Digestive System Flashcards by Annika w

What are the four functions of the digestive system

Ingestion (taking in food)
Digestion (breakdown of foods)
Absorption (taking small molecules into the body)
Elimination (removal of the undigested waste)

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What is the structure of the digestive system

A tube that runs through the body from the mouth to the anus

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What is found in the mouth for ingestion

Jaw, incisors for biting (take food in)

Taste buds to decide quality of food (sweet+ salty=good, sour+bitter=bad)

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What does a bitter taste indicate

Poison

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What is the digestion of the mouth

-mechanical- chewing involving molars and tongue
-chemical- enzymes (salivary amylase)
Once the breakdown occurs a bolus of food in produced

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How much saliva (salivary amylase) is produced per day, where is it produced, what is it made of and what is its job?

Saliva(1-2 L per day)
Produced in salivary glands (parotid, submandibular, sublingual~2of each)-accessory glands
Made of: water, mucus, salivary amylase
Salivary amylase breaks down starch

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What is the Pharynx and what are the openings?

"Cross roads"
Openings:
Mouth
Esophagus
Nasal cavity
Trachea (Larynx)
Eustachian tubes (ears)

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What is the process of swallowing (pharynx continued)

-involves a series of events to make the “bolus”
Tongue pushed bolus to pharynx
Trachea moves up, epiglottis covers trachea
Uvula folds back and blocks nasal cavity
Bolus moves into the esophagus

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What is the uvula?

The dangling bit and the back of the mouth

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What is the esophagus

short muscular tube
moves bolus from pharynx to stomach
uses waves of muscular contractions (PERISTALSIS)
can work in reverse (choking, throwing up)

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What is the tube leading into the stomach?

Esophagus

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What are the two sphincters and where are they found?

Cardiac Sphincter, Pyloric Sphincter

Found leading to and from stomach (gateway)

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What is the duodenum

Tube leading from stomach

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What is the space inside the stomach called

Lumen

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What is the thick mucus lining the stomach

Mucin

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What is the layer under the mucin

Mucosa

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What is the submucosa

Contains blood vessels and is the second layer of the stomach

What is the serosa

The lining of the stomach

What are the divots in the mucosa called

Gasteric Pits

What are the three cells found in the gasteric pits and what do they make

Goblet cells: make mucin
Parieta cells: make HCI
Chief cells: make Pepsinogen

What are be functions of the stomach

1) storage: stomach can hold 2-3L of partially digested food
2) mechanical: stomach contractions blend food into think liquid (CHYME)
3) chemical digestion: HCI breaks bonds in food, pepsin begins breakdown of proteins, gasterin

What activates pepsinogen into pepsin

HCI

What does pepsin do to proteins

Cuts protein into different chunks (proteins into peptides)

What is Gastrin and what does it do

A digestive hormone

released by cells near pyloric sphincters when food enters the stomach
gastric pits respond to gastrin by releasing Gastric Juice (HCI and Pepsin)

What is the Duodenum?

- first 10cm of the small intestine - receives input from 3 sources 1) from stomach- chyme 2) from pancreas- pancreatic juice 2) from liver- bile

What is the liver and what are its functions

``` Large complex organ with many functions Detoxifies blood Stored excess glucose as glycogen Produces blood proteins Produces urea Recycles old blood cells Produces bile ```

What is bile

Acts as a fat emulsifier Mechanical digestion-not an enzyme Increases surface area of fat available for enzyme action

Where is bile stored and released

Bile is stored in the gall bladder and released through the bile duct

What is the pancreas

Acts as an exocrine and endocrine glands exocrine secretion: pancreatic secretion released into the duodenum (external) Endocrine secretion: insulin, glucagon

What is the pancreatic juice made of

``` NaHCO3 (sodium bicarbonate)-neutralizes stomach (ph 2-8) Pancreatic Amylase (starch to maltose) Lipase (fats-fatty acids +glyceride) Nuclease (DNA or RNA-nucleotides) Trypsinogen (inactive) ```

What is insulin

Instructs cells to remove glucose from blood | Instructs liver to produce glycogen (stored glucose)

What is glucagon

(Opposite of insulin) Instructs cells to release glucose to blood Instructs liver cells to break down glycogen

What is gastrin

``` Digestive hormone Source: stomach Trigger: bolus enters stomach Target: gastric pits Action: releases HCI and pepsinogen ```

What is C.C.K

Source: duodenum Trigger: chyme enters duodenum Target: gall bladder Action: releases bile (more if fatty food)

What is Secretin

Source: duodenum Trigger: chyme enters the duodenum Target: pancreas Action: release pancreatic juice

What is Enterogasteone

Source: duodenum Trigger: chyme enters duodenum Target: stomach Action: stops chyme release

How long is the small intestine

20 feet

What lines the outside of cells in the small intestine

Microvilli

What is the lacteal

The 'pillar' in the centre of villi that helps collect all of the nutrients

What is epithelium

Cells lining the villi

What are the functions of the small intestine

1) finishes chemical digestion Pancreatic enzymes work here Also produces many finishing enzymes (disaccharides and peptides) 2) most absorption occurs in small intestine

What gets absorbed by the villi into the lacteal and taken into blood

Lacteal: fatty acid, glycerol Blood: monosaccharide, amino acid, nucleotide