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ATAR Human Bio > digestive system > Flashcards

digestive system Flashcards

(65 cards)

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1
Q

Soluble fibre

A

Better health (low cholesterol, low blood sugar, linked to lower heart disease and cancer)

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2
Q

Rate food passes: Size of meal

A

Larger meals move faster through the alimentary canal

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3
Q

Rate food passes: High protein/fat content

A

Slows movement from stomach to small intestine

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4
Q

Rate food passes: Alcohol and caffeine

A

Stimulate increased movement through the canal

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5
Q

Constipation

A

Movement is slowed, contents stay longer, water absorbed, harder to defecate

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6
Q

Constipation causes

A

Lack of roughage, lack of exercise, emotional problems

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7
Q

Diarrhoea

A

Frequent defecation of watery faeces, may cause dehydration

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8
Q

Diarrhoea causes

A

Irritation of intestines increasing peristalsis; bacterial/viral infection, parasites, cancer, coeliac disease

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9
Q

Bowel cancer

A

Uncontrolled cell growth in colon wall, may spread through body

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10
Q

Bowel cancer causes

A

Linked to diet, smoking, alcohol, overweight and obesity

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11
Q

Coeliac disease

A

Inherited; immune response to gluten damages villi, no nutrient absorption

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12
Q

Coeliac disease symptoms

A

Muscle cramps, joint pain, tingling in legs due to malnutrition

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13
Q

Coeliac disease treatment

A

Follow a gluten-free diet

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14
Q

Why do cells need nutrients?

A

To make energy for all their cell activities.

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15
Q

What does the digestive system do?

A

Extracts nutrients from the food we eat.

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16
Q

What can small molecules do in digestion?

A

Diffuse from the alimentary canal into blood (e.g., vitamins, minerals, water).

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17
Q

What must happen to larger molecules before absorption?

A

They need to be broken down (e.g., carbs, proteins, fats).

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18
Q

What are the main activities of the alimentary canal?

A

Ingestion, mechanical digestion, chemical digestion, movement, absorption, elimination.

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19
Q

What is mechanical digestion?

A

Cutting and grinding of food (teeth), stomach churning; breaking into smaller pieces.

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20
Q

What is chemical digestion?

A

Breaking complex molecules into simpler ones using enzymes (e.g., salivary amylase).

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21
Q

What is the alimentary canal?

A

A continuous tube from mouth to anus where nutrients are absorbed.

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22
Q

What are the three layers of the alimentary canal wall?

A

Circular muscle, longitudinal muscle, mucosa.

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23
Q

What happens in the mouth?

A

Ingestion, mechanical digestion with teeth, chemical digestion with salivary amylase.

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24
Q

What is saliva made of?

A

Mucus and amylase.

