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Physiology 214 > The digestive system- 1 > Flashcards

The digestive system- 1 Flashcards

1
Q

How does the digestive system contribute to homeostasis?

A

It transfers nutrients, water, electrolytes from external to internal environment. (This is also the function of the digestive system)

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2
Q

True or False:
The digestive system directly regulates concentration of internal constituents.

A

FALSE

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3
Q

Does the digestive system change water, nutrients or electrolyte uptake?

A

No

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4
Q

The digestive system optimizes conditions for:

A

Digestion and absorption

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5
Q

label

A
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6
Q

GI system = ?

A

Gastrointestinal system (digestive system)

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7
Q

What role does food play?

A
  1. Used by cells to generate ATP
  2. Source of building material for renewal and addition of body tissues
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8
Q

is eaten food ready to be used by cells?

A

NO,

  1. Food must be digested (broken down) into simple molecules.
  2. SImple molecules must then be absorbed from GIT
  3. Then distributed via circulation to cells.
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9
Q

What are the 4 main digestive processes?

A
  1. Motility (movement)
  2. Secretion (release)
  3. Digestion (breakdown)
  4. Absorption (uptake)
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10
Q

Name and describe the two types of basic motility

A

1. Propulsive movements:
-Propel/push contents forward through the digestive tract
-Rate of propulsion differs from one region to another
(esophagus vs small intestine)

2. Mixing movements:

  • Mix food
  • Facilitate absorption
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11
Q

What causes motility? are there any exceptions?

A

Smooth muscles, and yes…

Exceptions: Ends of GI tract- mouth and anus -Motility is caused by skeletal muscle

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12
Q

Why is the mouth and the anus (motility) controlled by skeletal muscle?

A

For voluntary and involuntary reflexes

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13
Q

Part of the respiratory passageway is located between the trachea and the pharynx. It keeps the airway open, prevents food from entering the airway, and produces sounds

A

The larynx

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14
Q

Visceral smooth muscle; contracts as a unit, electrically coupled, often has spontaneous action potentials.

A

unitary smooth muscle

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15
Q

Characteristic of smooth muscle to adapt to increased length and relaxation; stress-relaxation response

A

Plasticity

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16
Q

Explain the motility in the mouth

A
  1. The mouth receives food into the GI tract.
  2. Chewing tears and grinds food, reducing lumps to a size that can be swallowed.- also mixes ingested food with saliva, moistening it enough to be easily swallowed.

Summary:

Type- chewing

Function-

Mechanical breakdown of food particles

Mixing food with saliva

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17
Q

Chewing is part voluntary and involuntary…what sets the pattern and rhythm of chewing?

A

The cortex and brain stem centers

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18
Q

True or false:

The esophagus serves a digestive or absorptive function.

A

False, it is simply a conduit between the pharynx and stomach

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19
Q

What is the motility in the esophagus?

A

Peristalsis- a progressive wave of muscle contractions

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20
Q

What initiates primary peristalsis?

A

Swallowing

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21
Q

describe the motility of the esophagus

A
  1. Tongue separates a bolus
  2. Soft palate closes the nasopharynx
  3. The larynx rises and the glottis closes- to cover the trachea
  4. epiglottis falls to cover the closed glottis.
  5. Pharyngeal muscles contract and upper esophageal sphincters relax.
  6. Bolus enters the esophagus, and lower esophageal sphincters (LES) and stomach relax.
  7. Bolus moves toward the stomach
  8. Respiratory passages open ( everything reverts to normal)
  9. Bolus enters the stomach and LES closes-prevents regurgitation
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22
Q

what causes the variations of the force of peristaltic contractions?

A

the size of the bolus

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23
Q

stimuli from what is delayed to the CNS to modify the pressure generated by the esophageal muscles?

A

from the distention of the esophagus wall

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24
Q

What happens if a bolus of food doesn’t progress all the way to the stomach?

A

Secondary peristalsis

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25
Q

describe what happens during secondary peristalsis:

A
  1. The esophagus is distended
  2. Afferent signals are relayed to the CNS
  3. This leads to the second wave of peristaltic contractions.
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26
Q

Summarise what the motility is of the esophagus ( what it is and function)

A

-Primary and secondary peristalsis

Function=propel a bolus of food to the stomach

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27
Q

Name 3 functions of the stomach:

A
  1. It stores food
  2. Mixes food with gastric juice for digestion
  3. Empties chyme into duodenum
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28
Q

What allows for different movements (which serve each function) of the stomach?

A

The muscular structures of the stomach wall.

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29
Q

what happens in the stomach during a swallow?

