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digestion Flashcards

(78 cards)

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1
Q

An adequate diet must supply what three needs

A

Chemical energy for cellular processes(ATP)
Organic building blocks for macromolecules
Essential nutrients

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2
Q

To meet the need for ATP, animals ingest and digest nutrients including

A

Carbohydrates
Proteins
Lipids
For use in cellular respiration and energy storage

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3
Q

what are essential nutrients

A

Essential amino acids, fatty acids, vitamins
Substances that an animal requires but cannot assemble from simple organic molecules
they can collect and synthesize all other forms of these compounds but the essential ones must be consumed to be obtained

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4
Q

All organisms require a standard ___ amino acids to make a complete set of proteins

A

20

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5
Q

Essential fatty acids

A

Used to regulate membrane fluidity
Synthesize a group of signaling molecules called eicosanoids
Also serve as source for ATP generation
Animals cant make double bonds → need from diet

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6
Q

Vitamins

A

Organic molecules that are required in the diet in very small amounts

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7
Q

Vitamin A deficiency

A

Night blindness → inability to see well in dim light
Regeneration of rhodopsin is incomplete
Retinal is derived from vitamin A

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8
Q

Maintaining homeostasis is important so that

A

so that glucose, amino acids, and fatty acids remain in interstitial fluid for cells to take up

Carbs, fats, and proteins are consumed via digestive tract
We can use them immediately or store the nutrients

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9
Q

Overall goals of the digestive tract

A

Take food and break it down to absorbable units

Digestion sends secretions that contain enzymes to break down big molecules in food

Move the absorbable units from the inside (lumen) of the digestive tract across the epithelial cell of the digestive tract wall and into the interstitial fluid

These are then taken up by the circulatory system for distribution

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10
Q

Food processing involves what steps

A

Ingestion, digestion, absorption, and elimination

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11
Q

the GI tract is lined with __ which is where nutrients and molecules must be able to pass through to get to the interstitial fluid

A

epithelial cells

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12
Q

food enters the digestive tract in

A

lumen of GI tract
cavity/inside of GI tract
tube

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13
Q

Ingestion

A

The act of eating or feeding

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14
Q

digestion

A

Food is broken down into molecules small enough for the body to absorb
Both mechanical and chemical processes are typically required

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15
Q

digestion mechanical and chemical

A

Mechanical→ chewing and grinding
Chemical → cleaves out large molecules into smaller components

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16
Q

Why is chemical digestion necessary

A

Animals cannot directly use the proteins, carbohydrates, nucleic acids, fats, and phospholipids in food
These molecules are too large to pass through cell membranes
When broken down into smaller components, the animal can use these products to assemble the large molecules it needs

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17
Q

Elimination

A

Undigested material passes out the digestive system

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18
Q

Absorbable units

A

Monosaccharides, amino acids, nitrogenous bases, sugars, phosphates, glycerol, fatty acids, monoglycerides → from the building blocks

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19
Q

Carbohydrates breakdown
steps

A

Start with polysaccharides
Salivary glands form salivary amylase
Turns bigger molecules smaller (smaller polysaccharides)
In small intestine pancreatic amylase breaks down larger molecules to disaccharides
intestinal epithelium enzymes turn disaccharides into monosaccharides

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20
Q

Protein breakdown

A

Start with Pepsin in the stomach that breakdown proteins to small polypeptides

In small intestine there are many enzymes from the pancreas that break down the polypeptides into small peptides

Small intestine will have dipeptides, aminopeptides, which break down to amino acids

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21
Q

Nucleic acid breakdown

A

Digestion takes place in small intestine where pancreatic nucleases break DNA and RNA into nuclleotides
Nucleotidases break nucleotides to nucleosides in small intestine
Nucleosidases and phosphatase break nucleosides to nitrogenous bases, sugars, and phosphates

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22
Q

Fat digestion

A

small intestine
take fat and break it down with pancreatic lipase to glycerol and fatty acids

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23
Q

Function of different parts of human digestive system
Mouth

A

Food is chewed and lubricated with saliva
Salivary amylase breakdown polysaccharides

