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digest Flashcards

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1
Q

define digestion

A

digestion is the process fo breaking down carbohydrate, protein, and fat molecules into products small enough to be absorbed into the blood and into the cells

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2
Q

in what ways does digestion change nutrients

A
  1. large to small
  2. insoluble to soluble
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3
Q

define mechanical digestion

A

the physical breakdown of food particles into smaller pieces to increase surface area

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4
Q

how does increased surface area help digestion

A

The increased surface area allows more effective chemical digestion, as the chemicals can access more of the food.

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5
Q

where does mechanical digestion happen and how

A

The teeth cut, tear and grind the food.
Churning action in the stomach breaks the food down further.

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6
Q

define chemical digestion

A

chemical digestions uses enzymes to break down large complex molecules into smaller simpler molecules so that they can be absorbed into the bloodstream

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7
Q

What do amylases break down?

A

Amylases break down carbohydrates into monosaccharides like glucose, fructose, and galactose.

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8
Q

what do protases break down?

A

protases break down proteins into peptides and amino acids

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9
Q

What do lipases break down?

A

Lipases break down lipids (fats) into fatty acids and glycerol.

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10
Q

What do nucleases break down?

A

Nucleases break down nucleic acids into nucleotides.

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11
Q

what is the alimentary canal

A

the continuous tube that runs form the mouth to teh anus along with associated organs such as the pancreas and the gallbladder, the alimentary canal makes up the digestive system.
The lining of the alimentary
canal is the surface through
which nutrients are absorbed.

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12
Q

define mastication

A

process of mechanically breaking down food using teeth and jaw muscles to prepare it for swallowing and digestion
(chewing)

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13
Q

what is the purpose of saliva during mastication

A

saliva contains mucus to lubricate the food and an digestive enzyme called salivary amylase that begins the chemical digestion of starch into disaccharide maltose

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14
Q

what is ingestion

A

intake of food

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15
Q

what is a bolus

A

semi-solid mass of chewed food mixed with saliva, ready for swallowing

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16
Q

how do you swallow?

A

To swallow, the tongue moves upwards and backwards, pushing the bolus into the back of the mouth, the pharynx, which leads to the oesophagus.

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17
Q

What is the oesophagus?

A

The oesophagus is a tube about 23–25 cm long that connects the pharynx to the stomach.

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18
Q

how many layers does the muscle wall of the oesophagus have and what types of layers are these?

A

The oesophagus has a double layer of muscle:

  • Circular muscle (fibres in a circle)
  • Longitudinal muscle (fibres along the length)
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19
Q

What is peristalsis?

A

Peristalsis is the wave-like movement caused by circular muscle contractions that push food along the oesophagus.

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20
Q

What helps food move smoothly through the oesophagus?

A

The secretion of mucus lubricates the inner lining, helping food move more easily.

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21
Q

What type of digestion happens in the stomach?

A

The stomach performs both mechanical and chemical digestion.

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22
Q

Are nutrients absorbed in the stomach?

A

No, nutrients are not absorbed in the stomach because the inner surface is covered by a thick layer of mucus.

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23
Q

What is the role of the stomach lining?

A

The stomach lining secretes gastric juice, which contains hydrochloric acid, mucus, and digestive enzymes.

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24
Q

What is chyme?

A

Chyme is a thick, soupy liquid formed when food is mixed with gastric juice in the stomach.

