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XBiology > Digestion > Flashcards

Digestion Flashcards

1
Q

Alimentary Canal def

A

refers to the one-way digestive tract running from the mouth to the anus

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2
Q

Digestive System def

A

refers to the digestive tract and organs associated with digestion

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3
Q

Ingestion def

A

process of putting food into the body

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4
Q

Digestion def

A

process of breaking food into molecules small enough for body’s cells to absorb

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5
Q

Egestion def

A

removal of undigested material from the anus

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6
Q

Has undigested food ever been in the body?

A

NO! It’s never been in the body’s cells!

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7
Q

Excretion def

A

process of removing substances from the body that was once part of living tissue (eg. pee or sweat)

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8
Q

Mechanical Digestion def

A

involves shredding, grounding, or shaking food to break it down by physical means

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9
Q

Where does physical digestion occur? And how do you know it is physical?

A
  • Mouth and stomach

- No enzymes therefore no bonds being broken

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10
Q

Chemical Digestion def

A

involves the breakdown of smaller food particles with the help of digestive enzymes

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11
Q

Mouth: teeth

A

carries out mechanical digestion by smashing food MAKING IT EASIER TO SWALLOW

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12
Q

Mouth: saliva (composition, names of salivary glands, volume of saliva a day, function)

A
  • 99% water, ions, mucous, enzymes
  • Produced by 3 pairs of salivary glands: parotid, submaxillary, and sublingual which secrete approx 1 L of saliva a day
  • Carries out chemical digestion as the digestive enzyme amylase begins the BREAKDOWN OF CARBOHYDRATES
  • Softens and moistens food during chewing which PREVENTS ABRASIONS inside the mouth
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13
Q

Mouth: tongue

A
  • Helps MANIPULATE the food while chewing into a ball called a bolus
  • PUSHES BOLUS into the pharynx
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14
Q

Pharynx aka Throat (leads to what?, function, essential structure)

A
  • Leads to esophagus and trachea
  • Voluntarily contracting muscles to PUSH FOOD into esophagus
  • Trachea moves up so that entrance is sealed off by epiglottis to prevent food from entering trachea (or else you will die)
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15
Q

Esophagus: general function, length

A
  • Approx 25 cm long and 2 cm wide

- Conducts food from pharynx to the stomach

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16
Q

Esophagus: Mucosa (structure and function)

A
  • Inner layer
  • Contains glands supported by connective tissue
  • SECRETES MUCOUS without enzymes which help transport the food
  • Connective tissue HOLDS ORGANS IN PLACE
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17
Q

Esophagus: Submucosa (structure)

A

Contains blood vessels, nerves, and connective tissue

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18
Q

Esophagus: Muscularis (structure and function)

A
  • Contains circular (inner) and longitudinal (outer) muscles which works against gravity to PERFORM PERISTALSIS
  • Upper ⅓ has straited muscle (voluntary) so if you are sick, you will vomit
  • Lower ⅔ has smooth muscle (involuntary)
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19
Q

Peristalsis: def

A

wave-like muscular contraction which pushes bolus from upper to lower end of esophagus OR chyme through intestines

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20
Q

Stomach: (volume of food, time to empty, new name of food, backflow, functions)

A
  • Holds 1.5 L of food
  • Takes about 2-6 hours after a meal for the stomach to empty
  • When the food leaves the stomach, it is referred to as chyme which is a semi-liquid, partially digested meal
  • If backflow occurs into the esophagus, heartburn will occur
  • In general, the stomach functions to STORE FOOD and PERFORM mechanical and chemical digestion
21
Q

Stomach: 4 layers

A
  1. Longitudinal muscle (outermost layer)
  2. Circular muscle
  3. Oblique muscle
  4. Rugae (innermost wall)
    - Accordian like folds, elastic
    - Allow stomach to EXPAND and CONTRACT
    - Contain gastric pits which consist of gastric glands which produce gastric juice
22
Q

Stomach: gastric juice (pH, volume, components and their function)

