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Chapter Six Flashcards

The digestive system supplies nutrients for the body (75 cards)

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1
Q

Digestion

A

The process of breaking down carbohydrates, proteins and fat molecules into products small enough to be absorbed into the blood and cells

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2
Q

Mechanical digestion

A
  • The physical breakdown of food particles into smaller pieces to increase surface area
  • Increased SA allows for more effective chemical digestion
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3
Q

Chemical digestion

A

The break down of large complex molecules into smaller more simple molecules, small enough to be absorbed into the blood stream

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4
Q

Alimentary canal

A
  • The continuous tube that runs from the mouth to the anus, together with associated organs make up the digestive system
  • The lining of the alimentary canal is where nutrients is absorbed
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5
Q

The mouth

A
  • Mastication
  • Bolus is formed
  • Swallowing
  • Enzyme action
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6
Q

Common name for mastication

A

Chewing

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7
Q

Bolus

A

A ball of saliva and food

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8
Q

Salivary glands

A
  • Assists in the creation of the bolus (lubrication)
  • Produces enzymes for chemical digestion of carbohydrates
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9
Q

Teeth

A
  • Mechanical digestion
  • 4 incisors
  • 2 canines
  • 4 premolars
  • 6 molars
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10
Q

Incisors

A

Used for biting and cutting

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11
Q

Canines

A

Used for tearing

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12
Q

Premolars

A

Used for crushing and grinding

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13
Q

Molars

A

Used for crushing and grinding

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14
Q

Oesophagus

A
  • Circular and longitudinal muscles
  • Peristalsis pushes bolus down the oesophagus into the stomach
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15
Q

Peristalsis

A

Wave like muscle contractions

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16
Q

Stomach

A
  • Muscular churning (mechanical digestion) to mix food with gastric juice and form chyme
  • Circular, longitudinal and oblique muscles to cause these contractions
  • Has a protective mucous lining to protect against HCl
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17
Q

Gastric juices

A
  • Released by the gastric glands in the wall of the stomach
  • Contains HCl, mucous and enzymes
  • Enzymes start chemical digestion
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18
Q

Chyme

A

Pulpy acidic fluid which passes from the stomach to the small intestine containing gastric juices and partly digested food

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19
Q

Pyloric sphincter

A
  • A circular muscle that prevents food from continuously entering the small intestine
  • Every 2-8 hours it opens and allows chyme to be pushed into the duodenum
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20
Q

Absorption in the stomach

A
  • Due to the thick layer of mucus, nutrients are not absorbed in the stomach
  • Limited absorption of water, alcohol, glucose and some drugs
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21
Q

Small intestine

A
  • Duodenum : first part of small intestine
  • Jejunum : the middle section of the small intestine
  • Illeum : the final part of the small intestine
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22
Q

Mechanical digestion in the small intestine

A

Bile from the liver and gall bladder emulsify fats

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23
Q

Chemical digestion in the small intestine

A
  • Intestinal juice from the lining of the duodenum
  • Pancreatic juice from the pancreas
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24
Q