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25
What are the four types of teeth?
4 incisors (cutting), 2 canines (tearing), 4 premolars, 6 molars.
26
What is the bolus?
A ball of food formed in the mouth.
27
What is the function of the oesophagus?
Moves food to the stomach using peristalsis.
28
How long is the oesophagus?
23-25 cm.
29
What is peristalsis?
Wave of constriction from circular and longitudinal muscle pushing food down.
30
What additional muscle layer does the stomach have?
An inner oblique muscle layer.
31
What is the oesophageal sphincter?
A valve at the top of the stomach.
32
endothelial cells?
thin semi-permeable cell that controls the movement of substances in the cappilary and tissue.
33
What is gastric juice made of?
Hydrochloric acid, mucus, and digestive enzymes.
34
Where is gastric juice secreted from?
Gastric glands inside gastric pits in the stomach lining.
35
What protects the stomach lining from acid?
A thick mucous layer.
36
What activates pepsinogen?
Acid in the stomach converts it into pepsin.
37
What does pepsin do?
Breaks down proteins.
38
Why can’t nutrients be absorbed in the stomach?
Because of the thick layers of muscle and mucosa.
39
What can be absorbed in the stomach?
Some alcohol and drugs.
40
What is the pyloric sphincter?
A valve at the lower end of the stomach controlling flow into the small intestine.
41
How long does food stay in the stomach?
Between 2-8 hours.
42
Small intestine - Duodenum
Shortest section: ~25cm long Curved from stomach around pancreas Most chemical digestion occurs here
43
Small intestine - Jejunum
Middle section Main site for absorption of carbohydrates and proteins**
44
Small intestine - Ileum
Last section Absorption of vitamin B12, bile salts, and any remaining nutrients
45
Chemical Digestion (Small Intestine) - Intestinal Juice
Secreted by glands in the lining of the small intestine Contains enzymes: Peptidase: Proteins -> amino acids Intestinal amylase (sucrase, lactase, maltase) -> Carbohydrates -> sugars Intestinal lipase: Lipids -> fatty acid + glycerol
46
Chemical Digestion (Small Intestine) - Pancreatic Juice
* Secreted by the pancreas * Enters duodenum through the common bile duct * **Neutralizes stomach acid** * Contains enzymes: Pancreatic Amylase -> Carbs ->Sugars Trypsin (Pancreatic protease): proteins ->amino acids Pancreatic lipase: Lipids -> fatty acid + glycerol Ribonuclease and deoxyribonuclease -> Digest RNA/DNA -> nucleotides
47
Mechanical Digestion (Small Intestine) - Bile
Secreted by the liver, stored in the gall bladder Emulsifies lipids (increases surface area for lipase)
48
Mechanical Digestion (Small Intestine) - Peristalsis/Segmentation
Muscular contractions that mix and move chyme through the small intestine
49
Absorption in the Small Intestine - Diffusion
Movement of digested products across the intestinal wall into the blood along the concentration gradient Simple diffusion: water and water-soluble vitamins -> capillaries
50
Absorption in the Small Intestine - Fatty Acids & Glycerol
Recombine in villi cells Enter lacteals (lymph capillaries)
51
Absorption in the Small Intestine - Fat-soluble Vitamins
Absorbed into lacteals
52
Absorption in the Small Intestine - Active Transport
Movement of simple sugars -> capillaries Movement of amino acids -> capillaries
53
Increasing Surface Area in the Small Intestine
Long length of the small intestine Mucosa is folded Mucosa covered in villi (finger-like projections) Cells have microvilli
54
Villus (Structure & Function)
~1mm long Contains a lacteal (lymph capillary) surrounded by a blood capillary One cell layer thick Constantly moves to increase contact with chyme and aid absorption (by intestinal muscle)
55
Fate of Absorbed Nutrients (Capillaries)
Carried to the liver by the hepatic portal vein Processed (detoxified) in the liver Then transported to the heart
56
Fate of Absorbed Nutrients (Lacteals)
Empty into the blood at the end of the lymphatic system
57
Large Intestine - General
~1.5m long Takes 18-24 hours for material to pass through No villi or digestive juices Secretes large amounts of mucus
58
Large Intestine - Structure: Caecum
6 cm long pouch Connects the small to the large intestine Appendix is attached here
59
Large Intestine - Structure: Appendix
Small tube attached to the caecum
60
Large Intestine - Structure: Colon
Longest part of the large intestine Has an inverted U shape
61
Large Intestine - Structure: Rectum
Last section of the large intestine Semi-solid material (faeces) is stored here
62
Defecation
Semi-solid material pushed into rectum triggers stretch receptors Muscles around anus relax Faeces pass out through the anus
63
Anus
External opening of the large intestine Surrounded by a circular muscle (anal sphincter) Faeces are eliminated here
64
Absorption in the Large Intestine
Most of the remaining water is absorbed Bacteria break down remaining organic compounds (some produce vitamins)
65
Faeces - Composition
Semi-solid material after absorption Contains: water, undigested food (cellulose), bacteria, bile pigment (colour), and broken-down cells

ATAR Human Bio (15 decks)

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