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Biology 30S > Digestive System > Flashcards

Digestive System Flashcards

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1
Q

What is anatomy?

A
  • the study of vital structures of body parts
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2
Q

What is physiology?

A

The study of vital functions of body parts

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3
Q

What is the digestive system?

A

A body system that is specialized to ingest food, break it down into useful substances for the body, and absorb it while eliminating waste

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4
Q

What is digestion?

A

The process by which large food molecules are broken down into simpler forms

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5
Q

What is the digestive tract?

A

The long tube made up of organs through which food passes and is broken down into simpler compounds

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6
Q

The digestive tract extension

A
  • extends from the mouth to the anus

- makes a continuous tube “exterior to the body” with two points of contact to the outside

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7
Q

What is the digestive tract also known as?

A

Gastrointestinal (GI) Tract, alimentary canal

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8
Q

What organs make up the tract? 8 PTS

A

Organs containing food

  • mouth
  • esophagus
  • stomach
  • small intestine
  • large intestine
  • rectum
  • Anus
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9
Q

2 types of digestive processes

A

Physical/ mechanical digestion

Chemical digestion

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10
Q

What is physical/mechanical digestion?

A
  • making food smaller to expose more surface area

- through chewing, churning, segmenting

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11
Q

What is chemical digestion?

A
  • breaking of chemical bonds

- breakdown through chemicals/enzymes, hydrolysis of macromolecules

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12
Q

What are accessory organs?

A
  • structures that aid in digestion, but do not contain food
  • organs aid in chemical digestion by releasing chemicals and enzymes
  • not part of digestive “tract”
  • ex. Salivary glands, liver, gall bladder, pancreas
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13
Q

What does the mouth do? Location and what it does

A
  • location of mechanical digestion (primarily)

- crushing, tearing, grinding food with the teeth and tongue

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14
Q

What is the chemical digestion done in the mouth?

A
  • salivary glands release saliva to lubricator food with liquid/mucus, and start chemical digestion with salivary amylase
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15
Q

What is salivary amylase?

A
  • enzyme that breaks down starch into simper sugars (disaccharides)
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16
Q

What is Bolus?

A

Lump of food in the mouth or esophagus

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17
Q

The process in the pharynx

A

Bolus is pushed from mouth to pharynx (throat) by the tongue

  • starts swallowing reflex
  • epiglottis covers trachea as trachea moves up in the swallowing process
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18
Q

The esophagus process

A
  • food enters the esophagus by passing over the epiglottis and trachea
  • u can’t breath and swallow at the same time
  • esophagus is right behind trachea
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19
Q

What does the uvula do?

A

Helps prevent food from getting into the nasal cavity when swallowing

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20
Q

What does the peristalsis do?

A
  • involuntary muscular contractions of the esophagus to move food to the stomach
  • occurs all along the digestive tract (to move food down with contractions)
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21
Q

What is the Esophageal spincter ?

A

Ring like muscular structure from the esophagus to the stomach

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22
Q

What is the stomach known as, and what is its function?

A
  • the J shaped organ
  • used primarily for storage, and some digestion
  • bc it pushes food to small intestine
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23
Q

How is the stomach used for storage?

A
  • The stomach stretches and expands (Rugae;folds) like an accordion
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24
Q

How is the stomach used for PHYSICAL digestion?

A
  • peristalsis pushes food to the bottom, churning and breaking it
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25
Q

How does the stomach do chemical digestion? What is the pH range in the stomach?

A
  • gastric juices (water, mucus, salts, HCl, and enzymes [pepsin]) softens and breaks down protein
  • pH of 1-3 (acts to kill bacteria) in the stomach
  • chyme is made
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26
Q

What is chyme?

A
  • Food mixed with gastric juices
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27
Q

What is pepsin? What does it do?

A
  • enzyme released in the stomach
  • first step in protein digestion
    Protein —> polypeptides
28
Q

What is the pH of pepsin to work?

A
  • only active and low pH of HCl in the stomach

- if pH is too high, and then becomes denatured

29
Q

3 reasons why the stomach does not digest itself. In other words, how can you prevent the stomach from digesting?