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25
How does mechanical digestion occur in the stomach?
Through waves of muscular contraction. The stomach has oblique, circular, and longitudinal muscle layers that help churn food and mix it with gastric juice.
26
What enzyme is used in chemical digestion in the stomach?
The enzyme pepsin (a gastric protease) breaks down proteins into shorter chains (peptides).
27
What helps pepsin work properly in the stomach?
Hydrochloric acid, which also kills many bacteria that enter with food.
28
What is the pyloric sphincter?
A thick ring of circular muscle that regulates the flow of food from the stomach to the duodenum. It opens after 2–8 hours.
29
What is the duodenum?
The first part of the small intestine that receives food from the stomach and curves around the pancreas. Most chemical digestion happens here.
30
what are gastric pits?
Gastric pits are indentations in the stomach lining that contain specialised cells involved in digestion.
31
What is the role of mucous cells?
Mucous cells produce mucus to protect the stomach lining from the acidic gastric juice.
32
What do parietal cells do?
Parietal cells secrete hydrochloric acid (HCl) to create an acidic environment and activate pepsinogen into pepsin.
33
What is the function of chief cells?
Chief cells produce pepsinogen, which is activated by HCl to form pepsin, an enzyme that digests proteins.
34
What is the role of G cells?
G cells secrete gastrin, a hormone that stimulates gastric juice production and increases stomach motility.
35
What is the small intestine?
The small intestine is the longest part of the alimentary canal (about 6–7 meters) and receives food from the stomach via the pyloric sphincter.
36
What are the three regions of the small intestine?
Duodenum Jejunum Ileum
37
What happens in the jejunum?
The jejunum is the middle section where carbohydrates and proteins are absorbed. its lining allows for effective absorption.
38
What happens in the ileum?
The ileum is the final part, where vita
39
what organs produce, store and concentrate bile
the liver produces bile, the gall bladder stores and concentrates bile
40
How do bile and pancreatic juice enter the small intestine?
Through the common bile duct into the duodenum.
41
What is the role of bile salts in digestion?
Bile salts break fat into tiny droplets (emulsification), increasing surface area for lipase to work.
42
explain what the pancreas produces?
The pancreas produces pancreatic juice containing digestive enzymes: pancreatic amylase - helps break down starch into simple sugars pancreatic protease - It breaks down proteins into short chains of amino acids. ribonuclease- digests RNA deoxyribonuclease - digests DNA pancreatic lipases - they break down fats into fatty acids and glycerol.
43
What does intestinal juice do?
It contains enzymes that complete digestion of carbohydrates, proteins, and fats.
44
Where does chemical digestion continue in the body?
In the small intestine, using pancreatic juice, bile, and intestinal juice.
45
what is segmentation
Segmentation is a type of movement in the gastrointestinal tract, particularly in the small intestine. It involves rhythmic contractions of the circular muscles in the intestinal walls, which: 1. Break up and mix the contents of the intestine (chyme) with digestive enzymes and intestinal fluids. 2. Expose nutrients to the intestinal lining for better absorption.
46
what is the difference between peristalsis and segmentation
peristalsis: -adjacent segments of the alimentary canal organs alternately contract and relax -food is moved distally along the tract - primarily propulsive, some mixing may occur (mainly just moves food forward) segmentation: - mainly focuses on mixing rather than propulsion, ensuring thorough digestion and nutrient absorption. - nonadjacent segements of the alimentary canal organs alternately contract - food is moved forwards then backwards - primarily mixes food and breaks it down mechanically, may include some propulsion
47
What happens to the products of digestion in the small intestine?
The products of digestion, along with substances such as vitamins, minerals and water, are absorbed through the wall of the small intestine into the blood.
48
How is the small intestine designed to absorb nutrients effectively?
It has folds, villi, and microvilli to increase surface area for absorption.
49
What are villi and what do they do?
Villi are tiny finger-like projections that absorb digested food. Each villus contains a lacteal (lymph capillary) and blood capillaries.
50
How are amino acids absorbed in the small intestine?
By active transport into the blood capillaries.
51
How is glucose (a simple sugar) absorbed?
By active transport into the blood capillaries.
52
How are water and water-soluble vitamins absorbed?
By diffusion into the blood capillaries.
53
Where do substances absorbed into blood capillaries go?
They go to the liver through the hepatic portal vein for processing or to the body cells.
54
Where do substances absorbed into lacteals go?
Through the lymph system, then into the bloodstream via veins in the upper chest.
55
What are the parts of the large intestine?
The large intestine includes the caecum, colon, rectum, and anus. The appendix is attached to the caecum.
56
Does the large intestine have villi or secrete digestive juices?
No. It has no villi and does not secrete digestive juices, but it does secrete mucus.
57
How long does material take to pass through the large intestine?
About 18–24 hours.
58
What happens to the material in the large intestine?
Most remaining water is absorbed, and the contents become more solid (forming faeces).
59
What role do bacteria in the large intestine play?
Bacteria break down remaining organic compounds and produce vitamins that are absorbed into the blood.
60
What nutrients are absorbed in the large intestine?
Vitamins (from bacteria) and mineral nutrients.
61
what is faeces?
Faeces is the semi-solid material left after water absorption and bacterial action.
62
what is the caecum
a pouch where the small intestine joins the large intestine
63
what is the colon
the longest part of the large intestine shaped in a inverted u
64
what is the anal sphincter
the circular muscle around the anus that relaxes or tightens to open or close the anus
65
what is the rectum
It acts as a reservoir where stool accumulates before being ready for elimination
66
what is the anus
the exit point of waste, where faeces is expelled from
67
what is the largest organ in the body that supports digestion?
liver
68
other than producing bile what are three other functions of the liver?
- It processes toxins and removes them from the blood. - creates substances necessary for blood clotting after injury. - It helps maintain healthy blood sugar levels.
69
What is the gallbladder and where is it located?
The gallbladder is a small, pear-shaped organ beneath the liver.
70
What is the main function of the gallbladder?
It stores and concentrates bile made by the liver to be secreted into the small intestine to help breakdown and absorb fats.
71
Where is the pancreas located?
behind the stomach
72
What is one key digestive function of the pancreas?
It produces enzymes that break down sugars, fats, proteins, and starches.
73
What is the pancreas’s role with hormones?
It releases hormones into the bloodstream to regulate blood sugar, stimulate stomach acids, control appetite, and help stomach emptying.

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