Absorption in the small intestine

A
  • After the nutrients is fully chemically digested it is absorbed through the wall of the SI into the capillaries
  • Small intestine is big to increase surface area
  • Folded into villi and microvilli to further increase SA
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25
Capillary in the small intestine absorb... and are taken to...
- Simple sugars - Amino acids - Water - Water soluble vitamins Taken by the hepatic portal vein to the liver
26
Lacteal
- Lymph capillary inside villus - Surrounded by network of capillaries
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Lacteal in the villus absorbs... and is taken to...
- Fatty acids and glycerol ( which are recommbined with villi to make fats) These substances are absorbed into the lacteal and transported to the lymph system
28
Large intestine
- Further absorption of water and some salts - Bacterial activity (digestion of cellulose) - May take 18-24 hours for food to pass through the large intestine
29
Elimination of faeces
Temporary storage in the rectum and then eliminated through the anus
30
Enzymes
Increase the rate of reaction, without it food would not digest fast enough for ourr needs
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Substances involved in digestion
- HCl - Pepsin - Pepsinogen - Salivary amylase - Pancreatic amylase - Pancreatic lipase - Trypsin - Nuclease - Peptidase - Bile
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Substances located in the stomach
- HCl - Pepsin - Pepsinogen
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Substances located in the mouth
Salivary amylase
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Substances located in the small intestine
- Peptidase - Trypsin - Lipase - Amylase - Intestinal juices - Bile (from the liver/gall-bladder)
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Bile
- Produced in the liver, stored in the gall-bladder - Released from the gall-bladder to the duodenum - NOT an enzyme - Mechanical digestion
36
Digestion in the mouth
- Salivary amylase > Starch/Complex carbohydrates (polysaccharides) > Simple sugars (monosaccharides) - Teeth crush, grind, tear, cut and bite food into smaller pieces
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Digestion in the stomach
- HCl > activated pepsinogen > pepsin > proteins > polypeptides > amino acids - Churning of the stomach mechanically break down foods
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Digestion in the duodenum
- Pancreatic amylase > starch > disaccharides - Trypsin > proteins > polypeptides - Pancreatic lipase > lipids > fatty acids + glycerol - Nucleases > RNA + DNA
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Digestion in the small intestine
- Amylases ( maltase, lipase, sucrase) > maltose, sucrose, lactose > glucose - Lipase > lipids > fatty acids + glycerol - Peptidase > polypeptides > amino acids - Bile and peristalsis are forms of mechanical digestion here
40
Movement of the alimentary canal
- Speed can vary depending on size and contents of a meal - Large meals cause greater stretching of the stomach and will be pushed into the small intestine quicker - High protein/fat content slows the movement from the stomach to small intestine - Alcohol and caffeine stimulate the movements of the stomach
41
Constipation
- Occurs if the movements of the LI are reduced and the contents remain there for a long period of time - Contents become drier and harder than usual and defecation becomes difficult and possibly painful - Caused by roughage (cellulose or insoluble fibre) in the diet
42
Diarrhoea
- Frequent defecation or watery faeces - Causes by irritation in the SI or LI which increases peristalsis so contents pass through before there is an adequate amount of water absorbed - Result of bacteria, virus, parasite, cancer, coeliac disease or lactose intolerance
43
Bowel cancer
- An uncontrolled growth of cells in the wall of the large intestine - May be linked to diet, high alcohol consumption + smoking - A diet high in processed and red meat and low in fibre may increase the risk of bowel developing bowel cancer
44
Coeliac disease
- Unable to tolerate gluten - If they eat food containing gluten, their immune system responds by damaging or destroying the villi - Without healthy villi, nutrients cannot be absorbed and the person becomes malnourished no matter how much food they eat
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Bile salts
Bile acids that are conjugated with glycine or taurine
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Caecum
Where the small intestine joins the large intestine
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Longitudinal muscle
Muscles with fibres that run lengthwise along the body and the circular fibres encircle it
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Mucosa
The moist inner lining of some organs and body cavities
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Segmentation
Division into seperate parts or sections
50
Appendix
A small tube attached to the caecum
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Colon
The longest part of the large intestine
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Three main parts of the colon
- Ascending colon - Transverse colon - Descending colon
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Ingestion
The process of taking food, drink or another substance into the body by swallowing or absorbing it
54
Sphincter muscle
Ringlike muscles surrounding and able to contract or close a bodily passage or opening
55
Exocrine gland
A gland that makes substances such as sweat, tears, saliva and digestive juices and releases them through a duct or opening to a body surface
56
Emulsification
The process of breaking down complex fat molecules into smaller fat molecules
57
Fatty acid
A carboxylic acid consisting of a hydrocarbon chain and a terminal carboxyl group
58
Hepatic portal vein
A blood vessel that carries blood to the liver from the intestines, spleen, pancreas and gallbladder
59
Central nervous system
The complex of nerve tissues that control the activities od the body
60
Dietary fibre
The parts of plant foods your body can't digest or absorb
61
What are faeces made up of
Water, undigested foods, bacteria, bile and remains of dead cells from the intestinal lining
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Involuntary
Done without will or conscious control
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Motor nerve
Nerve carrying impulses from the brain or spinal cord to a muscle or gland
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Receptors
An organ or cell able to respond to light, heat or other external stimulus and transmit a signal to a sensory nerve
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Sensory nerve
Any nerve that conveys impulses from a sense organ to the central nervous system
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Stimulus
A thing or event that evokes a specific functional reaction in an organ or tissue
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Structure of oesophagus
Mucosa > Submucosa > Muscle layers (circular and longitudinal) > Outer layer fibrous tissue
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Intestinal juice
- Peptidase - Sucrase - Lactase - Maltase - Lipases
69
What is the pH level in the stomach
2-3
70
What is the function of the longitudinal layer in the stomach (outer most layer)
It is involved in peristalsis
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What is the function of the circular layer in the stomach (middle layer)
It contributes to the pyloric sphincter and helps control the movements of food into the duodenum
72
What is the function of the oblique layer in the stomach (inner lost layer)
- Unique to the stomach - Tapers off before duodenum and is important for the churning of food and digestion
73
What is crohn’s disease
An autoimmune condition which damages the lining of the small intestine
74
Structure of the small intestine
- Inner lining/mucosa has folds that extend into the interior - Mucosa has small finger like projections/ folds called villi - Villi contain microvilli and inside is a lacteal surrounded by blood capillaries - Villi is the site of nutrient absorption
75
What does damage to villi mean
- Nutrients won’t be absorbed and no matter how much a person eats they remain malnourished - SA has decreased
Human Bio
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