A
  • it only secretes gastric juices when food is present (not when stomach is empty)
  • some stomach cells secrete mucus which protect stomach lining
  • pepsin is inactive (won’t break down protein due to wrong shape) until it is in the presence of HCl
30
Q

Absorption in the stomach

A
  • Little absorption
  • not enough digestion (hydrolysis) yet
  • water, salt, aspirin, alcohol do absorb in his stomach
31
Q

What is the pyloric sphincter and what does it do?

A
  • A true sphincter: muscular ring

- Control flow of chyme into small intestine from stomach

32
Q

What does the small intestine do?

A
  • allows for digestion and absorption

- has physical and chemical digestion

33
Q

How does physical digestion work in the small intestine?

A
  • segmentation
  • chyme moves back and forth between segments of the small intestine formed by circular muscle contraction
  • chyme is very much a liquid now
34
Q

How does chemical digestion work in the small intestine?

A
  • aided by several accessory organs and lining cells
  • primarily the type of digestion in the small intestine
  • Peristalsis still occurs
35
Q

What is the structure of the small intestine?

A
  • Circular ridges in interior
  • ridges themselves are highly folded into villi, which have cells containing Projections (microvilli)
    See villi card
36
Q

What does villi do?

A
  • increase service area for absorption of nutrients into the body
  • each villus contains blood vessels and lymph vessel structures for transportation of nutrients
37
Q

What is microvilli, and what does it do?

A
  • The brush border of the intestinal wall
  • absorption
  • Release of digestive enzymes
38
Q

How long is the small intestine, and what are the three parts to it?

A
  • 5.5 m to 6 m in length total

- duodenum, jejenum, ileum

39
Q

What is the duodenum?

A
  • first 25 cm of the small intestine after the stomach

- ducts from liver/gallbladder and pancreas introduce chemicals for chemical digestion

40
Q

What is the jejunum?

A
  • Second section of small intestine
  • 2.5 m
  • increased folding and secretory glands (release enzymes from villi) for digestion and absorption
41
Q

What is the ileum? What does it do?

A
  • third section of small intestine
  • 3 m
  • fewer and smaller villi
  • absorption
  • pushes undigested material to large intestine
42
Q

What does the pancreas do?

A
  • releases pancreatic fluid to duodenum with enzymes
43
Q

Function of specific types of enzymes in the pancreas?

A

trypsin and chymotrypsin: proteases that digest protein
Pancreatic amylase: carbohydrate digestion
Lipases: digest fats
- Enzymes activated by other enzymes released from cells of the villi
- bicarbonate released to neutralize acidic stomach contents to pH of about eight

44
Q

What is the function of the liver?

A
  • releases bile
    Bile pigments and bile salts
  • more surface area for digestion (when enzymes and fat mix together)
45
Q

What are bile pigments?

A
  • waste pigments from destroyed old blood cells to be eliminated (not for digestion)
46
Q

What do bile salts do?

A
  • role in digestion of fats by acting as a detergent
    emulsifier - allows for two normally unmixable liquids to be mixed: fats and digestive liquid [including lipases] mix)
  • more SA for digestion when enzymes and fat mix together prob
47
Q

What does the gallbladder do?

A
  • stores bile from the liver

- release bile by a duct upon arrival of chyme in the duodenum

48
Q

Where does most chemical digestion occur for macromolecules?

A
  • small intestine in the duodenum

- all four categories of macromolecules are being digested at this point

49
Q

What is a full process in which carbohydrates are digested and absorbed?

A

Carbohydrases digest carbohydrates

  1. Salivary amylase (minimal digestion of starch in mouth, pH 7)
    - no additional chemical digestion in the stomach
  2. pancreatic amylase is released in the duodenum
    - completes starch to disaccharide conversion
    - other carbohydrases convert disaccharides to monosaccharides (lactase, Maltase)
  3. monosaccharides are absorbed by active transport into intestinal lining cells then villi blood capillaries
  4. Move to liver by bloodstream (vessel)
  5. Liver converts other monosaccharides to glucose
  6. Storage of glucose units in glycogen (polymer)
  7. Glucose is used in the body for energy
50
Q

What is the full process in which lipids are digested and absorbed?

