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Human Anatomy > Digestion Lecture Notes > Flashcards

Digestion Lecture Notes Flashcards

1
Q

Why do we need food?

A

To get organic molecules to the cells so they can be fed into the metabolic pathways for energy to create ATP
Replace body components: Lost in urine, metabolic breakdown, etc.
Grow new tissue
Gain energy sources

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2
Q

Ingestion

A

Take something into your digestive system

Food into your GI tract

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3
Q

Mastication

A 
Chewing of the food in your mouth
Physical breakdown;
Doesn't break the bonds between the atoms
Makes big clumps into smaller clumps
Increases the surface area of the food
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4
Q

Digestion

A

Chemical breakdown
Need to break chemical bonds so you go through a complicated polypeptide protein to small fragments, or individual amino acids

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5
Q

Absorption

A

Uptake of small molecules by cells

Uptake process

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6
Q

Egestion

A

Eliminate the non-absorbable material
There is stuff you take in that you cannot absorb
Defecation or vomiting

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7
Q

Internal Nares

A

Opening of Pharynx

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8
Q

Epiglottis

A

Flap above Glottis

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9
Q

Sphincters

A

Bands of muscles that remain contracted

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10
Q

Hypopharyngeal Sphincter

A

Lies at the Esophagus

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11
Q

Do the sphincters remain opened or closed typically?

A

The sphincters remain closed unless there is food entering

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12
Q

What happens during the swallowing reflex?

A

As the food is swallowed, the larynx moves upwards, sphincters are relaxed

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13
Q

Peristalsis

A

Food moves down the esophagus via peristalsis action

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14
Q

Why produce saliva?

A

Produce saliva to give you watery fluid in order for chemical reactions to take place
Salivary glands produce water, and the digestive enzyme Amylase

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15
Q

Amylase

A

Breaks down amylose (plant starch)

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16
Q

Where does digestion begin?

A

Digestion begins in the mouth

Start carb digestion in the mouth and finish carb digestion in the small intestine

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17
Q

Chyme

A

The material that is working down the GI tract
When chyme enters the stomach, it is extremely acidic
The gastroesophegeal sphincter makes sure the acidic chyme cannot make its way back up into the GI tract

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18
Q

Heartburn

A

Movement of acid chyme upstream to esophagus and the gastroesophageal sphincter has failed doing its job

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19
Q

Epimere

A

Segmented throughout the GI tract

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20
Q

Mesomere

A

Forms kidneys and gonads

Segmented throughout the tract

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21
Q

Hypomere

A

Not segmented
Broad sheets
Dorsal and ventral mesentary
Outermost sheet known as parietal peritoneum
Inner sheet that surrounds gut tube = visceral peritoneium

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22
Q

Mesentaries

A

Connect to body wall

The place where two serous membranes come together and attach to body wall

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23
Q

Stomach

A 
Organ of storage
Layers of smooth muscles
Circular band of muscles
Top = esophagus
Cardiac region = top of stomach
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24
Q

Chief cells

A

Secrete pepsinogen

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25
Q

Pepsinogen

A

An inactive digestive enzyme that is converted into pepsin (active enzyme) in the presence of high acid produced by parietal cells
Pepsin is a protease that breaks down proteins into protein fragments at specific peptide sites

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26
Q

Protease

A

Each one, catalyzes the cleavage of different amino acids
Each breaks down a different pair of an amino acid
Need a variety because there are a variety of peptide bonds

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27
Q

Zymogen

A

Inactive protease

Inactive forms are made so we do not eat ourselves

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28
Q

Pepsinogen

A

Inactive form of pepsin
Cells secrete pepsinogen which is then activated and becomes pepsin
It wants to be activated when it comes into contact with food

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29
Q

Parietal cells

A

Secrete HCl

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30
Q

Effects of HCL

A

HCL denatures proteins (unravels it so the amino acids are exposed);
If you eat a meal with a lot of protein, your pH can become very low due to HCl secretions
HCl activates pepsin;
Pepsinogen is converted into pepsin in the presence of HCl;
Its shape becomes active when in an active solution
Needs to be in contact with acid chyme
Kills many varieties of bacteria
The acidity from HCl will erode away the living cells that should not be destroyed