A
  • pH of 2
  • 3L of gastric juice is secreted each day which contain;
  1. Hydrochloric acid
    - Chemically BREAKS down food particles
    - ACTIVATES enzymes
    - KILLS bacteria in food
  2. Pepsinogen
    - Gets converted into pepsin which DIGESTS PROTEIN
  3. Mucous
    - Lines stomach and PROTECTS it from HCl
  4. Rennin
    - SLOWS down fat so it can be digested
23
Q

Stomach: sphincters (name, structure, function, closed or nah)

A
  1. Cardiac Sphincter
    - Ring of muscle around top of stomach
    - Opens with every wave of peristalsis to ALLOW BOLUS OF FOOD to enter the stomach
    - Mostly closed
  2. Pyloric Sphincter
    - Ring of muscle around bottom of stomach
    - Helps REGULATE PASSAGE of chyme into duodenum of small intestine
    - Mostly closed
24
Q

Small Intestine: length + why

A
  • Largest component of digestive tract (6m long)

- To ensure all NUTRIENTS ARE ABSORBED to get the most energy because energy is scarce!

25
Q

Small Intestine: general functions

A
  1. Finishes digestion by breaking food into its simplest form
    - Proteins into amino acids
    - Carbohydrates into monosaccharides
    - Fats or lipids into 1 glycerol, 3 fatty acids
  2. Absorbs products of digestion into body
    - 80% of absorption occurs here, the other 20% occurs in stomach and large intestine
26
Q

Small Intestine: what happens after food passes through absorptive cells?

A
  • Water soluble nutrients (proteins, carbs) flow into blood capillaries of the villi to transport to liver to process and then to all body’s cells
  • Fatty products of digestion (fat) are absorbed into lacteal which are tiny lymphatic vesicles in the villi that connect to hlymphatic system
27
Q

Small Intestine: regions

A

Region #1: Duodenum

  • 25 cm long
  • First part

Region #2: Jejunum

  • 2.5 m long
  • Middle part

Region #3: Illeum

  • 3.5 m long
  • Last part
28
Q

Small Intestine: layer 1

A

Serosa/Mesentery

  • Outermost layer
  • Sheet of connective tissue
  • PREVENTS TANGLING of small intestine
29
Q

Small Intestine: layer 2

A

Circular Muscle

- For PERISTALSIS

30
Q

Small Intestine: layer 3

A

Longitudinal Muscle

- For PERISTALSIS

31
Q

Small Intestine: layer 4

A

Inner Mucosa Layer

  • Consists of many folds that consists of many villi: finger-like projections which face the lumen (space inside) of the small intestine
  • Increases surface area to ABSORBS MORE NUTRIENTS for energy because energy is scarce
  • Epithelium (absorptive cells) line the surface of the villi
  • Each absorptive cell contains many microvilli
  • ALWAYS IN CONTACT WITH FOOD
32
Q

Pancreas: location + function

A
  • Right beside duodenum of small intestine

- Secretes pancreatic juice containing digestive enzymes into duodenum of the small intestine

33
Q

Pancreas: pancreatic juice

A
  • Basic/alkaline to NEUTRALIZE chyme as it enters duodenum
  • Digestive enzymes include tripsinogen and pepsinogen (digest protein into amino acids), amylases (digest carbohydrates into monosaccarides), and lipases (digest lipids into 1 glycerol and 3 fatty acids)
34
Q

Liver: function, def of juice it excretes, def of process

A
  • Secretes bile

Bile: doesn’t contain digestive enzymes but contains bile salts which emulsifies fat

Emulsification: process in which large droplets of fat are broken into tiny droplets by a physical reaction TO SPEED UP FAT ABSORPTION

35
Q

Gall Bladder: structure + function

A
  • Bag

- Stores bile until needed

36
Q

Large Intestine aka colon: length, general functions

A
  • Approx 1.5m long
  • COMPLETES RE-ABSORPTION OF WATER
  • 90% of water is reabsorbed by the intestines which causes feces to become solid
    Water is also scarce
  • FORMS CERTAIN VITAMINS
  • Colon contains large flora of bacteria which feed off organic matter of feces, producing vitamins (vitamin K) and gases (methane)
  • COMPLETES NUTRIENT ABSORPTION
  • Salts and some vitamins are reabsorbed in the colon
  • ELIMINATION OF FECES
37
Q

