lipids get into blood stream?
- through lacteals (lymphatic vessels) - lymph vessels all drain back to vena cava and get back into circulation
42
explain: function/purpose of short chain fatty acids
- primary E source for colon cells ⤷ good for intestinal health - regulate immune sys. in gut - stim. release of PYY and GLP-1 ⤷ reduce appetite - important signaling mol. for comms between brain and gut
43
question: how are short chain fatty acids produced?
- need proper gut biome and a good diet - com from fermentation of dietary fiber by gut microbiome of large intestine

biology 2a03 (11 decks)

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