A
  • lipid digestion starts in adults in the duodenum
    1. Bile emulsifiers fat droplets (physical process)
    2. Lipases secreted in the duodenum hydrolyzes triglycerides into glycerol and fatty acids
    3. Glycerol and fatty acids are absorbed by simple diffusion into intestinal lining cells
  • simple diffusion because it’s non-polar
    4. In the intestinal lining cells, fat units are reassembled into triglycerides, coated with proteins for solubility, and enter lymph vessels (lacteal) by diffusion
    5. Fats enter the bloodstream from lymph vessels in chest region, lose the protein coating and are disassembled (again to glycerol and fatty acids) by lipase for transport by the blood
51
Q

What is a complete process in which proteins are digested and absorbed?

A
  1. Pepsin in the stomach converts proteins to polypeptides
  2. Small intestine - trypsin/chemotrypsin (pancreatic proteases activated by other enzymes released in small intestine)
  3. Hydrolyzes polypeptides into shorter peptides, 2 to 10 amino acids long
  4. Peptidases enzymes from pancreas and small intestine —> split off individual amino acids
  5. Amino acids absorbed by active transport into villi, diffuse into blood capillaries, and move to liver by bloodstream for processing and distribution
52
Q

What is a full process in which nucleic acid‘s are absorbed and digested?

A
  1. Digested by nucleases in the small intestine to yield nucleotides
  2. Nucleosidases hydrolyzed nucleotides to bases, sugars, and phosphates
  3. These are absorbed to the villi epithelial cells and then the bloodstream by active transport
53
Q

Regulation/control of small intestine processes

A
  • controlled by the nervous system (Brain, spinal cord, and nerves)
  • also the endocrine system (hormone-releasing glands and tissues)
  • sight/smell and consumption of food can stimulate secretion from cells/organs to help body prepare for digestion
54
Q

What is a hormone?

A
  • signalling molecule

- carries a message, messenger molecule)

55
Q

How does the hormone gastrin work?

A
  • food proteins in the stomach stimulate gastrin release to bloodstream
  • Gastrin stimulates acid (HCl) and pepsin precursor release (inactive pepsin)
  • Low pH inhibits gastrin release (bc of HCl)
  • gastrin inhibited = acid release inhibited (stopped)
  • call the negative feedback mechanism because gastrin caused HCl release, and stops it
56
Q

What is a negative feedback mechanism?

A
  • Mechanism by which the release of a hormone causes an effect, but the effect slows down its release
57
Q

What causes hormone release in the duodenum?

A
  • chyme movement from stomach to duodenum stimulates hormone release to the bloodstream from the duodenum
58
Q

What are the hormones released in the duodenum? What do they do?

A
  • Secretin
  • CCK (cholecystokinin)
  • GIP (gastric inhibitory peptide)
  • these hormones inhibit stomach contractions to keep more food from entering the duodenum
59
Q

What is CCK And GIP especially stimulated by?

A

High fat content

60
Q

What is secretin Especially stimulated by?

A

High acidity

61
Q

Which hormone would stimulate more bile injection?

A
  • CCK
  • bile is necessary to Emulsify fats
  • stimulates increased pancreatic secretions (enzymes) and gallbladder contractions to release bile
62
Q

Which hormone would stimulate more bicarbonate release?

A
  • secretin
  • increased pancreatic release of bicarbonate to neutralize Chyme
  • because bicarbonate neutralizes the high acidity of the stomach for pancreatic enzymes to work
63
Q

What is the function of the large intestine? 5

A
  • does not function in digestion —>undigested chyme is left
  • concentrates and eliminates waste
  • absorbs water and salts as feces is formed
  • therefore it maintains homeostasis of water and salt balance in the body
  • intestinal bacteria break down faeces further and produce vitamin B-12 and potassium and some amino acids
64
Q

What is the structure of the large intestine?

A
  • 1.5 m long
  • ascending, transverse, and descending colon
  • appendix is located at the junction of the ileum and a large intestine
  • Note that the appendix is the vestigial organ of no confirmed use
65
Q

What is the structure and function of the rectum?

A
  • last 20 cm of the large intestine
  • faeces enter the rectum from the large intestine
  • rectum holds feces until elimination through the anus by peristalsis
66
Q

What is the structure and function of the anus?

A
  • anus is controlled by two sphincter sets
  • one is controlled involuntarily by the nervous system (interior)
  • One under voluntary control

Biology 30S (14 decks)

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