Large Intestine aka colon: 7 structures

A

Caecum
- Chamber in which chyme passes from small into large intestine

Ascending Colon
- Goes up the right side of abdominal cavity

Transverse Colon
- Goes across the middle of the abdomen

Descending Colon
- Goes down the left side of the abdominal cavity

Sigmoid Colon
- Leads descending portion of the colon to the rectum

Rectum
- Stores feces until it can be egested

Anus
- Actual site of elimination

38
Q

Feces at rectum composition

A
  • Feces is 25% water and 75% solid at this point
  • The solid part consists of 30% bacteria, 30% undigested roughage (fiber) which acts like scrapper for colon, 20% fats, and 15% inorganic matter
39
Q

Esophageal Sphincter (function & structure)

A
  • Ring of muscle
  • Entrance to stomach
  • PREVENTS ACIDIC CONTENTS of stomach from backing up into esophagus; relaxes to allow bolus of food to enter stomach
40
Q

System

A
  • Smell/sight of food triggers salivary glands to secrete saliva that contains amylase to break down water-soluble particles
  • Teeth performs mechanical digestion which makes it easier to swallow and exposes more surface area of food to saliva
  • Tongue molds food into a bolus and when swallowed, enters esophagus to begin passage to stomach via peristalsis
  • Food enters stomach via esophageal sphincter and undergoes chemical and mechanical digestion that forms chyme
  • Stomach nerves will release partially digested food into small intestine when small intestine is empty
  • Food is pushed via peristalsis into duodenum
  • Duodenum receives secretions from the pancreas and the gall bladder which help break down food
  • Jejunum breaks down remaining proteins and carbohydrates
  • Illeum finishing absorbing nutrients and pushes remaining undigested material into large intestine
  • Large intestine reabsorbs water
  • Bacteria in colon break down undigested matter further
  • Leftover solid waste is egested
41
Q

Macromolecule: def

A

A very large molecule made up of smaller molecules linked together; nutrients that our bodies need to provide energy, regulate cellular activites, and to build tissues

42
Q

Carbohydrates: function & types

A

Provide quick energy for use by cells

  1. Monosaacharides
    - Molecules with 3-7 C atoms (2 atoms of H and 1 atom of O for each atom of C)
    - Eg. glucose, fructose
  2. Disaacharides
    - Made up of 2 monosaacharides
    - Eg. sucrose, maltose, lactose
  3. Polysaccharides
    - Made up of many monosaacharides
    - Eg. starch, cellulose, glycogen
43
Q

Carbohydrates: digestion

A

MOUTH (polysaacharides → “salivary amylase” → disaccharides)

SMALL INTESTINE (polysaacharides & disaccharides → “carbohydrases” → monosaccharides)

44
Q

Lipids: function & structure

A

Stores energy reserves for later use, cushions internal organs

  • Insoluble in water
  • 1 molecule of glycerol (3 C atoms) attached to fatty acid chain (lots of C and H)
45
Q

Lipids: digestion

A

SMALL INTESTINE (fat droplets → “bile” → emulsified fat droplets → “lipases” → 1 glycerol & 3 fatty acids)

46
Q

Proteins: function & structure

A
  • Aids in muscle movements, speed up chemical reactions, provide immunity, transport ions, provide support for cells
  • Made from amino acids which join by peptide bonds into chains called polypeptides
47
Q

Proteins: digestion

A

STOMACH (proteins → “pepsin” → small polypeptides)

SMALL INTESTINE (smaller peptides → “proteases” → peptides → “peptidases” → amino acids)

48
Q

Nucleic Acid: types

A
  • Ribonucleic Acid

- Deoxyribonucleic Acid

49
Q

Nucleic Acid: digestion

A

SMALL INTESTINE (DNA & RNA → “nucleases” → nucleotides → “nucleosidases” → sugars, phoshates)

XBiology (9 decks)

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