The Digestive system Flashcards

1
Q

Functions of the digestive system

A

1.Break down food into nutrients
2.Nutrients absorbed in the body
3. Transported through the circulatory system. Nutrients in the cell can be used as a source of energy or used for the synthesis of chemical compounds

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2
Q

The 4 stages of digestion

A
  1. Ingestion: taking in nutrients(eating/drinking)
  2. Digestion: breaking down complex molecules into smaller ones
  3. Absorption: Taking up of digestion molecules
  4. Egestion: removal of waste
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3
Q

Gastrointestinal tract(G1 tract)

A

the passageway or tube that extends from the mouth to the anus and in which the process of digestion takes place

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4
Q

Mechanical(physical) digestion

A

-large pieces of food become smaller pieces, increasing the surface area
-Chewing of the food in the mouth
-Churning and mixing of food that occurs in the stomach

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5
Q

Chemical digestion

A

-Parts of the digestive tract produce digestive enzymes
-Different enzymes break down macromolecules to small organic molecules that can be absorbed

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6
Q

Physical and chemical digestion in the mouth

A

-Digestion starts in the mouth
-Food is broken down physically by the teeth and tongue
-The salivary glands release a substance called saliva
-Saliva contains a mixtures of water, mucus, and enzymes

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7
Q

Amylase

A

enzyme found in saliva that breaks starch down to simple sugars

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8
Q

Bolus

A

Food that has been chewed and mixed with saliva becomes a bolus

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9
Q

How the body works with bolus

A

-As the bolus is pushed into the pharynx. the soft palate is raised to prevent food from entering the nasal passage
-A structure called the epiglottis also covers the entrance to the trachea so food does not enter our lungs but instead down the esophagus

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10
Q

The esophagus

A

-The esophagus is a muscular tube that passes food from the pharynx to the stomach.
- Wave like muscle contractions called peristalsis move it towards the stomach.

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11
Q

Stomach

A

-Mechanical and chemical digestion occur in the stomach
-The stomach is j-shaped, it stores food, and has a capacity of 2L

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12
Q

Sphincters

A

-Food enters and exits the stomach through sphincters
-Sphincters are muscles surrounding a tube-like structure
-The bulus enters the stomach when the esophageal sphincters relaxes
-When the esophageal sphincter contracts, it prevents food from moving back into the esophagus

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13
Q

Gastric juice

A

-The stomach releases gastrin which stimulates the release of gastric juice secreted by the cells in the stomach lining

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14
Q

Gastric juice contains a mixture of

A

-HCI (hydrochloric acid): breaks down food fibres & bacteria
-Enzymes (pepsin)
-Mucus: Protect stomach lining from HCI
*im stomach lining is destroyed—> ulcers will form

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15
Q

Cells of the stomach

A

-Parietal
-Cheif

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16
Q

Parietal cells:

A

stomach cells found in the glands(secrete HCI)

17
Q

Cheif cells:

A
  • Gastric cheif cells found in stomach produce pepsin, which breaks down large protiens into peptides(smaller protiens)
    -Replaced every 2-4 days
18
Q

Chyme

A

-Chyme travels out of the stomach by the pyloric sphincter into the small intestine
-Chyme is a mixture of: water, digested food, and gastric juices

19
Q

Stomach absorption

A

the stomach absorbs: water, alcohol, some medications(aspirin)

20
Q

Acid reflux

A

if the esophageal sphincter does not close completely, acid from the stomach enters the esophagus causing a burning sensation in the throat
-Called heartburn

21
Q

Stomach ulcers

A

-The acid found in the stomach can kill almost all bacteria except Helicobacter pylori
-This bacteria prevents mucus producing cells from making enough mucous to protect the stomach lining
-When the lining is exposed to the stomach acid, an ulcer can develop

22
Q

Small intestine

A

Three parts: duodenum, jejunum, Ileum
- Main function is to complete the digestion(chemically) of macromolecules and to absorb their component subunits
- After the pyloric sphincter, chyme enters the duodenum
-Duodenum is first 25cm of the small intestine

23
Q

Majority of digestion occurs in the..

A

Duodenum

24
Q

Secretions from pancreas and gall bladder enter the duodenum via a…

A

duct

25
Q

Pancreas and gall bladder secretes..

A

-maltose(carbs breakdown)
-Peptidase(protein breakdown)

26
Q

Absorption in the small intestine:

A

-Most absorption takes place in the Jejunum and Ileum
-After the duodenum, the jejunum and ileum contain villi which increase the surface area

27
Q

villi

A

-Villi help absorb glucose, amino acids, fatty acids, glycerol
-Each villus has a small lymphatic vessel called a lacteal and a network of blood capillaries surrounded by a layer of epithelial cells
-Microvilli extend into the intestinal lumen to create a “brush border”
-Nutrients are absorbed across the epithelium and then across the unicellular wall of the capillaries or lacteals
-Nutrients then enter bloodstream and are dispersed throughout the body

28
Q

Liver

A

-Has 4 functions: Synthesis, breakdown, detoxification, storage

-Synthesis: produces bile which breaks down fats. bile is stored in the gall bladder

-Detoxification: Removes toxins from the body including alcohol and chemicals

-Storage: Vitamins and carbs(such as glycogen) are stored in the liver

29
Q

Pancreas

A

-Increase the PH of chyme from 2.5 to 9 due to the production of sodium bicarbonate which is an alkaline(base)
-Secretes enzymes for digestion
- Carbs-breaks down carbs
- Lipase-(breaks down fats)
- Trypsin(breaks down protiens)

30
Q

Large intestine

A

-Water, sodium, chlorine are absorbed
-Bacteria living in colon releasing vitamin k and b also absorbed

31
Q

Egestion

A

-Egestion is the removal of the indigestible components of food(cellulose/fibre)
-The rectum stores and compacts waste
-Cellulose(found in plant cell walls) aids in the ejection of material from the bowels. It’s the main source of our dietary fibre
-Lack of cellulose in the diet can increase the risk of colon cancer