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31
Q

Globlet Cells

A

Secrete mucus

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32
Q

Mucus

A

Alkaline neutralizes the HCL
Coats the epithelial cells of the stomach to help protect them from HCL
Epithelial cells are replaced every 4 days

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33
Q

Gastric Ulcer

A

An erosion of the lining of the stomach
The stomach was eaten away by the chyme
Caused by an acid loving bacteria

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34
Q

Heliobacter Pylori

A

Can burrow underneath the mucus lining and they secrete toxins that will help erode the mucus lining allowing the chyme to get to the soft tissue and cause the ulcer

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35
Q

3 Regions of Small Intestine

A

Duodenum
Jejunum
Illium

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36
Q

Duodenum

A

Can’t be covered with mucus to protect it, because you need the lining for absorbtion
Neutralize chyme by adding HCO3-

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37
Q

Pancreas

A

Located on top of duodenum and secretes pancreatic juice
Pancreatic Juice produces: Bicarbonate ions, many digestive enzymes (most inactive form)
Pancreatic juice is added to chyme in the beginning of the duodenum; this avoids a duodenum ulcer and changes to pH

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38
Q

Segmentation of Small Intestine

A

Irregular contraction
Mixing the chyme
The rate of segmentation changes as you move through the regions of the small intestine

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39
Q

Surface area of small intestine

A

Huge surface area needed for membrane transport in absorbtion

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40
Q

Absorption in the Small Intestine

A

To Increase surface area:
Long tube, small intestine makes up most of the GI tract
Villi, finger-like projections; water soluble solutes enter blood in the capillaries; lipids enter lymphatic system via lacteals
Microvilli: extensions of the cell membrane, form brush border, greatly increase surface area to enhance rate of absorption

41
Q

Large Intestine

A

Has bacteria living there
Bacteria lives on the material that you do not digest
The bacteria in your large intestine receive fragment of plant cell walls and other things that you can’t digest
Bacteria in large intestine can produce the enzyme cellulase

42
Q

Cellulose

A

Most common carbohydrates
Animals can’t break down cellulose because we can’t produce it
Comes from plants; Cell wall that surrounds cytoplasm of the plant cell (inside, after cell wall, it digestible):
Digestive enzymes can’t break down cellulose to get to the inside –> we can physically break it down by chewing

43
Q

Do harmful bacteria live in large intestine?

A

It is very difficult for harmful bacteria to live in large intestine because there is already naturally occurring bacteria living there
If you have a bacterial infection and are taking antibiotics, it can effect the bacterial population in your intestines

44
Q

Cecum

A

Storage chamber for bacteria at the start of the large intestine
Found in other animals
Not in dogs because they don’t eat plants

45
Q

Appendix

A

Cecum
This is why we can remove it and be fine
Filled with lymphoid material
May be a site of vitamin B production

46
Q

Liver

A

Purpose: Metabolic Intraconversions

Has 1 digestive impact; regulates glucose levels, metabolic regulation (non digestive functions)

47
Q

Glycogenesis

A

Implies “creation” [creation of glycogen from glucose]
Creates glycogen (polymer of glucose molecules)
How we store our carbohydrates

48
Q

Glycogenolysis

A

Production of glucose by catabolizing glycogen

Liver will take stored glycogen and make glucose molecules to enter the blood for use

49
Q

Gluconeuogenesis

A

Conversion of non-carbohydrates into glucose

50
Q

Lipogenesis

A

Forms triglycerides for storage

51
Q

Purpose of Liver in digestion

A

Creates bile

52
Q

How does blood go to the liver

A 
Standard artery (oxygenated blood)
Hepatic vein (deoxygenated blood)
53
Q

Hepatic-sites

A

Liver Cells

54
Q

Bile contains

A

Bile salts

Bilirubin

55
Q

Bile Salts

A

Job is to emulsify lipids

56
Q

Emulsification

A

No bonds are broken

Breaks big clumps into little clumps, nothing is digested

57
Q

Digestion

A

Breaking bonds to make big molecules into smaller molecules

58
Q

Bilirubin

A

Break down product of heme (from hemoglobin)
The hold heme is converted to bilirubin which is dumped into bile
Travels to the duodenum, where it is screened and passed through
Bacteria makes bilirubin convert into urobilinoen

