Gastrointestinal System Flashcards

1
Q

Ingestion

A

The intake of food into the GI tract via the mouth

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2
Q

Mechanical Processing

A

Physical breakdown of food by the teeth, stomach and intestines

Increases the surface area of food, allowing enzymes to work more efficiently

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3
Q

Chemical Processing

A

Breakdown of complex molecules (polymers) into monomers using enzymes and other substances

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4
Q

Secretion and Absorption and Egestion

A

Secretion: release of water, acid, enzymes, buffers and salts which aid in chemical digestion and absorption

Absorption: uptake of useful molecules across the epithelium of the GI tract and into interstitial fluid

Egestion: removal of waste products

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5
Q

Breaking down of polymers

A

we cannot absorb polymers such as proteins, lipids and carbohydrates so they must be broken down by chemical and physical digestion

Proteins are broken down into amino acids
Lipids are broken down into fatty acids and glycerol
Carbohydrates are broken down into monosaccharides

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6
Q

What is someone lacking if they are lactose intolerant

A

lactase enzyme

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7
Q

Layers of the GI tract wall

A

Serous: fibrous connective tissue - structure and support

Muscularis: two layers of smooth muscle. Antagonist pair. Lognitudinal muscle (down GI tract) and circular (around circumference of GI tract). creates peristalsis

Submucosa: connective tissue layer which contains blood vessels, lymph vessels and nerves

Mucosa: inner lining, cells get replaced every 5-7 days

Lumen

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8
Q

Chemical and Physical processing in the mouth

A

Chemical: amylase breaks down starch into maltose, saliva makes food softer and helps form a bolus. Taste sensation increases to prepare the rest of the digestive system = stimulation of gastric juices

Mechanical: teeth. Food is broken down into smaller pieces creating a larger surface area for enzymes to act on. helps mix food with saliva

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9
Q

Voluntary phase of swallowing (deglutition)

A

tongue pushes bolus into the pharynx whilst oesophagus is kept closed. Bolus travels down the oesophagus via peristalsis

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10
Q

Involuntary phase of swallowing (deglutition)

A

soft palate rises to close the passage to the nasal cavity and the epiglottis decompresses over the trachea

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11
Q

How does peristalsis occur?

A

circular muscle contracts behind bolus and longitudinal muscle contracts in front of bolus

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12
Q

Where are these 4 sphincters
Oesophageal
Pyloric
ileo-caecal
Odi

A

oesophageal = Between the oesophagus and cardia part of the stomach
pyloric = connects the stomach to the duodenum
ileo-caecal = small intestine to caecum
Odi = bile duct

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13
Q

What is food mixed with in the stomach?

A

hydrochloric acid and gastric juices to create chyme

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14
Q

How many muscle types in the stomach & name them

A

3

circular, longitudinal and oblique

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15
Q

4 parts of the stomach

A

cardia, fundus, body and pylorus

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16
Q

Functions of the stomach

A

storage area
mechanical and physical processing
Protective - hydrochloric acid kills bacteria

17
Q

Mechanical and chemical processing in the stomach

A

Mechanical: 3 layers of muscle. stomach folded into rugae to expand as it fills

Chemical: gastric juices (hydrochloric acid, lipases, intrinsic factor and mucus

18
Q

What is intrinsic factor?

A

helps with the absorption of vitamin B12

Vitamin B12 is a water soluble vitamin with an important role in the functioning of the brain, nervous system and blood

19
Q

What would happen if insulin was taken as a tablet?

A

Would have less of an affect because it would get broken down in the stomach by pepsin since it is a hormone and hormones are proteins

20
Q

What reflex regulates stomach emptying?

A

Enterogastric reflex

21
Q

Why does chyme need to be neutralised in the small intestine?

A

because the stomach has a pH of 2 and the small intestine has a pH of 7-8

22
Q

What are the 3 parts of the small intestine

A

Duodenum, jejunum and ileum

23
Q

Mechanical and chemical processing in the small intestine

A

Mechanical: peristalsis, segmentation

Chemical: microvilli secrete enzymes such as maltase, sucrase and peptidases. Other secretions from accessory organs also help break down complex molecules

24
Q

Villi and Microvilli

A

on the walls of the small intestine - majority of nutrients are absorbed

Create a larger surface area for absorption

highly vascular to maintain a diffusion gradient

25
Absorption
nutrients are absorbed through epithelial cells in microvilli and enter the bloodstream via capillaries or the lymphatic system via lacteals
26
Where are amino acids and glucose taken after they are absorbed
to the liver via the hepatic portal vein
27
Where are fats absorbed
into lacteals to enter the lymphatic system. They eventually enter the bloodstream at the subclavian vein
28
Order of segments in the large intestine
ascending colon, transverse colon, descending colon and sigmoid colon
29
Functions of large intestine
absorption of water, ions and vitamins formation of faeces
30
What is faeces made of
water, inorganic salts, undigested food and epithelial cells
31
Cause of diarrhea and constipation
Diarrhea = bacteria inside stomach increase the rate of peristalsis Constipation = codeine slows peristalsis. Too much water absorbed
32
Appendix
attached to the posteromedial surface of the caecum little function in humans but is painful when inflammed
33
Process of excretion
rectal walls stretch = activation of the parasympathetic nervous system = we can ignore signals until another mass enters the rectum long rectal muscles contract = increased pressure = voluntary contraction of diapghram and accessory muscles = relaxation of internal anal sphincter
34
Where is bile produced and what is it's function
Liver emulsified fats making them more water soluble bile enters the duodenum when we are eating When we are not eating the sphincter of Odi closes and bile backs up into the gall bladder
35
Functions of the pancreas
Endocrine (directly into bloodstream) and Exocrine gland (into gland) Insulin - beta cells Glucagon - alpha cells secretes enzymes such as amylases and lipases produces sodium bicarbonate (reduces acidity of stomach contents)
36
What are the following processes deamination transamination protein synthesis
Deamination: removal of amino acids to enable the conversion into carbohydrates Transamination: converting one amino acid to another protein synthesis: making proteins from amino acids
37
What is the livers role in lipid metabolism
fatty acids are oxidised to form ATP liver is involved in the synthesis of lipoproteins, cholesterol and phospholipids and is responsible for breaking down cholesterol to form bile salts
38
True or false as the rectum fills, the rectal walls stretch and activate the sympathetic nervous system
False Activates the parasympathetic nervous system