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24
Q

what happens in the Oral cavity, pharynx, and esophagus

A

Swallowing causes epiglottis to block entry to the trachea, and the bolus is guided by larynx, the upper part of the respiratory tract

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25
sphincter makeup and sphincter movement when eating
Upper sphincter Regulates passage of food into the esophagus and not the trachea Lower sphincter Opens to allow food to enter stomach Esophageal sphincter is typically contracted to allow breathing and trachea to be open. When eating the sphincter is relaxed and the esophagus opens
26
Stomach
Smooth muscular bag Stores your meal and then slowly release it into small intestine In the stomach there is HCl that kills bacteria, denature macromolecules, and activate pepsinogen. There is also pepsin which starts the digestion of proteins
27
Where does HCl and pepsin in the stomach come from
Parietal cell sends HCl into your stomach Sends hydrogen ions and chloride ions into your stomach Chief cells secrete pepsinogen(inactive form of pepsin) Enzyme that starts the digestion of other enzymes
28
why wouldn't chief cells digest itself
it makes the inactive form of pepsin, pepsinogen and gets activated by the presence of HCl
29
Mucus
Secreted by the stomach’s mucous cells Coats the walls of the stomach and protects it from being eroded and digested by HCl and pepsin
30
Ulcers
Mainly caused by bacteria in stomach that starts digesting stomach
31
Small intestine
where Digestion is completed and absorption takes place made up of duodenum, jejunum, and ileum
32
duodenum
first portion of small intestine Secretions from the gallbladder and pancreas enter the small intestine lumen here Acid chyme from stomach and detergent-like bile from liver/gallbladder come together and enter duodenum
33
Pancreas
Send pancreatic juice with bicarbonate fluid to neutralize stomach acid Also sends digestive enzymes with it to duodenum
34
Gallbladder
Sends detergent-like bile to aid on fat digestion; made in liver Gallbladder stores bile because you only need it when you consume food aid in fat digestion
35
Following the duodenum, the small intestine’s main job involves
the absorption of nutrients
36
the small intestine's most absorption takes place in the
jejunum
37
jejunum
The longest section of the small intestine Nutrients have to move across the epithelial cells that line the lumen Small intestine is folded to increase surface area and allow for increased absorption
38
Last segment of the small intestine is
ileum
39
ileum function
Main function is to absorb vitamin B12, bile salts, and whatever products of digestion are remaining for absorption
40
Absorption
To absorb materials from the inside of the intestine, molecules need to travel across epithelial cells to the interstitial space and then get taken up by the capillaries for distribution throughout the body by the circulatory system
41
Villi and microvilli function
Specifically looking for prticuar molecules to transfer across epithelial cekks Villi and microvilli increase surface area to pull molecules in
42
Hepatic portal vein
Goes from one capillary in small intestine to the capillaries in the liver and then to the heart Carries nutrient rich blood from the capillaries of the villi of the small intestine to the liver, then to the heart The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules
43
how does lipase come about digsesting fat in the small intestine
When you eat fat they form fat globules Bile salts break up large fat globules increasing exposure of triglycerides on the surface to hydrolysis Triglycerides are broken down to fatty acids and monoglycerides by lipase Lipase chews around the edges of fat droplets Would take forever so bile breaks down fat globules to droplets After diffusing into epithelial cells, monoglycerides and fatty acids reform into triglycerides
44
why are fats reformed into triglycerides
This is the form of fats that can be sent around the body Triglycerides are combined with phospholipids, cholesterol, and proteins and formed into chylomicrons Enter lacteals and are carried away by lymph Chylomicrons are water soluble
45
Large intestine
Primary job is to make feces All the secretions that were sent in the GI tract lumen in the stomach and small intestine were dissolved in water Whatever hasn’t been taken up by small intestine Water reabsorption takes place here
46
Regulation of digestion We have periods of inactivity of our digestive system Must be able to turn process on and off what is it controlled by
hormones\ gastrin CCK and secretin
47