59
Q

How does bilirubin convert into urobilinoen

A

This is done by bacteria in the large intestine

Either passes out with the feces or is digested along the walls of the large intestine and leaves with the urine

60
Q

What is another function of the liver

A

Detoxifies things; ex: alcohol, hormones

Where ammonia is converted into urea

61
Q

Pancreatic Juice

A

Contains Bicarbonate ions
Inactive digestive enzymes
Neutralizes the pH and allows all the other digestive enzymes to work fine; HCL & digestive enzymes made from the small intestine

62
Q

The Pancreas secretes

A

Protease
Lipases
Nucleases
Amylases

63
Q

Starch Digestion

A

Start: Amylase in the saliva
Stops once it gets to the stomach because it is too acidic
Continues in the pancreas where amylase is secreted
Amylose (starch) is a disaccharide = fragments
The fragments must be broken down into smaller things
Monosaccharides are made and they can now be absorbed

64
Q

Absorption of Glucose

A

Enters via active transport

65
Q

Absorption of Galactose

A

Enters via active transport

66
Q

Absorption of Fructose

A

Enters via facilitated diffusion

67
Q

Intrinsic Control of Gastric Function

A

Contraction of smooth muscles

a. Via pacemaker action
b. Stretching will increase contractions
c. If you eat a meal, and distend your stomach (stretch muscle cells) it will contract more rapidly

68
Q

Extrinsic Control of Gastric Function

A

Controlled by the brain= Cephalic Phase
Autonomic NS at work
a. Parasympathetic NS at work
i. Vagus Nerve
b. Increase blood flow to the stomach
You smell food cooking –> begin salivating and stomach starts secreting
Increase blood flow to stomach by dilating arterioles

69
Q

Gastric Phase

A 
When food enters the stomach
Protein fragments cause
1. G cells to create gastrin
2. Parietal cells to create HCL
3. Chief cells to create pepsinogen
70
Q

Positive Feedback in Gastric

A
  1. The more pepsinogen you secrete, the more fragments you get, the more digestion occurs, etc.
  2. More fragments→more gastrin→more secretion→more fragments (it’s a loop)
71
Q

Gastrin

A

Isn’t secreted in the lumen
Is secreted by G cells into the blood
Is a hormone that circulates throughout your body
Target for gastrin are the chief cells and parietal cells for the stomach
Acts on the stomach to increase the secretion of HCL and pepsinogen
a. Very potent at doing this
b. Is driving this secretion
Gastrin is inhibited by low pH (acid)
Intact proteins buffer pH of chyme

72
Q

Intestinal Phase

A

Neural reflex to inhibit gastric secretion and emptying
Gastric Inhibitory Protein (GIP)
a. Inhibits gastric secretion and emptying of the stomach

73
Q

What turns on the secretion of GIP and natural reflex?

A
  1. Both occur when there is an increase in osmotic concentration of chyme in the duodenum
  2. Stretching of duodenum
  3. Presence of fat in the duodenum
    a. There are sensors in the duodenum that are triggered when there is a high fat content; This means that you are not done digesting
74
Q

Gastric Inhibitory Peptide

A

Secreted from the duodenum

Stimulated by stretching, high fat, high osmotic concentration

75
Q

CCK

A

Cholestokin
Lipids in duodenum causes CCK to be produced
Acts on pancreas to produce digestive enzymes

76
Q

Secretin

A

Stimulated by low pH and stretching
When the duodenum experiences low pH (when it gets acidic chyme) it causes it to secrete secretin
Acts on the pancreas to stimulate HCO3-

77
Q

Secretin and CCK

A

Nervous input from stretching
Act on the liver to produce bile
Nervous input feeds back to the gall bladder, causing it to contract

78
Q

Does the pancreas secrete hormones?

A

Yes, the pancreas also secretes hormones
The pancreas is both an exocrine and endocrine organ because it has its own hormones to secrete as well as others
Exocrine: organ/tissue
i. Secretes via a duct to a specific location
Endocrine:
i. Insulin
ii. Glucagon

79
Q

Can we make essential amino acids?

A

No

We get them from animals

80
Q

What do Glucagon and Insulin regulate?