A
  1. Receptive relaxation occurs in the fundus and body of the stomach.
  2. Relaxation occurs with each swallow and permits the stomach to accommodate a volume of at least 1L with little increase in pressure.
  3. Peristaltic contractions mix stomach contents and empty chyme into the duodenum.
  4. The frequency of gastric peristaltic contractions is 3-5/min
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30
Q

Peristaltic waves begin ____________, ripple over the body and become _______ over the muscular _________ and _______

A

Midstomach

Stronger

antrum and pylorus

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31
Q

What do antral contractions do?

A

They force chyme toward the duodenum and pulverize small lumps

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32
Q

Explain how food and gastric juice is mixed:

A
  1. Antral contractions squirts a small amount of chyme through the constantly contracted pyloric sphincter with each powerful antral contraction.
  2. As the contraction progresses, it closes the sphincter completely and most of the chyme is forced back into the stomach.
  3. This retropulsion mixes the food and gastric juice.
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33
Q

Why does the volume and contents of the stomach regulate the strength of contractions?

A

Because the frequency of peristaltic contractions are constant

-The greater the volume, the more rapidly the contents are emptied.

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34
Q

What are the functions of the duodenum?

A
  1. Regulates gastric emptying
  2. regulates fat, acid, and hypertonic solutions in the duodenum
  3. duodenal distention and slow gastric emptying
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35
Q

summarise the motility of the stomach:

A

Motility:

  1. Receptive relaxation
  2. Peristalsis

Functions:

  1. Relaxation- accommodates meals
  2. Peristalsis mixes and empties stomach content
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36
Q

What are the two types of secretion the digestive system produces?

A

exocrine and endocrine secretions

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37
Q

Specialized cells found in lining of GIT and accessory organs (pancreas)

release digestive juices when stimulated (neural or hormonal)

A

Exocrine glands

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38
Q

What are the digestive juices?

A
  1. Water
  2. Electrolytes

3. Enzymes

4. Mucus

5. Bile salts

-→ organ specific

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39
Q

What excretes enzymes

A

Exocrine glands

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40
Q

What excretes hormones

A

Endocrine glands

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41
Q

Describe exocrine glands

A
  1. Larger component
  2. Secretes 1.5-2L/day, rich in digestive enzymes
  3. Has alkaline pH due to its content of NaHCO3
  4. Produced by pancreatic acinar cells
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42
Q

Describe endocrine glands

A
  1. Smaller component
  2. COnsists of islets of Langerhans-4 cell types
  3. Secretes 4 hormones
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43
Q

what 4 hormones do endocrine glands release?

A

Insulin

Glucagon

Pancreatic polypeptide

somatostatin

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44
Q

What are the 3 categories of energy-rich food?

A

Carbs

Proteins

Lipids

-Digestion is needed to break food down (from macromolecules)

45
Q

What is the ratio of C:H:O in carbohydrates

A

1:2:1

46
Q

How are most carbs classified as?

A

Mono-, di-, or poly-saccharide

47
Q

Saccharide =?

A

Sugar

48
Q

What are the building blocks (monomers) of all carbohydrates?

A

Monosaccharides

49
Q

What are the three monosaccharides of carbohydrates?

A

Gluces

Fructose

Galactose

50
Q

Which monosaccharide is the most abundant and what are some of its properties?

A

Glucose

  • it is water soluble
  • Easily transported through an organsm
  • Energy source for cellular resp.

[Energy source for cells]

-

51
Q

what is the main monosaccharide found in sugar of fruits?

A

Fructose

52
Q

Galactose

A

Primary monosaccharide found in milk

53
Q

What is the general monosaccharide formula?

A

C6H12O6

54
Q

How are disaccarides forme?

A

When 2 monosaccharides are joined together via dehydration

-Forming glycosidic linkages

55
Q

What are the three disaccharides?

A

Maltose

sucrose

lactose

56
Q

Glucose + Glucose

A

Maltose= Malt sugar

57
Q

Glucose + Fructose

A

Sucrose

=Table sugar

58
Q

Glucose + Galactose

A

Lactose

=milk sugar

59
Q

How are polysaccharides formed?

A

When glucose monomers link together to form long chains

60
Q

What are polysaccharides ideal for?

A

Storing energy

61
Q

Energy storage in plants

A

Amylose- straight chain

Amylopectin-Branched

62
Q

Animal energy storage

A

Glycogen-highly branched chain

63
Q

why is glycogen so branched?

A

To enable it to be broken down quickly to supply cells/tissue with energy

64
Q

Polysaccharides which act as structural molecules?

A

Cellulose

chitin

peptidoglycan

65
Q

Most abundant polysaccharide?