gastrin
Produced by cells in the stomach wall Sense arrival of food Turns on gastric secretions stimulates production of gastric juices As stomach empties(chyme leaves), gastrin production goes down gastrin signals digestion to begin
48
CCK and secretin
Presence of chyme in duodenum stimulates release of CCK which stimulates the pancreas to release HCO3- and enzymes and cause contraction of gallbladder to squeeze bile and aid in digestion of fat Secretin reacts to drop in pH and thus neutralizes low pH from chyme that enters duodenum by secreting bicarbonate CCK and secretin then inhibit gastric juices and stomach
49
Where do we store carbohydrates, fats,, abd proteins
As triglycerides in fat cells Releases fatty acids back into circulation to feed other cells
50
Carbohydrates are found in the form of ___in liver and muscles
glycogen
51
How we maintain blood glucose
breakdown of glycogen Insulin and Glucagon
52
Insulin
Beta cells in pancreas create insulin Leads to transport of glucose from blood into body cells and storage of glucose as glycogen lowers blood glucose concentration when the blood glucose level rises
53
Glucagon
Blood glucose level decreases Glucagon is secreted by alpha cells of the pancreas Glucagon signals the breakdown of glycogen and releases glucose into the blood
54
Diabetes
Elevated blood glucose, dehydration, poor circulation, acidosis
55
Type 1 diabetes
Doesn’t make insulin Caused by destruction of insulin producing beta cells in the pancreas Autoimmune disease
56
Type 2
Insulin is there but cells stop responding Producing so much insulin that your cells become insensitive to insulin Insulin is produced but target cells fail to take up glucose from the blood and the blood glucose level remains elevated
57
Regulating appetite
Satiety center in hypothalamus feels hunger Ghrelin stimulates hunger between meals Eating leads to an increase in insulin and PYY which act to decrease appetite
58
OB mouse was missing something that was turning off the satiety signal
Leptin Leptin acts on your brain to decrease appetite
59
bolus
Mixture of saliva and food shaped into a ball
60
Each bolus of food is received by a throat region called the ___ which leads to what two passageways
Pharynx Esophagus and trachea
61
Esophagus
Muscular tube that connects to the stomach
62
Trachea
Windpipe that leads to the lungs
63
Within the esophagus, food is pushed along by
Peristalsis Alternating waves of smooth muscle contraction and relaxation
64
Upon reaching the end of the esophagus, the bolus encounters
A sphincter A ringlike valve of muscle Regulates passage of the ingested food into the next compartment→ stomach
65
The stomach, located below the diaphragm, has two major roles in digestion which are
Storage and to process food into a liquid suspension
66
The stomach secretes a digestive fluid called
Gastric juice
67
The mixture of ingested food and gastric juice is called
Chyme
68
What two components of gastric juice help liquefy food in the stomach
Hydrochloric acid and protease/pepsin
69
What two types of cells in the gastric glands of the stomach produce the components of gastric juice
Parietal cells and chief cells
70
How do more pepsinogen become activated
Pepsin can activate the remaining pepsinogen by clipping pepsinogen and exposing its active site → positive feedback
71
alimentary canal
same as GI tract digestive tract mouth to anus
72
The arrival of chyme in the duodenum triggers
Release of the hormone secretin which stimulates the pancreas to secrete bicarbonate Bicarbonate neutralizes the acidity of chyme and acts as a buffer for chemical digestion in the small intestine
73
Bile production is metabolically linked to what other vital liver function
The destruction of red blood cells that are no longer fully functional Pigments released during red blood cell disassembly are incorporated into bile pigments which are eliminated from the body with feces
74
In exiting the small intestine, chylomicrons first enter a
Lacteal A vessel at the core of each villus
75
How is water reabsorbed
By osmosis when sodium and other ions are pumped out of the lumen of the small intestine
76
The alimentary canal ends with the
Large intestine which includes the colon cecum and rectum Colon leads to the rectum and anus
77
Cecum
A pouch that has an important role in fermenting ingested material The colon completes the recovery of water that began in the small intestine leaves behind feces
78
The terminal portion of the large intestine is the
Rectum → where feces are stored before elimination out of the anus

mcdb1b (10 decks)

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