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mcdb1b > digestion > Flashcards

digestion Flashcards

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
Q

sphincter makeup and

sphincter movement when eating

A

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

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26
Q

Stomach

A

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

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27
Q

Where does HCl and pepsin in the stomach come from

A

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

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28
Q

why wouldn’t chief cells digest itself

A

it makes the inactive form of pepsin, pepsinogen and gets activated by the presence of HCl

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29
Q

Mucus

A

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

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30
Q

Ulcers

A

Mainly caused by bacteria in stomach that starts digesting stomach

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31
Q

Small intestine

A

where Digestion is completed and absorption takes place

made up of duodenum, jejunum, and ileum

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32
Q

duodenum

A

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
Q

Pancreas

A

Send pancreatic juice with bicarbonate fluid to neutralize stomach acid
Also sends digestive enzymes with it to duodenum

34
Q

Gallbladder

A

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
Q

Following the duodenum, the small intestine’s main job involves

A

the absorption of nutrients

36
Q

the small intestine’s most absorption takes place in the

A

jejunum

37
Q

jejunum

A

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
Q

Last segment of the small intestine is

A

ileum

39
Q

ileum function

A

Main function is to absorb vitamin B12, bile salts, and whatever products of digestion are remaining for absorption

40
Q

Absorption

A

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
Q

Villi and microvilli
function

A

Specifically looking for prticuar molecules to transfer across epithelial cekks
Villi and microvilli increase surface area to pull molecules in

42
Q

Hepatic portal vein

A

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
Q

how does lipase come about digsesting fat in the small intestine

A

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
Q

why are fats reformed into triglycerides

A

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
Q

Large intestine

A

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
Q

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

A

hormones\

gastrin
CCK and secretin

47
Q

gastrin

A

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
Q

CCK and secretin

A

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
Q

Where do we store carbohydrates, fats,, abd proteins

A

As triglycerides in fat cells
Releases fatty acids back into circulation to feed other cells

50
Q

Carbohydrates are found in the form of ___in liver and muscles

A

glycogen

51
Q

How we maintain blood glucose

A

breakdown of glycogen
Insulin and Glucagon

52
Q

Insulin

A

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
Q

Glucagon

A

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
Q

Diabetes

A

Elevated blood glucose, dehydration, poor circulation, acidosis

55
Q

Type 1 diabetes

A

Doesn’t make insulin
Caused by destruction of insulin producing beta cells in the pancreas
Autoimmune disease

56
Q

Type 2

A

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
Q

Regulating appetite

A

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
Q

OB mouse was missing something that was turning off the satiety signal

A

Leptin
Leptin acts on your brain to decrease appetite

59
Q

bolus

A

Mixture of saliva and food shaped into a ball

60
Q

Each bolus of food is received by a throat region called the ___ which leads to what two passageways

A

Pharynx
Esophagus and trachea

61
Q

Esophagus

A

Muscular tube that connects to the stomach

62
Q

Trachea

A

Windpipe that leads to the lungs

63
Q

Within the esophagus, food is pushed along by

A

Peristalsis
Alternating waves of smooth muscle contraction and relaxation

64
Q

Upon reaching the end of the esophagus, the bolus encounters

A

A sphincter
A ringlike valve of muscle
Regulates passage of the ingested food into the next compartment→ stomach

65
Q

The stomach, located below the diaphragm, has two major roles in digestion which are

A

Storage and to process food into a liquid suspension

66
Q

The stomach secretes a digestive fluid called

A

Gastric juice

67
Q

The mixture of ingested food and gastric juice is called

A

Chyme

68
Q

What two components of gastric juice help liquefy food in the stomach

A

Hydrochloric acid and protease/pepsin

69
Q

What two types of cells in the gastric glands of the stomach produce the components of gastric juice

A

Parietal cells and chief cells

70
Q

How do more pepsinogen become activated

A

Pepsin can activate the remaining pepsinogen by clipping pepsinogen and exposing its active site → positive feedback

71
Q

alimentary canal

A

same as GI tract
digestive tract
mouth to anus

72
Q

The arrival of chyme in the duodenum triggers

A

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
Q

Bile production is metabolically linked to what other vital liver function

A

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
Q

In exiting the small intestine, chylomicrons first enter a

A

Lacteal
A vessel at the core of each villus

75
Q

How is water reabsorbed

A

By osmosis when sodium and other ions are pumped out of the lumen of the small intestine

76
Q

The alimentary canal ends with the

A

Large intestine which includes the colon cecum and rectum

Colon leads to the rectum and anus

77
Q

Cecum

A

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
Q

The terminal portion of the large intestine is the

A

Rectum → where feces are stored before elimination out of the anus

mcdb1b (10 decks)

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