A

Regulate the circulating levels of glucose and amino acids in the body
After a meal, increase glucagon and insulin levels
If fasting, decrease levels
Need to maintain levels during fasting
a. Want to make glucose, and dump it into the blood
b. Can make it by breaking down glycogen storage and through glucogenesis (making glucose out of other things)

81
Q

Glucagon

A

From alpha cells in the pacreas (in the islets of Langerhaus)

82
Q

Insulin

A

From beta cells in the pancreas (in the islets of Langerhans)

83
Q

Somatostatin

A

From delta cells in the pancreas

Hormone which acts on your brain and inhibits growth hormone

84
Q

After a carbohydrate meal

A

Glucose concentrations rise
This causes insulin to be secreted and the inhibition of glucagon
a. Insulin is responsible for the uptake of glucose by the metabolizing cells
b. This reduces high blood glucose levels because cells are taking it away (ex: nervous tissue uses glucose for fuel, muscle cells turn it into glycogen to store it, the liver stores glycogen as well, fat cells use it to make triglycerides)
Glucagon causes the break down of glycogen into glucose (dumped into the blood from the liver)
a. This is why glucagon is inhibited

85
Q

After a protein meal

A

If you just eat protein, you will produce insulin in response to the amino acids;
Insulin causes the uptake of amino acids and glucose (even though you did not have any glucose in your meal)
Uptake of glucose will cause a decrease in blood glucose levels
a. This is why glucagon has to be secreted because there is an initial drop in glucose

86
Q

Glucose levels

A

After a meal: Glucose levels rise
up to about 170 mg%
During fasting: Glucose falls down to 50 mg%
Too high of glucose levels can damage the cells

87
Q

Diabetes mellitus

A

Too high glucose concentration in the blood

88
Q

Why would you have too high glucose concentration in the blood or diabetes mellitus?

A

Don’t produce enough insulin
a. Insulin causes glucose to be taken up into metabolizing cells
Make insulin, but target cells do not respond
a. Target cells may not have the receptors

89
Q

Type 1 diabetes

A

Beta cells do not produce enough insulin
Beta cells are destroyed by the immune system or virus invaded beta cells on the pancreas
Usually occurs in childhood
Only way to get by: need regular insulin injections

90
Q

Type 2 diabetes

A

Later onset, develops with age
May be genetic predisposition
It is much more prevalent in inactive, overweight people
Can be prevented by losing weight and exercising

91
Q

Triglyceride

A

Glycerol + Fatty Acids

With big carb meals, your liver and adipose tissues will convert glucose to triglycerides causing you to gain weight

92
Q

Glucose Sparing

A

Occurs during a fast
Glucagon rises as insulin falls
Glucagon causes glycogen in the liver to be broken down into glucose to enter the blood and fuel the nervous system
During a fast:
1. Initially lose fat, then you lose muscle mass
During a fast, decrease glucose concentration in blood
1. Glucagon is secreted
Acts on the liver in two ways:
i. Glycogen is converted into glucose
ii. Fatty acids are converted into ketones
Acts on adipose tissue
i. Lipolysis
1. Glycerol
2. Fatty acids

93
Q

Glucose is fuel for

A

The Nervous System

94
Q

Ketones and Fatty Acids are fuel for

A

Other tissues

95
Q

Epinephrine

A 
From Adrenal Medulla
Effects were similar to glucagon:
1. Lipolysis produced
2. Gluconeogenesis produced
3. Increased substrates in the blood to fuel the stress (the fast)
96
Q

Glucocorticoids

A

From Adrenal Cortex
Hormones cortisol, corticosterone, etc.
They stimulate the cells to promote lipolysis and ketogenesis
Stimulate liver to make enzymes for gluconeogenesis
Stimulate skeletal muscles to break down proteins into amino acids

97
Q

Thyroxine

A

From Thyroid gland is secreted
Secreted in inactive form and then converted into active form
Increases cellular metabolism
Causes ion pumping by the cells
Stimulates Na+/K+ pumps (BMR increases_; need to make more ATP to maintain
Acts on DNA to increase protein synthesis
Mental retardation is linked to low levels of thyroxine

98
Q

Hyperthyroidism

A

You produce too much thyroxine

99
Q

Somatotrophin

A

Growth hormone
Stimulates by increase in amino acid concentration in blood after protein meal
Inhibited by increase glucose concentration in the blood
Growth hormone is stimulated after a protein meal and during a fast

Human Anatomy (30 decks)

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