A

Cellulose

  • straight chain
  • found in cell walls of plants → adds strength
  • it is a polymer of glucose, but it differs in configuration due to the bonds between each glucose unit.
  • Most organisms cant break cellulose down, and thus, can’t use it as an energy source
66
Q

Polysaccharide which forms exoskeleton of insects and crustaceans?

A

Chitin

-Unique properties is due to chitin having amino groups attatched to its sugar monomers

67
Q

complex polysaccharides found in cell walls of bacteria

A

Peptidoglycan

  • Flexible and rugged due to its structure
  • each monomer has a peptide chain attatched to it
68
Q

Carbohydrates can be refered to as….

A

Simple sugars or complex carbohydrates

69
Q

Monosaccharides and disaccharides?

A

Simple sugars

70
Q

Polysaccharides

A

Complex carbohydrates

71
Q

Amino acid structure

A
  1. Carboxyl group [O=C-OH]
  2. Amino group [N-H2]
72
Q

What makes amino acids unique?

A

R group-gives amino acids properties

73
Q

Order of amino acids in polypeptide chain

A

Primary structure

74
Q

Pleated sheet/ helix- due to H bonding or other chemical reactions between the R groups or other chemical reactions of nearby amino acids

A

secondary protein structure

75
Q

The overall shape of a polypeptide

A

Tertiary structure

  • Secondary structure folds and twists upon itself
  • then referred to as proteins
76
Q

Interaction of multiple proteins= large protein complexes?

A

Quaternary structure

77
Q

Hemoglobin and sodium channels in the cell membrane

A

Quaternary structure protein

78
Q

Hydrophilic biomolecules

A

lipids

79
Q

long term energy storage

A

The primary function of lipids

80
Q

Hormone precursors, key component of cell membranes, protection, insulation, and lubrication

A

Other functions of lipids

81
Q

4 basic groups of lipids

A
  • Triglycerides
  • phospholipids
  • Steroids
  • waxes
82
Q

What do all lipids have in common

A

All insoluble in water

83
Q

Fats-solid at room temp, used by animals.

Oils-Liquid at room temp, used by plants for long term energy storage.

A

triglycerides

84
Q

Subunits of triglycerides

A

Glycerol and 3 fatty acids

85
Q

3 parts of fatty acid

A

Acid group (OH)

Hydrocarbon chain

Methyl group (C-H3)

86
Q

Single C-C fatty acid

A

Saturated fatty acid

87
Q

Double bonds result in what

A

Kinks in the fatty acid chain affects melting point of fat

88
Q

animal fats

A

saturated fatty acids

89
Q

Veg oils

A

unsatturated

90
Q

Trans fatty acid

A

when H bonds are on opposite sides of double bond

91
Q

How do triglycerides form?

A

Through dehydration sysnthesis

92
Q
  • Glycerol and 2 fatty acids
  • Phosphate group attached to 3rd carbon of glycerol
A

Phospholipids

93
Q

4 fused rings of carbon- to which different functional groups are attached

A

Steroids

94
Q

Precursor for the synthesis of other steroids:

Such as testosterone, estrogen, vit D, cortisone

A

Cholesterol

95
Q

stabilizes plasma membrane

A

Cholesterol

96
Q

difference between estrogen and testosterone

A

Testosterone has =O

Estrogen has -H

97
Q

Nonpolar fats and repel water, are found in the outer coating on leaves and outer surfaces of animals.

A

Waxes

98
Q

Occurs in the small intestine- in the ileum

A

Digestion

99
Q

Digestion is incomplete

A

False

100
Q

Where are digested substances transferred to?

A

From GIT to blood or lymph

101
Q

finger-like projections found on the inner wall of the ileum

A

villi

102
Q

Lymph vessel found in the middle of villi which is surrounded by a network of capillaries

A

Lacteal

103
Q

water-soluble vitamins and minerals are absorbed where? and how?

A

through the walls of the villi, by diffusion and active transport

104
Q

How is water drawn into the blood during digestion?

A

The absorption of digested food into the blood increases the water potential of the content in the ileum, water is drawn into the blood by osmosis.

105
Q

Enter the epithelium of the villus by diffusion

A

Glycerol and fatty acid

106
Q

what happens after glycerol and fatty acid are diffused into the epithelium of the villi?

A

They recombine into fine lipid droplets, which then enter the lymph in the lacteal

107
Q

Lipid soluble vitamins are also absorbed into the lacteal

A

Vitamins A and D

108
Q

What happens after everything has been absorbed by the villi?

A

Everything is transported to the main lymph vessels and then to the blood stream

Physiology 214 (26 decks)

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